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

Abstract

Polymeric materials are increasingly used in the automotive industry, aeronautics, medical device industry, etc. due to their advantage of providing good mechanical strength at low weight. The incremental forming process for polymeric materials is gaining increasing importance because of the advantages it offers: relatively complex parts can be produced at minimum cost without the need for complex and expensive dies. Knowing the main strains and especially the thickness reduction is particularly important as it directly contributes to the mechanical strength of the processed parts, including in operation. For the design of experiments, the Taguchi method was chosen, with an L18 orthogonal array obtained by varying the material on two levels (polyamide and polyethylene) and the other three parameters on three levels: punch diameter (6 mm, 8 mm and 10 mm), wall angle (50°, 55° and 60°) and step down (0.5 mm, 0.75 mm and 1 mm). The output parameters were strain in the x direction, strain in the y direction, major strain, minor strain, shear angle and thickness reduction. Two analyses were conducted: signal-to-noise ratio analysis with the smaller-is-better condition and analysis of variance. The optimum values for which the thickness was reduced were the following: wall angle of 50°, punch diameter of 10 mm and step down of 0.75 mm.

Thermo-Mechanical Numerical Simulation of Friction Stir Rotation-Assisted Single Point Incremental Forming of Commercially Pure Titanium Sheets

“…Nevertheless, the large-scale applications of SPIF are restricted due to their much longer processing time than during conventional SMF [23]. This disadvantage can be compensated by the fact that in SPIF much larger deformations can be obtained without the risk of wall cracking [24] and the forming forces are much lower than during conventional SMF [25]. The technological parameters affecting the possible use of SPIF are tool rotational speed [26], tool diameter [27], lubrication conditions [28] and step size [29].…”

Experimental Evidence on Incremental Formed Polymer Sheets Using a Stair Toolpath Strategy

“…ISF represents a viable alternative to conventional technologies based on heatingshaping-cooling manufacturing routes, guaranteeing high levels of the materials' formability and being able to be carried out at room temperature; a clamped sheet is progressively deformed by a forming tool that, when controlled using a CNC machine, describes a path to manufacture the final part [8]. Due to its characteristics, it is strongly oriented towards the production of batches with small and medium sizes in a variety of fields; for example, aircraft canopies or medical prostheses can be obtained from polymer sheets formed using ISF [9]. Furthermore, recent studies have highlighted that ISF for polymer parts allows a reduction in energy consumption compared to conventional processes [10].…”