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 Encoder Replacement: Step-by-Step Procedure

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## When to Replace the Encoder

Replace the encoder when:
- Encoder battery voltage below 3.0V (replace battery first, then encoder if alarms persist)
- Position feedback noise causing erratic motion
- Physical damage to encoder body or cable
- Encoder alarm that persists after battery replacement and cable check

## Before You Start

**Record all drive parameters.** Encoder replacement requires re-zeroing the press, which changes position offsets. Back up all parameters to PC before starting.

**Order the correct encoder.** Encoder model is on the motor nameplate. Common types:
- Yaskawa: 23-bit absolute (PAO-23)
- Siemens: EnDat 2.2 or DRIVE-CLiQ
- Mitsubishi: 22-bit absolute (OSA22)
- Fanuc: αi or βi series

## Replacement Procedure

1. Lock out / tag out press. Confirm zero energy.
2. Disconnect encoder cable at motor end.
3. Remove encoder cover (typically 4 screws).
4. Note encoder orientation before removal (mark with paint pen).
5. Remove encoder mounting screws.
6. Pull encoder straight off motor shaft — do not rotate.
7. Install new encoder in same orientation.
8. Reconnect cable. Check connector is fully seated.
9. Power up drive. Clear encoder alarm.
10. Perform homing procedure per press manual.
11. Verify BDC position matches mechanical BDC.
12. Run 10 test strokes at 10% speed. Check position repeatability.

## After Replacement

Re-enter all position offsets (BDC, TDC, die protection windows). These are lost when encoder is replaced.

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After replacing the encoder, the most critical step is the encoder zero-point alignment. If the zero point is off, the drive's commutation angle is wrong and the motor runs inefficiently —sometimes producing only 70-80% of rated torque. On Yaskawa, run Fn008 after encoder replacement. On Mitsubishi, run the encoder zero calibration in setup mode.

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Keep the old encoder even if it's failed. The serial number and model info on it are needed to order the exact replacement. I've seen shops throw away the old encoder and then struggle to identify the correct replacement because the press documentation was incomplete. Label it and put it in the parts cabinet.