Engineering Review: Air-cooled 6-Axis Collaborative Welder – Bursa, Turkey

Technical Field Report: Implementation of 6-Axis Collaborative Welder Systems in Bursa’s Automotive Tier-2 Sector

1. Project Overview and Environmental Context

This report details the field integration and performance validation of air-cooled 6-Axis Collaborative Welder units within a Tier-2 automotive component facility located in the Nilüfer Industrial Zone (NOSAB), Bursa, Turkey. The objective was to transition a high-volume production line for structural brackets from manual MIG/MAG stations to a fully Automated Welding workflow.

Bursa presents a unique manufacturing environment; the local industrial ecosystem demands high-speed output with stringent ISO quality standards, yet the mid-sized workshops often face space constraints that preclude the installation of massive, fenced industrial robots. The choice of a collaborative system was driven by the need for a compact footprint and the ability for operators to work alongside the machines during part loading/unloading sequences.

2. Hardware Configuration: The 6-Axis Collaborative Welder

The core of the installation is a 6-Axis Collaborative Welder integrated with an air-cooled MIG power source. While water-cooled torches are common in heavy industry, the decision to use air-cooled technology was predicated on reducing maintenance overhead and eliminating the risk of coolant leaks contaminating the mild steel workpieces.

2.1 Kinematics and Reach

The 6-axis DOF (Degrees of Freedom) is critical for the complex geometries found in automotive seating and chassis brackets. Unlike 4-axis or 5-axis systems, the 6-Axis Collaborative Welder allows for optimal torch orientation—specifically the maintenance of a consistent push or pull angle across radial transitions. In Bursa, we encountered several brackets with deep “V” grooves where the 6th axis was the deciding factor in maintaining a constant stick-out distance, which is vital for stable arc voltage.

2.2 Air-Cooled Duty Cycle Management

Air-cooled torches have a lower duty cycle compared to water-cooled counterparts (typically 60% at max amperage). To mitigate this in an Automated Welding environment, we programmed “air-purge” cycles into the transition moves. This involves the cobot moving between weldments at a speed that maximizes convective cooling. We monitored the neck temperature of the torch and found that by keeping the average current below 220A for Mild Steel welding, we could maintain a 90% “up-time” without triggering thermal protection on the contact tip.

3. Achieving Synergy: Automated Welding in a Collaborative Environment

The transition to Automated Welding is not merely about replacing a human arm with a mechanical one; it is about the digital handshake between the robot controller and the welding inverter. In the Bursa workshop, the synergy between the 6-Axis Collaborative Welder and the automated power source allowed for “on-the-fly” parameter adjustments.

3.1 Synergic Curve Implementation

For this project, we utilized synergic MIG programming. The operator selects the material type (Mild Steel) and wire diameter (1.0mm), and the system automatically calculates the optimal voltage and wire feed speed. The 6-Axis Collaborative Welder communicates via EtherCAT with the power source, ensuring that as the robot decelerates for a tight corner, the wire feed speed drops proportionally to prevent burn-through or excessive bead build-up.

3.2 Collision Detection and Safety

In a traditional automated welding cell, a collision usually results in a bent torch or a broken mounting bracket. The collaborative nature of our 6-axis system means that high-sensitivity torque sensors in each joint detect even a 10Nm resistance. During the initial “teaching” phase in the Bursa plant, this saved the torch assembly twice when a fixture was misaligned. This safety layer allows for a more aggressive optimization of the Automated Welding path without the fear of catastrophic hardware failure.

4. Process Specifics: Mild Steel Welding Performance

Mild steel (S235JR and S355JR grades) remains the backbone of Bursa’s manufacturing output. While it is more forgiving than aluminum or stainless, the challenges of Mild Steel welding in an automated setup involve spatter control and thermal distortion.

4.1 Spatter Management and Gas Coverage

We utilized a 80/20 Argon/CO2 shielding gas mix. The 6-Axis Collaborative Welder was programmed to perform a “nozzle clean” routine every 50 cycles. One lesson learned in the field was the importance of the anti-spatter injection timing. If the air-cooled torch is too hot, the anti-spatter fluid evaporates too quickly. We adjusted the Automated Welding logic to perform the cleaning cycle immediately after the longest cooling dwell time, increasing nozzle life by 40%.

4.2 Penetration and Travel Speed

For 3.0mm mild steel plates, we targeted a travel speed of 45 cm/min. The 6-Axis Collaborative Welder maintained a repeatability of ±0.05mm, which allowed us to narrow the weld pool. This precision resulted in a Heat Affected Zone (HAZ) that was 30% smaller than manual welds. In mild steel welding, controlling the HAZ is critical to preventing the embrittlement of the base metal near the fusion line, especially in automotive components subject to vibration.

5. Lessons Learned and Field Observations

The deployment in Bursa provided several hard-won insights that are not found in the equipment manuals.

5.1 The “Grounding” Factor

Bursa’s industrial power grid can be noisy. We initially faced intermittent communication drops between the 6-Axis Collaborative Welder and the wire feeder. We traced this to high-frequency interference from neighboring CNC machines. Lesson: Always implement a dedicated, isolated ground for the Automated Welding controller and use shielded cables for all encoder signals. Once we re-grounded the welding table directly to the building’s main earth bus, the “arc-start” failures dropped to zero.

5.2 Tack Welding Consistency

Automated Welding is only as good as the fit-up. We discovered that if the manual operators tacks were inconsistent in size, the cobot would either “blow through” the tack or leave a high spot. We had to standardize the manual tacking process—specifying a 2mm tack length—to ensure the 6-Axis Collaborative Welder could maintain a steady travel speed across the joint without manual intervention.

5.3 Thermal Drift in Mild Steel

Mild steel has a high coefficient of thermal expansion. Over a production run of 100 parts, the fixtures in the Bursa shop would heat up, causing a slight 1-2mm shift in the part position. We solved this by integrating a simple “touch-sense” routine using the welding wire itself as a probe. Every 10 parts, the 6-Axis Collaborative Welder touches three points on the fixture to recalibrate its zero-point, ensuring the Automated Welding path remains centered on the joint.

6. Economic and Quality Metrics

After three months of operation in Bursa, the data indicates a significant shift in production efficiency:

• Arc-on Time: Increased from 35% (manual) to 78% (automated).
• Rework Rate: Mild steel welding defects (porosity/undercut) dropped from 8% to 0.5%.
• Consumable Life: Contact tips on the air-cooled torch lasted 15% longer due to the precise, stable arc provided by the 6-Axis Collaborative Welder’s software.

7. Conclusion

The integration of the 6-Axis Collaborative Welder in Bursa confirms that for Tier-2 automotive suppliers, air-cooled automated welding is not only viable but superior for mild steel applications up to 6mm thickness. The synergy between collaborative robotics and advanced welding power sources bridges the gap between manual flexibility and industrial-scale automation. The primary takeaway for field engineers is to focus heavily on the “pre-weld” environment—grounding, fixture heat-soak, and tacking standards—to truly unlock the potential of an Automated Welding system.

Report Prepared By:
Senior Welding Engineer
Bursa Project Office