Effect of Tool Geometry on Punching Performance

In today’s competitive industrial environment, the quality of a product is no longer the major factor which influences purchase by a customer, it is simply a prerequisite for competing in the market. To compete and survive, the necessity is to provide the product at an affordable price, a target that can only be attained through actions such as improving the efficiency of manufacturing operations. In sheet metal industries, the cost of tooling contributes a considerable part to the overall manufacturing cost of a component. It is imperative to keep this cost down by ensuring the tool operates uninterrupted for long periods of time, achievable in one way by reducing the stress on the tool during punching by optimizing the clearance between the die and the punch. This paper deals with this problem using finite element techniques. Having created models of various punch configurations, one is able to analyze the effect of variations in tool geometry on punching force and tool deformation, a parameter highly relevant in assessing performance in terms of the accuracy of machined components. Computed results using FE models are compared against results obtained through experimentation. Due to the nature of the punching process being inherently noisy, consideration was given to noise levels, how they are affected by changes in tool geometry, and the subsequent effect on the workforce considering the fact that reducing stress on the operator could only improve quality and productivity. Finally, some suggestions are given as to how the efficiency of a punching tool and quality of the punched product can be improved.