Know Why Rubber Extruder Overloads

  • The rubber extruder overload is a descriptive term for a state or condition where the main motor driving the extruder is surpassing full load. Although potential factors that result in an extruder high motor load are listed below, it is possible that the main cause is simply that an under-powered drive motor was supplied for the application. If many of your products are pushing operating parameters to near the full load mark, I would suggest considering installing a larger motor. It is advisable to contact the extruder manufacturer to make sure that larger motors can be installed without exceeding the design limitations of the complete drive system. A guide to trouble-shooting excessive motor loads includes the following checklist:


    • Ensure that the dry feed system is delivering the correct feed rate and that the feed rate is consistent. Excessive dry feed rates can lead to high motor loads.

    • Lack of adequate process steam injection into the extruder barrel can also result in high motor loads. Not only must adequate steam be supplied, but the steam flow rate must be consistent. Often the barrel fill will be great enough partially or completely to block the injection ports reducing steam inputs and causing high motor loads.

    • Increasing extrusion moisture by adding more extruder or preconditioner water will be helpful in reducing motor loads if the process will accept increased moisture levels.

    • Increasing steam addition to the preconditioner will usually reduce extruder motor load because of the added moisture and added thermal energy, both of which reduce product viscosity and reduce motor load.

    • Insufficient die open area can result in high motor loads. This may be because the existing die area is decreased because of blocked orifices or because the original open area was not adequate. Every effort should be made to avoid prolonged overload conditions as most electrical drives are protected from extended high amperage loads which can result in overheated electrical systems. Electrical starters or variable frequency drive (VFD) systems will stop when overloaded for extended times and then the extruder will have to be freed from a plugged condition which is time consuming and frustrating.

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