Find: | Have: | Formula: |
Revolutions per minute (RPM) | SFM | (SFM x 12) / (Diameter of drill x 3.1416) |
Surface feet per minute (SFM) | RPM | (Diameter of drill x RPM x 3.1416) / 12 |
Feed rate per RPM (FR) | SFM and FM | (Diameter of drill x FM x 3.1416) / (SFM x 12) |
Feed rate per RPM (FR) | RPM and FM | FM / RPM |
Feed rate per minute (FM) | FR and RPM | RPM x FR |
SFM | RPM and drill dia. | .26 x RPM x drill diameter |
RPM | SFM and drill dia. | 3.8 x (SFM / drill diameter) |
Material | SFM* |
Aluminum and Aluminum Alloys | 150-300 |
Brass and Bronze (free cutting) | 150-300 |
Brass and Bronze (high tensile) | 70-120 |
Cast Iron (soft) | 80-120 |
Cast Iron (medium) | 60-90 |
Cast Iron (hard) | 30-70 |
Copper | 70-100 |
Magnesium | 200-400 |
Nickel Base Alloys | 20-50 |
Plastic and Related Materials | 100-200 |
Wood | 200-300 |
Material | SFM* |
Alloyed – under 200 B.H. | 60-90 |
Alloyed – 200 – 300 B.H. | 40-70 |
Alloyed – over 300 B.H. | 20-30 |
Cast and Forged | 40-70 |
Heat Treated – 35 – 40 R.C. | 30-40 |
Heat Treated – 40 – 45 R.C. | 20-30 |
Heat Treated – over 45 R.C. | 10-20 |
Mild – .2 – .3 Carbon | 70-100 |
Mild – .4 – .5 Carbon | 50-80 |
Stainless – 300 Series | 20-50 |
Stainless – 400 Series | 30-70 |
Tool – over 1.0 Carbon | 40-60 |
Titanium Alloys | 20-50 |
Diameter (in.) | Light Feeds | Heavy Feeds |
1/8 | .0005 – .0010 | .0015 |
3/16 | .0010 – .0015 | .0020 |
1/4 | .0015 – .0020 | .0025 |
5/16 | .0020 – .0025 | .0030 |
7/16 | .0025 – .0030 | .0035 |
1/2 | .0035 – .0040 | .0045 |
5/8 | .0045 – .0050 | .0055 |
3/4 | .0055 – .0060 | .0065 |