Engineering Review: Intelligent Arc Control Cobot Welding Machine – Bursa, Turkey

Field Engineering Report: Implementation of Intelligent Arc Control in Bursa’s Automotive Tier-1 Sector

1.0 Introduction and Site Context

This report outlines the technical deployment and performance evaluation of the 6-axis Cobot Welding Machine integrated with Intelligent Arc Control (IAC) at a primary fabrication facility in Bursa, Turkey. Bursa remains the epicenter of the Turkish automotive industry, and the facility in question specializes in the high-volume production of sub-frame components and heavy-duty bracketry.

The objective was to replace manual Metal Active Gas (MAG) stations with Collaborative Robotics to address two critical issues: inconsistent penetration profiles in Carbon Steel welding and a localized shortage of certified high-pressure welders. Unlike traditional industrial robots that require extensive safety cell infrastructure, the deployment of the Cobot Welding Machine allowed for a flexible shop-floor layout, maintaining the proximity of the human operator for real-time quality oversight.

2.0 The Synergy: Collaborative Robotics and Shop Floor Integration

In the context of the Bursa workshop, the “Collaborative” in Collaborative Robotics is not merely a safety rating; it is a functional workflow. We integrated the Cobot Welding Machine into a “work-cell sharing” configuration. This allows the operator to perform part fit-up and tacking on one side of a dual-station turntable while the cobot executes the final structural welds on the other.

2.1 Lead-Through Programming for Rapid Iteration

One of the primary advantages observed was the lead-through teaching capability. In Carbon Steel welding, especially with varying tolerances in stamped parts, the ability for a senior welder to manually guide the cobot arm to define the tool path significantly reduced setup time. We transitioned from a CAD-to-Path programming model to a “Expert-to-Path” model. This ensured that the specific nuances of the weld pool—such as torch angle adjustments for gravity compensation in out-of-position fillets—were captured accurately.

2.2 Safety and Proximity

The use of Collaborative Robotics eliminated the need for pneumatic light curtains and heavy fencing that typically congest Turkish production floors. By utilizing the cobot’s internal torque sensors, we established a safety protocol where the machine operates at full production speed when the operator is outside the laser-scanner zone and switches to a reduced-speed collaborative mode upon entry. This maximized the “Arc-on” time without compromising ISO 10218-1 safety standards.

3.0 Technical Analysis of Carbon Steel Welding Performance

The core of this deployment focused on S235JR and S355JR Carbon Steel welding. These materials, while standard, present challenges in terms of mill scale consistency and heat-induced distortion when handled at high travel speeds.

3.1 Intelligent Arc Control (IAC) and Gap Bridging

The “Intelligent” component of the Cobot Welding Machine refers to the high-speed feedback loop between the power source and the cobot controller. During the Bursa trials, we encountered fit-up gaps of up to 1.5mm on 4mm thick carbon steel lap joints. Traditional robotics would typically result in burn-through or lack of fusion in these scenarios.

The IAC software dynamically adjusts the wire feed speed and current frequency at 20kHz. By sensing the arc impedance changes, the Cobot Welding Machine automatically modified the weave amplitude to bridge the gaps without operator intervention. This resulted in a 22% reduction in scrap rates compared to the previous manual baseline.

3.2 Heat Input and Metallurgy

Controlling the Heat Affected Zone (HAZ) is vital for the structural integrity of automotive brackets. Through the application of Collaborative Robotics, we achieved a constant travel speed that manual welders simply could not sustain over an 8-hour shift.
* **Manual Travel Speed:** 25–35 cm/min (highly variable).
* **Cobot Travel Speed:** 45 cm/min (constant).

The consistency of the Cobot Welding Machine ensured that the cooling rate ($t_{8/5}$ time) remained within the optimal window to prevent the formation of brittle martensite in the S355JR grain structure.

4.0 Lessons Learned from the Bursa Field Site

Engineering a successful Cobot Welding Machine deployment requires more than just unboxing the hardware. Several site-specific variables in the Turkish industrial environment provided valuable technical lessons.

4.1 Power Quality and Grounding

We identified that voltage fluctuations in the industrial zone could interfere with the sensitive electronics of the Collaborative Robotics system. Initial errors in the encoder feedback were traced back to poor common-grounding practices between the welding table and the cobot pedestal.
* **Lesson:** Always implement a dedicated high-frequency grounding strap for the Cobot Welding Machine to isolate the control logic from the welding return current.

4.2 Wire Feeding and Conduit Friction

In Carbon Steel welding, the use of large 250kg bulk drums is common to reduce downtime. However, the long conduit runs to the cobot arm introduced “wire hunting” at the arc. The cobot’s precision is wasted if the wire delivery is erratic. We resolved this by installing a low-friction ceramic liner and a secondary drive roll (push-pull system) integrated into the cobot’s 6th axis.

4.3 Managing Mill Scale and Surface Prep

Bursa’s humid climate can lead to rapid oxidation of stored carbon steel plates. We found that the Intelligent Arc Control’s “Clean Start” logic—which provides a brief burst of high energy to break through the oxide layer before settling into the programmed spray transfer—was essential for eliminating cold-start porosity.

5.0 Comparative Metrics: Manual vs. Cobot

To justify the capital expenditure (CAPEX) for the Turkish facility, we tracked the following data points over a 30-day period:

| Metric | Manual MAG | Cobot Welding Machine |
| :— | :— | :— |
| **Duty Cycle (Arc-on time)** | 35% | 78% |
| **Weld Defect Rate (NDT)** | 4.2% | 0.8% |
| **Gas Consumption (Ar/CO2)** | High (due to over-welding) | 15% Reduction (optimized flow) |
| **Post-Weld Spatter Cleaning** | 3 mins/part | < 30 secs/part | The synergy between Collaborative Robotics and the operator meant that the operator was no longer a “welder” but a “cell manager,” overseeing three Cobot Welding Machines simultaneously.

6.0 Structural Integrity and Compliance

All Carbon Steel welding procedures were qualified to EN ISO 15614-1. The Cobot Welding Machine produced macro-sections with superior throat thickness consistency. The digital data logging capabilities of the system allowed for 100% traceability of weld parameters (Current, Voltage, Gas Flow) for every serial number produced. This is a critical requirement for European automotive exports coming out of Turkey.

7.0 Conclusion

The deployment in Bursa confirms that the Cobot Welding Machine is the most viable path for medium-to-high volume Carbon Steel welding in regions facing skilled labor shortages. The success of the project relied not on replacing the human element, but on leveraging Collaborative Robotics to handle the repetitive, high-heat execution while the human operator managed the complex fit-up and quality variables.

Future phases will involve integrating “Seam Tracking” sensors to further enhance the cobot’s ability to compensate for part-to-part variations in real-time, moving toward a fully autonomous “lights-out” capability for the night shifts in Bursa.

**Signed,**
*Senior Welding Engineer*
Field Operations – Bursa District