Practically every non-metallic gasket is cut from a sheet or roll of gasket material. Cutting methods include oscillating knife, laser, waterjet and steel punch dies although the most common process is steel rule die cutting. It’s cost-effective for medium quantity orders but needs special tools. Knowing a little about the process will help gasket buyers understand when this might be the one to use.
The “cookie cutter” process
A steel rule die is a steel strip bent to the profile of the part being cut. This is embedded into a plywood or phenolic board that holds it in shape. The exposed edge of the steel knife is sharpened so it can cut through the material. The board is then mounted into a press. Bringing the tool down into the gasket material cuts out the gasket.
To use the material efficiently gasket makers typically “nest” steel rule dies. This might mean cutting a small gasket from the center of a much larger one or combining a number of different gasket shapes in one tool.
For higher volume production a gasket maker might use a rotary die machine. Here the steel rule die is wrapped around a cylinder. Strip material is fed underneath and the die cuts out the gasket shapes as it rotates.
When cutting all the way through normal practice is to have a relatively soft sacrificial material underneath. This helps extend the life of the cutting edge. However, sometimes it’s better not to cut all the way through. This is “kiss cutting,” because the knife just “kisses” the backing material. It keeps the gaskets together in a single sheet while making them easy to separate when needed. This simplifies storage and is particularly useful when the gasket material has a pressure sensitive adhesive backing.
Dies for your gaskets
We’ve been cutting gaskets at Hennig for many years and have a lot of dies in inventory. If you want die cut gaskets it’s possible we already have the tools needed. Call or email to find out.