Rubber must maintain its properties through a lifetime of dynamic straining. Rubber needs to be resilient enough to do its functionality even after being compressed, stretched or twisted thousands, or even an incredible number of times.
Chemical. Rubber is often required to withstand a number of chemicals. For applications in motors or generators, it should be resistant to gasoline and oils. Some commercial equipment will discover a variety of harsh fluids such as cleaning solvents, acids or alkalis. Rubber tubes can have any number of harsh fluids pumped through them. Without right formulation, a rubber compound could virtually dissolve or crumble when faced with these corrosive elements.
The first step in rubber formulation is to develop detailed requirements relating to conditions that the rubber will need to withstand. It is fairly straight forward to recognize the mechanical/dynamic requirements; nevertheless , chemical and environmental factors are commonly misunderstood. Inside this case a plastic formulation chemist with a great deal of experience is necessary. The chemist has seen a huge variety of applications and can help identify what conditions a product could possibly experience out in the field.
After thoroughly understanding all the requirements, a rubber formulation chemist can derive a recipe of dozens components to create the compound. Rubber formulation is extremely complex and can draw on literally hundreds of potential variables. Since of the scale of this complexity, there are not many tools and instructions to analytically determine the exact formulation that will optimize performance for a given application. Achieving optimum performance with rubber gasket is far more of an “art” than the usual “science”, and requires experienced and educated formulators.
One example that demonstrates the complexity of rubber formulation involves a peristaltic tube application. This specific tube was used in an agricultural product to pump fertilizers and weed killers through it, with the pumping action occurring from alternating cycles of data compresion and relaxation of the rubber tube. The water pump manufacturer purchased a rubber tube from one provider that normally exceeded 250, 000 cycles at inbound testing, but occasionally amounts would fail at less than 10, 000. Typically the manufacturer sought out a new supplier, and a new rubber formulation was developed that exceeded 3, 500, 000 cycles to failure. Needless to say, the customer was extremely happy.
When the product is developed and tested, it is ready for manufacturing. Manufacturing custom formulated rubber requires extremely tight process controls. Because seen from the peristaltic tube example, a very small variation can considerably affect the performance of the rubber.
Are there are times when it is impossible to meet a set of requirements with any rubber ingredients? The answer of course is “yes”; but more commonly the issue is cost, rather than what is possible. A rubber component is a relatively expensive product when compared with plastic or even precious metals, and in some cases the needed formulation is too costly for practical use. However, for a lot of critical applications rubber often performs with higher elegance and lower total cost than the choices, and certainly with the highest level of flexibility.