Improve Single Point Incremental Forming Process Performance Using Primary Stretching Forming Process

Incremental forming (IF) is one of the sheet metals forming technique where is a sheet formed into a final workpiece using a series of small incremental sheet deformations. In Incremental sheet metal forming process, one of the important steps is to produce the forming part with acceptable performance such as product accurate and uniform thickness distribution with a homogenous grain distribution that consider as the main challenge of incremental sheet metal forming process. This work is carried out to find the best method to control the product performance of the final parts using a new method of applying a primary stretching forming process with a hemispherical forming tool followed by single point forming SPIF. Different primary forming depth (10, 20, 30 and 40 mm) were applied to find their effect on the forming behavior of the final product and compare them to the single point forming product without using a primary forming process. The experimental results showed the improvement in microstructure by applying SPIF process after primary stretching, with grain size of 36 mu m at 40 mm forming depth as compared to 52 mu m when using pure SPIF, a twining effects presence in both cases. A high improvement with a minimum dimension deviation of (6%) with respect to the forming process in single point incremental forming process without a primary forming process that result forming deviation equal to (11.6%) with respect to the desired design. The thickness distribution of the final product also improved by applying the primary stretching forming process before the SPIF process reaches to (6.9%, 9.1%, 14.9% and 21.5%) at forming depth (10, 20, 30 and 40) mm, respectively.