The aerospace, automotive, commercial and electronics industries form the largest market for rubber extrusion and rubber molding products. These products are used in the manufacture of various items from rubber caps, plugs and seals to bushings, connectors, reducers and drain tubes, all items that form part of our daily lives.
There are three kinds of rubber molding processes. The first is injection molding which is the most efficient way of creating molded rubber products and is derived from the plastics molding process. Here the rubber is heated and placed under pressure within the mold while it is still hot to form the desired shapes.
With compression molding, the rubber compound is formed first into what is called a pre-form which is similar to the end product. It is then placed in the mold cavity which is closed placing both heat and pressure on the pre-form. Excess material flows out into overflow grooves and is used to make more molding.
The final process called transfer molding is quite similar to compression molding in that there are pre-forms created from secondary raw material. The difference comes in the placement of the pre-forms where in this case they are placed in a pot above the mold cavities. This means that when the pre-forms are compressed, they will flow into the cavities to form the desired molds.
Rubber extrusion is different from rubber molding by virtue of the process. Rubber extrusion uses unvulcanized rubber which is softer and pliable. This rubber is forced through an extrusion die which bears the required cross section shape by the extruder. Once the extruded rubber has been forced out, it is then vulcanized to give it increased firmness so that it can be used for the intended purpose. During vulcanization, the rubber may shrink depending on the rubber compound used, more so in the centre that at the ends and this should be provided for during the extrusion process.
The most common types of polymers used in both the rubber molding process and the rubber extrusion process include:
* Butyl rubber
* Ethylene propylene diene monomer (M-class) rubber, commonly referred to as EPDM
* Nitrile rubber
These are required to meet industry set temperature, weather and technical specificiation standards in order to be safely used to manufacture the various products.
Speaking of products, there are a number of extruded rubber products, the more popular ones being
drain tubes, vibration reducers, door and window seals, exhaust collars, cabinet seals, pump discharge holes, pressure switch tubing among others. Molded rubber products have been around for longer and form the bulk of rubber-to-metal bonded products are well as compression molded parts that we use in everyday life. There are specifically customized products that can be developed including molded seals, manifold, panel and refrigeration compressor grommets, rubber caps and plugs for various applications, strain relief bushings and vibration mounts among others.
It is clear that these products are used for very safety-sensitive areas. Imagine if the window seals on your boat gave way while you were at high speed, or if the vibration reducers failed to absorb the shock and vibrations in your car. The results can be very uncomfortable at best and even possibly damaging to both you and your equipment. This is why these companies are required to adhere to a strict standard in the production and manufacture of their molded and extruded rubber products.
There have been cases where defective molded or extruded rubber products have resulted in malfunction of sensitive equipment or even damage to them which has cost the owner of said equipment massive losses in terms of repairs and lack of productivity. In other cases, the defective products have been the direct or indirect cause of injury to an individual. In both cases, it is important to remember that the manufacturer of these products is liable for that damage and therefore you should retain a qualified attorney to ensure that your rights are protected in this matter.