Incorrect spacer dimensions in NXB-GEN-833-013 kit causing joint play in R-50 wrist

Description

We are performing scheduled maintenance on the wrist assembly (Joints 5 and 6) of our R-50 robot. We ordered the NXB-GEN-833-013 Washer And Spacer Set to replace the existing hardware as per the service manual. After installing the new spacers and washers from the kit and torquing the fasteners to spec, we noticed significant axial play in the J5 axis. When we re-ran the mastering and calibration routine, it failed with a positioning deviation fault. We disassembled the joint and measured the key spacers from the new kit with our digital calipers. They appear to be approximately 0.15mm thinner than the original parts we removed and what is specified in the R-50 maintenance prints. This tolerance issue is preventing proper pre-loading of the joint bearings, leading to vibration and inaccuracy. Production is currently halted on this line until we can resolve the joint integrity.

Symptoms

• Excessive axial play in J5 axis after maintenance.
• Audible chattering from wrist assembly during motion.
• Robot fails joint calibration routine.
• Measured components from kit are out of specification.

Resolution

The customer's measurements were confirmed to be correct. The lot number provided for the NXB-GEN-833-013 Washer And Spacer Set was traced to a batch with a known manufacturing tolerance issue. A replacement kit from a verified, in-spec batch was shipped to the customer via expedited freight at no charge. The customer was instructed to replace the out-of-tolerance components with the new set and perform the full joint calibration procedure. The follow-up call confirmed that the new kit resolved the joint play and the robot successfully passed all calibration and functional tests.

Resolution Steps

1. Confirmed the customer's detailed measurements and symptoms were indicative of a component tolerance issue.
2. Requested the lot number printed on the packaging of the NXB-GEN-833-013 kit.
3. Cross-referenced the provided lot number (BN-774-2023Q4) in our quality control database and confirmed it was part of a flagged batch.
4. Issued RMA #R78819 for the defective kit and created a no-charge sales order for a replacement NXB-GEN-833-013 set from a verified lot.
5. Advised the customer to discard the out-of-spec hardware to prevent accidental future use.
6. Provided instructions to re-assemble the J5 joint using the new kit, ensuring proper torque sequence and values.
7. Guided the customer through the robot's standard mastering and calibration routine for the affected axes.
8. Verified with the customer that the robot was back in operation with no vibration or positioning errors.