Minimizing the Forces in the Single Point Incremental Forming Process of Polymeric Materials Using Taguchi Design of Experiments and Analysis of Variance

Abstract

The aim of the present paper is that of conducting a study on the basis of which the optimal parameters for the manufacturing of polymer parts by means of the single point incremental forming process can be chosen in such a way that the process forces have minimum values. Two polymeric materials with a 3 mm thickness, polyamide and polyethylene, were chosen for the analysis. The other input parameters that were considered were: the punch diameter, the step on vertical direction and the wall angle. The Taguchi method was chosen for the design of experiments. Each of the input parameters, except for the material, were varied on three levels—for the punch diameter: 6 mm, 8 mm and 10 mm; for the step on vertical direction: 0.5 mm, 0.75 mm and 1 mm; and for the wall angle: 50°, 55° and 60°. Forces were measured in the three directions of the coordinate axes and the results were analyzed based on the signal-to-noise ratio and an analysis of variance with the aim of minimizing the values of the forces. Considering the input parameters analyzed, it was concluded that the forces are most influenced by the material, followed by the punch diameter, the step on vertical direction and the wall angle.

A numerical approach to optimize the toolpath strategy for polymers forming

“…5 reports the trend of the vertical (FZ) and of one only horizontal force (FX) for the different toolpath strategies. It is possible to note that the forces for the first two strategies show the typical trend for the manufacture of cone frusta by ISF with a spiral toolpath [5,7].…”

Minimizing the Main Strains and Thickness Reduction in the Single Point Incremental Forming Process of Polyamide and High-Density Polyethylene Sheets

“…The friction between the hemispherical punch and the polymeric material is lower in the case of PA than in the case of HDPE due to the crystalline structure leading to better surface quality. This also leads to lower deformation forces in the case of PA than in the case of HDPE [ 14 ]. Moreover, since HDPE, with its tighter bonds between the molecular chains, is stiffer, the maximum values of the strains in both x and y directions as well as of the major strain, thickness reduction and shear angle are lower than those obtained under the same manufacturing conditions for polyamide.…”

“…Both materials, PA and HDPE, are materials with high elongation at break and, in order to highlight their mechanical characteristics, they were subjected to uniaxial tensile testing in a previous paper [ 14 ]. Thus, for PA, the following mean values were obtained: for Young’s modulus, E = 1827.3 MPa; for maximum tensile stress, σ max = 41.5 MPa; and for tensile strain at maximum tensile stress, ε max , Ts = 126.5%.…”

“…Polymeric materials that can be processed by SPIF are diverse, starting from materials such as polyamide and polyethylene [ 14 ], polyvinylchloride [ 15 ] and polycarbonate [ 16 ] to composite materials having as the basic matrix one of the aforementioned materials reinforced with different fibers (most often glass fiber) [ 17 ]. The percentage of glass fiber varies, with the most recent studies analyzing the behaviour of these materials during SPIF when using polyamide 6 reinforced with 30 wt.% glass fiber [ 18 ].…”

“…Among the most important output parameters of SPIF are the forces and deformations occurring during the forming process. The study of the variation of forces in the SPIF manufacturing of polymeric materials has been carried out either by simulation using the finite element method for glass polymers and polyvinylchloride and polycarbonate sheets [ 41 ] or by experiment for polyamide and polyethylene [ 14 ]. The work of Rai et al allows the prediction of forces and the calculation of the fracture energy based on a numerical simulation for the frustum of pyramid-shaped parts made of polycarbonate [ 42 ].…”