The type of equipment in a production line dictates the frequency of maintenance needs. Some equipment requires daily or weekly maintenance, such as greasing bearings and checking the oil in gearboxes.
Dry extruders work under the principle of friction, pressure and heat to process or cook the product. This means that certain parts of the extruder – the internal screw and steamlock configuration, and the external compression chambers – are where the most wear will be seen. These parts should be inspected after every 600 hours of use.
When making inspections, always check these items for wear:
Inlet screws – Product entering the inlet is the most abrasive, because it has not yet broken down in the cooking process. Screws can be rotated front to back and end to end, provided the wear is not too severe. Timely rotation of the inlet screws will increase the service life of these parts.
Compression screws and steamlocks – Look for cracks and make sure outside diameters are maintained
Rifling in the inlet and compression chambers – Raised grooves in the chambers will wear down over time. These grooves can be rebuilt with a welder using mild steel electrodes, and maintaining the tolerance listed in the operator’s manual. Check wearsleeves in the compression chambers for wear. You can remove and turn wearsleeves once before replacing them.