The next episode of Tale of the Tape is here! Matt Tempelis walks us through the importance of compression deflection and compression set.
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Transcript:
Hello and welcome to another episode of Tale of the Tape. I'm Matt Tempelis, President of Engineered Materials and your Minister of Tape. Today I'd like to talk about the importance of compression deflection and compression set when selecting foam for your gasketing application. We've talked a lot about a variety of application requirements. Compression deflection and compression set are some of the most important because they really get down to some of the critical criteria of what you're using your gasket for.
Compression deflection measures the force required to compress a specific size foam a specific distance. Typically the compression level is 25%, and the number that is reported back is in pounds per square inch. It's a great indicator of a foam's firmness and feel, and it's a key to choosing the right thickness material and the force required to create a positive seal. We'll take a look at the nominal compression deflection values of a couple of different foams right now. The Crushed EPDM EF0 from Armacell and the PVC Foam LC 710 from Gaska both have less than1 PSI compression deflection, and you can feel and see how soft those materials are. If you're talking about the OER from Armacell Vinyl Nitrile, it’s about 2 to 4 lbs. It feels very soft to the touch and you can see it compressing, but it does have some push back. Lastly, the 2003 Neoprene from Armacell has 9 to 13 lbs. It's very firm foam and it's very challenging to compress. You can see the differences in compression deflection amongst these four samples.
Compression set measures the thickness loss of foam under compression from its original thickness. ASTM D1056 measures it after a specific compression percentage for a specific time under a specific temperature. Typically, the percentage used is compressing a foam 50% of its original thickness and then seeing how it rebounds. The higher the compression set number percentage, the higher the foam deformation that you can expect under compression. And the fact that that foam will not return to its original thickness. The lower the percentage, the more resilient that foam is. Let's see what we're talking about with regards to compression set right now. Armacell's OER Vinyl Nitrile closed cell foam does experience a percentage of compression set. We did put it under 50% compression and we do see a loss of thickness at that compression.
How much compression deflection and compression set do you need for your application? Well, obviously it depends on your requirements. Certainly it is best to choose the thinnest material that will work for your application. You avoid unnecessary costs and avoid or minimize leak paths that can cause failure. Compression deflection will tell you kind of that feel of that material, how soft or firm it is. It will also give you a great view to how much force that needs to be applied to create a positive seal while avoiding compression set limits. You never want to compress your foam too much because it actually breaks down closed cell foam. Compression set really gives you a view to how much thickness you're going to lose and whether or not you may need that. Your application is going to tell you if you need a very resilient, low compression set material or that your positive seal can handle some compression set in the application.
I hope you see how important compression deflection and compression set are in designing your gasketing and sealing applications. We have a variety of different foam products here on site at Engineered Materials that we can laminate pressure sensitive adhesives to, cut into custom parts to meet your specific application requirements. We're here to help you. We'll see you next time on Tale of the Tape.
