Proper dispersion involves incorporating all of the raw materials in a rubber formulation into a uniform and homogenous mixture.
Rubber compounders are often challenged to improve overall dispersion quality and batch consistency, while simultaneously finding ways to reduce compound mixing time and increase mixer output in order to save costs.
The quality of dispersion can vary depending on the equipment and the individual formulation. However, there are general principles that can be applied to achieve the optimal level of dispersion at the most economical mixing conditions.
Dispersion has a direct effect on and is predictive of many physical properties in a rubber compound. Good dispersion provides consistency of properties within the same batch and consistency of properties between batches. It also creates a smooth and uniform surface appearance on finished parts.
Improper dispersion can lead to undesirable physical and mechanical properties, including imperfections in product appearance, reduced service life and poor part performance.
Many factors influence dispersion, including the rubber formulation, raw material quality, raw material temperature and the types of raw materials used. Equipment age and mixing conditions (mixing time, temperature, pressure and rotor speed) also play a role in dispersion, as well as the type of downstream equipment and finishing capabilities.
Therefore, it is advantageous for a rubber compounder to have as much control as possible over the entire mixing process.
Inside a climate-controlled facility, a plant-wide control system provides exceptional process control during compound mixing, improving accuracy and consistency batch to batch. In addition, manufacturing discipline and attention to detail in lean practices, plant 5S and standard work reduce the risk of contamination in rubber compounds.