Rubber is a non-abrasive material that can shrink and stretch easily. Rubber molding has been used to create products for various industries. The material is used in tires and for insulation.
Here are the four steps involved in creating rubber products:
Choosing the Right Process
There are three main processes: Injection molding, compression molding, and rubber extrusion. Manufacturers use injection molding to create standard or customized products. This process can produce precision parts in high quantities.
If the manufacturer wants to create rubber products of intermediate precision, they use compression molding, which can produce rubber parts of various sizes. The manufacturer scales up or down their mold cavity to get an object of a desired size. Compression molding is preferred because it needs fewer tools and can produce prototypes quickly.
Rubber molding starts with the vulcanization of rubber. Vulcanization is a chemical process that adds helpful properties to the rubber. Vulcanized rubber can maintain flexibility even after exposure to high temperatures in the mold cavity. If the manufacturer uses the rubber extrusion process, vulcanization happens toward the end of the process.
During vulcanization, the manufacturer adds sulfur to the uncured rubber. Other additives include color pigments, anti-oxidants, and coagulants. These additives boost the bonds between the molecules to improve the strength and elasticity of rubber.
Adding Rubber Into Molding Machine
The manufacturer feeds the correct amount of vulcanized rubber into an injection molding machine.
As the rubber enters the injector, it’s exposed to high temperatures. The rubber turns into a liquid state and flows into a mold cavity. As the rubber material solidifies, it takes the shape of the mold cavity.
For injection molding, the vulcanized rubber is fed into the extruder. The material flows into a feed hopper and divides into many streams. Each of these streams flows into a flute inside the feed hopper. These flutes have revolving screws that transport the rubber to the die.
During injection and compression molding, various machines apply pressure and heat to the mold following the commands of a computer program. Once the uncured rubber attains the right size and shape, the manufacturer opens the mold and removes the part. To increase its quality, the part can undergo other processes, such as post-curing.
For rubber extrusion, the manufacturer increases the temperature and pressure of the extruder as the rubber comes into contact with a die. The pressure pushes the rubber through the openings into a specific texture, depending on the requirements. Since the material will swell, the cross sections of the extruded parts need tolerance allowance.
Once the rubber leaves the extruder, the manufacturer will vulcanize it. Vulcanization corrects any inaccuracies in length and shape, such as the usual swelling at the center.
Find Rubber Products Today
Rubber molding and extrusion can create various types of rubber products. The exact process depends on the required quality of rubber and the type of industry the rubber is intended for. You can use rubber in the solar, automotive, and appliance industries.