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Maintaining tight die cutting tolerances is imperative! However, holding tight die cutting tolerances can be a challenge when cutting flexible, soft, and thick materials. At Frank Lowe, we’re proud to be the leading die cutting and custom manufacturing firm. We use cutting-edge techniques and innovative equipment to maintain the tightest die cutting tolerances — even when combined with laminations. Let’s take a closer look at die cutting tolerances and why other firms may not be able to produce the same results.
Even with the most cost-efficient tooling, die cutting a firm, thin material with a reduced allowable tolerance is very common. However, die cutting a complex, soft, thick material can create complications for meeting tight tolerance requirements. Most of this can be directly attributed to deflection and compression.
In the most simple form, die cutting is nothing more than cutting through a material with force. In the process, the sharp knife or dies slices through the elastomer to the rigid surface underneath. If the material is soft, however, the elastomer will compress and become thinner. At the same time, the material will initially want to resist. Even though the blade is sharp, it doesn’t immediately penetrate the softer material.
When the material starts to compress, it will naturally restructure itself and the unstressed cells will be rearranged, which is called deflection. With deflection, the material is attempting to position itself in a particular manner, typically away from the cutting edge of the blade. As the soft elastomer compresses until it can longer flex, the blade will eventually slice through it and make contact with the contact surface.
For example, if you have ever tried to cut a fresh loaf of bread with a standard knife — one that isn’t serrated —you can understand compression and deflection. As you press down on the loaf of bread with the blade, the bread will flex, compress, and distort prior to making a complete cut. In other words, the bread is rearranging and moving.
Similar to bread, whenever a soft, thick elastomer is being die cut, such as foam, the material will compress prior to the die cutting through it. What makes it difficult is that not all compressions are the same or consistent. In many instances, cells near the top will have compressed more than the cells near the bottom, which can cause an uneven cut profile as well as jagged edges that are not perpendicular to the bottom or top of the material. This is called the dish effect or apple core effect.
As the thickness of the material increases or as the softness increases, these effects can be more noticeable and dramatic. This remains true whether softness is measured in modulus, density, durometer, or compression force deflection. Materials that are thinner — even if they are soft — will experience this effect to a substantially lesser degree. In fact, the uneven edge cut on thinner materials may not be recognizable to the unaided eye. However, when you take a closer look at the gasket or component under magnification, it can easily be seen.
When creating a die cut gasket, part, or component for any engineering solution or application, the importance of materials selection cannot be understated. The ability of the elastomer or foam to fill voids, flex, easily compress, and conform to irregular surfaces can offer a full range of benefits. These materials can be used to block light, seal, absorb vibration and shock, and much more because of their conformability and softness.
Different elastomers and foams are regularly chosen for the exact properties that can make them more difficult to die cut. Because of the inherent softness and conformity of many foams and elastomers, extreme precision is required. At Frank Lowe, precision die cutting and expert materials selection are two of our specialties. We’ll carefully work to understand your application, guide you to the most suitable elastomer, and then provide die cuts with tight tolerances that will fit into strictly defined spaces.
Since 2002, Randy Cohen has served as the Senior Vice President of Frank Lowe — leading Sales and Marketing as well as a variety of Administrative operations. Randy has 25 years of experience with a background in sales & marketing, production and business management, serving both government agencies and private industry. He holds a B.A from Syracuse University and a Masters and Professional Diploma from Fordham University. Randy uses his unique set of experiences to help businesses and entities across all sectors explore, pursue, and create better solutions.