Accurate calculation of profile rubber extrusion

[Kinish]

We manufacture bonded aluminium to rubber parts by compression moulding. Extruded uncured rubber profile is bonded to aluminium extrusion. There seems to be too much excess rubber to trim after moulding at present.

Do you know how to calculate accurate profile for the extruded uncured rubber given the mould dimensions and also aluminium profile dimensions i.e. how do you calculate the volume change (if any) between uncured and cured rubber? Is there much variance in volume change for different types of rubber?
Any useful websites would be a great help.

 

[polym3]

The amount of shrikage is really dependant on the compound formulation. Highly filled rubber tends to shrink less than unfilled or low filler containing compounds.

I believe the rule of thumb in estimating shrikage is in the area of about 3% - but I would suggest you have someone else confirm this number.