When selecting a foam for your application, have you ever wondered if open or closed-cell foams are more effective? At Marian, we recommend materials based on a product’s application. This is certainly true when it comes to foam materials for use as gaskets. This means in order to recommend the best material, our first step is to understand the conditions, forces, stress and other requirements the gasket will experience in your application.
Open cell foam is composed of interconnected cells in a web-like fashion that has some amount of openness within each cell connected to the next cell in the web. To be considered open cell, more than 50% of its cells must be open. A common misconception is that open cell materials are an inferior material for use in static gaskets and seals.
It's true that in an uncompressed state, open cell foam (even micro-cellular) will allow some level of ingress. Because of this, you wouldn't want to use an open cell foam in a life vest.
Closed cell foams are composed of a cluster of independent bubbles with gas trapped inside each cell. Most closed cell foam materials have some open cells within their matrix. These may be cells that did not fully form during the blowing process. Typically, a foam should have more than 70% closed cells before it can be labeled as such.
When the openings within the cell are very small in a dense (heavy) foam, the material is known as micro-cellular open cell. These materials can form a more effective seal when sufficiently compressed and offer a longer service life than many closed-cell foams when used in gaskets.
Under constant compression, a closed cell foam may lose compression force due to permeation of the gas enclosed in the cells or cell rupture from pressure. Under the same conditions, the micro-cellular open cell structure is able to maintain compression force because the cell structure is an interconnected web and not dependent on the gas trapped inside each cell. Learn more about compression set resistance in foam.
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Marian works with the top foam suppliers to offer our customers the highest-quality material solutions for their applications. Learn more about the foam and sponge materials we die-cut, laminate with PSA, and more for our customers.
Marian has maintained a strong relationship with Rogers Corporation since the 1970s and is recognized as a Rogers Corporation Preferred Converter. This means that we are a trusted supplier and converter of their materials.
Are you working on an application requiring a static sealing foam gasket and don't know where to start? Contact us and we'll put you in touch with one of our technical material specialists in your area.