Experimental studies and finite element simulation on positive and negative incremental forming of AISI 316L Sheets

Abstract

Incremental sheet forming (ISF) process has been identified as a potential and economically viable process for sheet metal prototypes and low volume production. The process is very flexible and can be carried out on a computer numerical control (CNC) milling machine, robots or machines specially designed for ISF applications. In this process, a flat sheet is held in a simple fixture and is deformed into required shape by a spherical-ended tool. The path of the tool is controlled by a part program generated using computer aided manufacturing (CAM) software. The main attractive features of this process are simple tooling, and better forming characteristics than the conventional sheet metal forming processes. The process has been demonstrated as a potential process for forming complex shapes, automotive service panels, head light casing and customized bio-medical parts, such as, ankle support, plate prosthesis, implants for arthroplasty, cranial implants etc. newlineIn this study, AISI 316L stainless steel sheets of uniform thickness 0.8 mm were used in Incremental Sheet Forming (ISF) with the target of investigating influence of forming parameters using four different techniques such as Single Point Incremental Sheet Forming (SP-ISF), Rubber Pad Support - Incremental Sheet Forming (RPS-ISF), Static Pressure Support - Incremental Sheet Forming (SPS-ISF) and Metal Die Support - Incremental Sheet Forming (MDS-ISF). Taguchi Design of Experiments combined with Entropy-VIKOR has been deployed for the study of the influence of forming parameters (tool diameter, step depth, feed rate and spindle speed) on output responses (thickness of the wall and surface roughness). The objectives were to maximise the Thickness of Top Wall Angle (Th TWA) and Thickness of Bottom Wall Angle (Th BWA) and to minimise the Surface roughness of Top Wall Angle Surface Roughness (SR TWA) and Surface roughness of Bottom Wall Angle Surface Roughness (SR BWA). newline newline