CNC Feeds, Speeds & MRR Matrix
Calculate spindle RPM, linear feed rate, and material removal rate for CNC milling using surface-speed and chip-load reference data for common alloys and plastics.
Machining Parameters
Cutting Data Results
Spindle Speed
—
revolutions / minute
Feed Rate
—
inches / minute (IPM)
Material Removal Rate
—
in³ / minute
Feed per Revolution
—
inches / rev
Chip Thickness (max)
—
inches
Spindle Power Est.
—
horsepower at spindle
Formula Breakdown
Waiting for input…
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Chip Load Reference Table
Typical recommended chip loads (in/tooth) for common materials by operation, plus recommended surface speeds.
| Material | Surface Speed | Slotting | Side Milling | Plunging |
|---|
Informative Guides & Helper Articles
Best Practices for CNC Feeds, Speeds & MRR
Shop-proven best practices for setting CNC speeds and feeds: tool selection, chip management, coolant, and stable cutting techniques.
Read Article →Common Errors in CNC Feeds, Speeds & MRR
Fix the most common CNC cutting-data mistakes: wrong units, overspeed, chip thinning, chatter, and power overloads that wreck tooling.
Read Article →Future Trends in CNC Feeds, Speeds & MRR
Adaptive control, tool-wear monitoring, and AI-driven cutting-data optimization: where CNC feeds and speeds are heading.
Read Article →Ultimate Guide to CNC Feeds, Speeds & MRR
Master CNC cutting data: surface speed, RPM, chip load, feed rate, and material removal rate formulas explained for machinists.
Read Article →Top CNC Feeds, Speeds & MRR Optimization Tips
Raise CNC metal removal rates with high-efficiency milling, optimal step-overs, chip-thinning feeds, and load-monitored tuning.
Read Article →How to Use the CNC Feeds & Speeds Calculator
Computes spindle RPM, feed rate, and chip load from surface speed and material tables.
- Select material and tool (diameter, flutes, coating).
- Accept or adjust SFM; RPM = 3.82 x SFM / D.
- Check chip load against the material table.
RPM and Chip Load: Two Equations
RPM = 3.82 x SFM / D and feed = RPM x flutes x chipload - chipload (thickness per tooth) decides tool life and finish. Aluminum with carbide runs 250-600 SFM; stainless 100-150; titanium 50-80, and feed must scale or teeth rub (rubbing work-hardens, then burns tools). Corrections beginners skip: slotting takes 50-70% of profiling chipload; radial engagement under 25% permits raising feed (chip thinning). Sounds tell more than math: chirping = feed too low; squealing = rubbing.
CNC Feeds & Speeds Calculator FAQ
What is chip load?
Feed per tooth - the thickness each edge shears. Too low: rubbing and work-hardening. Too high: snapped cutters.
Why is aluminum melting to the tool?
Chip evacuation: chips re-cut and weld. Air blast, higher feed, fewer flutes, polished (uncoated) flutes for aluminum.
Slotting vs profiling?
Full-width slotting takes 50-70% of profiling chipload; light radial engagement lets you raise feed via chip thinning.