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Repairing worn shafts using laser metal deposition

TWI has carried out an extensive programme for an Industrial Member on applying laser metal deposition (LMD) to both new and worn shafts from industrial rotating equipment.

The Member contacted TWI to carry out repairs to the worn shafts and, after assessing the repair, identified laser metal deposition as the most appropriate process to return the shafts to service. The LMD process conducts much less heat into the substrate material than many conventional techniques, creating a fine microstructure with low levels of dilution between layers and low distortion. Due to the exceptional clad the laser deposition process provides, the member was able to introduce the process to new shafts.

TWI has been developing the laser metal process for the last decade - exploring its use for everything from repair of high-value parts to fabrication of large freeform components in a number of industries.

LMD is an additive manufacturing process that uses a laser beam as an energy source focused on a substrate through a nozzle to create a melt pool. Metal powder or wire is then added to the melt pool. The melted particles fuse and solidify while the nozzle is manipulated around the substrate to form a new layer of the component. Fabrication and repairs in titanium, nickel, aluminium, steel, and cobalt can be made with reduced material wastage, and reduced tooling costs. The process benefits from a large working envelope and near net capabilities, and produces functionally graded parts and fully customised parts to suit individual requirements.

TWI assessed the worn shafts and selected LMD as the best repair process, setting immediate objectives to procure, install, and commission additional equipment to the client’s satisfaction, as well as to produce two cladded test pieces for analysis using agreed deposit geometry from the client’s plan. One shaft was supplied specifically for experimenting with process parameters and, following this, TWI produced a welding procedure specification for the client’s approval. 

Using a Trumpf DMD505 system, deposition material was added to two worn shafts using the approved weld procedure (which took the deposit geometry supplied by the client) to give a new surface suitable for post-deposition machining.

TWI was able to procure, install, and commission the right equipment to the client’s satisfaction, and subsequently combine the laser deposition system, its parameters, and surface preparation procedures to meet the client’s acceptance criteria. This was done with the technical ability acquired from extensive experience gained from previous laser metal deposition projects.

For more information, please email contactus@twi.co.uk.

Avatar Roger Fairclough Principal Project Leader - Laser Additive Layer Manufacture

Roger Fairclough holds a BEng(Hons) degree in Mechanical Engineering, having Chartered Engineer and European Engineer status and being a member of both the Institutions of Mechanical Engineers and of Welding. He is a Principal Project Leader at TWI, and involved with Laser Additive Layer Manufacture using both SLM and LMD processes. Over the last thirteen years he has managed a variety of projects for TWI designed to develop innovative ALM technologies for UK manufacturing companies. Roger has over forty years’ experience within the UK engineering industry, having worked in the mining, power generation, R & D and steel manufacturing sectors. Prior to working for TWI, he was Chief Engineer for an international company producing nickel superalloys and components for the aerospace and oil and gas industries.

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