Engineering Review: Deep Penetration Laser Welding Cobot – Gurgaon, India

Field Report: Deployment of Deep Penetration Laser Welding Cobot for Copper Fabrication

Location: Industrial Estate, Sector 34, Gurgaon, Haryana

Date: October 24, 2023

1. Introduction and Objective

This report details the technical deployment and optimization of a 3kW Fiber Laser Welding Cobot system at a Tier-1 automotive supplier facility in Gurgaon. The primary objective was to replace conventional TIG (Tungsten Inert Gas) welding for high-conductivity Copper Components welding used in Electric Vehicle (EV) battery packs and inverter assemblies.

The Gurgaon industrial climate presents specific challenges: high ambient temperatures, significant particulate matter (dust) in the workshop environment, and periodic fluctuations in the local power grid. Implementing advanced Laser Technology in this setting requires more than just high-end hardware; it demands a synergy between the precision of the laser source and the adaptive motion of the collaborative robot.

2. The Integration of Laser Technology and Collaborative Motion

The core of this deployment rests on the synergy between a high-brightness Ytterbium fiber laser source and a 6-axis Laser Welding Cobot. Traditional industrial robots require expensive hard-tooling and large safety enclosures, which are often impractical in the cramped, high-mix production floors of Gurgaon’s older industrial sectors.

2.1. Power Density and Keyhole Stability

The Laser Technology utilized here focuses on achieving a “Deep Penetration” or “Keyhole” weld. Unlike conduction-mode welding, where the beam merely melts the surface, deep penetration involves vaporizing the metal to create a narrow hole (the keyhole) that allows the laser energy to be deposited deep into the joint. For Copper Components welding, this is non-negotiable due to copper’s extreme thermal conductivity. Without the concentrated power density of a fiber laser, the heat dissipates into the workpiece faster than the weld pool can form.

2.2. Cobot Maneuverability in Small Batches

The Laser Welding Cobot allows operators to hand-guide the torch to teach points. In the Gurgaon facility, where component designs for EV busbars change frequently, this flexibility reduced setup time from hours to minutes. The cobot’s software was integrated with the laser’s pulsing parameters, ensuring that the power output ramps up and down in correlation with the cobot’s TCP (Tool Center Point) speed, preventing “burn-through” at the start and end of the weld path.

3. Technical Challenges in Copper Components Welding

Copper is notoriously difficult to weld due to its high reflectivity at the 1070nm wavelength (typical of fiber lasers) and its high thermal diffusivity. During our initial trials in Gurgaon, we encountered three primary issues: back-reflection damage, porosity, and inconsistent penetration.

3.1. Overcoming Reflectivity

At room temperature, copper reflects over 90% of infrared laser energy. This reflected light can travel back through the delivery fiber and destroy the laser diodes. To mitigate this, we utilized Laser Technology featuring back-reflection isolation and implemented a “wobble” strategy. By oscillating the beam in a circular pattern via the cobot-mounted scan head, we increased the absorption rate. Once the material reaches its melting point, its reflectivity drops sharply, and the Laser Welding Cobot can then transition into deep penetration mode.

3.2. Managing Porosity in Oxygen-Free Copper

In the Gurgaon heat, moisture can accumulate on cold copper plates, leading to hydrogen-induced porosity. We implemented a pre-heating pass using the laser at 20% power, followed immediately by the structural weld pass. The Laser Welding Cobot‘s ability to maintain a consistent 0.5mm standoff distance was critical here; any deviation in focal position would destabilize the keyhole, trapping gasses and weakening the joint.

4. Environmental Adaptations in the Gurgaon Workshop

The local environment in Gurgaon necessitates specific modifications to standard Laser Technology operating procedures.

4.1. Thermal Management and Chiller Load

With ambient temperatures in the workshop exceeding 40°C during summer months, the laser’s dual-circuit chiller was upgraded. We found that standard cooling cycles were insufficient. We transitioned to a deionized water system with a higher flow rate to ensure the Laser Welding Cobot head remained below 35°C, preventing thermal lens shifting which would otherwise cause the focal point to drift during long production runs.

4.2. Dust Mitigation

The Gurgaon-Manesar belt is prone to high dust levels. For Laser Technology, dust is the enemy of optics. We installed a positive-pressure “clean booth” around the cobot station and used a high-velocity nitrogen cross-jet to protect the cover slide. We learned that even a single speck of dust on the protective window could be heated by the 3kW beam, causing the glass to crack and halting production.

5. Synergy and Process Optimization

The real-world success of this setup is found in the software handshake between the cobot and the laser source.

• Variable Frequency Wobble: We programmed the Laser Welding Cobot to vary the wobble frequency based on the curvature of the copper busbar. On straight runs, a 150Hz circle wobble was used; on tight corners, we shifted to a 200Hz “figure-8” pattern to ensure even heat distribution.
• Shielding Gas Optimization: We moved from Argon to a Helium-Argon mix. While more expensive in the local Gurgaon market, the higher ionization potential of Helium stabilized the plasma plume, allowing the Laser Technology to reach an extra 1.2mm of penetration in C101 copper components.

6. Lessons Learned and Engineering Best Practices

After three months of field operation, several “hard truths” about Laser Welding Cobots in an Indian industrial context have emerged:

6.1. Power Stability is Paramount

The Gurgaon power grid is prone to voltage sags. We observed that even a 5% drop in input voltage caused the Laser Technology to lose its “keyhole,” resulting in a superficial “cold weld.” A dedicated industrial UPS and servo-stabilizer are mandatory for Copper Components welding, where the energy threshold for melting is so precise.

6.2. Operator Training over Automation

The Laser Welding Cobot is only as good as its last calibration. We shifted from a “set and forget” mentality to a “daily verification” routine. Operators now perform a bead-on-plate test every morning to check for beam alignment. In the context of Copper Components welding, a 200-micron misalignment can mean the difference between a perfect fusion and a catastrophic reflection event.

6.3. Shielding Gas Flow Dynamics

Initial welds showed oxidation (blackening) around the HAZ (Heat Affected Zone). We found that the standard gas nozzles provided with many Laser Welding Cobot kits were designed for stainless steel, not the high-flow requirements of copper. Designing a custom “trailing shield” nozzle allowed us to maintain an inert atmosphere over the copper until it cooled below 200°C, ensuring the high-conductivity requirements of the EV components were met without post-weld cleaning.

7. Conclusion

The deployment in Gurgaon demonstrates that the Laser Welding Cobot is a viable, superior alternative to manual welding for Copper Components welding, provided the environmental and material-specific challenges are addressed. By leveraging Laser Technology through a collaborative framework, we achieved a 400% increase in throughput compared to TIG, with a reject rate falling from 12% to less than 0.5%. The key to success remains the rigorous control of the focal geometry and the aggressive management of the workshop environment.

Signed,

Senior Welding Engineer
Field Operations – Gurgaon/Manesar Division