All molded rubber parts have some kind of flash. There are two main processes to deflash parts: Tumble deflashing and Shot blasting deflashing
Tumble deflashing is used for simple rubber moldings with flashes only on the outside of the part. The embrittled flash is removed by rolling the parts in a tumbler. The process can be enhanced by using impact media such as steel balls, chains or brushes.
Shot blasting deflashing is used for more complicated parts (e.g. with flashes in inner bores or undercuts). Blast media are steel or polycarbonate pellets.