Co-Rotating Twin Feedscrews
Co-rotating twinscrew extruders are the machine of choice to compound resins and add fillers to a product. These machines have the benefit of a small footprint, short L/D, high throughput rates at lower melt temperatures and a self-wiping action flight to flight.
These machines are usually starve-fed and the normal filled volume and pressure in the machines is very low. As conveying elements transition to kneading elements, filled volume approaches 100% and pressure spikes. It is in this transition that most wear occurs, in the last conveying element and the first kneading blocks.
Extreme Coatings has developed our SF coatings to bring our success in single and parallel twin screws to co-rotating screw designs.
We apply .030” (.75 mm) coating thickens (.060”, 1.4 mm overall) to an element that has been specially pre-ground to accept this layer of coating. A post coating furnace fusing ensures this layer has a metallurgical bond to the element before final grinding and polish.
The result is a high percentage carbide layer, higher than used on traditional twinscrew elements, which can provide from two to four times more wear life depending on fill loading.
Extreme Coatings is working with major equipment manufacturers to refine the process and improve application techniques and coating formulations.
The targeted use of carbide coated elements in high pressure zones of co-rotating extruders can help maximize equipment life, maintain consistent production, ensure product quality, and reduce operating costs.