Is P-20 An Adequate Steel For Glass-Filled Nylon?

In a recent e-mail, I received this question regarding tool steel…
Kevin W.
Is P-20 an acceptable steel material to hold up to 60,000 annual volume for 10 years. The material is 15% glass fill nylon with 25% talc fill?
My Response
By itself, P-20 lacks the wear resistance to produce half a million cycles using a glass-filled material. A coating of titanium nitride on both the core and cavity should prevent wear on the P-20. Additionally, this coating is gold in appearance… so wear will be easy to identify when more coating is necessary.
Since the gate is a high shear location, it typically receives the most wear. I strongly recommend using a hardened gate insert to avoid welding and repairs in this area. Likewise, if you are using a hot runner gate, you should use a hardened drop rather than machining the gate into the P-20 cavity block.
The biggest caveat to this recommendation is thin wall molding. If the part has thin walls, or requires high injection pressures… P-20 is not likely to maintain its structural integrity for 600,000+ cycles.
Additional Thoughts
Without knowing more about the application and your tool steel supplier, it is hard to recommend a specific tool steel. Depending on availability and price, there are often multiple steels that will suit your application. A good supplier should be able to review your application with you and recommend a metal that will meet your specific needs.

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