Engineering Review: Robotic MIG 6-Axis Collaborative Welder – Bursa, Turkey

Field Engineering Report: Implementation of 6-Axis Collaborative Welder in Bursa Automotive Tier-2 Supply Chain

1.0 Introduction and Site Overview

This report details the operational deployment and performance validation of a 6-Axis Collaborative Welder integrated into an Automated Welding cell in Bursa, Turkey. The facility, located within the Nilüfer Industrial Zone (NOSAB), specializes in the fabrication of exhaust manifolds and heat shields for the regional automotive sector. The primary engineering challenge addressed during this deployment was the high-rejection rate associated with manual MIG welding on 1.0mm to 1.5mm stainless steel (AISI 304) components.

The transition to a 6-Axis Collaborative Welder was necessitated by the need for geometric versatility that traditional 3-axis linear actuators could not provide, specifically regarding the complex curvatures of thin metal sheet welding. In the Bursa context, where skilled manual welders are increasingly difficult to retain for high-volume, repetitive tasks, the synergy between collaborative robotics and automated welding protocols represents a critical shift in local production logic.

2.0 Technical Specification: The 6-Axis Collaborative Welder

The hardware deployed is a high-payload collaborative robot (cobot) optimized for MIG/MAG applications. Unlike standard industrial robots, this 6-Axis Collaborative Welder utilizes integrated force-torque sensors at each joint, allowing for “lead-through” programming. In a workshop environment like Bursa’s, this allows the lead technician to manually guide the torch along the weld path, recording waypoints without deep-code proficiency.

2.1 Kinematic Freedom and Torch Orientation

The “6-axis” designation is not a luxury but a requirement for thin metal sheet welding on non-linear paths. To maintain a consistent 15-degree push angle on a 1.2mm lap joint, the robot must simultaneously adjust its wrist (J5 and J6 axes) while traversing a 3D spline. During the Bursa trials, we observed that 5-axis systems struggled with torch-to-workpiece clearance in tight radii, leading to excessive spatter and inconsistent penetration. The 6th axis allows for rotational correction that keeps the wire tip centered in the root despite varying part tolerances.

3.0 Automated Welding Integration Logic

Automated welding is often misunderstood as merely “moving a torch fast.” In our Bursa implementation, the integration logic focused on the handshake between the cobot controller and the synergic MIG power source. We utilized a fieldbus communication protocol (EtherNet/IP) to allow the robot to modulate wire feed speed and voltage in real-time based on its TCP (Tool Center Point) velocity.

3.1 Synergic Pulse Control

For thin metal sheet welding, we implemented a “Pulse-on-Pulse” regime. The 6-Axis Collaborative Welder signaled the power source to drop current during cornering maneuvers where the robot’s linear speed momentarily decreased. This synchronization is the core of automated welding; without it, the heat input at the corners of a thin-gauge bracket would cause immediate burn-through. In the Bursa facility, this automation reduced post-weld grinding by 85% compared to manual processes.

4.0 Challenges in Thin Metal Sheet Welding

Thin metal sheet welding (specifically below 2.0mm) is unforgiving regarding thermal expansion. In Bursa, the ambient temperature fluctuations in the factory floor (ranging from 10°C in winter mornings to 35°C in summer) affected the material’s structural rigidity during the arc-on phase.

4.1 Gap Bridging and Fixturing

The most significant “lesson learned” involved the fit-up tolerances. Automated welding assumes a zero-gap or constant-gap condition. However, stamped parts in the Bursa plant often exhibited variances of ±0.5mm. We solved this by implementing a “weave” pattern programmed into the 6-Axis Collaborative Welder. By oscillating the torch at a frequency of 2.5Hz with a 1.0mm amplitude, the automated system successfully bridged gaps that would have previously caused a “blow-through” in a standard linear path.

4.2 Heat Input Management

To prevent warping of the 1.0mm sheets, we utilized a “stitch” welding sequence rather than a continuous bead. The cobot’s ability to rapidly reposition between segments—without the fatigue-induced hesitation of a human welder—allowed us to manage the Heat Affected Zone (HAZ) effectively. We set the interpass temperature limit at 150°C, monitored via infrared sensors integrated into the cell’s safety PLC.

5.0 Synergy: The “Bursa” Workshop Dynamics

The deployment in Bursa revealed a unique synergy between high-end 6-Axis Collaborative Welders and local manufacturing culture. Bursa’s industry is characterized by “High-Mix, Low-Volume” (HMLV) batches due to the variety of vehicle models produced in Turkey.

5.1 Collaborative Safety and Floor Space

Because the unit is a collaborative welder, we eliminated the need for bulky safety fencing typical of traditional automated welding cells. This allowed the Bursa team to integrate the robot into an existing manual assembly line. The “synergy” here is physical: the robot handles the precision welding of the thin metal sheet, while the human operator performs the rapid loading/unloading and visual QC in the same workspace. This hybrid approach increased the units-per-hour (UPH) from 12 to 45.

6.0 Lessons Learned and Engineering Recommendations

After 2,000 production cycles in the Bursa facility, several technical truths have emerged regarding the use of a 6-Axis Collaborative Welder for thin-gauge applications.

6.1 Wire Feed Consistency

We initially faced arc instability. The culprit was the 4-meter umbilical cord of the cobot. In automated welding, any drag in the wire liner manifests as micro-stutters in the arc. Recommendation: Use a neck-mounted wire drive or a high-spec Teflon liner for 0.8mm ER70S-6 wire to ensure the 6-axis movement doesn’t kink the feed path.

6.2 Gas Shielding in Complex Geometries

The 6-axis mobility often puts the torch in orientations where the shielding gas “pockets” or drifts due to factory drafts. We increased the flow rate to 18 L/min and switched to a 90% Argon / 10% CO2 mix. This stabilized the arc column, which is essential when the “Thin Metal Sheet welding” process leaves no room for porosity.

6.3 Calibration of the TCP

In a 6-axis system, if the Tool Center Point (TCP) is off by even 0.5mm, the rotation of the 6th axis will “throw” the wire out of the joint. We implemented a daily automated TCP check routine using a fixed pointer. This is a non-negotiable step for any automated welding setup in a high-precision environment.

7.0 Conclusion

The deployment of the 6-Axis Collaborative Welder in Bursa has validated that automated welding of thin metal sheets is not only feasible but superior to manual intervention when thermal management is prioritized. The 6-axis flexibility provides the necessary torch angles to maintain the metallurgical integrity of the joint, while the collaborative nature of the robot allows for seamless integration into existing Turkish manufacturing workflows. Future iterations will focus on integrating AI-based vision systems to adjust the weld path in real-time for even greater compensation of part variance.

Report End.
Prepared by: Senior Welding Engineer
Location: Bursa, Turkey