Enter your spindle's continuous rating (also called S1, or 100% load) for Spindle torque, max and Spindle power, max. Don't use the short-time ratings, such as 10% ED, 30-minute or 200% load, that manufacturers also publish. This article explains how to read torque and power charts and pick the right value.
Both fields are required when you add a machine. For their units and limits, see Machine details CAM Assist needs.
Why the continuous rating?
CAM Assist uses torque and power to keep the cutting parameters it calculates within what your spindle can deliver. The continuous rating is what the spindle can sustain without stopping: it can run at that load non-stop without overheating or cutting back its output.
Spindle charts usually show several curves:
| Curve | What it means | Use it? |
|---|---|---|
| Continuous, Cont, S1 or 100% | What the spindle can deliver indefinitely | Yes |
| 30-minute rating | What it can deliver for up to 30 minutes before it must drop back | No |
| 10% ED, 15% ED, 25% ED and so on | What it can deliver for that percentage of a short duty cycle, with the rest spent at lower load | No |
| 200% load or peak | A short burst above the continuous rating | No |
The short-time curves are higher than the continuous curve. Entering them would let CAM Assist plan cuts your spindle can only hold for a short time.
How to read a chart
- Find the curve labeled continuous, Cont, S1 or 100%.
- For torque, read the flat top of that curve (its highest value). For power, read the flat top of the continuous power curve.
- Enter the values in your unit setting (N·m or ft-lb for torque, kW or hp for power).
If the chart shows a range
Some manufacturers give a range, for example 198–135 N·m or 11–7.5 kW. Enter the lower value. It's the safer choice.
If the chart is at 200% load
Some manufacturers, including Haas, quote torque and power at 200% spindle load. Halve these values to get the 100% (continuous) rating.
| Chart value at 200% load | Enter in CAM Assist |
|---|---|
| 125 N·m (92 ft-lb) | 62.5 N·m (46 ft-lb) |
| 22.4 kW (30 hp) | 11.2 kW (15 hp) |
Constant torque and constant power
A spindle has two main operating regions:
- Constant torque: from 0 rpm up to the base (corner) speed, the spindle can deliver its full torque. Power rises with speed.
- Constant power: above the base speed, power stays roughly flat and torque falls as speed rises.
Torque and power are linked by spindle speed:
Power (kW) = torque (N·m) × spindle speed (rpm) ÷ 9,549
So at low rpm, such as large face mills or big drills, torque is usually the limit. At high rpm, power is.
The balance between torque, power and top speed depends on the motor and whether the spindle has a gearbox. A spindle with a higher top speed often has less torque.
What this means for you
- Look up your spindle's torque and power charts in the machine manual or from the manufacturer.
- Enter the continuous values. If you're unsure between two values, enter the lower one.
- If you imported the machine from a Mastercam file, CAM Assist fills in placeholder torque and power values. Replace them with your machine's real ratings. See Machine details CAM Assist needs.
- In the cutting parameters explorer, the spindle power and torque rows under Loads and power show how much of your spindle a cut uses. See What do the Cutting Parameters Explorer measures mean?