Mullins Rubber Products specializes exclusively in Heavy Duty Truck/Trailer Suspension Bushings. We develop all of our own compounds, and do all of of our own mixing. Thus, our bushings work, and work better than any other bushings in the world.
In order for rubber to vulcanize or "cure", it must first be mixed with a variety of chemicals and ingredients to give it the physical properties needed to meet customer specifications. These ingredients consist of:
Carbon black - for reinforcement and hardness.
Various processing oils - to blend the carbon black with the rubber, and for low temperature properties.
Sulfur - as a vulcanizating agent.
Zinc Oxide and Stearic Acid - which serve as catalysts and activators.
Accelerators - to speed the curing process, and set the cure.
Antioxidants and Antiozonants - To give flex and fatigue protection.
There are many other materials that can be used as fillers, extenders, or reinforcing agents in rubber. It depends on what you want from your "compound" (the mixed rubber). We want good suspension bushings, so we stay away from fillers and extenders.
Mixing is done by either internal mixers or rubber mills. The picture above is one of our take-off mills, being run by Russ Maye, one of our senior mixers, and Assistant Foreman of our mill room. We depend on people like Russ to give us quality material.
We mix over 3,000,000 pounds of rubber a year, and all of it must pass our rigid Quality Control checks for cure properties, tensile, elongation, and hardness, before it is released for molding.