Smart CNC Speeds & Feeds Calculator
Optimize your milling process. Auto-suggests RPM & Feed based on Material.
The Ultimate Guide to CNC Speeds and Feeds
Whether you are a professional machinist or a hobbyist, understanding Speeds and Feeds is the key to efficient CNC milling. Incorrect settings can lead to tool breakage, poor surface finish, or chatter. Our calculator simplifies this by using industry-standard formulas.
The Golden Formulas 📐
1. Spindle Speed (RPM): Determines how fast the tool spins.
RPM = (Vc × 1000) / (π × D)2. Feed Rate (VF): Determines how fast the tool moves across the material.
Feed Rate = RPM × z × fzz: Number of Flutes | fz: Chip Load per Tooth (mm)
Material Guidelines for Carbide Tools
Different materials require different cutting speeds (Vc). Here is a quick reference guide used in our calculator:
Vc: 200 - 400 m/min
Aluminum is soft and sticky. Use 2 or 3 flute end mills with high RPM to prevent chip welding.
Vc: 60 - 90 m/min
Requires rigid setup. Use 4 flute tools. If blue chips appear, your speed is correct.
Vc: 40 - 60 m/min
Work hardens quickly. Do not dwell! Keep the tool moving and use coolant.
Troubleshooting Common CNC Problems
- 🚨 Tool Breakage: Usually caused by too much Chip Load or runout. Reduce the feed rate or check tool runout.
- ⚠️ Chatter (Vibration): Caused by long tool stick-out or high RPM. Reduce RPM by 10% or hold the tool shorter.
- ✅ Poor Surface Finish: Increase RPM slightly or reduce the Feed Rate for a finishing pass.