The Precision Touch in Custom Metal Stamping

Very intricate and complex products can be produced using a metal stamping die. This is due to advances in die design and build technologies. Products can be cut, formed, drawn, twisted, coined, extruded, welded, and tapped. Also, parts can be assembled in the die by employing a variety of technologies. As a result, the metal stamping process economically competes with other processes such as chemical etching, laser cutting, screw machining and die casting, even at low production quantities.

The following design parameters are intended to make product designers aware of how their decisions affect the metal stamping process. If a functional feature must be designed despite any of these general parameters, it is recommended that the designer work with the supplier’s engineers to minimize the adverse the metal stamping process, thus reducing the cost of the die and parts.

Avoid Sharp Corners
Internal corners should be filleted with a radius that is equal to at least one material thickness. Sharp external corners can be attained in a stamping die only by making 2 separate cuts. This most often produces a burr as the material at the intersection flows away from the cutting forces on the 2^nd cut.

Avoid Very Small Features
Small features relative to the material thickness cause high stresses in metal stamping components. Although specialized methods exist to produce features with dimensions equal to or less than one material thickness, they decrease the capability and reliability of the metal stamping process.

Avoid Small Bend Radii
The smallest permissible bend radius is dependent upon the material type and temper. If too small of a radius is used, the material on the outside of the bend will crack. Normally a bend radius equal to the material thickness is adequate. However, with extra hard or spring tempered copper-based material and full hard stainless steels, the bend radius should be increased to 1 1/2 to 2 times the material thickness.

Avoid Severe Transitions on Cylindrical Parts
As a cylindrical part transitions from one diameter to another, the material must stretch. This is a result of the difference in the amount of material required for each diameter. As shown in the diagram below, this stretching must occur over a gradual transition in order to avoid tearing. It is best to utilize a transition angle no more than 45° on a medium tempered material (soft tempered material allows more, hard tempered less).