Erodex Surface preparation and finishing cabinet removes recast layer from EDM process
UK – Lapp Blaster, a surface preparation and finishing cabinet from Erodex, has been designed to remove the recast layer created by the EDM process, and to effectively shot-peen the annealed heat-affected zone.
According to the company, the Lapp Blaster removes the re-deposited molten metal particles from the surface of the workpiece, and peens the remaining surface. Peening a surface spreads it plastically, causing changes in the mechanical properties of the surface. It helps negate the propagation of surface micro-cracks. The Lapp Blaster compresses the surface to increase crack resistance and improve surface finish, with a 0.3 µm Ra achieved within a few seconds of processing, Erodex said.
While the Lapp Blaster can be applied to an automated process, Erodex expects most of the cabinets to be manually operated. Subsequently, the ergonomics of loading and unloading workpieces, working at a comfortable operating height without fatigue and visibility through the large viewing windows with high-grade internal lighting will be positive considerations. Required are a single phase 240V electrical supply and shop-floor compressed air at 4 bar.
As a respected EDM consumables supplier, the company is all too aware of the constraints put on the application of both the wire and die-sink EDM process, especially in the aerospace industry.
As Sales Director Steve Rolinson explained: “The aerospace industry recognises EDM as a valuable process for component production. EDM machines can compromise the surface integrity of these components. Therefore, secondary machining operations, including grinding, milling, or chemical etching, were required to remove the recast layer and heat-affective zone to avoid micro-cracks."
“Tests have indicated that the Lapp Blaster will allow aerospace manufacturers to use the EDM process to manufacture even more components. Manufacturers could possibly eliminate secondary machining operations, reducing costs and decreasing delivery times”, Robinson added.
With a twin-working volume of 590 mm x 400 mm x 250 mm, the Lapp Blaster 6040 Duo will be able to accommodate the majority of parts that have been produced by the EDM process. Two nozzle sizes are fitted, a 2.5 mm diameter for peening and a 5 mm diameter for preparation and cleaning.