Cutting Parameters Reference
Feed and Speed Formulas
RPM from Surface Speed
RPM = (SFM x 12) / (pi x diameter_inches)
RPM = (SMM x 1000) / (pi x diameter_mm)
Where SFM = Surface Feet per Minute, SMM = Surface Meters per Minute.
Feed Rate
Feed (mm/min) = RPM x Number_of_Flutes x Chip_Load_per_Tooth
Feed (in/min) = RPM x Number_of_Flutes x Chip_Load_per_Tooth
Material Removal Rate
MRR = ADOC x RDOC x Feed_Rate
Where ADOC = Axial Depth of Cut, RDOC = Radial Depth of Cut.
Depth of Cut Guidelines
Roughing
| Parameter |
Endmill Rule |
| ADOC (axial) |
1-2x tool diameter |
| RDOC (radial) |
40-60% of tool diameter |
| Step-over |
40-60% of tool diameter |
Finishing
| Parameter |
Endmill Rule |
| ADOC (axial) |
0.5-1x tool diameter |
| RDOC (radial) |
5-15% of tool diameter |
| Step-over |
5-15% of tool diameter |
Adaptive/HEM Clearing
| Parameter |
Rule |
| ADOC (axial) |
Up to 3-4x tool diameter |
| RDOC (radial) |
5-15% of tool diameter |
| Engagement angle |
< 40 degrees |
| Benefit |
Constant chip load, reduced tool wear |
Material-Specific Parameters
Aluminum 6061-T6
| Tool Dia |
RPM |
Feed (mm/min) |
Chip Load |
SFM |
| 3mm, 2-flute |
24,000 |
600-900 |
0.013-0.019mm |
750 |
| 6mm, 3-flute |
18,000 |
800-1200 |
0.015-0.022mm |
900 |
| 10mm, 3-flute |
12,000 |
720-1080 |
0.020-0.030mm |
1000 |
| 12mm, 4-flute |
9,000 |
720-1080 |
0.020-0.030mm |
900 |
Steel 1018 (Mild)
| Tool Dia |
RPM |
Feed (mm/min) |
Chip Load |
SFM |
| 6mm, 3-flute |
4,000 |
360-480 |
0.030-0.040mm |
250 |
| 10mm, 4-flute |
2,500 |
300-400 |
0.030-0.040mm |
250 |
| 12mm, 4-flute |
2,100 |
250-340 |
0.030-0.040mm |
250 |
Brass (360 Free-Machining)
| Tool Dia |
RPM |
Feed (mm/min) |
Chip Load |
SFM |
| 6mm, 2-flute |
10,000 |
600-800 |
0.030-0.040mm |
500 |
| 10mm, 3-flute |
6,000 |
540-720 |
0.030-0.040mm |
500 |
Stainless Steel 304
| Tool Dia |
RPM |
Feed (mm/min) |
Chip Load |
SFM |
| 6mm, 4-flute |
2,700 |
270-430 |
0.025-0.040mm |
170 |
| 10mm, 4-flute |
1,600 |
160-260 |
0.025-0.040mm |
170 |
Plastics (Delrin/Acetal)
| Tool Dia |
RPM |
Feed (mm/min) |
Chip Load |
SFM |
| 6mm, 1-flute |
18,000 |
1800-2700 |
0.10-0.15mm |
900 |
| 6mm, 2-flute |
18,000 |
900-1400 |
0.025-0.038mm |
900 |
Note: Single-flute preferred for plastics to prevent chip welding.
Tool Selection Guidelines
| Operation |
Tool Type |
Notes |
| Roughing pockets |
Endmill (3-flute for aluminum, 4-flute for steel) |
Largest diameter that fits |
| Finishing |
Endmill or Ballnose (for 3D surfaces) |
Smaller for detail |
| Drilling |
Drill bit or endmill helical plunge |
Match hole diameter |
| Profiling |
Endmill |
Match corner radius requirement |
| Deburring |
Chamfer mill (90 or 120 deg) |
Match edge requirement |
| 3D surfaces |
Ballnose |
Step-over determines scallop height |
Scallop Height (Ballnose Finishing)
Scallop Height = R - sqrt(R^2 - (stepover/2)^2)
Where R = ballnose radius. For 0.01mm scallop with 6mm ballnose: stepover = 0.49mm.
Tool Life Considerations
- Aluminum: carbide endmills last 60-120 minutes at recommended parameters
- Steel: carbide endmills last 30-60 minutes
- Reduce feed by 15-20% for extended tool life
- Increase RPM and reduce chip load for better surface finish
- Coolant (flood or mist) extends tool life 2-3x in steel
