OK, I ran some tests on the bench.
Equipment:
Wantai WT86STH118-6004B 1200 oz/in stepper motor 5.6 amp
Wantai DQ860MA Drive
60 Volt Power Supply
Stepper Speed Controller
3M Infrared thermometer
Conditions:
Motor clamped to a wood bench with a C-clamp, 3 sides exposed to still air
800 Step / Rev, SW 5 OFF, SW 6,7,8 ON
5.6 Amp, SW1,2,3 OFF
SW4 OFF
Power Supply voltage = 60.0
I took a temperature reading every 5 minutes during the test
Ambient temperature at START of test = 77 F
Starting temperature of motor case = 88 F
The first 10 minutes was Power ON, Motor OFF to test standstill temperature rise.
At 10 minutes I turned the Motor ON, about 1 REV/Sec (equivalent to 12 IPM on a 0.200 pitch leadscrew)
Maximum temperature was at 55 minutes (45 minutes running time) = 161 F
The last 15 minutes (55-70) was power ON, Motor OFF to test standstill temperature again.
Ambient temperature at END of test = 80 F
As you can see, the temperature rise was pretty constant as long as the motor was running. I don't know what the max safe operating temperature of the motor is. The high temperature is due to running current, not standstill current.
The only suggestion that I have is to turn down the current to the minimum that will run the machine.
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