Interactive Chip Formation Model
Feed per tooth — the depth of material each cutting edge removes per revolution — drives feed rate, chip evacuation, and tool life. This tool converts a target FPT into a programmable feed rate, and includes a radial chip-thinning correction for light-engagement milling that most basic calculators skip.
Feed per tooth (FPT, also written fz) is the linear distance the workpiece advances during the time one cutting edge is engaged — the thickness of the chip that single edge removes. It is the parameter tool manufacturers rate an edge to handle, and it is the foundation every feed rate is built from: multiply it by the number of flutes and the spindle speed and you get the programmable table feed.
FPT is a per-edge load, not a machine setting. Two tools cutting the same feed rate can be loading their edges completely differently if flute count or RPM differ. Always reason in FPT first, then convert to feed rate — never the other way around.
Calculate and compare
Choose a model and unit system. Every orange-outlined field is editable; results update instantly. Need RPM from a cutting speed first? Use the Milling Formula Calculator.
The programmed feed per tooth is scaled up so the actual chip thickness still matches your target — otherwise a light radial pass rubs instead of cutting.
Check your inputs — radial depth of cut must be greater than 0 and less than the cutter diameter, and every other field must be greater than 0.
Radial engagement is ≥ 50% of diameter — the chip already reaches full thickness, so RCTF = 1 (no correction applied).
Engineering interpretation
Every carbide end mill line has an FPT range it was ground and coated to handle. Treat the reference ranges below as a starting point, then confirm against FM Carbide's product data for your exact tool — geometry, coating, and flute count all shift the safe window.
Below roughly 50% radial engagement, the actual chip is thinner than the programmed FPT because each edge only touches a shrinking arc of material. Left uncorrected, the edge rubs instead of shearing — accelerating wear and building heat. That is exactly what RCTF compensates for.
A calculated feed rate is a starting point. A tightly curled, warm-colored chip usually signals a healthy load; dust or discoloration signals rubbing or excess heat. For ball-nose and corner-radius tools, base RPM on the effective cutting diameter at your actual axial depth, not the nominal tool diameter.
Reference ranges
| Material family | ≤ 6 mm (¼") | 6–12 mm (¼–½") | 12–20 mm (½–¾") | > 20 mm (> ¾") |
|---|---|---|---|---|
| Low & medium-carbon steel | 0.018–0.035 mm | 0.025–0.050 mm | 0.038–0.075 mm | 0.050–0.100 mm |
| Alloy & hardened tool steel | 0.011–0.025 mm | 0.015–0.035 mm | 0.023–0.053 mm | 0.030–0.070 mm |
| Stainless steel | 0.014–0.028 mm | 0.020–0.040 mm | 0.030–0.060 mm | 0.040–0.080 mm |
| Cast iron | 0.021–0.042 mm | 0.030–0.060 mm | 0.045–0.090 mm | 0.060–0.120 mm |
| Aluminum & non-ferrous | 0.028–0.063 mm | 0.040–0.090 mm | 0.060–0.135 mm | 0.080–0.180 mm |
| Titanium & nickel HRSA | 0.011–0.021 mm | 0.015–0.030 mm | 0.023–0.045 mm | 0.030–0.060 mm |
12 mm, 4-flute end mill, target FPT 0.05 mm, radial depth 2 mm (16.7% of D), 3,000 RPM:
Match flute count, coating, and geometry to the material and engagement you actually run — FM Carbide end mills are ground for predictable chip formation across the full FPT range.
Got your chip load dialed in?
Pair it with quality APMT & face milling inserts for consistent results.
View Indexable Milling Inserts →Put the numbers to work
Your feeds and speeds are only as good as the cutter running them. These solid carbide end mills are ground to hold those numbers under load.
New to speeds and feeds? Read the full breakdown in TechTalk.