Case Studies

Case Study 5

The use of pinch trim dies has eliminated the need to machine the ends of many drums and drawn washers; reducing the cost of these parts by almost $1ea.

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When looking at the edge of a drawn cup or can there are really 3 options:
1. You can leave the edge as is from the forming or drawing operation

2. You can machine it square or with some other geometry

3. You can use a pinch trim in the die

A regular formed edge may be acceptable in many instances, however it produces a very inconsistent edge over the profile of the part as you can see from the image below.

Formed Edge Profile

To counteract this inconsistency in the run out, the parts are often machined.  Below you can see the before and after picture of this same part.

Formed vs Machined Edge Profile

You can also change the geometry of the edge from a rounded…

Formed Edge 1

to either a square or some other geometry machined into the edge.

Machined Edge Square Machined Edge With Chamfer

The final option is the pinch trim. This method can provide a uniform profile and run out, but does not require a secondary (and often expensive) operation.

Pinch Trim1