WeldZero: Improving Quality in Car Bonnet Laser Welds

WeldZero is a government-funded Innovate UK project which aimed to eliminate welding defects and improve automated welding solutions across industry, through a better understanding of welding processes.

The project began in March 2020 and finished in September 2022, using a variety of digital tools to monitor and improve weld quality while lowering overall manufacturing costs.

One part of the project saw TWI, BMW Group Plant Swindon and Lancaster University work together to gain an understanding and improve the quality in sheet steel laser welded MINI car bonnets. This work built upon TWI’s experience in laser process monitoring and the use of different sensors to help keep track of those processes.

To address cosmetic imperfections that can occur as a result of the fast and fully automated welding process, in-process imaging was developed by TWI and combined with work from Lancaster University to deliver automatic weld imperfection detection. This could then be implemented into production to allow for earlier detection of process set-up problems that could otherwise lead to imperfect welds. This would ultimately increase the quality standard of bonnets produced.

A factory acceptance test was performed at the project completion in order to validate the technologies on the MINI team’s equipment, with the following achievements being confirmed:

• A low-cost imaging solution, comprising a CMOS camera, wavelength filter, and LED illumination, as developed by TWI. With correct camera settings, weld bead images of a quality sufficient for subsequent analysis by a machine learning algorithm could be collected in-process.
• After suitable training of the algorithm, this then allowed for in-production predictions to be made which could help the earlier detection. This would then allow operators to intervene sooner to correct the process.

The WeldZero Project has received funding from Innovate UK under No 105812

(Main image reproduced courtesy of BMW)