Threading Tools Technical Support
Speed and Feed Chart
| Material | HB/Rc | SFM: Uncoated | SFM: AlTiN+ | Tool Diameter .040-.050* | Tool Diameter .060-.092* | Tool Diameter .120-.152* | Tool Diameter .180-.232* | Tool Diameter .290-.362* | Tool Diameter .373+* |
|---|---|---|---|---|---|---|---|---|---|
| Cast Iron | 160 HB | 75-200 | 200-550 | 0.003 | 0.004 | 0.005 | 0.007 | 0.008 | 0.009 |
| Cabon Steel | 18 Rc | 75-200 | 200-450 | 0.003 | 0.005 | 0.006 | 0.007 | 0.008 | 0.009 |
| Alloy Steel | 20 Rc | 75-200 | 200-425 | 0.003 | 0.004 | 0.005 | 0.006 | 0.007 | 0.008 |
| Tool Steel | 25 Rc | 75-175 | 175-300 | 0.002 | 0.003 | 0.004 | 0.005 | 0.006 | 0.007 |
| 300 Stainless Steel | 150 HB | 75-175 | 175-350 | 0.003 | 0.003 | 0.004 | 0.005 | 0.006 | 0.007 |
| 400 Stainless Steel | 195 HB | 75-210 | 130-420 | 0.003 | 0.004 | 0.005 | 0.006 | 0.006 | 0.007 |
| High Temp Alloy (Nickel & Cobalt Base) | 20 Rc | 50-130 | 130-300 | 0.002 | 0.003 | 0.003 | 0.004 | 0.005 | 0.005 |
| Titanium | 25 Rc | 50-100 | 120-275 | 0.003 | 0.003 | 0.004 | 0.005 | 0.006 | 0.007 |
| Heat Treated Alloys (38-45 Rc) | 40 Rc | 50-100 | 100-200 | 0.002 | 0.002 | 0.003 | 0.004 | 0.004 | 0.005 |
| Aluminum | 100 HB | 75-250 | 250-750 | 0.004 | 0.005 | 0.007 | 0.008 | 0.010 | 0.011 |
| Brass, Zinc | 80 HB | 75-300 | 250-650 | 0.003 | 0.005 | 0.006 | 0.007 | 0.008 | 0.009 |
SFM = Surface Feet per Minute
Parameters are a starting point based on machinability rating at hardness listed. Check machinability rating of the material to be machined and adjust First Pass Depth.
Helpful Formulas and Information
| Formula Name | |
|---|---|
| Pitch | 1 ÷ TPI (Threads per Inch) |
| Acme Thread Depth | Pitch x 0.5 |
| Stub Acme Thread Depth | Pitch x 0.3 |
| NPT Pipe Thread Depth | Pitch x 0.76 |
| Internal 60° Thread Depth | Pitch x 0.54 |
| Feed Rate | Pitch x Number of Thread Starts |
Minimum Depth per Pass should not be less than 0.0003.
Threads not ending in a relief need at least one thread pitch length of pullout.
Make sure the feed rate calculation does not exceed the maximum feed rate of the machine.
| Problem | Cause | Solution |
|---|---|---|
| Rapid Flank Wear | Cutting Conditions | Check for excessive feed and speed. See above chart for recommendations. |
| Tool | Select a coated tool. | |
| Part | Make sure prior operation did not work harden the metal. | |
| Built-up Edge | Tool | Select a coated tool. |
| Cutting Force | Increase the number of passes. | |
| Heat | Use an SCT coolant holder. If coolant is not available, use shop air and a coated tool. | |
| Corner Breakage | Cutting Conditions | Reduce the depth-of-cut on the first pass. |
| Program | If there is no thread relief, withdraw the tool on an angle. | |
| Part | End in thread relief. | |
| Chips Wrapping Around Tool | Tool | Use a tool that is at least 30% smaller than the hole diameter. |
Radial Infeed is not recommended. Modified flank at 1° is recommended.
For unfavorable length-to-diameter ratios or difficult-to-machine materials, the number of passes will need to be increased up to 40% more.
Depth of cut per pass should not be less than 0.0003 inch.
*First Pass Depth
Troubleshooting Common Problems