Mold Design for compression molded EPDM part
Mold Design for compression molded EPDM part
(OP)
I have to design a mold to be used in compression molding an EPDM part. My dilemma right now is figuring out how to adjust the mold cavity and core dimensions to account for both the mold material (Aluminum) CTE and part material (EPDM) shrink rate.
I have read various posts and literature online that say you simply scale your dimensions by 1+S, where S is the shrink rate in decimal format. However, I don't know if this takes into account the thermal expansion of the mold material. Also, can someone nail down for me what the definition of Shrink Rate is, I have seen a couple of different definitions such as :
S=(DMA-DPA)/DMA , where DMA=Mold dimension at Ambient Temp and DPA=Part dimension at Ambient Temp.
The other is:
S=(DPH-DPA)/DPH , where DPH=Part dimension at Highest Temp and DPA=Part dimension at Ambient Temp.
Any help or advice would be greatly appreaciated, thank you.
I have read various posts and literature online that say you simply scale your dimensions by 1+S, where S is the shrink rate in decimal format. However, I don't know if this takes into account the thermal expansion of the mold material. Also, can someone nail down for me what the definition of Shrink Rate is, I have seen a couple of different definitions such as :
S=(DMA-DPA)/DMA , where DMA=Mold dimension at Ambient Temp and DPA=Part dimension at Ambient Temp.
The other is:
S=(DPH-DPA)/DPH , where DPH=Part dimension at Highest Temp and DPA=Part dimension at Ambient Temp.
Any help or advice would be greatly appreaciated, thank you.





RE: Mold Design for compression molded EPDM part
You will also get different numbers based on whether your mold is steel or aluminum.
RE: Mold Design for compression molded EPDM part
RE: Mold Design for compression molded EPDM part
Thanks again for your help.
RE: Mold Design for compression molded EPDM part
RE: Mold Design for compression molded EPDM part