Tuesday, August 14, 2012

High Precision Blanking Tool Design

Special products require special tooling and design. Blanking thin foil type material is a challenge of its own. E.g., a 0.002 - 0.005 thickness stock to be blanked requires such small amount of cutting clearance that it is a very difficult task for most tool makers and for the equipment to do properly.

For this particular design the finished blank was made of three layers. There were two carbon film layers of 0.003 thick with a copper foil between 0.0005 thickness. The requirements were the following:

1. The part must be perfect, have no bur at all.
2. Part is rejected if the carbon chips off from the metal.
3. Part is rejected if the carbon is separated from the metal at any given area.

The customer provided samples, made by others that did not meet the request and were then rejected.

• The above criteria was achieved by using the right amount of cutting clearance for the design that this particular material needed.
• To avoid separation of the layers, the blank must have the least amount of flexing.
• To eliminate chipping of the brittle carbon layers that were only semi bonded to the copper were another challenge.
• A gentle even holding pressure was required to hold the material while it was blanked, while reducing the travel distance of the blank inside the die cavity.

To accommodate all of the above, the tool had to be well guided, with low impact movement with no vibration or sudden shocks.

The part was to be handled by lab technicians so the tool could be built for this "Clean Room" environment.

The result was excellent as expected, and the parts came out perfect.

The combination of a good design and precision tool making was the key to this success.

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