Glass fiber, calcium carbonate, talc and similar mineral fillers give plastic products mechanical strength and dimensional stability, but they create intense abrasive effects on screw and barrel surfaces during processing. Material selection is critically important for operational continuity at facilities processing this type of raw material.
How Do Abrasive Fillers Cause Wear?
Glass fiber and mineral particles are in constant contact with the screw flight backs and the barrel inner surface during melt flow. Over time, these hard particles cause micro-scratches and surface loss on standard nitrided surfaces, causing the clearance to grow rapidly.
Recommended Materials for These Applications
- Bimetal barrel (tungsten-carbide-based coating): high wear resistance, long service life
- Screws with hard chrome or ceramic-based coating: provide an additional protective layer
- A heat-treated screw body made from tool steel: a basic requirement for structural strength
Effect of Filler Ratio on Material Selection
As the filler ratio increases (for example, 30% glass fiber and above), the service life of standard nitrided sets shortens noticeably. In such high-ratio applications, a bimetal solution becomes more economical in the long run, even though its initial cost is higher.
The Importance of Screw Geometry
As much as material selection, screw channel depth and compression ratio must also be designed to suit abrasive fillers. An excessive compression ratio can cause unnecessary friction and additional wear in filled raw materials; therefore, screw geometry should be optimized specifically for the raw material processed.
Conclusion
For facilities processing raw materials containing abrasive fillers, the right combination of material and geometry is the key to production continuity and cost efficiency. You can receive a material recommendation tailored to your needs by sharing the raw material formulation you process.
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