STARRAG Micro forging process eliminates hand finishing and polishing
Starrag UK has announced the revolutionary Dengeling micro forging process that could be adopted by Starrag LX machining centres to offer unprecedented levels of improved surface finish, wear protection and workpiece residual strength to finish–machined components - including aerofoil blades on Starrag milling machines, for example – and where hand finishing and polishing can be eliminated.
For example, components that traditionally exhibit a surface roughness after milling of Ra 2.2 microns can be micro-forged with the new process to finishes of Ra 0.2 – a ten-fold improvement!
Initial tests have shown that the automated process is more precise and more controllable that traditional shot peening and it offers shorter set-up and lead times, as well as repeatable quality compared to conventional shot peening and traditional hand-finishing routines.
The Dengeling process operates via specially-developed ThorCAM software which, for example, automatically detects and ‘protects’ edges, sharp edges, steep surfaces and small radii.
The micro forging ‘machining cartridge’ containing all necessary energy and media supplies for the forging ‘tool’, a hard metal ball, can be integrated into the machine’s milling head and all actions are fully integrated with the machine CNC.
Alternatively, it can be supplied as a standalone ‘toolholder cartridge’ where energy and media supplies need to be connected manually and where control of the unit is separate from the machine CNC.
Based on electro-magnetic principles, during current flow the coil produces a force (Lorentz force) and its direction is orientated along the coil. Reversing the current flow changes the direction of the force. Alternating voltage generates mechanical vibrations at a frequency range of up to 600 Hz.
The result that the high kinetic energy induced into the component creates a ‘shock wave’ that radiates to the edge of the workpiece, penetrating up to 10 mm deep and ‘distorting’ the material structure to selectively increase internal compressive and endurance stresses.
The process is already producing outstanding results for diemakers, where the aim is that Dengeling produces similar surface quality to hand finishing but in a shorter time. In one instance, using a 20 mm diameter micro forging tool at a feed rate of six m/min, overall time savings of 44 per cent were achieved.
Surface roughness after milling can be rougher and coarser for micro forging compared with that required for hand polishing, so more time savings can be made via reduced milling times.