Inconsistent Wire Feeding and Excessive Spatter with MIG431-006 Torch on R-50

Description

We recently installed a new NexBot Drives MIG431-006 Mig/Mag Welding Torch (SKU: NXB-GEN-MIG431-006) on our R-50 series robot. Since the installation, we've been experiencing significant issues with weld quality. The primary problem is inconsistent wire feeding, which causes a stuttering arc and results in excessive spatter on the workpiece. We are welding 6mm mild steel plates and have tried adjusting the wire feed speed and voltage parameters in the controller, but the issue persists across a wide range of settings. We have also checked the gas flow rate, which is stable at 20 L/min. This is causing significant post-weld cleanup time and a high rejection rate for the welded components. The previous torch did not exhibit these issues with the same wire spool and gas mixture. We need assistance diagnosing if this is a faulty torch or a configuration problem.

Symptoms

• Excessive weld spatter
• Inconsistent wire feed speed
• Audible stuttering or popping from the arc
• Porosity and poor bead appearance

Resolution

The investigation determined that an incorrect contact tip was installed in the NexBot Drives MIG431-006 torch head. The customer was using 1.2mm welding wire, but a 1.0mm contact tip had been mistakenly installed during setup. This mismatch caused excessive friction, leading to inconsistent wire feeding and arc instability. The issue was resolved by replacing the incorrect tip with the correctly sized 1.2mm contact tip. A test weld program was executed, which confirmed that the wire feed was now smooth and weld quality was restored to expected levels, eliminating the spatter and porosity issues.

Resolution Steps

1. 1. Confirmed with the operator that 1.2mm ER70S-6 welding wire was being used.
2. 2. Safely powered down and locked out the R-50 robot cell and welding power source.
3. 3. Unscrewed the gas nozzle and contact tip adapter from the MIG431-006 torch.
4. 4. Removed the installed contact tip and inspected the size marking, which indicated '1.0'.
5. 5. Identified the mismatch between the wire (1.2mm) and the contact tip (1.0mm) as the root cause.
6. 6. Provided the customer with the correct 1.2mm contact tip (Part of Maintenance Kit SKU: NXB-MIG-CONKIT-400).
7. 7. Installed the new 1.2mm tip, reassembled the torch, and restored power to the cell.
8. 8. Executed a test weld cycle, which produced a clean, consistent weld bead with no spatter.