Machine Service Case Overview | Drive Malfunction NILES ZP12

Key Points

• Even after turning on the master (hydraulic) system, the axes would not move
• The NCU started normally (7-segment display: “6”)
• Due to an E/R module failure, no power was supplied to each drive (DC 600V)
• After replacing the E/R module, all axes were restored
• A concurrent alarm “26020 (Z-axis encoder initialization failure)” was also confirmed

Customer

【Manufacturing company in the Kansai area】

Target Machine

【NILES ZP12】
CNC: SIEMENS

Inquiry / Reported Issue

We received an inquiry that none of the axes would move at all, even after turning on the master (hydraulic) system.It did not appear to be an operational issue, and the situation suggested a possible problem in the drive system.

In addition, the customer reported that alarm “26020” was also occurring.

Our Response

We conducted an on-site inspection of the SIEMENS drive system. First, we checked the NCU startup status and confirmed that the 7-segment display showed “6” = normal startup condition. However, we confirmed the following conditions:

• The E/R module operation lamp was OFF (not lit)
• No power supply to each drive (DC 600V)

Based on these findings, we determined that the E/R module was faulty.

Diagnosis and Solution Method

Diagnostic Details

• Checked the power supply to each SIEMENS drive
• Confirmed NCU startup status (normal)
• Checked E/R module operation lamp (not lit)
• Confirmed no DC 600V supply to the axis drives

From this, we concluded that the issue was not on the machine body side, but rather a failure of the E/R module itself. We also checked alarm “26020”. The content indicated: Z-axis encoder hardware fault (initialization failure).

Furthermore, the following points were suggested:

• No encoder signal error lamp was lit on the Z-axis drive
• A possible issue with the scale (HEIDENHAIN)

Action Taken

We carried out the following work:

• Replaced the faulty E/R module
• Confirmed power re-supply
• Confirmed axis movement

After replacement, we confirmed that each axis (drive) operated normally. Regarding the Z-axis encoder alarm, improvement may be possible through one of the following:

• Scale replacement
• Repair
• Cleaning

Therefore, we asked the customer to consider the future course of action.

Result After Work

By replacing the E/R module, all axes were restored to normal operation.

For the Z-axis alarm, the decision was to monitor the condition for now, and to proceed with scale replacement if necessary.

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