Question 1

Do plastics require coolant during machining?

Accepted Answer

Generally, yes for production work. Coolant prevents heat buildup that causes melting, dimensional expansion, and poor surface finish. For prototype or short runs, air blast can suffice for materials like Delrin. Nylon and acrylic benefit significantly from flood coolant to prevent heat-related issues.

Question 2

What is the best tool coating for plastic machining?

Accepted Answer

Uncoated polished carbide is generally preferred for plastic machining. The polished surface reduces friction and prevents material adhesion. DLC (Diamond-Like Carbon) coatings further reduce friction but add cost. Avoid TiAlN coatings for plastics — they increase friction and generate more heat.

Question 3

How do I prevent white lines or stress marks in machined acrylic?

Accepted Answer

White lines occur from micro-cracking caused by tool exit stresses. Use sharp, polished tools with zero or slightly negative rake. Reduce feed rate on the final pass by 50%. Annealing the acrylic after machining at 80°C for 2 hours can relieve internal stresses and reduce visible stress marks.
⚡ Calculated for Carbide-Tooling.com High-Performance Series. View Catalog →

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