The bolt shown is specially made with an "X" head instead of a standard hexagonal head. When the rubber is injected into the mold, the pressure keeps the bolt down and the rubber molds around the "X" head, completely encapsulating it. The design of the bolt head insures that the bolt will not slip or rotate when the rubber is turned. The plastic lock nut is added after molding.
Mechanical encapsulation is a very cost effective way to bond rubber to metal or plastic. It eliminates the need for specialty adhesives and allows for easier reclamation of the metal insert in the case of fallout. Custom Rubber Corp. can assist you in determining if mechanical bonding would be sufficient for your application.
The molded rubber parts pictured are not in stock or for sale. These are examples of custom-manufactured products that illustrate Custom Rubber Corp.'s capabilities.