Robotic Laser Beam Reduced Pressure Welding: Narrow Gap Laser Cleaning Capability Development

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Project Code: 36212

Start date and planned duration: January 2025, 12 months

Objective

To modify an existing hand-held laser welding nozzle and improve technology capabilities for:
1. In-situ narrow gap laser welding and cleaning operations.
2. Improved safety and performance
To demonstrate in-situ laser welding and cleaning capability over the conventional manual cleaning operation

Project Outline

In this proposed work a combined in-situ narrow gap laser cleaning and welding approach will be investigated, aiming to eliminate manual cleaning between (multi-pass) welding operations, with the view to improve productivity, quality and overall operational cost reduction. To successfully weld large complex engineering components (eg from 10mm thickness) and achieve desired quality, often a traditional narrow gap arc welding process with multi-pass approach is used. Owing to its high automation and throughput, laser welding technologies are now being considered as a potential alternative to the arc welding process. For both welding technologies, manual inter-pass cleaning operation is necessary to remove contamination, slag and heat tint from the weld fusion zone. Otherwise the consequence of surface contamination results in poor weld quality, resulting in substantial re-work impacting productivity and operational cost.

Industry Sectors

- Aerospace

- Automotive

The market information indicates that there is a strong uptake of handheld laser technology, particularly within general fabrication industries. Literature published so far has highlighted clear productivity advantages offered by the handheld laser welding technology over the more traditional arc welding process. However, the market penetration for narrow gap, multi-pass, thick-section handheld laser welding has not yet taken place. Furthermore, thick section welding applications currently use manual grinding to remove slag and contamination between welding passes. There is a strong need by heavy industry (such us submarine, defence and nuclear) to replace the manual approach with a more efficient approach.

Cleaning with the laser is clearly unquantified as an approach, and shielding nozzle/gas flow related deficiencies compared to conventional laser cleaning still needs to be addressed and very much desired by aerospace and automotive sector.

Benefits to Industry

In applications requiring thick section welding surface cleaning between weld passes is currently performed via manual grinding or wire brush, which is labour intensive, time consuming and potentially offering inconsistent results. This latter point also leads to a risk of surface contamination, potentially resulting in poor welding quality, affecting material performance. Recent acquired capability of a handheld laser system at TWI laser lab, with both welding and cleaning functionalities, could provide an opportunity for a combined in-situ welding and cleaning operation covering also narrow gap welding applications.

The successful outcome of the project will provide following benefits to the industry:

Allow the operator to control the relative nozzle position between welding and cleaning operations
Provide better control over inert gas shielding and prevent unnecessary and excessive oxides build up
Improve safety related to hazards from welding fume and scattered laser radiation