Inspecting a Profile Tolerance for a Die Cut Gasket

[cfordyce05]

What is the industry standard for the method of inspecting a die cut gasket? We are trying to inspect with an optical CMM. Our customer provided a drawing with a parasolid file for the gasket but the profiles are made up of splines instead of lines and arcs. The software cannot inspect a surface profile with splines. Should the drawing really have a line profile tolerance instead of the surface profile tolerance? The gasket is only .015in thick. The only dimensions on the drawing are a true position on 4 bolt holes and an all around profile tolerance of .010 on the inner and outer gasket profiles.

Thank you,

Casey

 

[Stijloor]

What is the industry standard for the method of inspecting a die cut gasket? We are trying to inspect with an optical CMM. Our customer provided a drawing with a parasolid file for the gasket but the profiles are made up of splines instead of lines and arcs. The software cannot inspect a surface profile with splines. Should the drawing really have a line profile tolerance instead of the surface profile tolerance? The gasket is only .015in thick. The only dimensions on the drawing are a true position on 4 bolt holes and an all around profile tolerance of .010 on the inner and outer gasket profiles.

Thank you,

Casey

Profile of a line would be a much better control considering the 2-D geometry of the part. Often such parts are inspected with an optical comparator and an approved mylar. Talk to your customer and see if they could provide you with some means that would better fit your inspection capabilities.

Such issues should have been "hammered out" during contract review...

 

[Ninja]

Is the gasket flexible (like an O-ring)?

Often, the CMM will have trouble using lines and arcs unless the gasket is set "perfectly" on the stage.
A normal way to work around this is to use closed splines...that way you'll get an average ID/OD for sample testing.

For detailed comparison to spec, you would need to pay much more attention to part placement, especially if circularity or mulitple independant wall thickness measurements are needed.

My Vertex actually has an "Oring" tool built in that makes use of the spline approach (that's the only reason I'm familiar with the approach...I don't make or measure gaskets).

HTH