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Chinese Institute benefits from Cambridge's twin spot laser

Connect, no. 150, September/October 2007, p.3

The BAMTRI building in Beijing
The BAMTRI building in Beijing

When China's leading aerospace welding and joining institute BAMTRI recently needed to develop a twin beam laser welding technique it turned to TWI for help.

TWI was approached to develop a twin spot laser welding technique and supply a twin-spot optical process head.

It has a decade of experience in twin beam laser welding, defining the specification of laser equipment for given applications and integrating laser welding systems.

What BAMTRI wanted was help with the design and procurement of the required kit, development of the welding procedures, and training of its staff. Under the leadership of TWI's Mandarin speaking Steve Shi TWI rose to the challenge.

More specifically it was instructed to supply a twin spot welding head equipped with a fibre receiver for a Lumonics Multiwave style optical fibre. Under the terms of the contract it had to demonstrate the use of twin spot welding at its Cambridge headquarters and also help BAMTRI install and commission its own twin spot head in Beijing.

TWI's job was made possible because it already owned its own twin spot laser designed by High YAG and already has a good track record of success. It is a very flexible process tool in that the separation of the spot and the relative beam intensity in each spot can be changed by simply rotating two orthogonally mounted micrometer drives.

Further flexibility is achieved in that the line of separation of the spots can be rotated with respect to the welding direction. At TWI the head is used with a Trumpf 4kW Nd:YAG laser using a 0.6mm diameter fibre for delivery ofthe beam. This is the same as the Lumonics laser used at BAMTRI.

The project went well. It included performing a series of trials using a similar twin spot head to that recommended by TWI for the Chinese operation. Two BAMTRI engineers worked at TWI for two weeks and a reciprocal arrangement, using TWI engineers at BAMTRI for a week, worked very successfully.

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