Effects of toolpath on defect phenomena in the incremental forming of thin polycarbonate sheets

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One of its main strengths is that it allows reaching greater formability, compared to conventional sheet forming processes; in contrast, defect phenomena like twisting and wrinkling occur frequently and strongly influence the geometric accuracy of the formed parts. All these aspects are dramatically accentuated when forming soft materials like thermoplastics. With these premises, the following research aims to investigate the effects of the toolpath strategy on the occurrence of failures and defects in the incremental sheet forming under very severe process conditions; thin polycarbonate sheets were formed to obtain cone frusta with a fixed wall angle, imposing four unidirectional helical trajectory-based toolpaths, one traditional and three stair strategies. The analysis of the forming force trends, the evaluation of the worked surface quality and the monitoring of the defectiveness highlight understanding the advantages of an appropriate toolpath strategy to improve the accuracy of the incremental sheet forming of thermoplastic parts. Incremental sheet forming Polycarbonate Defectiveness Forming forces Surface quality Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Introduction Thermoplastics are strongly used in the manufacturing industry [ 1 ] because of their good properties like light-weight, strength, corrosion resistance, price, etc. Typical parts made of them are manufactured with operations oriented to mass production both for the energy costs and the investments in equipment and tools; they provide for repetitive actions of heating, shaping, and cooling [ 2 ]. Furthermore, processes usually employed in sheet metal forming are frequently considered to manufacture thermoplastic sheet components with different shapes [ 3 ]; in these cases, the forming processes strongly depend on the material properties and the temperature [ 4 ]. Recently, the significant advances in the use of computers applied to manufacturing have augmented the interest in developing procedures with a higher level of flexibility: consider, for example, the incredible development of additive manufacturing technologies [ 5 ]. The incremental sheet forming (ISF) moves along the same lines: it is a relatively recent technology that guarantees high customization, thanks to the layered manufacturing principle typical of rapid prototyping, and cost-effectiveness, because it does not require dedicated equipment. In this process, which guarantees high levels of materials’ formability and the carrying out at room temperature, a forming tool controlled by a CNC machine describes a path and deforms progressively a clamped sheet; by doing so, it manufactures the final part geometry [ 6 ] starting from sheets of pure metals, alloys, polymers, and composites [ 7 , 8 ]. ISF is an effective alternative to conventional technologies based on heating-shaping-cooling manufacturing operations. Thanks to its flexibility, this process is strongly oriented toward the production of batches with small and medium size; in addition, it allows reducing energy consumption, compared to conventional processes, so as shown by recent researches on polymer forming [ 9 ]. The firsts studies on the polymer ISF concerned polyvinylchloride (PVC) sheets [ 10 ], before being extended to other commercial polymers [ 11 ] and new materials like the biocompatible polycaprolactone (PCL) [ 4 ]. Once checked the feasibility of the process, significant researches were carried out to investigate the influence of the main process parameters on the formability limits of different polymers like polyamide (PA), polycarbonate (PC), polyethylene terephthalate (PET), PVC and polypropylene (PP) [ 12 – 15 ]. The way to better estimate the formability limits was investigated in [ 2 , 16 ], while new solutions to improve the quality of the ISF polymer parts represents a very hot focus; consider, for example, a prior cold-rolling process of the sheets [ 17 ] or their self-heating as the effect of the feed rate and the spindle [ 18 ]. Failure and defect modes that interest ISF sheets represent another significant field of investigation, since they influence the materials’ formability and worsen the geometrical accuracy of ISF parts [ 4 , 19 ]. When incrementally formed, polymer sheets can be affected by ductile fracture at the transition zone between the wall and the corner radius or tearing along the walls, as well as defects like wrinkling and twisting [ 10 ]; these ones are strictly connected, since wrinkles can be twisted around the axis of revolution in the direction of tool rotation. The twisting phenomenon is common for all the ISF materials, but it is particularly relevant for materials with soft behaviour like thermoplastics; consider, for example, that twist angles on axisymmetric components obtained by a unidirectional toolpath were equal to about 6° and 22° for aluminum alloy [ 20 ] and polycarbonate sheets [ 21 ], respectively. This defect is caused by an uncontrolled pivoting of the formed components around the clamping frame, because of the in-plane shear generated by the tangential forces that the forming tool exerts on the sheet; in addition, it is more probable for higher and more regular plane forces, which determine a combination of continued strain accumulation and asymmetric strain levels [ 22 , 23 ] and, considering polymer sheets, higher normal forces can determine significant indentation that accentuates the phenomenon [ 24 , 25 ]. A way to reduce this defectiveness is to choose a more suitable toolpath strategy. For example, a dramatic reduction of the twisting phenomenon was observed by adopting an alternate toolpath instead of a unidirectional one, so as verified in [ 6 ] and, for PC parts, in [ 21 ]; by doing so, the amount of twist produced in a layer was recovered in the successive one almost completely. Despite this, severe forming conditions in terms of sliding forces on thin thermoplastic sheets, characterized by low mechanical resistance, can induce significant instability and generate wrinkling, also using an alternate toolpath strategy [ 26 ]. Monitoring and measuring the ISF forming forces represents an efficient tool for the control of the process quality [ 27 ]; their reduction limits the risk of failures and defects on the ISF polymer sheets and on the tools, as well as can improve the surfaces’ quality of the components, and allows reducing or avoiding lubricants to lower friction and sticking of material to the tool. These aspects can also involve energy implications that are of relevant interest in a perspective of sustainable manufacturing, since they can determine a positive impact on the environment [ 28 , 29 ]. According to what reported above, a way to reduce the defect phenomena on ISF polymer sheets provides for acting on toolpath strategies that lower the forming forces in the sheet plane, in line with previous authors’ numerical works [ 30 , 31 ]. The single-point incremental forming (SPIF), i.e. the simplest variant of ISF that involves the use of a simple tool, a clamping frame, and the absence of dies, was used in this work to manufacture cone frusta with fixed wall angle starting from thin PC sheets; the forming process was carried out by setting typical ISF parameters [ 21 ] and four different unidirectional helical trajectory-based toolpath strategies. From the experimental campaign, some important features like the forming forces, the twist angle and the surface roughness were analyzed, as well as the deformation states, the failures and the defects were monitored, to investigate the influence of the selected toolpath strategies on the defectiveness of incrementally formed polymer parts. Materials and methods The SPIF tests were carried out at room temperature on Makrolon PC sheets, supplied by Bayer, with a thickness t = 1.0 mm. It is an amorphous thermoplastic polymer also known as a “transparency metal” because of its relevant mechanical and physiochemical properties like toughness, stiffness, strength, heat and flame resistance, and dimensionally stability, among others [ 32 ]; its main applications are in the fields of communication, transport, medical apparatus, aerospace environment, and so on [ 33 ]. The main tensile properties of the PC sheets are: Young modulus E = 2.3 GPa; strain at failure ε f = 60%; yield stress σ y = 60 MPa. The engineering stress–strain curves (like the ones for parent sheets, 2 mm in thickness, reported in [ 17 ]) show linear and nonlinear elastic behavior, shear-band forming and post-yield behavior with necking and its propagation corresponding to strain softening, common to many amorphous thermoplastics [ 34 ]. A C.B. Ferrari high-speed four-axis vertical machining center, driving the forming tool (a hemispherical head stainless steel stylus with a diameter D = 10 mm) at a feed rate of 1000 mm/min, was used to deform the sheets. The experimental campaign provided the manufacture of cone frusta with a fixed wall angle α = 60° (significantly lower than the maximum one, equal to 80°, measured through varying wall angle cone frusta tests in similar conditions [ 21 ]), height h = 35 mm, radius of the major base R = 35 mm and a square flange with a side L = 100 mm, corresponding to the internal area of a clamping frame acting as sheet blocking system. A CAD representation of a cone frustum and of the forming tool with the corresponding main geometrical features is reported in Fig. 1 , while Fig. 2 shows the experimental setup during a SPIF test. The cone frusta were manufactured by four unidirectional helical toolpath-based strategies (two repetitions for each case). Figure 3 and Fig. 4 report a not-to-scale schematization of, respectively, the three-dimensional view of some turns of the helixes and a quarter turn in the XY and YZ-plane views; the arrows show the toolpath directions. The first strategy (Fig. 3a and Fig. 4a) was considered as a reference toolpath ( ref_tp ): it was based on a common helical toolpath with a step down (the vertical distance between two consecutive turns) equal to sd = 1 mm (the same for all the strategies considered in this work); the tool described 60 equally spaced points for each complete turn of the conical helix, covering the distance between two consecutive points by a segment. The other three strategies (labelled as stairA_tp , stairB_tp and stairC_tp ) had in common the description of a stair path providing for an alternation of an upward and a downward segment between two consecutive points of ref_tp ; for all the cases, the ramp height of the upward segment along the Z-axis was rh = 1.5 mm (equal to about the elastic springback of the components along the Z-axis and measured in preliminary tests). stairA_tp strategy (Fig. 3b and Fig. 4b) provided that, considering two consecutive points on the helix, the peak of the stair had the same (x,y) coordinates of the second point (the downward segment was placed along the Z-axis and had a length equal to rh ; stairA_tp and ref_tp strategies overlap in the XY-plane, see Fig. 4b left). For stairB_tp and stairC_tp strategies, the projection of one of the two stair segments on the XY-plane was radial ( rs ); in detail, it was centrifugal for s tairB_tp and centripetal for stairC_tp and its length was equal to rs = rh = 1.5 mm (see Fig. 3c-d and Fig. 4c-d). The tool/sheet interaction induces a localized and incremental deformation of the sheet, peculiar to this forming process; at the same time, it can determine failures and defects, whose occurrence was reduced by lubricating the sheets with mineral oil for cold forming [ 35 ]. Some tests were also carried out in dry conditions, to investigate the influence of the lubrication on the process by varying the toolpath strategy. The occurrence and the growth of failures and defects were investigated as a function of the toolpath strategies; concerning this, the magnitude of the twisting phenomenon was evaluated by measuring the twist angle θ : it was the angle described by a cross, marked on the bottom (the side not in contact with the tool) of the plane sheets [ 26 ]. Moreover, the deformation states of the cone frusta were analyzed through cross section observations, carried out by a Hirox RX-100 digital microscope. Information on the process was also collected monitoring the forming forces; concerning this, a Kistler 9257A piezoelectric dynamometer acquired at 2000 Hz two components of the forming forces, the vertical and one horizontal ( F Z and F X , respectively, see the reference system in Fig. 1 ); subsequently, the data were filtered through a NI 9239 input module and the VBA 1.0 B software. Finally, the quality of the worked surfaces was estimated by measuring their mean roughness ( R a ). Ten measurements, according to ISO 4288 − 1996 standard relatively to the recommended cut-off values were conducted for each case, divided equally over the lateral walls along the circumferential and the meridional directions (see Fig. 1 ); they were performed by means of a Mitutoyo Surftest SJ-301 roughness tester, with differential inductance used as the detecting method and with Gaussian filter. Results and discussion Before showing the results of the tests, Fig. 5 reports a histogram of the work time depending on the toolpath strategies. They are not the same, due to the different lengths; they pass from 367 s for ref_tp to 870 s for stairB_tp and stairC_tp . All the tests under lubricated conditions were carried out without the occurrence of tearing, in line with the results of the formability tests described in [ 21 ]. At the same time, they all show twisting (see Fig. 6); it is promoted by the in-plane forces exerted in the same circumferential direction and magnified by the indentation that affects the transition zone between the minor base and the lateral wall of the formed PC sheets [ 25 , 36 , 37 ], where necking occurs (as the 30x microscope observation in Fig. 7 shows). The histogram of Fig. 8 reports the mean values of the twist angles. It is evident that the stair path strategies guarantee a reduction of the twisting phenomenon, due to a non-continuous and reduced torque action of the tool around the Z-axis; the angle reduces from 29.4° ( ref_tp ) to 17.2° ( stairB_tp ), while it presents similar and intermediate values for the other two strategies (22.5° and 23.8° for stairA_tp and stairC_tp , respectively). The considerations on the twisting reflect on the occurrence of wrinkles; the cone frusta obtained by stairB_tp (that guarantees the lowest twist angle) do not show wrinkles, differently from what observed for the other three strategies. Wrinkles are not particularly significant for stairA_tp and similar for the other two strategies (highly interested by the twisting) and affect the transition area between the minor base and the lateral wall (see Fig. 6). Passing to the tests carried out in dry conditions, stairB_tp ones fail for a vertical quote of about z = 25 mm but without the occurrence of wrinkling; this translates into a reduced formability of the sheets compared to the lubricated conditions. On the other hand, the other ones suffer a very significant instability for which it is possible to affirm that the tests can be completely failed. This instability, caused by both severe loading conditions (because of the absence of lubrication) and significant thinning (as a result of high wall angles on thin sheets; see the wall thickness in Fig. 7 , value in good agreement with the Cosine’s law of thickness distribution [ 38 ]), determines the formation of wrinkles along the lateral wall. Images from ref_tp and stairB_tp tests (the limit cases with respect to the magnitude of twisting) in dry conditions are reported in Fig. 9. The interpretation of the forming forces furnishes further information on the carrying out of the ISF process. Figure 10a shows that the trend for ref_tp strategy is typical of SPIF cone frusta obtained by a common unidirectional helical toolpath with a step down [ 39 ]: the continuous and constant tool/sheet contact involves that F Z follows the tensile behavior of the material; the first turns (about five) allow reaching yielding, then the polymer chains align themselves along the meridional direction and this induces anisotropy in the material. In detail, it experiences a significant increase of the tensile properties in the direction of chain alignment (with a consequent increase of the forming force) and a decrease normal to this direction (circumferential) [ 40 ]. This is a further cause of the significant twisting interesting ISF polymers. F X shows a sinusoidal trend, with increasing amplitude as well as the vertical one. This component furnishes information on a combination of effects, i.e. the force for the flattening by the vertical displacement of the tool, the friction associated to the tool/sheet interaction and the action for the thrust on the cone walls [ 41 ]. Moreover, a more detailed analysis can provide information on the occurrence of wrinkles. Limiting the observation to one turn and considering the absence of geometrical singularities like ribs in the cone frusta, a nearly constant value of F Z and the sinusoidal trend of F X (corresponding to a component of a rotating vector with constant modulus, i.e. the in-plane force), reflect on the lack of wrinkles (Fig. 10b; before wrinkling, 11th turn) [ 26 ]. On the contrary, the presence of noise in the signal, as highlighted in Fig. 10c (after wrinkling, last turn), indicates the presence of wrinkles. These observations, possible to ref_tp thanks to the regularity of the force signals, were not for the stair path-based ones, characterized by an irregular trend of the forces. To compare the four strategies and considering their different working times, a part of the toolpath was considered, corresponding to the 19th and the 20th turns (see Fig. 11; the figure also reports the average of F Z and of the absolute values of F X , labelled as F Z,m and | F X | m respectively, for a quantitative comparison). The fluctuation of the forces increases from the reference to the other three strategies, resulting similar for the last two ones; the stair paths guarantee less severe contact conditions on average, even if loading and unloading determine higher force peaks: in particular, differently from stairA_tp , both stairB_tp and stairC_tp allow reaching very low F Z,m (about 230 N, compared to about 340 for ref_tp ) and F Z values (under 100 N), since these paths during the upward segment reduce considerably the pressure between the tool and the sheet (not only on the minor base but also on the lateral wall of the components) through a partial elastic recovery, and facilitate for the tool to cross the indentation (this is particularly true for the stairB_tp strategy, in light of the results in terms of twist angle). Despite this, any toolpath determines no-contact between the tool and the sheet because in any time F Z goes to zero. Concerning the tests in dry conditions (for the limit cases), the graph of the forces for ref_tp clearly highlights the occurrence of wrinkles with a significant irregularity of the vertical component, followed by an increase in the amplitude of the horizontal one (see Fig. 12a). For the stairB_tp , the irregularity of F Z corresponds to the tearing of the sheet (see Fig. 12b; the test was stopped after it). Finally, Fig. 13 reports the R a values, measured with a cut-off of 0.8 mm. The roughness is slightly lower for ref_tp and along the circumferential direction (along the meridional direction, it is affected by the technological signatures that the forming tool leaves along its path). However, all the toolpath strategies in lubricated conditions guarantee very high surface quality, with roughness values typical of burnished surfaces. The roughness increases significantly for dry tests when using ref_tp , differently from stairB_tp for which lubrication conditions are quite irrelevant, due to the non-continuous tool/sheet contact that makes less severe the wear action of the tool in absence of lubricants. Conclusions This paper investigates the effects of the toolpath strategy on defect phenomena in the single-point incremental forming of thin polycarbonate sheets. They were worked to manufacture cone frusta with a fixed wall angle by using a reference and three stair-based unidirectional helical toolpath strategies; deformation states, surface quality, failures and defects were analyzed, as well as the forming forces were monitored. First of all, the stair paths present higher length and, then, higher working times. Under lubricated conditions, all the components do not experience tearing; despite this and due to the asymmetric nature of the unidirectional toolpaths and the soft nature of the polycarbonate, in all the cases the incremental formed sheets suffer from twisting, which reaches almost 30° when using the reference strategy. The worst cases also show wrinkles along the lateral wall of the cone frusta. Twisting phenomenon can be reduced by using the stair toolpaths (in particular, the twist angle is about 17° for the one labelled stairB_tp ), because of a discontinuous and lower torque action and a facilitated crossing of the indentation for the tool. The above considerations are confirmed by the analysis of the forming forces that also represent a valid tool to monitor the control, since the correct interpretation of values and trends of the forces allows individuate failures and defects. From the roughness measures, all the toolpath strategies guarantee high surface quality. Finally, the tests on lubricated and dry conditions allow affirming that the best solution to form incrementally the polycarbonate sheets is choosing stairB_tp strategy. In fact, it guarantees reduced defectiveness in lubricated conditions and the sheets do not incur instabilities in dry conditions, though suffering a reduced formability; in addition the lubrication results quite irrelevant in terms of surface roughness. These conclusions, added up FEM predictions of reduced energy consumption from a previous authors’ work on stair-based toolpath strategies, makes stairB_tp , and more generally an opportune choice of the toolpath strategy, a viable way on the improvement of ISF towards more efficiency and green manufacturing process. Declarations Competing Interests The authors have no relevant financial or non-financial interests to disclose. Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Author Contributions All authors contributed to the study conception and design. Material preparation was performed by Antonio Formisano and Massimo Durante. Data collection and analysis were performed by Antonio Formisano, Luca Boccarusso and Dario De Fazio. The first draft of the manuscript was written by Antonio Formisano and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. References Rosa-Sainz A, Centeno G, Silva MB, Vallellano C (2021) Experimental failure analysis in polycarbonate sheet deformed by spif. J Manuf Process 64:1153–1168. https://doi.org/10.1016/J.JMAPRO.2021.01.047 Rosa-Sainz A, Centeno G, Silva MB et al (2020) On the Determination of Forming Limits in Polycarbonate Sheets. Mater (Basel) 13:928. https://doi.org/10.3390/ma13040928 Shaw MT (1980) Cold forming of polymeric materials. Annu Rev Mater Sci 10:19–42 Bagudanch I, Centeno G, Vallellano C, Garcia-Romeu ML (2017) Revisiting formability and failure of polymeric sheets deformed by Single Point Incremental Forming. Polym Degrad Stab 144:366–377. https://doi.org/10.1016/j.polymdegradstab.2017.08.021 Tofail SAM, Koumoulos EP, Bandyopadhyay A et al (2018) Additive manufacturing: scientific and technological challenges, market uptake and opportunities. Mater Today 21:22–37. https://doi.org/10.1016/J.MATTOD.2017.07.001 Jeswiet J, Micari F, Hirt G et al (2005) Asymmetric Single Point Incremental Forming of Sheet Metal. CIRP Ann 54:88–114. https://doi.org/10.1016/S0007-8506(07)60021-3 Bertini L, Kubit A, Al-Sabur R et al (2022) Investigating Residual Stresses in Metal-Plastic Composites Stiffening Ribs Formed Using the Single Point Incremental Forming Method. Mater (Basel) 15:8252. https://doi.org/10.3390/MA15228252 Behera AK, de Sousa RA, Ingarao G, Oleksik V (2017) Single point incremental forming: An assessment of the progress and technology trends from 2005 to 2015. J Manuf Process 27:37–62. https://doi.org/10.1016/J.JMAPRO.2017.03.014 Bagudanch I, Garcia-Romeu ML, Sabater M (2016) Incremental forming of polymers: Process parameters selection from the perspective of electric energy consumption and cost. J Clean Prod 112:1013–1024. https://doi.org/10.1016/j.jclepro.2015.08.087 Franzen V, Kwiatkowski L, Martins PAF, Tekkaya AE (2009) Single point incremental forming of PVC. J Mater Process Technol 209:462–469. https://doi.org/10.1016/j.jmatprotec.2008.02.013 Martins PAF, Kwiatkowski L, Franzen V et al (2009) Single point incremental forming of polymers. CIRP Ann 58:229–232. https://doi.org/10.1016/J.CIRP.2009.03.095 Carrino L, Durante M, Formisano A et al (2014) Wear behavior of WC-Co carbides with addition of Cr3C2 and Ni Novakova-Marcincinova L, Novak-Marcincin J, Barna J, Torok J (2012) Special materials used in FDM rapid prototyping technology application. In: INES 2012 - IEEE 16th International Conference on Intelligent Engineering Systems, Proceedings Echrif SBM, Hrairi M (2014) Significant parameters for the surface roughness in incremental forming process. Mater Manuf Process. https://doi.org/10.1080/10426914.2014.901519 Le VS, Ghiotti A, Lucchetta G (2008) Preliminary studies on single point incremental forming for thermoplastic materials. Int J Mater Form 1:1179–1182. https://doi.org/10.1007/s12289-008-0191-0 Martínez-Donaire AJ, García-Lomas FJ, Vallellano C (2014) New approaches to detect the onset of localised necking in sheets under through-thickness strain gradients. Mater Des 57:135–145. https://doi.org/10.1016/J.MATDES.2014.01.012 Durante M, Formisano A, Boccarusso L, Langella A (2020) Influence of cold-rolling on incremental sheet forming of polycarbonate. Mater Manuf Process 35:328–336. https://doi.org/10.1080/10426914.2020.1726946 Formisano A, Lambiase F, Durante M (2020) Polymer self-heating during incremental forming. J Manuf Process 58:1189–1199. https://doi.org/10.1016/J.JMAPRO.2020.09.031 Zhu H, Ou H, Popov A (2020) Incremental sheet forming of thermoplastics: a review. Int J Adv Manuf Technol 111:565–587 Formisano A, Boccarusso L, Capece Minutolo F et al (2017) Negative and positive incremental forming: Comparison by geometrical, experimental, and FEM considerations. Mater Manuf Process 32:530–536. https://doi.org/10.1080/10426914.2016.1232810 Durante M, Formisano A, Lambiase F (2018) Incremental forming of polycarbonate sheets. J Mater Process Technol 253:57–63. https://doi.org/10.1016/j.jmatprotec.2017.11.005 Chang Z, Chen J (2020) Mechanism of the twisting in incremental sheet forming process. J Mater Process Technol 276:116396. https://doi.org/10.1016/J.JMATPROTEC.2019.116396 Duflou JR, Vanhove H, Verbert J et al (2010) Twist revisited: Twist phenomena in single point incremental forming. CIRP Ann 59:307–310. https://doi.org/10.1016/J.CIRP.2010.03.018 Banhart J (2005) Aluminium foams for lighter vehicles. Int J Veh Des 37:114. https://doi.org/10.1504/IJVD.2005.006640 Asghar J, Lingam R, Shibin E, Reddy NV (2014) Tool path design for enhancement of accuracy in single-point incremental forming. Proc Inst Mech Eng Part B J Eng Manuf 228:1027–1035. https://doi.org/10.1177/0954405413512812 Durante M, Formisano A, Lambiase F (2019) Formability of polycarbonate sheets in single-point incremental forming. Int J Adv Manuf Technol 102:2049–2062. https://doi.org/10.1007/s00170-019-03298-w Wang J, Nair M, Zhang Y (2016) An Efficient Force Prediction Strategy in Single Point Incremental Sheet Forming. Procedia Manufacturing. Elsevier, pp 761–771 Bhushan B, Caspers M (2017) An overview of additive manufacturing (3D printing) for microfabrication. Microsyst Technol 23:1117–1124. https://doi.org/10.1007/s00542-017-3342-8 Liu F, Li Y, Ghafoor S et al (2022) Sustainability assessment of incremental sheet forming: a review. Int J Adv Manuf Technol 119:1385–1405. https://doi.org/10.1007/s00170-021-08368-6 Formisano A, Durante M, Boccarusso L, Memola Capece F (2023) A numerical approach to optimize the toolpath strategy for polymers forming. Mater Res Proc 28:1697–1702. https://doi.org/10.21741/9781644902479-183 Formisano A, Boccarusso L, Durante M (2023) Optimization of Single-Point Incremental Forming of Polymer Sheets through FEM. Mater 2023, Vol 16, Page 451 16:451. https://doi.org/10.3390/MA16010451 Hou ZX, Wu J, Wang ZR (2004) A study of the bulge-forming of polycarbonate (PC) sheet. J Mater Process Technol 151:312–315. https://doi.org/10.1016/j.jmatprotec.2004.04.080 Beşliu I, Tamaşag I, Slătineanu L (2021) An Experimental Study on Incremental Forming Process of Polycarbonate Sheets. Macromol Symp 395:2000282. https://doi.org/10.1002/masy.202000282 Cao K, Ma X, Zhang B et al (2010) Tensile behavior of polycarbonate over a wide range of strain rates. Mater Sci Eng A 527:4056–4061. https://doi.org/10.1016/j.msea.2010.03.088 Beșliu-Băncescu I, Slătineanu L, Dodun O, Nagîț G (2021) Influence of Lubrication and Cooling on the Quality of Single-Point Incremental Forming Parts of Polycarbonate Sheets. J Manuf Mater Process 5:75. https://doi.org/10.3390/JMMP5030075 Wagih A, Maimí P, Blanco N, Costa J (2016) A quasi-static indentation test to elucidate the sequence of damage events in low velocity impacts on composite laminates. Compos Part Appl Sci Manuf 82:180–189. https://doi.org/10.1016/J.COMPOSITESA.2015.11.041 Bansal A, Lingam R, Yadav SK, Venkata Reddy N (2017) Prediction of forming forces in single point incremental forming. J Manuf Process 28:486–493. https://doi.org/10.1016/j.jmapro.2017.04.016 Hussain G, Gao L (2007) A novel method to test the thinning limits of sheet metals in negative incremental forming. Int J Mach Tools Manuf 47:419–435. https://doi.org/10.1016/j.ijmachtools.2006.06.015 Rosca N, Trzepieciński T, Oleksik V (2022) Minimizing the Forces in the Single Point Incremental Forming Process of Polymeric Materials Using Taguchi Design of Experiments and Analysis of Variance. Mater (Basel) 15:6453. https://doi.org/10.3390/ma15186453 Savitsky AV, Gorshkova IA, Frolova IL et al (1984) The model of polymer orientation strengthening and production of ultra-high strength fibers. Polym Bull 12:195–202. https://doi.org/10.1007/BF00275968 Durante M, Formisano A, Langella A, Capece Minutolo FM (2009) The influence of tool rotation on an incremental forming process. J Mater Process Technol 209:4621–4626. https://doi.org/10.1016/j.jmatprotec.2008.11.028 Cite Share Download PDF Status: Published Journal Publication published 27 Jun, 2024 Read the published version in The International Journal of Advanced Manufacturing Technology → Version 1 posted Editorial decision: Major Revisions Needed 23 May, 2024 Reviewers agreed at journal 22 Mar, 2024 Reviewers invited by journal 22 Mar, 2024 Editor assigned by journal 20 Mar, 2024 First submitted to journal 18 Mar, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4124482","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":282855558,"identity":"dd8de658-fc6d-4f6c-b6c3-581c524acefd","order_by":0,"name":"Antonio Formisano","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwklEQVRIiWNgGAWjYDAC5gNAwoCBgR9IgZg8hLWwJUC0SDZAtRDWA9YC0nUAKkBQC38b87FPNwrq5I1v5B48XFDDIGNPSIvEMbbk2TkGhw233chLODzjGDEOu99jzJxjcIBx2w2gRh42IrTIH+MBaamz3zwDpOUfEVoMIFqYEzdIALXwthGhxRDoF6CWw8kzzrwBaumT4OE5QECL3DHmw8w5f+ps+9tzjD/zfLOxZ28gZA0akCBR/SgYBaNgFIwCrAAA8R83qQ7DCnoAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-4909-8315","institution":"Universita degli Studi di Napoli Federico II","correspondingAuthor":true,"prefix":"","firstName":"Antonio","middleName":"","lastName":"Formisano","suffix":""},{"id":282855559,"identity":"fd696dc9-69b9-45f0-85ba-5751fff0da2e","order_by":1,"name":"Luca Boccarusso","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Luca","middleName":"","lastName":"Boccarusso","suffix":""},{"id":282855560,"identity":"4a874b32-4b67-4695-b9e1-87a0e612a181","order_by":2,"name":"Dario De Fazio","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Dario","middleName":"","lastName":"De Fazio","suffix":""},{"id":282855561,"identity":"08a8d442-88fc-4c73-b02a-5a983a0d63b3","order_by":3,"name":"Massimo Durante","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Massimo","middleName":"","lastName":"Durante","suffix":""}],"badges":[],"createdAt":"2024-03-18 15:39:46","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4124482/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4124482/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00170-024-14047-z","type":"published","date":"2024-06-27T13:13:34+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":53550735,"identity":"3a9a089c-f5a6-4306-8af3-3f030d272a71","added_by":"auto","created_at":"2024-03-27 11:20:43","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":149422,"visible":true,"origin":"","legend":"\u003cp\u003eGeometrical features of the fixed wall angle cone frusta and of the forming tool\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/8ec19397326ce526a085e6f4.png"},{"id":53550411,"identity":"9181a8e6-3fd5-415b-a0e5-29ef9906925c","added_by":"auto","created_at":"2024-03-27 11:12:43","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":781133,"visible":true,"origin":"","legend":"\u003cp\u003eExperimental setup during a SPIF test\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/faf17986c1f89e69d29b1196.png"},{"id":53550418,"identity":"f3729c1d-7e78-43b0-9b84-26951b400440","added_by":"auto","created_at":"2024-03-27 11:12:44","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":147229,"visible":true,"origin":"","legend":"\u003cp\u003eNot-to-scale 3D representation of two consecutive turns of the toolpath strategies: (a) ref_tp; (b) stairA_tp; (c) stairB_tp; (d) stairC_tp\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/fca1dc8fa92b5dd6edb88ef9.png"},{"id":53550419,"identity":"de08e0b9-b903-4ec0-a04f-8888ba3ac534","added_by":"auto","created_at":"2024-03-27 11:12:44","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":135272,"visible":true,"origin":"","legend":"\u003cp\u003eNot-to-scale XY and YZ-plane view of the toolpath strategies: (a) ref_tp; (b) stairA_tp; (c) stairB_tp; (d) stairC_tp\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/76cbfe976ebc814bae6b66ac.png"},{"id":53550422,"identity":"499a3d3e-c696-45cf-877c-b97980d7692e","added_by":"auto","created_at":"2024-03-27 11:12:45","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":202067,"visible":true,"origin":"","legend":"\u003cp\u003eWork time vs toolpath strategy\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/925050fe3701661557e92a53.png"},{"id":53550413,"identity":"e25e8429-8363-4bff-ae4a-8060862eed67","added_by":"auto","created_at":"2024-03-27 11:12:43","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1420792,"visible":true,"origin":"","legend":"\u003cp\u003eCone frusta obtained in lubricated conditions by the toolpath strategies: (a) ref_tp; (b) stairA_tp; (c) stairB_tp; (d) stairC_tp\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/036ad7fc3962a51aad4ee9cc.png"},{"id":53550423,"identity":"23ca5858-566f-4246-81ac-0d72fe8bad04","added_by":"auto","created_at":"2024-03-27 11:12:45","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":619139,"visible":true,"origin":"","legend":"\u003cp\u003eCross section microscope observation\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/bb6d40bf28dc433439b6d1a6.png"},{"id":53550415,"identity":"ef38326d-7a1c-4499-a66b-070875da3465","added_by":"auto","created_at":"2024-03-27 11:12:44","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":110007,"visible":true,"origin":"","legend":"\u003cp\u003eTwist angle vs toolpath strategy\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/1f5ad5fe931d0a2f572375fc.png"},{"id":53550421,"identity":"fbda2941-3e56-4d82-8a9e-27703669a71b","added_by":"auto","created_at":"2024-03-27 11:12:45","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":553766,"visible":true,"origin":"","legend":"\u003cp\u003eCone frusta obtained in dry conditions by the toolpath strategies: (a) ref_tp; (b) stairB_tp\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/9031dbe25a5c85d764eec734.png"},{"id":53550427,"identity":"97457acd-a6a8-4936-91df-e31db5b750ac","added_by":"auto","created_at":"2024-03-27 11:12:45","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":142603,"visible":true,"origin":"","legend":"\u003cp\u003eForming forces for tests in lubricated conditions by the toolpath strategy ref_tp: (a) complete trend; (b) 11th turn; (c) last turn\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/2dadf5c12f7a2708fa1b7b99.png"},{"id":53550736,"identity":"9d5fab41-db9f-40a3-a180-fc038a773bec","added_by":"auto","created_at":"2024-03-27 11:20:45","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":232609,"visible":true,"origin":"","legend":"\u003cp\u003eForming forces corresponding to the 19th and the 20th turns for tests in lubricated conditions by the toolpath strategies: (a) ref_tp; (b) stairA_tp; (c) stairB_tp; (d) stairC_tp\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/75e6d5cb0e0d9777684a9ea5.png"},{"id":53550416,"identity":"8e41479b-ec0f-4493-a202-933846bdd226","added_by":"auto","created_at":"2024-03-27 11:12:44","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":203307,"visible":true,"origin":"","legend":"\u003cp\u003eTrend of the forming forces for tests in dry conditions by the toolpath strategies: (a) ref_tp; (b) stairB_tp\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/e8d9493eb0c9a69fda9e07e1.png"},{"id":53550420,"identity":"9d6e97b6-615c-4b48-a833-b3a000ce6261","added_by":"auto","created_at":"2024-03-27 11:12:44","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":169652,"visible":true,"origin":"","legend":"\u003cp\u003eMean roughness vs toolpath strategy\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/d2c6fcd96cf3fdb933f2da63.png"},{"id":60585451,"identity":"2228640c-7688-4f30-9fcd-438b26b02589","added_by":"auto","created_at":"2024-07-18 13:13:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5011262,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4124482/v1/950459bb-253c-4f54-8b05-34da3daeeb6e.pdf"}],"financialInterests":"","formattedTitle":"Effects of toolpath on defect phenomena in the incremental forming of thin polycarbonate sheets","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThermoplastics are strongly used in the manufacturing industry [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] because of their good properties like light-weight, strength, corrosion resistance, price, etc. Typical parts made of them are manufactured with operations oriented to mass production both for the energy costs and the investments in equipment and tools; they provide for repetitive actions of heating, shaping, and cooling [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Furthermore, processes usually employed in sheet metal forming are frequently considered to manufacture thermoplastic sheet components with different shapes [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]; in these cases, the forming processes strongly depend on the material properties and the temperature [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRecently, the significant advances in the use of computers applied to manufacturing have augmented the interest in developing procedures with a higher level of flexibility: consider, for example, the incredible development of additive manufacturing technologies [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The incremental sheet forming (ISF) moves along the same lines: it is a relatively recent technology that guarantees high customization, thanks to the layered manufacturing principle typical of rapid prototyping, and cost-effectiveness, because it does not require dedicated equipment. In this process, which guarantees high levels of materials\u0026rsquo; formability and the carrying out at room temperature, a forming tool controlled by a CNC machine describes a path and deforms progressively a clamped sheet; by doing so, it manufactures the final part geometry [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] starting from sheets of pure metals, alloys, polymers, and composites [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eISF is an effective alternative to conventional technologies based on heating-shaping-cooling manufacturing operations. Thanks to its flexibility, this process is strongly oriented toward the production of batches with small and medium size; in addition, it allows reducing energy consumption, compared to conventional processes, so as shown by recent researches on polymer forming [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe firsts studies on the polymer ISF concerned polyvinylchloride (PVC) sheets [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], before being extended to other commercial polymers [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] and new materials like the biocompatible polycaprolactone (PCL) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Once checked the feasibility of the process, significant researches were carried out to investigate the influence of the main process parameters on the formability limits of different polymers like polyamide (PA), polycarbonate (PC), polyethylene terephthalate (PET), PVC and polypropylene (PP) [\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The way to better estimate the formability limits was investigated in [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], while new solutions to improve the quality of the ISF polymer parts represents a very hot focus; consider, for example, a prior cold-rolling process of the sheets [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] or their self-heating as the effect of the feed rate and the spindle [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFailure and defect modes that interest ISF sheets represent another significant field of investigation, since they influence the materials\u0026rsquo; formability and worsen the geometrical accuracy of ISF parts [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. When incrementally formed, polymer sheets can be affected by ductile fracture at the transition zone between the wall and the corner radius or tearing along the walls, as well as defects like wrinkling and twisting [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]; these ones are strictly connected, since wrinkles can be twisted around the axis of revolution in the direction of tool rotation. The twisting phenomenon is common for all the ISF materials, but it is particularly relevant for materials with soft behaviour like thermoplastics; consider, for example, that twist angles on axisymmetric components obtained by a unidirectional toolpath were equal to about 6\u0026deg; and 22\u0026deg; for aluminum alloy [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] and polycarbonate sheets [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], respectively. This defect is caused by an uncontrolled pivoting of the formed components around the clamping frame, because of the in-plane shear generated by the tangential forces that the forming tool exerts on the sheet; in addition, it is more probable for higher and more regular plane forces, which determine a combination of continued strain accumulation and asymmetric strain levels [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] and, considering polymer sheets, higher normal forces can determine significant indentation that accentuates the phenomenon [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA way to reduce this defectiveness is to choose a more suitable toolpath strategy. For example, a dramatic reduction of the twisting phenomenon was observed by adopting an alternate toolpath instead of a unidirectional one, so as verified in [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] and, for PC parts, in [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]; by doing so, the amount of twist produced in a layer was recovered in the successive one almost completely. Despite this, severe forming conditions in terms of sliding forces on thin thermoplastic sheets, characterized by low mechanical resistance, can induce significant instability and generate wrinkling, also using an alternate toolpath strategy [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMonitoring and measuring the ISF forming forces represents an efficient tool for the control of the process quality [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]; their reduction limits the risk of failures and defects on the ISF polymer sheets and on the tools, as well as can improve the surfaces\u0026rsquo; quality of the components, and allows reducing or avoiding lubricants to lower friction and sticking of material to the tool. These aspects can also involve energy implications that are of relevant interest in a perspective of sustainable manufacturing, since they can determine a positive impact on the environment [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAccording to what reported above, a way to reduce the defect phenomena on ISF polymer sheets provides for acting on toolpath strategies that lower the forming forces in the sheet plane, in line with previous authors\u0026rsquo; numerical works [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The single-point incremental forming (SPIF), i.e. the simplest variant of ISF that involves the use of a simple tool, a clamping frame, and the absence of dies, was used in this work to manufacture cone frusta with fixed wall angle starting from thin PC sheets; the forming process was carried out by setting typical ISF parameters [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] and four different unidirectional helical trajectory-based toolpath strategies. From the experimental campaign, some important features like the forming forces, the twist angle and the surface roughness were analyzed, as well as the deformation states, the failures and the defects were monitored, to investigate the influence of the selected toolpath strategies on the defectiveness of incrementally formed polymer parts.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003eThe SPIF tests were carried out at room temperature on Makrolon PC sheets, supplied by Bayer, with a thickness \u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.0 mm. It is an amorphous thermoplastic polymer also known as a \u0026ldquo;transparency metal\u0026rdquo; because of its relevant mechanical and physiochemical properties like toughness, stiffness, strength, heat and flame resistance, and dimensionally stability, among others [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e]; its main applications are in the fields of communication, transport, medical apparatus, aerospace environment, and so on [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. The main tensile properties of the PC sheets are: Young modulus \u003cem\u003eE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.3 GPa; strain at failure \u003cem\u003e\u0026epsilon;\u003c/em\u003e\u003csub\u003e\u003cem\u003ef\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;60%; yield stress \u003cem\u003e\u0026sigma;\u003c/em\u003e\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;60 MPa. The engineering stress\u0026ndash;strain curves (like the ones for parent sheets, 2 mm in thickness, reported in [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]) show linear and nonlinear elastic behavior, shear-band forming and post-yield behavior with necking and its propagation corresponding to strain softening, common to many amorphous thermoplastics [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eA C.B. Ferrari high-speed four-axis vertical machining center, driving the forming tool (a hemispherical head stainless steel stylus with a diameter \u003cem\u003eD\u003c/em\u003e\u0026thinsp;=\u0026thinsp;10 mm) at a feed rate of 1000 mm/min, was used to deform the sheets.\u003c/p\u003e\n\u003cp\u003eThe experimental campaign provided the manufacture of cone frusta with a fixed wall angle \u003cem\u003e\u0026alpha;\u003c/em\u003e\u0026thinsp;=\u0026thinsp;60\u0026deg; (significantly lower than the maximum one, equal to 80\u0026deg;, measured through varying wall angle cone frusta tests in similar conditions [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]), height \u003cem\u003eh\u003c/em\u003e\u0026thinsp;=\u0026thinsp;35 mm, radius of the major base \u003cem\u003eR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;35 mm and a square flange with a side \u003cem\u003eL\u003c/em\u003e\u0026thinsp;=\u0026thinsp;100 mm, corresponding to the internal area of a clamping frame acting as sheet blocking system. A CAD representation of a cone frustum and of the forming tool with the corresponding main geometrical features is reported in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, while Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e shows the experimental setup during a SPIF test.\u003c/p\u003e\n\u003cp\u003eThe cone frusta were manufactured by four unidirectional helical toolpath-based strategies (two repetitions for each case). Figure\u0026nbsp;3 and Fig.\u0026nbsp;4 report a not-to-scale schematization of, respectively, the three-dimensional view of some turns of the helixes and a quarter turn in the XY and YZ-plane views; the arrows show the toolpath directions.\u003c/p\u003e\n\u003cp\u003eThe first strategy (Fig.\u0026nbsp;3a and Fig.\u0026nbsp;4a) was considered as a reference toolpath (\u003cem\u003eref_tp\u003c/em\u003e): it was based on a common helical toolpath with a step down (the vertical distance between two consecutive turns) equal to \u003cem\u003esd\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1 mm (the same for all the strategies considered in this work); the tool described 60 equally spaced points for each complete turn of the conical helix, covering the distance between two consecutive points by a segment.\u003c/p\u003e\n\u003cp\u003eThe other three strategies (labelled as \u003cem\u003estairA_tp\u003c/em\u003e, \u003cem\u003estairB_tp\u003c/em\u003e and \u003cem\u003estairC_tp\u003c/em\u003e) had in common the description of a stair path providing for an alternation of an upward and a downward segment between two consecutive points of \u003cem\u003eref_tp\u003c/em\u003e; for all the cases, the ramp height of the upward segment along the Z-axis was \u003cem\u003erh\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.5 mm (equal to about the elastic springback of the components along the Z-axis and measured in preliminary tests).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003estairA_tp\u003c/em\u003e strategy (Fig. 3b and Fig. 4b) provided that, considering two consecutive points on the helix, the peak of the stair had the same (x,y) coordinates of the second point (the downward segment was placed along the Z-axis and had a length equal to \u003cem\u003erh\u003c/em\u003e; \u003cem\u003estairA_tp\u003c/em\u003e and \u003cem\u003eref_tp\u003c/em\u003e strategies overlap in the XY-plane, see Fig. 4b left).\u003c/p\u003e\n\u003cp\u003eFor \u003cem\u003estairB_tp\u003c/em\u003e and \u003cem\u003estairC_tp\u003c/em\u003e strategies, the projection of one of the two stair segments on the XY-plane was radial (\u003cem\u003ers\u003c/em\u003e); in detail, it was centrifugal for s\u003cem\u003etairB_tp\u003c/em\u003e and centripetal for \u003cem\u003estairC_tp\u003c/em\u003e and its length was equal to \u003cem\u003ers\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003erh\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.5 mm (see Fig. 3c-d and Fig. 4c-d).\u003c/p\u003e\n\u003cp\u003eThe tool/sheet interaction induces a localized and incremental deformation of the sheet, peculiar to this forming process; at the same time, it can determine failures and defects, whose occurrence was reduced by lubricating the sheets with mineral oil for cold forming [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. Some tests were also carried out in dry conditions, to investigate the influence of the lubrication on the process by varying the toolpath strategy.\u003c/p\u003e\n\u003cp\u003eThe occurrence and the growth of failures and defects were investigated as a function of the toolpath strategies; concerning this, the magnitude of the twisting phenomenon was evaluated by measuring the twist angle \u003cem\u003e\u0026theta;\u003c/em\u003e: it was the angle described by a cross, marked on the bottom (the side not in contact with the tool) of the plane sheets [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]. Moreover, the deformation states of the cone frusta were analyzed through cross section observations, carried out by a Hirox RX-100 digital microscope.\u003c/p\u003e\n\u003cp\u003eInformation on the process was also collected monitoring the forming forces; concerning this, a Kistler 9257A piezoelectric dynamometer acquired at 2000 Hz two components of the forming forces, the vertical and one horizontal (\u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eX\u003c/em\u003e\u003c/sub\u003e, respectively, see the reference system in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e); subsequently, the data were filtered through a NI 9239 input module and the VBA 1.0 B software.\u003c/p\u003e\n\u003cp\u003eFinally, the quality of the worked surfaces was estimated by measuring their mean roughness (\u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e). Ten measurements, according to ISO 4288\u0026thinsp;\u0026minus;\u0026thinsp;1996 standard relatively to the recommended cut-off values were conducted for each case, divided equally over the lateral walls along the circumferential and the meridional directions (see Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e); they were performed by means of a Mitutoyo Surftest SJ-301 roughness tester, with differential inductance used as the detecting method and with Gaussian filter.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eBefore showing the results of the tests, Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e reports a histogram of the work time depending on the toolpath strategies. They are not the same, due to the different lengths; they pass from 367 s for \u003cem\u003eref_tp\u003c/em\u003e to 870 s for \u003cem\u003estairB_tp\u003c/em\u003e and \u003cem\u003estairC_tp\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eAll the tests under lubricated conditions were carried out without the occurrence of tearing, in line with the results of the formability tests described in [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. At the same time, they all show twisting (see Fig.\u0026nbsp;6); it is promoted by the in-plane forces exerted in the same circumferential direction and magnified by the indentation that affects the transition zone between the minor base and the lateral wall of the formed PC sheets [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e], where necking occurs (as the 30x microscope observation in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e shows).\u003c/p\u003e\n\u003cp\u003eThe histogram of Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e reports the mean values of the twist angles. It is evident that the stair path strategies guarantee a reduction of the twisting phenomenon, due to a non-continuous and reduced torque action of the tool around the Z-axis; the angle reduces from 29.4\u0026deg; (\u003cem\u003eref_tp\u003c/em\u003e) to 17.2\u0026deg; (\u003cem\u003estairB_tp\u003c/em\u003e), while it presents similar and intermediate values for the other two strategies (22.5\u0026deg; and 23.8\u0026deg; for \u003cem\u003estairA_tp\u003c/em\u003e and \u003cem\u003estairC_tp\u003c/em\u003e, respectively).\u003c/p\u003e\n\u003cp\u003eThe considerations on the twisting reflect on the occurrence of wrinkles; the cone frusta obtained by \u003cem\u003estairB_tp\u003c/em\u003e (that guarantees the lowest twist angle) do not show wrinkles, differently from what observed for the other three strategies. Wrinkles are not particularly significant for \u003cem\u003estairA_tp\u003c/em\u003e and similar for the other two strategies (highly interested by the twisting) and affect the transition area between the minor base and the lateral wall (see Fig. 6).\u003c/p\u003e\n\u003cp\u003ePassing to the tests carried out in dry conditions, \u003cem\u003estairB_tp\u003c/em\u003e ones fail for a vertical quote of about \u003cem\u003ez\u003c/em\u003e\u0026thinsp;=\u0026thinsp;25 mm but without the occurrence of wrinkling; this translates into a reduced formability of the sheets compared to the lubricated conditions. On the other hand, the other ones suffer a very significant instability for which it is possible to affirm that the tests can be completely failed. This instability, caused by both severe loading conditions (because of the absence of lubrication) and significant thinning (as a result of high wall angles on thin sheets; see the wall thickness in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e, value in good agreement with the Cosine\u0026rsquo;s law of thickness distribution [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e]), determines the formation of wrinkles along the lateral wall. Images from \u003cem\u003eref_tp\u003c/em\u003e and \u003cem\u003estairB_tp\u003c/em\u003e tests (the limit cases with respect to the magnitude of twisting) in dry conditions are reported in Fig. 9.\u003c/p\u003e\n\u003cp\u003eThe interpretation of the forming forces furnishes further information on the carrying out of the ISF process. Figure 10a shows that the trend for \u003cem\u003eref_tp\u003c/em\u003e strategy is typical of SPIF cone frusta obtained by a common unidirectional helical toolpath with a step down [\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e]: the continuous and constant tool/sheet contact involves that \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e follows the tensile behavior of the material; the first turns (about five) allow reaching yielding, then the polymer chains align themselves along the meridional direction and this induces anisotropy in the material. In detail, it experiences a significant increase of the tensile properties in the direction of chain alignment (with a consequent increase of the forming force) and a decrease normal to this direction (circumferential) [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e]. This is a further cause of the significant twisting interesting ISF polymers. \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eX\u003c/em\u003e\u003c/sub\u003e shows a sinusoidal trend, with increasing amplitude as well as the vertical one. This component furnishes information on a combination of effects, i.e. the force for the flattening by the vertical displacement of the tool, the friction associated to the tool/sheet interaction and the action for the thrust on the cone walls [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eMoreover, a more detailed analysis can provide information on the occurrence of wrinkles. Limiting the observation to one turn and considering the absence of geometrical singularities like ribs in the cone frusta, a nearly constant value of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e and the sinusoidal trend of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eX\u003c/em\u003e\u003c/sub\u003e (corresponding to a component of a rotating vector with constant modulus, i.e. the in-plane force), reflect on the lack of wrinkles (Fig. 10b; before wrinkling, 11th turn) [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]. On the contrary, the presence of noise in the signal, as highlighted in Fig. 10c (after wrinkling, last turn), indicates the presence of wrinkles. These observations, possible to \u003cem\u003eref_tp\u003c/em\u003e thanks to the regularity of the force signals, were not for the stair path-based ones, characterized by an irregular trend of the forces.\u003c/p\u003e\n\u003cp\u003eTo compare the four strategies and considering their different working times, a part of the toolpath was considered, corresponding to the 19th and the 20th turns (see Fig. 11; the figure also reports the average of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e and of the absolute values of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eX\u003c/em\u003e\u003c/sub\u003e, labelled as \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ,m\u003c/em\u003e\u003c/sub\u003e and |\u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eX\u003c/em\u003e\u003c/sub\u003e|\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e respectively, for a quantitative comparison).\u003c/p\u003e\n\u003cp\u003eThe fluctuation of the forces increases from the reference to the other three strategies, resulting similar for the last two ones; the stair paths guarantee less severe contact conditions on average, even if loading and unloading determine higher force peaks: in particular, differently from \u003cem\u003estairA_tp\u003c/em\u003e, both \u003cem\u003estairB_tp\u003c/em\u003e and \u003cem\u003estairC_tp\u003c/em\u003e allow reaching very low \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ,m\u003c/em\u003e\u003c/sub\u003e (about 230 N, compared to about 340 for \u003cem\u003eref_tp\u003c/em\u003e) and \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e values (under 100 N), since these paths during the upward segment reduce considerably the pressure between the tool and the sheet (not only on the minor base but also on the lateral wall of the components) through a partial elastic recovery, and facilitate for the tool to cross the indentation (this is particularly true for the \u003cem\u003estairB_tp\u003c/em\u003e strategy, in light of the results in terms of twist angle). Despite this, any toolpath determines no-contact between the tool and the sheet because in any time \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e goes to zero.\u003c/p\u003e\n\u003cp\u003eConcerning the tests in dry conditions (for the limit cases), the graph of the forces for \u003cem\u003eref_tp\u003c/em\u003e clearly highlights the occurrence of wrinkles with a significant irregularity of the vertical component, followed by an increase in the amplitude of the horizontal one (see Fig. 12a). For the \u003cem\u003estairB_tp\u003c/em\u003e, the irregularity of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e corresponds to the tearing of the sheet (see Fig. 12b; the test was stopped after it).\u003c/p\u003e\n\u003cp\u003eFinally, Fig. \u003cspan class=\"InternalRef\"\u003e13\u003c/span\u003e reports the \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e values, measured with a cut-off of 0.8 mm. The roughness is slightly lower for \u003cem\u003eref_tp\u003c/em\u003e and along the circumferential direction (along the meridional direction, it is affected by the technological signatures that the forming tool leaves along its path). However, all the toolpath strategies in lubricated conditions guarantee very high surface quality, with roughness values typical of burnished surfaces. The roughness increases significantly for dry tests when using \u003cem\u003eref_tp\u003c/em\u003e, differently from \u003cem\u003estairB_tp\u003c/em\u003e for which lubrication conditions are quite irrelevant, due to the non-continuous tool/sheet contact that makes less severe the wear action of the tool in absence of lubricants.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis paper investigates the effects of the toolpath strategy on defect phenomena in the single-point incremental forming of thin polycarbonate sheets. They were worked to manufacture cone frusta with a fixed wall angle by using a reference and three stair-based unidirectional helical toolpath strategies; deformation states, surface quality, failures and defects were analyzed, as well as the forming forces were monitored.\u003c/p\u003e \u003cp\u003eFirst of all, the stair paths present higher length and, then, higher working times.\u003c/p\u003e \u003cp\u003eUnder lubricated conditions, all the components do not experience tearing; despite this and due to the asymmetric nature of the unidirectional toolpaths and the soft nature of the polycarbonate, in all the cases the incremental formed sheets suffer from twisting, which reaches almost 30\u0026deg; when using the reference strategy. The worst cases also show wrinkles along the lateral wall of the cone frusta.\u003c/p\u003e \u003cp\u003eTwisting phenomenon can be reduced by using the stair toolpaths (in particular, the twist angle is about 17\u0026deg; for the one labelled \u003cem\u003estairB_tp\u003c/em\u003e), because of a discontinuous and lower torque action and a facilitated crossing of the indentation for the tool.\u003c/p\u003e \u003cp\u003eThe above considerations are confirmed by the analysis of the forming forces that also represent a valid tool to monitor the control, since the correct interpretation of values and trends of the forces allows individuate failures and defects.\u003c/p\u003e \u003cp\u003eFrom the roughness measures, all the toolpath strategies guarantee high surface quality.\u003c/p\u003e \u003cp\u003eFinally, the tests on lubricated and dry conditions allow affirming that the best solution to form incrementally the polycarbonate sheets is choosing \u003cem\u003estairB_tp\u003c/em\u003e strategy. In fact, it guarantees reduced defectiveness in lubricated conditions and the sheets do not incur instabilities in dry conditions, though suffering a reduced formability; in addition the lubrication results quite irrelevant in terms of surface roughness.\u003c/p\u003e \u003cp\u003eThese conclusions, added up FEM predictions of reduced energy consumption from a previous authors\u0026rsquo; work on stair-based toolpath strategies, makes \u003cem\u003estairB_tp\u003c/em\u003e, and more generally an opportune choice of the toolpath strategy, a viable way on the improvement of ISF towards more efficiency and green manufacturing process.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eCompeting Interests\u003c/h2\u003e \u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e \u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\u003ch2\u003eAuthor Contributions\u003c/h2\u003e \u003cp\u003eAll authors contributed to the study conception and design. Material preparation was performed by Antonio Formisano and Massimo Durante. Data collection and analysis were performed by Antonio Formisano, Luca Boccarusso and Dario De Fazio. The first draft of the manuscript was written by Antonio Formisano and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRosa-Sainz A, Centeno G, Silva MB, Vallellano C (2021) Experimental failure analysis in polycarbonate sheet deformed by spif. J Manuf Process 64:1153\u0026ndash;1168. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.JMAPRO.2021.01.047\u003c/span\u003e\u003cspan address=\"10.1016/J.JMAPRO.2021.01.047\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosa-Sainz A, Centeno G, Silva MB et al (2020) On the Determination of Forming Limits in Polycarbonate Sheets. Mater (Basel) 13:928. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/ma13040928\u003c/span\u003e\u003cspan address=\"10.3390/ma13040928\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShaw MT (1980) Cold forming of polymeric materials. Annu Rev Mater Sci 10:19\u0026ndash;42\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBagudanch I, Centeno G, Vallellano C, Garcia-Romeu ML (2017) Revisiting formability and failure of polymeric sheets deformed by Single Point Incremental Forming. Polym Degrad Stab 144:366\u0026ndash;377. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.polymdegradstab.2017.08.021\u003c/span\u003e\u003cspan address=\"10.1016/j.polymdegradstab.2017.08.021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTofail SAM, Koumoulos EP, Bandyopadhyay A et al (2018) Additive manufacturing: scientific and technological challenges, market uptake and opportunities. Mater Today 21:22\u0026ndash;37. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.MATTOD.2017.07.001\u003c/span\u003e\u003cspan address=\"10.1016/J.MATTOD.2017.07.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJeswiet J, Micari F, Hirt G et al (2005) Asymmetric Single Point Incremental Forming of Sheet Metal. CIRP Ann 54:88\u0026ndash;114. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0007-8506(07)60021-3\u003c/span\u003e\u003cspan address=\"10.1016/S0007-8506(07)60021-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBertini L, Kubit A, Al-Sabur R et al (2022) Investigating Residual Stresses in Metal-Plastic Composites Stiffening Ribs Formed Using the Single Point Incremental Forming Method. Mater (Basel) 15:8252. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/MA15228252\u003c/span\u003e\u003cspan address=\"10.3390/MA15228252\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBehera AK, de Sousa RA, Ingarao G, Oleksik V (2017) Single point incremental forming: An assessment of the progress and technology trends from 2005 to 2015. J Manuf Process 27:37\u0026ndash;62. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.JMAPRO.2017.03.014\u003c/span\u003e\u003cspan address=\"10.1016/J.JMAPRO.2017.03.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBagudanch I, Garcia-Romeu ML, Sabater M (2016) Incremental forming of polymers: Process parameters selection from the perspective of electric energy consumption and cost. J Clean Prod 112:1013\u0026ndash;1024. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2015.08.087\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2015.08.087\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFranzen V, Kwiatkowski L, Martins PAF, Tekkaya AE (2009) Single point incremental forming of PVC. J Mater Process Technol 209:462\u0026ndash;469. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmatprotec.2008.02.013\u003c/span\u003e\u003cspan address=\"10.1016/j.jmatprotec.2008.02.013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMartins PAF, Kwiatkowski L, Franzen V et al (2009) Single point incremental forming of polymers. CIRP Ann 58:229\u0026ndash;232. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.CIRP.2009.03.095\u003c/span\u003e\u003cspan address=\"10.1016/J.CIRP.2009.03.095\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarrino L, Durante M, Formisano A et al (2014) Wear behavior of WC-Co carbides with addition of Cr3C2 and Ni\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNovakova-Marcincinova L, Novak-Marcincin J, Barna J, Torok J (2012) Special materials used in FDM rapid prototyping technology application. In: INES 2012 - IEEE 16th International Conference on Intelligent Engineering Systems, Proceedings\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEchrif SBM, Hrairi M (2014) Significant parameters for the surface roughness in incremental forming process. Mater Manuf Process. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/10426914.2014.901519\u003c/span\u003e\u003cspan address=\"10.1080/10426914.2014.901519\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLe VS, Ghiotti A, Lucchetta G (2008) Preliminary studies on single point incremental forming for thermoplastic materials. Int J Mater Form 1:1179\u0026ndash;1182. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s12289-008-0191-0\u003c/span\u003e\u003cspan address=\"10.1007/s12289-008-0191-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMart\u0026iacute;nez-Donaire AJ, Garc\u0026iacute;a-Lomas FJ, Vallellano C (2014) New approaches to detect the onset of localised necking in sheets under through-thickness strain gradients. Mater Des 57:135\u0026ndash;145. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.MATDES.2014.01.012\u003c/span\u003e\u003cspan address=\"10.1016/J.MATDES.2014.01.012\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDurante M, Formisano A, Boccarusso L, Langella A (2020) Influence of cold-rolling on incremental sheet forming of polycarbonate. Mater Manuf Process 35:328\u0026ndash;336. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/10426914.2020.1726946\u003c/span\u003e\u003cspan address=\"10.1080/10426914.2020.1726946\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFormisano A, Lambiase F, Durante M (2020) Polymer self-heating during incremental forming. J Manuf Process 58:1189\u0026ndash;1199. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.JMAPRO.2020.09.031\u003c/span\u003e\u003cspan address=\"10.1016/J.JMAPRO.2020.09.031\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhu H, Ou H, Popov A (2020) Incremental sheet forming of thermoplastics: a review. Int J Adv Manuf Technol 111:565\u0026ndash;587\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFormisano A, Boccarusso L, Capece Minutolo F et al (2017) Negative and positive incremental forming: Comparison by geometrical, experimental, and FEM considerations. Mater Manuf Process 32:530\u0026ndash;536. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/10426914.2016.1232810\u003c/span\u003e\u003cspan address=\"10.1080/10426914.2016.1232810\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDurante M, Formisano A, Lambiase F (2018) Incremental forming of polycarbonate sheets. J Mater Process Technol 253:57\u0026ndash;63. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmatprotec.2017.11.005\u003c/span\u003e\u003cspan address=\"10.1016/j.jmatprotec.2017.11.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChang Z, Chen J (2020) Mechanism of the twisting in incremental sheet forming process. J Mater Process Technol 276:116396. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.JMATPROTEC.2019.116396\u003c/span\u003e\u003cspan address=\"10.1016/J.JMATPROTEC.2019.116396\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuflou JR, Vanhove H, Verbert J et al (2010) Twist revisited: Twist phenomena in single point incremental forming. CIRP Ann 59:307\u0026ndash;310. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.CIRP.2010.03.018\u003c/span\u003e\u003cspan address=\"10.1016/J.CIRP.2010.03.018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBanhart J (2005) Aluminium foams for lighter vehicles. Int J Veh Des 37:114. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1504/IJVD.2005.006640\u003c/span\u003e\u003cspan address=\"10.1504/IJVD.2005.006640\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAsghar J, Lingam R, Shibin E, Reddy NV (2014) Tool path design for enhancement of accuracy in single-point incremental forming. Proc Inst Mech Eng Part B J Eng Manuf 228:1027\u0026ndash;1035. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/0954405413512812\u003c/span\u003e\u003cspan address=\"10.1177/0954405413512812\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDurante M, Formisano A, Lambiase F (2019) Formability of polycarbonate sheets in single-point incremental forming. Int J Adv Manuf Technol 102:2049\u0026ndash;2062. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00170-019-03298-w\u003c/span\u003e\u003cspan address=\"10.1007/s00170-019-03298-w\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang J, Nair M, Zhang Y (2016) An Efficient Force Prediction Strategy in Single Point Incremental Sheet Forming. Procedia Manufacturing. Elsevier, pp 761\u0026ndash;771\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBhushan B, Caspers M (2017) An overview of additive manufacturing (3D printing) for microfabrication. Microsyst Technol 23:1117\u0026ndash;1124. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00542-017-3342-8\u003c/span\u003e\u003cspan address=\"10.1007/s00542-017-3342-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu F, Li Y, Ghafoor S et al (2022) Sustainability assessment of incremental sheet forming: a review. Int J Adv Manuf Technol 119:1385\u0026ndash;1405. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00170-021-08368-6\u003c/span\u003e\u003cspan address=\"10.1007/s00170-021-08368-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFormisano A, Durante M, Boccarusso L, Memola Capece F (2023) A numerical approach to optimize the toolpath strategy for polymers forming. Mater Res Proc 28:1697\u0026ndash;1702. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.21741/9781644902479-183\u003c/span\u003e\u003cspan address=\"10.21741/9781644902479-183\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFormisano A, Boccarusso L, Durante M (2023) Optimization of Single-Point Incremental Forming of Polymer Sheets through FEM. Mater 2023, Vol 16, Page 451 16:451. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/MA16010451\u003c/span\u003e\u003cspan address=\"10.3390/MA16010451\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHou ZX, Wu J, Wang ZR (2004) A study of the bulge-forming of polycarbonate (PC) sheet. J Mater Process Technol 151:312\u0026ndash;315. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmatprotec.2004.04.080\u003c/span\u003e\u003cspan address=\"10.1016/j.jmatprotec.2004.04.080\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeşliu I, Tamaşag I, Slătineanu L (2021) An Experimental Study on Incremental Forming Process of Polycarbonate Sheets. Macromol Symp 395:2000282. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/masy.202000282\u003c/span\u003e\u003cspan address=\"10.1002/masy.202000282\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCao K, Ma X, Zhang B et al (2010) Tensile behavior of polycarbonate over a wide range of strain rates. Mater Sci Eng A 527:4056\u0026ndash;4061. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.msea.2010.03.088\u003c/span\u003e\u003cspan address=\"10.1016/j.msea.2010.03.088\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeșliu-Băncescu I, Slătineanu L, Dodun O, Nag\u0026icirc;ț G (2021) Influence of Lubrication and Cooling on the Quality of Single-Point Incremental Forming Parts of Polycarbonate Sheets. J Manuf Mater Process 5:75. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/JMMP5030075\u003c/span\u003e\u003cspan address=\"10.3390/JMMP5030075\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWagih A, Maim\u0026iacute; P, Blanco N, Costa J (2016) A quasi-static indentation test to elucidate the sequence of damage events in low velocity impacts on composite laminates. Compos Part Appl Sci Manuf 82:180\u0026ndash;189. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.COMPOSITESA.2015.11.041\u003c/span\u003e\u003cspan address=\"10.1016/J.COMPOSITESA.2015.11.041\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBansal A, Lingam R, Yadav SK, Venkata Reddy N (2017) Prediction of forming forces in single point incremental forming. J Manuf Process 28:486\u0026ndash;493. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmapro.2017.04.016\u003c/span\u003e\u003cspan address=\"10.1016/j.jmapro.2017.04.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHussain G, Gao L (2007) A novel method to test the thinning limits of sheet metals in negative incremental forming. Int J Mach Tools Manuf 47:419\u0026ndash;435. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijmachtools.2006.06.015\u003c/span\u003e\u003cspan address=\"10.1016/j.ijmachtools.2006.06.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosca N, Trzepieciński T, Oleksik V (2022) Minimizing the Forces in the Single Point Incremental Forming Process of Polymeric Materials Using Taguchi Design of Experiments and Analysis of Variance. Mater (Basel) 15:6453. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/ma15186453\u003c/span\u003e\u003cspan address=\"10.3390/ma15186453\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSavitsky AV, Gorshkova IA, Frolova IL et al (1984) The model of polymer orientation strengthening and production of ultra-high strength fibers. Polym Bull 12:195\u0026ndash;202. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00275968\u003c/span\u003e\u003cspan address=\"10.1007/BF00275968\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDurante M, Formisano A, Langella A, Capece Minutolo FM (2009) The influence of tool rotation on an incremental forming process. J Mater Process Technol 209:4621\u0026ndash;4626. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jmatprotec.2008.11.028\u003c/span\u003e\u003cspan address=\"10.1016/j.jmatprotec.2008.11.028\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Incremental sheet forming, Polycarbonate, Defectiveness, Forming forces, Surface quality","lastPublishedDoi":"10.21203/rs.3.rs-4124482/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4124482/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe incremental sheet forming has been largely investigating in the last two decades because of its versatility and cost-effectiveness which make this technology especially viable for manufacturing highly customized parts, as well as small and medium-sized batches. One of its main strengths is that it allows reaching greater formability, compared to conventional sheet forming processes; in contrast, defect phenomena like twisting and wrinkling occur frequently and strongly influence the geometric accuracy of the formed parts. All these aspects are dramatically accentuated when forming soft materials like thermoplastics. With these premises, the following research aims to investigate the effects of the toolpath strategy on the occurrence of failures and defects in the incremental sheet forming under very severe process conditions; thin polycarbonate sheets were formed to obtain cone frusta with a fixed wall angle, imposing four unidirectional helical trajectory-based toolpaths, one traditional and three stair strategies. The analysis of the forming force trends, the evaluation of the worked surface quality and the monitoring of the defectiveness highlight understanding the advantages of an appropriate toolpath strategy to improve the accuracy of the incremental sheet forming of thermoplastic parts.\u003c/p\u003e","manuscriptTitle":"Effects of toolpath on defect phenomena in the incremental forming of thin polycarbonate sheets","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-27 11:12:38","doi":"10.21203/rs.3.rs-4124482/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revisions Needed","date":"2024-05-23T16:45:00+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-03-22T21:12:58+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-03-22T20:56:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-03-21T02:11:40+00:00","index":"","fulltext":""},{"type":"submitted","content":"The International Journal of Advanced Manufacturing Technology","date":"2024-03-18T11:39:21+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"1593715b-19d8-4735-8e83-9e11db764e03","owner":[],"postedDate":"March 27th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-07-18T13:13:34+00:00","versionOfRecord":{"articleIdentity":"rs-4124482","link":"https://doi.org/10.1007/s00170-024-14047-z","journal":{"identity":"the-international-journal-of-advanced-manufacturing-technology","isVorOnly":false,"title":"The International Journal of Advanced Manufacturing Technology"},"publishedOn":"2024-06-27 13:13:34","publishedOnDateReadable":"June 27th, 2024"},"versionCreatedAt":"2024-03-27 11:12:38","video":"","vorDoi":"10.1007/s00170-024-14047-z","vorDoiUrl":"https://doi.org/10.1007/s00170-024-14047-z","workflowStages":[]},"version":"v1","identity":"rs-4124482","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4124482","identity":"rs-4124482","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}