Rubber Mixing Mills

Process of Rubber Mixing in Mills :

In mill mixing, the elastomer is first added to the nip (Gap between two rolls), open to about 6mm, at the top of the rolls. A band of elastomer then passes through the nip & is formed around the front roll. Depending on the elastomer used, varying degrees of difficulty may be encountered in forming the band initially. However after a few passes, a band will form & can be fed back into the nip continuously. The elastomer is then cut back & forth twice to assure proper blending & to allow the elastomer in the bank to go through the nip. All dry ingredients, except the fillers & the cure system, are then added to the nip. The compound is then cut back & forth twice to assure good dispersion of these dry ingredients throughout the batch.

The next step is to open the mill slightly & add the fillers slowly to the batch. In order to prevent excessive loading of fillers at the centre of the roll several times during this operation & thrown back in to the bank. When most of the fillers have been mixed into the compound, the liquid plasticizers & the rest of the fillers are added filler is visible, the batch is cut back & forth twice more to assure good distribution of fillers ''PIG'' roll the batch & feed the ''Pigs'' back into the nip at right- angles as a past of the cross-blending process.

The next step is to open the mill more & add vulcanizing agents to the batch. When the vulcanizing agents are well distributed, the entire batch is cut back & forth at least five times to assure thorough cross-blending, before being sheeted off the mill.