Optimization of multiple quality characteristics in two-point incremental forming of aluminum 1050 by grey relational analysis

Abstract

Incremental forming process is used to reduce the cost of sheet metal forming process when the low volume batches, customized parts or prototypes have to be manufactured. During recent years, some modifications were associated with this process to enhance formability, dimensional accuracy and product quality. In the present study, an experimental attempt was made to analyze formability of aluminum 1050 in two-point incremental forming process. Here, the effect of incremental forming parameters such as tool nose diameter, wall angle, spindle speed and deep step was studied on minimum thickness, surface quality, and springback. The obtained results showed that desirable thickness and corresponding formability are enhanced when the mandrel with lowest angle, i.e. 63° is utilized and tool tip diameter is 15 mm. It is also found that the increase in spindle speed causes reduction of formability due to exerting high temperature in the sheet material that increases thinning, while the increase in tool rotation improves both the dimensional accuracy and surface quality. Also, it was found that the increase in deep step and wall angle has a negative effect on quality characteristics. By performing multi-objective optimization through grey relational analysis, it is found that 15 mm tool nose diameter, 63° wall angle, 800 r/min spindle speed and 0.2 mm deep step are optimum parameter settings that cause 63% improvement in overall quality characteristic from initial parameter setting.