Although, three-dimensional printing has several advantages, however there are currently many limitations. In particular, printed products using composite materials such as fiber-reinforced plastic have yet to achieve the same mechanical properties as those obtained from conventional manufacturing methods. In addition, fabricating thin plates or thin shell shapes with sufficient strength is challenging. Incremental forming enables high-mix, low-volume production of thin sheets. This method applies incremental deformation to thin sheets, the desired shape is obtained by accumulating the deformation, and no dies are required. Carbon-fiber-reinforced plastic (CFRP) materials have high specific strength. Discontinuous-fiber CFRP is capable of large plastic deformation under appropriate conditions due to the discontinuity of the reinforcement, and its mechanical properties are nearly isotropic due to the random fiber arrangement. The authors focused on this property and studied the application of single-point incremental forming to discontinuous carbon-fiber-reinforced polyamides. In this study, the workpiece was formed by heating it locally to a deformable temperature by the frictional heat between the rotating tool and the workpiece. The forming experiment was also conducted in an oil bath to keep the entire material at a suitable forming temperature. The results showed that the spindle speed affected forming results even in an oil bath and that heating using an oil bath suppressed deviations from the sine law for thickness and wall angle due to elastic deformation.

1. [1] Nissan Motor Co., Ltd., “The shaping of things to come,” 2019. http://global.nissanstories.com/en/releases/the-shaping-of-things-to-come [Accessed August 17, 2023]
2. [2] E. Leszak, “Apparatus and process for incremental dieless forming,” US Patent, US-3342051-A, 1967. https://patents.google.com/patent/US3342051A/en [Accessed August 27, 2023]
3. [3] T. Obikawa, S. Satou, and T. Hakutani, “Dieless incremental micro-forming of miniature shell objects of aluminum foils,” Int. J. Mach. Tools Manuf., Vol.49, Nos.12-13, pp. 906-915, 2009. https://doi.org/10.1016/j.ijmachtools.2009.07.001
4. [4] A. K. Behera, B. Lu, and H. Ou, “Characterization of shape and dimensional accuracy of incrementally formed titanium sheet parts with intermediate curvatures between two feature types,” Int. J. Adv. Manuf. Technol., Vol.83, No.5, pp. 1099-1111, 2016. https://doi.org/10.1007/s00170-015-7649-2
5. [5] S. Matsubara, “A computer numerically controlled dieless incremental forming of a sheet metal,” Proc. Inst. Mech. Eng. B: J. Eng. Manuf., Vol.215, No.7, pp. 959-966, 2001. https://doi.org/10.1243/0954405011518863
6. [6] V. S. Le, A. Ghiotti, and G. Lucchetta, “Preliminary studies on single point incremental forming for thermoplastic materials,” Int. J. Mater. Form., Vol.1, No.1, pp. 1179-1182, 2008. https://doi.org/10.1007/s12289-008-0191-0
7. [7] V. Franzen, L. Kwiatkowski, P. A. F. Martins, and A. E. Tekkaya, “Single point incremental forming of PVC,” J. Mater. Process. Technol., Vol.209, No.1, pp. 462-469, 2009. https://doi.org/10.1016/j.jmatprotec.2008.02.013
8. [8] I. Bagudanch, M. L. Garcia-Romeu, G. Centeno, A. Elías-Zúñiga, and J. Ciurana, “Forming force and temperature effects on single point incremental forming of polyvinylchloride,” J. Mater. Process. Technol., Vol.219, pp. 221-229, 2015. https://doi.org/10.1016/j.jmatprotec.2014.12.004
9. [9] P. A. F. Martins, L. Kwiatkowski, V. Franzen, A. E. Tekkaya, and M. Kleiner, “Single point incremental forming of polymers,” CIRP Ann., Vol.58, No.1, pp. 229-232, 2009. https://doi.org/10.1016/j.cirp.2009.03.095
10. [10] M. B. Silva, L. M. Alves, and P. A. F. Martins, “Single point incremental forming of PVC: Experimental findings and theoretical interpretation,” Eur. J. Mech. – A/Solids, Vol.29, No.4, pp. 557-566, 2010. https://doi.org/10.1016/j.euromechsol.2010.03.008
11. [11] S. Alkas Yonan, C. Soyarslan, P. Haupt, L. Kwiatkowski, and A. E. Tekkaya, “A simple finite strain non-linear visco-plastic model for thermoplastics and its application to the simulation of incremental cold forming of polyvinylchloride (PVC),” Int. J. Mech. Sci., Vol.66, pp. 192-201, 2013. https://doi.org/10.1016/j.ijmecsci.2012.11.007
12. [12] S. Alkas Yonan, M. B. Silva, P. A. F. Martins, and A. E. Tekkaya, “Plastic flow and failure in single point incremental forming of PVC sheets,” Express Polym. Lett., Vol.8, No.5, pp. 301-311, 2014. https://doi.org/10.3144/expresspolymlett.2014.34
13. [13] I. Bagudanch et al., “Manufacturing of polymeric biocompatible cranial geometry by single point incremental forming,” Procedia Eng., Vol.132, pp. 267-273, 2015. https://doi.org/10.1016/j.proeng.2015.12.494
14. [14] R. Sridhar and D. Rajenthirakumar, “Incremental forming of polymer-numerical and experimental investigation,” Polym. Polym. Compos., Vol.24, No.7, pp. 489-498, 2016. https://doi.org/10.1177/096739111602400707
15. [15] T. Ikari, H. Tanaka, and N. Asakawa, “Development of a novel shell shaping method with CFRTP: Forming experiment using localized heating in processing point,” Mater. Sci. Forum, Vol.874, pp. 40-45, 2016. https://doi.org/10.4028/www.scientific.net/MSF.874.40
16. [16] H. Tanaka, K. Hoshino, and N. Asakawa, “Development of a CAM system with linear servo motor for automation of metal hammering,” Key Eng. Mater., Vol.625, pp. 360-365, 2014. https://doi.org/10.4028/www.scientific.net/KEM.625.360
17. [17] H. Tanaka, K. Yamada, and T. Ikari, “Feasibility study of laser-assisted incremental forming for carbon fiber reinforced thermo plastic based on 3D-CAD data,” Int. J. Automation Technol., Vol.17, No.2, pp. 144-155, 2023. https://doi.org/10.20965/ijat.2023.p0144
18. [18] W. L. Edwards, T. J. Grimm, I. Ragai, and J. T. Roth, “Optimum process parameters for springback reduction of single point incrementally formed polycarbonate,” Procedia Manuf., Vol.10, pp. 329-338, 2017. https://doi.org/10.1016/j.promfg.2017.07.002
19. [19] M. Bambach, “A geometrical model of the kinematics of incremental sheet forming for the prediction of membrane strains and sheet thickness,” J. Mater. Process. Technol., Vol.210, No.12, pp. 1562-1573, 2010. https://doi.org/10.1016/j.jmatprotec.2010.05.003
20. [20] G. Ambrogio, L. Filice, F. Gagliardi, and F. Micari, “Sheet thinning prediction in single point incremental forming,” Adv. Mater. Res., Vols.6-8, pp. 479-486, 2005. https://doi.org/10.4028/www.scientific.net/AMR.6-8.479