Pressure in compression molding
Pressure in compression molding
(OP)
What are the effects of pressure in compression molding, is it just there to stop the molding die top from lifting due to thermal expansion of the rubber in the tool or does it have any other advantages?
Are there any calculations that can be made to determine which tool or component requires how much pressure?
Are there any calculations that can be made to determine which tool or component requires how much pressure?





RE: Pressure in compression molding
The effect of the above pressure ranges on properties is acknowledged to be small or negligible, but studies of very high pressures of at least 350 MPa (50000 psi) have been found to change modulus and even to bring about crosslinking in the absence of curatives. For a review of such work do have a look at Martin Bellander's paper High Pressure Vulcanization issued by the Swedish Royal Institute of Technology in 1998. Relevant studies go back to Wilkinson and Gehman in JIEC, 1949, 41, 841-46 and their 1954 patent, US 2682082.
RE: Pressure in compression molding
So long as the cavity was filled, the part was considered good. Higher or lower pressures was not identified as a reason for a part failing a specification.
I hope that helps.
RE: Pressure in compression molding
RE: Pressure in compression molding
There are mold filling simulation software packages available however they are mostly geared to plastics and injection molding. Some simulation packages do have the ability to model elastomers/rubber but characterizing the material for the simulation can be challenging as curing may need to be taken into account or somehow dealt with.
Have a good day!