Plastic Milling Machining Guidelines

Milling typically involves high cutting speeds and medium feed rates for most thermoplastic parts

milling diagramMilling Guidelines

Milling is a common method for machining plastic parts. In this process, the plastic is held in place while a cylindrical cutter moves on an axis to mill flat surfaces, grooves, shoulders, etc. Both CNC and manual mills are used for plastics. Below are guidelines for milling several performance plastics.

High-speed steel (HSS) tooling works well for most thermoplastics. Carbide tooling is recommended for reinforced materials. High spindle speeds and table travel are possible with adequate clamping. Care is required when clamping stock to the mill bed to prevent deformation/springing of the material.
Standard roughing end mills work well for roughing cuts. Finish cuts should be made using either 2 flute or 4 flute mills, depending on the material and chip characteristics. For inside pockets, end mills with rounded corners should be used whenever possible. This will prevent the finished piece from having sharp inside corners, which can potentially be areas of stress concentration.

Special Measures: Preheat material to 250°F Caution when using coolants, susceptible to stress cracking Use carbide-tipped tools

The feed can be up to .55 mm/tooth

Material

α

Clearance

Angle (°)

ϒ

Rake

Angle (°)

V

Cutting

Speed (ft/min)

ABS 5 - 10 0 - 10 980 - 1640
Acetal (copolymer) 5 - 15 5 - 15 920 - 1640
Acetal (homopolymer) 5 - 15 5 - 15 920 - 1640
Noryl 10 - 20 5 - 15 980
Nylon 6 10 - 20 5 - 15 920 - 1640
PAI 2 - 5 0 - 5 300 - 330
PBT 5 - 15 5 - 15 980
PEEK 5 - 15 6 - 10 920 - 1640
PET 5 - 15 5 - 15 980
Polycarbonate 10 - 20 5 - 15 980
Polyethylene 10 - 20 5 - 15 920 - 1640
Polyproylene (homopolymer) 10 - 20 5 - 15 920 - 1640
Polysulfone 2 - 10 1 - 5 920 - 1640
PPS 5 - 15 6 - 10 920 - 1640
PTFE 5 - 15 5 - 15 920 - 1640
PVDF 5 - 15 5 - 15 920 - 1640
PPSU (Radel® R) 2 - 10 1 - 5 920 - 1640
Ultem® 2 - 10 1 - 5 920 - 1640
DuPont™ Vespel® Polyimide 2 - 5 0 - 5 300 - 330

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