When the ingredients arrive at the mixing department, the mixer reviews the recipe. The mixer then blends the ingredients on the mill in the manner specified on the recipe.
Once the ingredients have been fully blended, a sample of the mixed rubber slab is taken to the lab for analysis. The lab will test for various things in accordance to the materials desired specification. This ensures the rubber used is designed and capable to withstand the final seals environment and stresses. After the sample has been tested and approved, the material is released to the extruding department.