Greg McFadden
Key Veteran
Location: Spokane Valley, WA
| my local plastics supplier suggested I take speeds/feeds for aluminum and multiply by 4 and keep it cool. Unfortunately I don't have that kind of HP on my itty bitty little mill. I get a good finish when I run the spindle at about 5k and the feed rate up about 20ipm for a 1/4" diameter 2 flute cutter (which is about as fast as I can run). Some of our suppliers (for where I work) that I have worked with quite literally run as fast as they can (both spindle and feeds) with air or water cooling, but I can't recall the exact numbers
You might want to check, if that is a fiber filled delrin you may have more problems.
here is an exerpt from the machinery's handbook, 26th edition:
Milling of Plastics: Peripheral cutting with end mills is used for edge preparation, slotting
and similar milling operations, and end cutting can also be used for facing operations.
Speeds for milling range from 800 to 1400 ft/min for peripheral end milling of many thermoplastics
and from 400 to 800 ft/min for many thermosets. However, slower speeds are
generally used for other milling operations, with some thermoplastics being machined at
300–500 ft/min, and some thermosets at 150–300 ft/min. Adequate support and suitable
feed rates are very important. A table feed that is too low will generate excessive heat and
cause surface cracks, loss of dimensional accuracy, and poor surface finish. Too high a
feed rate will produce a rough surface. High-speed steel tools (M2, M3, M7, or T15) are
generally used, but for glass-reinforced nylon, silicone, polyimide, and allyl, carbide (C2)
is recommended.
The silence often, of pure innocence persuades, when speaking fails |
