TOLERANCES USED FOR
MOLDINGS IN THE RUBBER INDUSTRY
The dimensional tolerances in elastomers can be wider
than those used in other engineering practices. Consider the following considerations:
-All rubber shows some shrinkage after molding and this is denoted in the design. These variations depend on the type of rubber used, but even the same formula can differ from batch to batch.
-The parts that are not rubber and are attached to it, will increase the shrinkage, and hence the tolerances feasible.
-The moldings vary according to the type of product and the required precision. In general, the product is as precise as the mold; the more accurate you need, the more expensive the mold becomes and its maintenance.
-Our technical department pays special attention to carry out tolerance standards for products with a lot of variation in their sections.
-The dimensions can be affected in cases where the rubber product is irremediably distorted during the exit of the mold, in these cases a special assignment will be required.
- Rubber products made by extrusion require greater tolerance in their manufacture, than those produced in rubber moldings; since in the first case the material suffers from dilation and during the subsequent vulcanization, shrinkage and deformation normally occurs.
-The deformation can be reduced by giving support during vulcanization, the type of support will depend on the section that is being produced and the degree of control required. These characteristics determine the kind of tolerance applicable to each type of dimension.
-There are different tolerance classes for extrusion in solid rubber, each of them related to the particular types of dimensions that are being developed. These parameters are carefully applied by our specialized technicians and operators.
-In our industry we also have extrusion available in rubber sponges, also known as Microporous or Cellular Silicones.