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Dialing in the right chip load is the difference between clean edges, long tool life, and fast cycle times — and burnt material, chipped tooling, or stalled spindles. Use this reference to set feed rates on your KRC Phantom or any CNC router.
Chip load is the thickness of material each cutting edge removes per revolution — measured as inches (or millimeters) per tooth. Run too low a chip load and the tool rubs instead of cuts, generating heat that dulls the edge and scorches the workpiece. Run too high and you risk deflection, poor finish, and broken bits.
Worked example. A 2-flute 1/2" compression bit cutting 3/4" plywood at 18,000 RPM with a target chip load of 0.018" per tooth: 18,000 × 2 × 0.018 = 648 IPM. If your machine or hold-down can't sustain that feed, drop the RPM rather than letting the chip load fall too low — that keeps the chip thick enough to carry heat away in the chip instead of into the tool.
Starting-point chip load ranges (inches per tooth) for upcut, downcut, and compression spiral router bits in common materials. Begin in the middle of the range, then adjust based on edge finish, sound, and chip color.
| Tool Diameter | Soft Wood / Pine | Hard Wood | Plywood & MDF | Melamine / Laminate |
|---|---|---|---|---|
| 1/8" (3 mm) | 0.004 – 0.006 | 0.003 – 0.005 | 0.004 – 0.006 | 0.003 – 0.005 |
| 1/4" (6 mm) | 0.009 – 0.011 | 0.008 – 0.010 | 0.010 – 0.012 | 0.006 – 0.009 |
| 3/8" (10 mm) | 0.013 – 0.016 | 0.011 – 0.014 | 0.013 – 0.017 | 0.009 – 0.012 |
| 1/2" (12 mm) | 0.017 – 0.021 | 0.015 – 0.018 | 0.016 – 0.020 | 0.012 – 0.016 |
| 5/8" (16 mm) | 0.019 – 0.024 | 0.017 – 0.021 | 0.018 – 0.023 | 0.014 – 0.018 |
| 3/4" (19 mm) | 0.021 – 0.026 | 0.019 – 0.023 | 0.020 – 0.025 | 0.015 – 0.020 |
Ranges are conservative starting points for production routing. Compression bits generally tolerate the upper end of each range in panel goods; straight (O-flute) bits in plastics run lower.
| Tool Diameter | Acrylic / PVC | HDPE / Polycarbonate | Solid Surface (Corian-type) | Aluminum |
|---|---|---|---|---|
| 1/8" (3 mm) | 0.003 – 0.005 | 0.004 – 0.006 | 0.003 – 0.005 | 0.002 – 0.004 |
| 1/4" (6 mm) | 0.006 – 0.009 | 0.008 – 0.011 | 0.006 – 0.009 | 0.004 – 0.006 |
| 3/8" (10 mm) | 0.009 – 0.012 | 0.011 – 0.014 | 0.008 – 0.011 | 0.005 – 0.008 |
| 1/2" (12 mm) | 0.011 – 0.015 | 0.013 – 0.017 | 0.010 – 0.014 | 0.006 – 0.010 |
For aluminum and solid surface, use a single- or two-flute O-flute or specialized non-ferrous bit, apply coolant/lubricant or mist, and clear chips aggressively to prevent re-cutting and welding.
A correct chip load produces firm, opaque chips you can feel — not fine dust. Dust and a high-pitched whine mean the chip load is too low and the tool is rubbing. Chatter, deflection marks, or a bogging spindle mean it's too high.
If the calculated feed exceeds what your gantry, vacuum hold-down, or part fixturing can handle, lower the RPM to keep chip load in range rather than slowing the feed alone. Thin chips equal hot tools.
These figures assume a reasonable depth of cut (roughly 1× to 2× tool diameter in wood). Deeper passes, full-slot cuts, and ramping all increase load on the tool — reduce chip load or take multiple passes.
Sharp, application-correct tooling holds these ranges far longer. Compression bits leave clean top and bottom edges on laminated panels; coated carbide extends life in abrasive MDF and melamine. NuTek stocks router tooling and spares for the KRC line.
These chip load ranges are general starting points for CNC routing and do not replace the tooling manufacturer's published recommendations or your machine's documented limits. Always confirm spindle, hold-down, and tool ratings before increasing feed or speed, and make test cuts on scrap. Questions on setup for your KRC Phantom or other NuTek equipment? Our service team is glad to help dial it in.