Bearing shrinkage

[iceman5]

I am insert-molding an oilite bearing into a pulley. The plastic used for the pulley is a 10% glass-filled polycarbonate. My problem is in properly sizing the bearing so that when the plastic shrinks, the ID of the bearing will be at the proper size. Does anyone know of any formulae that would relate the wall thickness of the bearing and the shirnkage force to a press-fit so that I can use a standard bearing calculation to determine the ID reduction?

 

[unclesyd]

I haven’t seen anything specific on molding around bearings. What happens to the oil in Oilite while molding?

The sheaves and pulleys I’m familiar with all are inserted after molding. You can look at this calculator for shrink or interference fits to see if it might help.
Most of the bushing companies have vert good technical service departments.

http://www.beemerprecision.com/calculator.asp

 

[plasgears]

I would press fit and develop by test the amount of interference shrink. Porous bearings press nicely and hold in plastic because of the porosity roughness. My experience with your situation yielded about .001" ID shrink for .002" interference on a 5/8" OD. The press tool should guide the bearing at the ID.