Tangential Rotor Mixing Machines

Tangential mixer - volumetric effects of fat and thin rotors 

Most tangential machines do not have a eonsistent chamber length to diameter ratio. Therefore different sized machines have different wing angles and this results in differences in performanee between mixer sizes. Differences in performance will also arise from the changes in surface-to-volume ratio with machine size, giving different temperature control performance. 

Rotor tip eharacteristics vary with both machine size and wear, larger machines having a greater tip gap to allow better flow of the greater volume of compound across the tip. Tip widths vary from machine to machine, and from manufacturer to manufacturer. True tip width 

This theory of mixing is supported by consideration of power responses when mixing. The torque curve typically hits a peak shortly after the materials are fed into the machine, illustrating what is thought to be the peak point in dispersive action, and then shows reduction as the cycle progresses and viscosity falls. 

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In the case of the intermeshing rotor machine the majority of the mixing action takes place between the rotors with the shearing action being created by the rotor design. Unlike the tangential mixers where the rotors revolve at different speeds, the rotors in intermeshing machines run at the same speed. 

As may be expected, the mixing behaviour of tangential and intermeshing rotor mixers is very different. An attempt is made below to describe the mixing actions of the different concepts of machine in layman s terms, there being many learned texts published by various educational institutions which may be read by those wishing to explore this interesting subject further. 

In the tangential machine a thermocouple mounted in the end frame is more robust, but is often far less responsive than one mounted in the door top, although recent rotor designs which improve material flow to the ends of the mixing chamber should have improved the response of endframe thermocouples. Infrared probes are most commonly fitted in an endframe. 

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