What is a servo press?

A servo press uses servo motors for precise force and position control during forming operations.

How do I calculate servo press tonnage?

Use our free tonnage calculator at servopress.club/tonnage-calculator.html

Servo motor running hot - what should I check?

mchen_servo

Our 300T servo motor is running about 15°C hotter than it should be according to the manual. Not in alarm yet but I want to get ahead of it. Here's what I've checked so far.

**Temperature Limits
**
Most servo motors are rated for continuous operation at 40°C ambient with winding temperature rise of 80°C (Class B) or 105°C (Class F). Sustained operation above rated temperature **reduces insulation life by 50% for every 10°C excess**.

**Common Causes
**
**1. Duty Cycle Exceeds Rating**
Calculate actual duty cycle: (on-time / cycle-time) × 100%. Compare to motor's rated duty cycle.

**2. Cooling Fan Failure**
Check fan rotation direction — reverse rotation gives only ~30% of rated airflow. Clean fan blades regularly.

**3. Ambient Temperature Too High**
Derate motor by 3% per °C above 40°C. Consider adding forced air cooling for hot environments.

**4. Servo Gain Tuning Issues**
Poorly tuned gains cause the motor to hunt (oscillate), generating heat without useful work. Check for oscillation with a servo analyzer.

**5. Mechanical Binding**
Increased mechanical resistance forces the motor to work harder. A 10% increase in mechanical load can cause 20% increase in motor heating.

**Solutions
**
- Install motor temperature monitoring with alarm at 100°C and shutdown at 120°C
- Add thermal imaging to monthly maintenance routine
- Consider motor with higher thermal class (Class H) for demanding applications
- Optimize speed profile to reduce RMS current — slower approach, faster return

anna_plc

Temperature monitoring is key but most shops only look at the drive's estimated temperature, not actual. I always recommend adding a PT100 RTD directly on the motor winding if the motor doesn't have one built in. The drive's thermal model can be off by 15-20?C, especially on intermittent duty cycles.

raj_pm

We had chronic overheating on a 200T press that turned out to be a partially blocked cooling fan filter. Motor was hitting 140?C every afternoon when the shop got hot. Cleaned the filter, problem gone. Now it's on our daily checklist. Sometimes the fix is embarrassingly simple.

jim_apps

Dealt with this exact scenario on a Komatsu H2W 300T about two years back. Motor was creeping up 10-15°C over baseline every summer.

Turned out to be two things stacked on top of each other:

1. The cooling fan was running but the filter was maybe 60% clogged — not enough to trigger any alarm but enough to cut airflow significantly. We put it on a monthly cleaning schedule after that.

2. The motion profile was doing a full-speed return stroke that wasn't necessary for the part. Slowed the return by about 20% and peak motor current dropped noticeably. Less current = less heat, simple as that.

One thing I'd add to the checklist — check your drive's thermal time constant setting. On Yaskawa drives (Pn401/Pn402) this is supposed to match the motor's actual thermal characteristics. I've seen machines shipped from the builder with default values that don't match the installed motor. If the time constant is set too high, the drive won't derate soon enough and you'll cook the motor before the overload trips.

Also worth checking the grease in the motor bearings if the press has high hours. Degraded bearing grease adds friction heat that shows up as a general temperature rise. Easy to miss because it comes on gradually.

toolndye_dave

Quick update on motor temperature stuff — we just went through this again on a different press (Aida 200T, about 4 years old). Motor was running 12°C above baseline but only on certain jobs.

Turned out the motion profile on those jobs had a very aggressive decel segment — going from 250mm/s to 15mm/s in about 40ms right before contact. That dumps a huge amount of energy into the motor as regenerative current. The regen resistor was sized fine for the average cycle, but on these heavy-decel jobs it was saturating and the excess energy was heating the motor windings.

Fix was to soften the decel curve — stretched it from 40ms to 80ms. Parts were identical (we checked 200 pieces before and after), motor temp dropped 10°C. The forming speed at contact was the same, we just started decelerating earlier in the stroke. Sometimes you can solve a thermal problem without touching anything mechanical — just reshape the motion profile.

Also +1 on the PT100 recommendation above. The drive thermal model on our Yaskawa was reading 128°C when the actual winding temp was 142°C. That 14°C gap is the difference between "looks fine" and "should probably investigate."