Connect, no.120, September - October 2002, p.7

New mechanised system for electro-spark deposition

Mechanised ESD on gas turbine blade airfoil

Electro-spark deposition (ESD) is a micro-weld-surfacing process used for localised coating and build up repair. With one or two exceptions coatings are, at present, applied manually using a hand held coating applicator. However, TWI has recently adapted an ESD system for mechanised operation.

An ESD coating applicator has been attached to a simple counter-balanced pivot arm fixed to a 6-axis robot. The applied force is varied by adjusting the load at the opposite end of the pivot arm.

The purpose of this new facility is to improve coating quality whilst increasing deposition rate. The very low heat input that ESD imparts to the substrate allows materials, otherwise susceptible to heat affected zone cracking, to be surfaced.

Examples of fusion welding sensitive materials that can be surfaced using ESD include nickel superalloys for gas turbine blades and tool steels.

For further information, please contact Carole Reignier e-mail: carole.reignier@twi.co.uk or Dave Harvey e-mail: dave.harvey@twi.co.uk

Connect, no.120, September - October 2002, p.7

New mechanised system for electro-spark deposition

Robot mounted ESD applicator and pivot arm