A 7kW fibre laser and a laser Direct Metal Deposition (DMD) machine have recently been purchased as part of TWI's regional development programme.
Both systems will be the first of their kind to be installed in the UK and will be housed in a unique facility at TWI Technology Centre (Yorkshire) in Sheffield.
The fibre laser is being supplied by IPG Laser GmbH, a European manufacturing division of IPG Photonics. IPG have pioneered the development of high power fibre lasers by developing a platform originally used for supplying fibre amplifiers to the telecoms industry. Recently they have increased the power capabilities of such systems from a few hundred watts to over 10kW, with the potential of even higher power systems in the future.
The lasing medium in the fibre laser is a ytterbium-doped fibre that emits at a wavelength of 1070nm, close to the 1064nm wavelength available from Nd:YAG sources. The laser comprises a number of 200W fibre units, the outputs of which are combined, using proprietary technology, to provide high output powers in 100 to 300µm fibres. The scalability of this type of laser is one of its main advantages.
In addition, fibre lasers produce an output beam with a relatively high optical quality, have a small footprint and offer 20-30% wall plug efficiency which is higher than commercially available Nd:YAG and CO 2 sources. Its robust design is intended to allow the laser to be operational hours after delivery and suppliers IPG are confident that it is capable of more than 100,000 hrs without changing the diode pumping hardware.
The fibre laser will give TWI a chance to explore the possibilities of a radically new laser source.
TWI is launching a Group Sponsored Project to address this, Evaluation of high power fibre lasers and their performance.
The Direct Metal Deposition system is to be supplied by Trumpf in partnership with US deposition experts POM.
The Direct Metal Deposition system comprises a 2kW CO 2 laser and a patented deposition nozzle attached to a 5-axis gantry, controlled using 3D CAD software. Powder is melted onto a substrate using the laser and nozzle, allowing material to be built up in a controlled and accurate manner. Lasers are used because of their accuracy and low heat input allowing fully dense, defect-free deposits to be made. The equipment is capable of carrying out a number of operations, such as cladding, but will perform two main functions at TWI Yorkshire; repair and original part build.
The closed loop laser DMD system and support from Trumpf and POM will give TWI a competitive edge in DMD not only from a processing technology point of view, but also because process development trials can be carried out on an industrially relevant, commercially available piece of equipment.
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