Author’s Note: Since it’s been about 15 years since my Die Basics 101 series, I’ve been asked to write another series of articles on the fundamentals of stamping die design and construction. As experienced toolmakers and engineers retire, many companies have struggled to find and hire individuals with basic metal stamping tooling knowledge. I hope this series of articles will help to educate readers on all the critical steps and processes required to design and build a stamping die.
A stamping die is typically a one-of-a-kind, custom-designed tool. Unlike a store-bought item, it doesn’t come with instructions for assembly, operation, and maintenance. If even one of those factors isn’t done correctly, catastrophic tooling and stamping failure can result.
But first things first.
Should This Part Be Stamped?
Before you can even begin to think about the process needed to design and build the die, you must determine if the part in question can actually be made using sheet metal stamping. Many parts have dimensional and tolerancing characteristics that cannot be met using a conventional stamping process, so they must be manufactured using an alternative method, such as casting followed by machining to the specified tolerance.
It takes years of experience to be able to look at a part and determine if it can be stamped. And just because a part can be made with stamping doesn’t mean it should. Sheet metal stamping dies typically are meant to produce very large part volumes. For low part volumes, it sometimes makes sense to produce the parts using lower-cost methods like press brake bending, welding, and machining.
Process Engineering and Die Design
Don’t confuse a die designer with a process engineer. Process engineers determine the process steps that must be executed to transform flat sheet metal from a blank to a finished part. It may take a single-station line die or a 40-station progressive die. This is undisputedly the most important step that determines the success of the stamping operation. If the process for making the part, even a single forming or cutting operation, is not correct, the die and stamping process will fail.
Die designers determine the mechanical means for executing these process steps as easily as possible. The die designer makes decisions such as tool steel type, die geometry, and die length. Experienced die designers often act as the process engineer as well, meaning they determine the number of steps needed to make the part, as well as design the mechanical means of executing the process.
Part Geometry and Material
Before determining the steps needed to make the part, you must analyze the part print, looking carefully at the part geometry, the specified tolerance, and the material type and thickness. These last two factors are critical when deciding on the manufacturing process steps and tool design. Don’t assume the part can be made from the specified material. Just because it’s been designed to be made from a certain metal doesn’t mean it can be made from that material.
To make a good decision on the process steps required for part manufacture, both the process engineer and die designer must understand the effects that the part material has on the process and the tool design. The part material influences: