High-density polyethylene High-density polyethylene is a highly versatile polymer that exhibits excellent chemical resistance and is easily welded. Used extensively in the chemical industry, it has also been approved for use in food processing operations. The end uses for the material are extensive. In addition to food cutting boards, the material is successfully used for: chemical tanks and tank linings, ventilation ducts, fume hoods and industrial work surfaces. It can be blow molded, injection molded, and extruded. You may recognize it as “#2 plastic” by its recycling symbol. The only rule of thumb that can be offered is that most soft plastics (HDPE, UHMW, Polypropylene, etc.) respond best to Conventional Cutting, while some harder materials (Acrylic, Polycarbonate, Nylon) can occasionally respond better to Climb Cutting. Typically Climb Cutting will only show an improved performance in the smaller diameters (less than 3/8"), but of course there are always exceptions.

What endmill should I use when milling HDPE?

In general, larger tools like 1/8" and 1/16" flat endmills are better because they cut through material the fastest and are least likely to break. If you’re making a custom fixture, a 1/8" flat endmill is your best friend. For 3D shapes, a 1/8" or 1/16" ball endmill produces the smoothest contours. For best results, keep a set of endmills specifically for HDPE and other plastics, and never use them to cut metal or PCBs. This will allow for increased milling speeds and a better finish.

Recommended Feeds and Speeds

Source: https://othermachine.co/support/materials/hdpe/ Note: These feeds and speeds are used by default in Otherplan and are provided here as a reference. Tool: 1/8" flat endmill Feed rate: 23.622 in/min (600 mm/min) Plunge rate: 1.575 in/min (40 mm/min) Spindle speed: 12,000 RPM Max pass depth: 0.008" (0.21 mm) Tool: 1/16" flat endmill Feed rate: 23.622 in/min (600 mm/min) Plunge rate: 1.575 in/min (40 mm/min) Spindle speed: 12,000 RPM Max pass depth: 0.009" (0.23 mm) Tool: 1/32" flat endmill Feed rate: 23.622 in/min (600 mm/min) Plunge rate: 1.575 in/min (40 mm/min) Spindle speed: 12,000 RPM Max pass depth: 0.010" (0.25 mm) Tool: 1/64" flat endmill Feed rate: 23.622 in/min (600 mm/min) Plunge rate: 1.575 in/min (40 mm/min) Spindle speed: 12,000 RPM Max pass depth: 0.003" (0.08 mm) Tool: 1/100" flat endmill Feed rate: 23.622 in/min (600 mm/min) Plunge rate: 1.575 in/min (40 mm/min) Spindle speed: 12,000 RPM Max pass depth: 0.003" (0.08 mm) Tool: Engraving bit Feed rate: 39.370 in/min (1000 mm/min) Plunge rate: 1.575 in/min (40 mm/min) Spindle speed: 12,000 RPM Max Pass Depth: 0.003" – 0.020" (0.08 mm - 0.5 mm). Keep in mind the engraving tool has a variable width, depending on your “engraving cut depth.” The deeper the cut, the wider the tool. The shallower the cut, the narrower the tool. If you’re using an engraving tool and the generated path isn’t cutting part of your .svg file, try reducing the engraving cut depth. Advanced Feeds and Speeds Warning: These settings are for advanced users. Before using any of the information provided here, you must read the section above on fixturing your material. The feeds and speeds specified here are more aggressive (and thus faster and more fun), and improperly fixtured material can be knocked loose and damage itself and your machine. BitBreaker Mode must be enabled in order to change your feeds and speeds. Tool: 1/8" flat endmill Feed rate: 59 in/min (1500 mm/min) Plunge rate: 19.6 in/min (500 mm/min) Spindle speed: 16,400 RPM Max pass depth: 0.02" (0.5 mm) Tool: 1/16" flat endmill Feed rate: 59 in/min (1500 mm/min) Plunge rate: 19.6 in/min (500 mm/min) Spindle speed: 16,400 RPM Max pass depth: 0.02" (0.5 mm) Tool: 1/32" flat endmill Feed rate: 59 in/min (1500 mm/min) Plunge rate: 19.6 in/min (500 mm/min) Spindle speed: 16,400 RPM Max pass depth: 0.02" (0.5 mm) Tool: 1/64" flat endmill Feed rate: 59 in/min (1500 mm/min) Plunge rate: 19.5 in/min (500 mm/min) Spindle speed: 16,400 RPM Max pass depth: 0.01" (0.25 mm) Tool: 1/100" flat endmill Feed rate: 59 in/min (1500 mm/min) Plunge rate: 19.6 in/min (500 mm/min) Spindle speed: 16,400 RPM Max pass depth: 0.005" (0.13 mm) Tool: Engraving bit Feed rate: 59 in/min (1500 mm/min) Plunge rate: 19.6 in/min (500 mm/min) Spindle speed: 16,400 RPM Max Pass Depth: 0.003" - 0.020" (0.08 mm - 0.5 mm). Keep in mind the engraving tool has a variable width, depending on your “engraving cut depth.” The deeper the cut, the wider the tool. The shallower the cut, the narrower the tool. If you’re using an engraving tool and the generated path isn’t cutting part of your .svg file, try reducing the engraving cut depth.

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source: synergy_jim signs101.com 1/4" double spiral downcut on hdpe runs around 18,000 rpm's at 350inch per minute - this is assuming you are only taking 1/2" bit diameter deep. 1/8" single spiral downcut - hdpe cuts around 200 IPM @ 18,000 rpms. on 1/8" bit you should be cutting 1/16" of material per pass

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Best results were with a 1/4" straight double flute.

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https://www.youtube.com/watch?v=bAvWX8N8aDE 1/2" Solid Carbide Two Flute Upcut for Soft Plastics, Solid Surface, and Foam Speed: 18,000 RPM Feed: 350 IPM

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1 flute 6mm endmill, 8000 rpm, 1500mm/min feed and a maximum depth of 2mm https://www.youtube.com/watch?v=cJ2djerK1k8

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Source: http://community.carbide3d.com/t/experience-milling-hdpe/462/2 I was using the .125" endmills that came with the nomad (so, 2 flute). 7500 rpm spindle speed 68.3 in/min cutting feed rate (feed per tooth .0046") 17.075 in/min plunge feedrate .03" stepdown All climbmilling