Engineering Review: Air-cooled 6-Axis Collaborative Welder – Krakow, Poland

Field Engineering Report: Implementation of 6-Axis Collaborative Welder in Krakow Structural Steel Operations

1.0 Executive Summary and Site Context

This report details the technical deployment and performance evaluation of an air-cooled 6-Axis Collaborative Welder at a mid-sized fabrication facility in Krakow, Poland. The primary objective was the modernization of Structural Steel welding workflows, specifically focusing on the production of architectural support brackets and S355JR grade assemblies. Traditionally, these components required high-skill manual labor, which has become a bottleneck in the Lesser Poland industrial corridor due to labor shortages.

The transition to Automated Welding via collaborative systems (cobots) represents a strategic shift from dedicated high-cost robotic cells to flexible, human-centric automation. This report analyzes the synergy between the robotic motion control and the metallurgy of structural steel under field conditions.

2.0 Equipment Specification and Integration

2.1 The 6-Axis Collaborative Welder Architecture

The unit deployed is a 10kg payload 6-Axis Collaborative Welder equipped with an integrated air-cooled torch. In the Krakow facility, the 6-axis configuration is critical. Unlike 3- or 4-axis linear systems, the 6-axis freedom allows for complex torch angles (work and travel angles) necessary for multi-pass fillet welds on non-linear gussets.

The air-cooled variant was selected over water-cooled alternatives to minimize maintenance overhead and eliminate the risk of coolant leaks contaminating the structural steel surface, which can lead to hydrogen-induced cracking or porosity in the weld bead. While air-cooled torches have a lower duty cycle at high amperages, the collaborative nature of the task—where operators frequently swap parts—provides natural cooling intervals that align with the system’s thermal envelope.

2.2 Defining Automated Welding Synergy

The synergy between the 6-Axis Collaborative Welder and Automated Welding logic is found in the “Lead-Through Programming” interface. In this Krakow site, we utilized the cobot’s force-torque sensors to allow senior welders to hand-guide the robot to weld start and end points. The automation then takes over, maintaining a consistent travel speed and arc length that human hands cannot replicate over an eight-hour shift. This marriage of human intuition for fit-up variability and robotic precision for execution defines the modern automated workflow.

3.0 Technical Application: Structural Steel Welding

3.1 Material and Preparation

The Krakow project utilized S355JR structural steel. Proper surface preparation was paramount; all mill scale was removed via mechanical grinding at the weld zone. Structural Steel welding requires deep penetration to meet Eurocode 3 standards. We utilized a 1.2mm G3Si1 wire with an M21 gas mixture (82% Argon / 18% CO2).

3.2 Parameter Optimization

For the 8mm fillet welds required on the support brackets, the 6-Axis Collaborative Welder was programmed with the following parameters:

• Wire Feed Speed: 8.5 m/min
• Voltage: 26.5V
• Travel Speed: 35 cm/min
• Torch Angle: 45° Work / 10° Travel (Push)

The 6-axis movement allowed for a slight “weaving” pattern during the root pass, which ensured side-wall fusion in tighter geometries where manual torch access was historically problematic.

4.0 Lessons Learned: Field Observations from Krakow

4.1 Thermal Management of Air-Cooled Torches

A significant lesson learned involved the ambient temperature of the Krakow workshop during the winter months. While the cold air aided in cooling the torch, it also increased the risk of rapid cooling in the Heat Affected Zone (HAZ) of the structural steel welding. We had to implement a pre-heat protocol for thicker sections (>15mm) to maintain an interpass temperature that prevented martensitic grain formation.

Furthermore, we found that automated welding cycles exceeding 15 minutes of continuous arc-on time led to contact tip expansion in the air-cooled torch. This caused “wire burn-back” issues. We mitigated this by optimizing the 6-axis pathing to include a 30-second “air-purge” move between parts, allowing the internal fan to dissipate neck heat.

4.2 Spatter Management and Gas Coverage

In a collaborative environment, the operator is in close proximity to the arc. Excessive spatter is not just a quality issue; it is a safety and maintenance concern. By fine-tuning the 6-Axis Collaborative Welder’s inductance settings, we achieved a “Short-Arc” transfer that minimized globular spatter. This reduced the post-weld cleaning time—a key metric in the overall ROI of automated welding.

4.3 The “Collaborative” Safety Reality

Krakow’s safety inspectors were initially skeptical of the “no-cage” setup. However, the 6-axis cobot’s power and force-limiting (PFL) functions were validated on-site. The lesson here is that automated welding does not mean “unattended welding.” The operator’s role shifted from manual torch manipulation to “jig loading and quality oversight.” The synergy here is that the welder’s expertise is used to verify fit-up, while the robot handles the repetitive strain of the arc.

5.0 Performance Metrics vs. Manual Baselines

Data collected over a 30-day period in the Krakow facility showed the following improvements when using the 6-Axis Collaborative Welder for structural steel welding:

• Arc-On Time: Increased from 25% (manual) to 65% (automated).
• Reject Rate: Decreased from 4.2% to 0.8% (primarily due to the elimination of stop-start craters).
• Consumable Efficiency: 12% reduction in shielding gas waste due to optimized post-flow settings in the automated cycle.

6.0 Structural Integrity and Metallurgical Validation

Macro-etch tests were performed on-site on sample S355 joints. The automated welding process produced a consistent throat thickness of 5.8mm on a nominal 6mm fillet, well within the allowable tolerance. The 6-axis motion ensured that the transition from the horizontal to the vertical plane in curved structural joints was fluid, preventing the “notching” effect often seen in manual welding when a welder resets their stance.

The heat input (kJ/mm) was calculated for every joint. The 6-Axis Collaborative Welder maintained a heat input of 1.1 kJ/mm, which is optimal for preserving the toughness properties of Krakow-sourced S355JR steel. Manual operators often fluctuated between 0.8 and 1.6 kJ/mm, leading to inconsistent grain structures.

7.0 Conclusion

The deployment of the air-cooled 6-Axis Collaborative Welder in Krakow demonstrates that automated welding is no longer reserved for high-volume automotive lines. In the realm of structural steel welding, the 6-axis cobot provides the necessary dexterity to handle complex geometries while maintaining the thermal discipline required for high-strength alloys.

The primary takeaway for future deployments is the importance of the air-cooled torch’s duty cycle management. For heavy structural applications, the synergy of the system relies on the operator’s ability to sync part-loading with the robot’s thermal recovery. This Krakow site now serves as a blueprint for “Low-Volume, High-Complexity” automation in Eastern European heavy industry.

Report End.
Senior Welding Engineer, Krakow Field Office