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Form in place shaped gaskets can provide some surprising benefits to traditional circular gaskets. The traditional shape of an FIP gasket is the result of a gasket compound flowing out of a round tube. Rheology aside, the shape is some form of circular arc, however as the tip skims closer to the substrate, the tip starts to carve a shape into the top of the gasket. The result of this action is typically a flattened rectangular shape with rounded vertical walls. This result is due to three factors: the proximity of the tip to the substrate, the flow rate of the compound as it comes out of the dispense tip, and the rate of travel of the tip over the substrate. When the flow rate is high enough, the travel rate is slow enough, or the gap to the substrate is small enough, the substrate in effect becomes the final wall in a pressure vessel.
With this process, it is possible to create shapes in the side of a dispense tip and extrude material out of the side of the needle. And there is no limit to the possibilities. For example, ridges on the top of the gasket will reduce the amount of compressive force required for engagement between surfaces. This can give some of the advantages of foamed gaskets without going to the expense of the foam generating hardware.
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