CNC Speed & Feed Calculator

Precision machining parameters: compute RPM, feed rate, material removal rate (MRR), and spindle power. Updated with radial/axial depth & 15+ material presets.

Material Library (click to load):
Aluminum 6061 Mild Steel Stainless 304 Cast Iron Titanium Ti6Al4V Brass / Bronze Copper Plastic (Acetal) Tool Steel (A2) Inconel 718
Presets include Vc (carbide), fz, and specific cutting force (for power).
mm
= 0.472 inch
m/min
≈ 656 SFM
mm/tooth
≈ 0.0031 inch/tooth
mm
(% of tool diameter: 50%)
mm
(DOC along spindle axis)
Specific cutting force Kc (for power estimation) is preset by material — adjust in advanced settings.
RPM curve (Vc constant) Current tool diameter

Engineering Guide: Speed, Feed, MRR & Power

Essential formulas for production machining (metric):

Spindle Speed (RPM):
n = (Vc × 1000) / (π × D) (Vc m/min, D mm)
Feed Rate (mm/min):
Vf = n × Z × fz
Material Removal Rate:
MRR (cm³/min) = (Vf × ae × ap) / 1000
Spindle Power (kW):
P = (MRR × Kc) / η (Kc = specific cutting force, η = efficiency)

? Material-Specific Cutting Data (Carbide recommendations)

Material Vc (m/min) fz (mm/tooth) 4-flt Kc (kW/cm³/min) Hardness (HB)
Aluminum 6061 250-600 0.08-0.15 0.3-0.5 95
Mild Steel (1018) 90-150 0.05-0.10 1.2-1.8 130
Stainless 304 60-90 0.04-0.08 2.0-2.5 200
Cast Iron 70-120 0.07-0.12 0.9-1.3 180
Titanium Ti6Al4V 40-70 0.03-0.06 1.8-2.2 320
Brass / Bronze 150-300 0.08-0.15 0.6-0.8 100
Copper 80-150 0.07-0.12 1.0-1.3 90
Tool Steel A2 (200 HB) 60-100 0.04-0.08 1.8-2.2 200
Inconel 718 25-40 0.02-0.05 2.8-3.5 350
Plastic (Acetal) 200-600 0.10-0.25 0.1-0.2 —

*Kc values are approximate for sharp carbide tools; adjust for tool wear and coolant.

⚙️ How to Optimize Cutting Parameters

Radial engagement (ae)

Light radial cuts (≤25% D) allow higher feed and speed. Heavy roughing (50-100% D) reduces tool life — reduce feed by 20-40%.

Axial depth (ap)

ap up to 1.5×D is common; deeper cuts require lower feed or speed to avoid chatter.

Pro tip: For finishing passes, use ae ≤ 10% D, increase Vc by 15%, and reduce fz by 20-30% for better surface finish.

CNC Machining FAQs — Speeds, Feeds, MRR

MRR = feed × ae × ap. Without ae, you can't calculate actual volume removed. Our calculator uses ae and ap to give realistic MRR and power demand.

Power (kW) = (MRR × Kc) / η. Kc = specific cutting force (material property). Default η = 0.8 (80% efficiency). You can adjust Kc via material preset.

For same material, fz can be 20-30% higher than 4-flute due to better chip evacuation. Our calculator uses same fz; adjust manually.

Yes, for HSM with light radial engagement (5-10% D) you can increase Vc by 30-50% and reduce ae accordingly.

Climb milling (recommended) reduces heat and tool wear. Our calculator doesn't change parameters but climb allows slightly higher feeds.