Patent #'s 10525627 and 10220559
We were recently presented with a new (to us) material to test with our hollow gasket process: Tangent Industries 60102 material. This material has some interesting characteristics: low or almost no tack after cure, soft, and relatively low UV exposure energy requirements.
One other characteristic was interesting however: the viscosity relative to silicones (which had occupied the bulk of our previous testing) was much, much lower. The net result of addressing this characteristic has given us process controls far more advanced than our previous attempts and have had follow-on implications for previously tested materials.
Image number one shows the cut-out section of a gasket with approximately a 0.15inch diameter and a hollow that accepts a 0.090 inch pin gauge without deforming (see image two). A 0.107 pin gauge actually still slides easily into the gasket center but it also raises the gasket and so clearly the hollow is larger than the 0.090 height might imply. However, calculating surface areas conservatively, the hollow provides a 34% reduction in material usage.
When designing applications for hollow gaskets, a solid "O" ring interpretation works quite well. Traditional solid FIP gaskets always require an escape zone - somewhere for the gasket to go to when it is under compression. With the hollow gasket, the hollow becomes the escape zone. For a properly designed application where the deformation does not exceed the hollow, no escape zone is necessary.
While extremely crude, images three and four attempt to show the reduction in effective durometer of a gasket due to the hollow. Image three shows the very rough measurement of a solid gasket and image four shows a gasket with the exact same height but with a hollow. This quick visual could do with a more precise technique, but even subjectively the gasket is half to a third the effective durometer. Interesting as well that as the gasket is compressed, a solid, traditional gasket has a somewhat linear increase in resistance. The hollow gaskets have minimal initial resistance and then rapidly increases once the hollow is collapsed.
One concern was whether the gasket could recover once collapsed and as seen in images five and six, the recovery is excellent with this 60102 material.
Images five and six also brought to light the fact that hollow gaskets do not require the same UV intensity of solid gaskets simply because there is less material the UV light needs to penetrate. This enhances the ability of low intensity systems to yield excellent results.
Image seven is simply a fun visual indicator of the difference between solid and hollow gaskets. By using a pin across both a solid and hollow gasket, it is easier to get an appreciation for the difference!