In the rubber industry, equipment such as open mixers and internal mixers are often used for rubber mixing. What are the differences between an open mill and an open mill? What are its characteristics? Below, a mechanical engineer from Lina will explain the difference between an open mill and an internal mill



There are many differences between open mill rubber mixing and internal mill rubber mixing, not just in terms of reducing labor intensity and improving operating conditions. If the internal mixing process is not well designed, workers would rather open mill rubber mixing because it is easy to operate and already very skilled, and the resulting rubber is basically problem free;

The rubber produced by mixing, although the amount of material mixed in one batch is several times that of the open mill, the process is not well designed, and the rubber material may be burnt or unevenly dispersed and scrapped. The actual labor has already been expended, and raw materials have also been wasted, requiring re mixing. Therefore, how to design the process of the internal mill and strictly control the temperature is a major problem for rubber mixing in the internal mill. Only by using it reasonably can we achieve twice the result with half the effort.

The difference in performance between the glue refined on the open mill and the glue refined in the internal mill can be significant. This difference can also be attributed to the failure of the internal mill's operation process, resulting in mixing failure, burnt or uneven dispersion of the glue material.



Difference between open mill and internal mill:

The mixing amount of the open mill is small, and various mixing amounts are easy to add because it is open and has fast heat dissipation. The temperature effect is not so obvious. If the temperature is too high, it can be stopped for a period of time to cool down before mixing again; The one-time mixing of the internal mixer is several times that of the open mixer. During the mixing process, it is necessary to strictly control the temperature changes and the order of adding small materials, which will affect the uniformity and coke burning of the mixing; The discharge temperature must be strictly controlled, and there is a large difference between the temperature inside the mixer and the temperature of the rubber material. Therefore, the relationship between this temperature must be considered when controlling the temperature, otherwise the rubber material is prone to burning (usually the internal temperature of the rubber material is 50-60 degrees higher than the temperature inside the machine)



Furthermore, due to the large mixing volume, it was previously considered to add sulfurization through an open mill. However, it was later discovered that this was not feasible because one truck of material from the internal mill was equivalent to several trucks of material from the open mill, making it impossible to mix and add sulfur. If sulfur was added through an open mill, it would be necessary to divide one truck of material from the internal mill into several trucks of material from the open mill. However, this is not feasible in reality because you cannot guarantee uniform mixing for each truck of material, and the recalculated composition of the divided rubber material is generally uneven and incorrect. The added sulfur will also be incorrect and unreasonable. Therefore, sulfurization must also be added through the mixing process, and temperature control is more important at this time



What is the difference between an open mill and an internal mill? The most fundamental difference, as described in this article, is the difference in craftsmanship. When choosing between open mill or internal mixing during rubber mixing, it is still based on the characteristics of the rubber material.