The open mill, also known as the two-roll mill, is a long-standing and widely used mixing and plasticizing equipment in the rubber and plastic industry. It is mainly used for raw material mixing, plasticization, hot mixing of rubber and plastic, as well as rubber sheet calendering and forming. With the characteristics of simple structure, convenient operation, and uniform mixing effect, it still occupies an important position in the rubber and plastic processing field.

The core working parts of the open mill are a pair of parallel, counter-rotating rolls, and its working principle is based on the extrusion, shearing, and kneading effects of the rolls. During production, the rolls are adjusted to the set temperature through heating or cooling devices. After rubber and plastic raw materials are put between the two rolls, they are softened and plasticized gradually under the extrusion and shearing force of the rolls. At the same time, with the assistance of manual or automatic turning devices, the raw materials are fully mixed with additives (such as carbon black, vulcanizing agents, plasticizers, etc.) to finally form mixed rubber or rubber sheets that meet the process requirements. The rotation speed, speed ratio, temperature, and distance of the rolls can be flexibly adjusted according to raw material characteristics and production needs to achieve the best mixing and forming effect.

Compared with other mixing equipment, the open mill has unique advantages. On the one hand, the mixing process is intuitive and controllable. Operators can real-time observe the plasticization state and mixing uniformity of raw materials, adjust process parameters in a timely manner, and avoid insufficient mixing or over-mixing. On the other hand, the equipment has a simple structure, small floor space, convenient installation, commissioning, and maintenance, and low initial investment cost, which is suitable for the production needs of small and medium-sized enterprises. At the same time, the open mill can not only be used for mixing but also complete various processes such as hot mixing, reclaiming, and sheeting, realizing multi-purpose with one machine and improving production flexibility.