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 Press Motor: Repair vs. Replace Decision Guide

admin

**Question:** Our servo press motor is making noise and we are getting intermittent encoder alarms. The motor is 8 years old. Repair shop quoted $4,000 to rewind and replace bearings. A new motor is $12,000. How do we decide?

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**Answer:**

Here is a framework to make this decision rationally.

## Assess the Motor Condition First

Before deciding repair vs. replace, get a full condition assessment:

1. **Insulation resistance**: measure with a megohmmeter at 500V.
- Above 100 megaohm = good
- 10-100 megaohm = marginal
- Below 10 megaohm = replace

2. **Winding resistance balance**: measure resistance between each phase pair. Should be within 2% of each other. Imbalance above 5% indicates winding damage.

3. **Bearing condition**: with the motor uncoupled, spin the shaft by hand. Rough or gritty = replace bearings.

4. **Encoder condition**: intermittent encoder alarms - check the encoder cable first (most common cause). If the cable is good, the encoder itself may be failing.

## The Decision Framework

**Repair makes sense when:**
- Insulation resistance is above 50 megaohm (winding is fundamentally sound)
- The failure is isolated (bearings only, or encoder only)
- The motor is a non-standard frame size that is hard to replace
- Lead time for a new motor is 12+ weeks

**Replace makes sense when:**
- Insulation resistance is below 50 megaohm
- Multiple failures at once (bearings + encoder + winding issues)
- The motor is 10+ years old and has been repaired before
- New motor comes with 2-year warranty vs. 6-month on repair

## For Your Specific Situation

8 years old with noise and encoder alarms: get the insulation resistance test done first. If above 50 megaohm, the $4,000 repair is reasonable. If below 50 megaohm, the winding is degraded and you will be back for another repair in 1-2 years - spend the $12,000 now.

## Total Cost of Ownership

- Repair: $4,000 now, likely another repair in 3-4 years ($4,000-$6,000), then replacement. Total over 8 years: $10,000-$14,000.
- Replace now: $12,000 now, likely good for 10+ years. Total over 8 years: $12,000.

The numbers are close. The insulation resistance test result is the deciding factor.

raj_maintenance

At 8 years old with noise and encoder alarms, I'd replace. A rewind fixes the electrical side but doesn't address bearing wear, shaft runout, or encoder degradation. And a rewound motor is never quite as good as new —the insulation system is different and the thermal characteristics change. For a critical production press, the $8,000 difference between repair and new is cheap insurance.

pete_retrofit

One option not mentioned: refurbished motors from the OEM. Yaskawa and Fanuc both offer factory-refurbished motors at about 60% of new price with a full warranty. You get essentially a new motor (new bearings, new encoder, rewound stator) with OEM quality control. Best of both worlds.