There is no particular rule of thumb for amount of cycles for cleaning injection rubber molds. That is influenced by the type of rubber, the type of cure system, process aids, mold releases, temperature of cure and mostly by how you define "good surface finish."
The most common ways to clean a...
To elaborate further on BCAREY's response, Buna-N, NBR and Nitrile are the same base co-polymer as he described. Hycar (now Nipol), Paracril, Krynac, and numerous others are brand names of the manufacturer of the base co-polymer. However, there are other differences than their ACN...
The stiffening point of the diaphragm will be controlled by the acrylonite content of the base material, the degree of hydrogenation and the specific formulation of the HNBR but generally speaking HNBR has a Tg of about -15 to -40 deg C. That can be lowered by the addition of low temperature...