Product category:
Abrasive machining - manual and CNC machines
News Release from: NCMT | Subject: VIPER grinding - horizontal machining centre
Edited by the Manufacturingtalk Editorial
Team on 21 June 2006
HMC VIPER-grinds and mills turbine blade
On a horizontal machining centre, using the VIPER grinding technique, 5-axis machining of a nickel alloy compressor blade involved grinding a radial dovetail root form, including a milling operation.
On a Makino A55 machining centre, three separate demonstrations at UK Makino agent's technology centre in Coventry, underlined the flexibility of the machine as a platform for producing components by grinding and other metal cutting operations in very few set-ups, or even one hit Five-axis machining of a nickel alloy compressor blade involved grinding a radial dovetail root form followed by a combination of grinding and finish milling of a small-radius scallop, which the grinding wheel was unable to access
This article was originally published on Manufacturingtalk on 21 Jun 2006 at 8.00am (UK)
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Abrasive machining ousts milling and broaching
'Very impressive performance extreme removal' - or VIPER - grinding is 10 times faster at removing metal than milling when machining aerospace and industrial turbine blades.
Root slots VIPER ground on turbine disc
Believed to be a 'world first', a horizontal machining centre was demonstrated the complete VIPER grinding of root slots on a turbine disc at rates up to four times faster than milling.
Total cycle time was 5.5 min.
Conventionally, blades are first ground and then set up for a second operation on a machining centre.
Savings in handling, fixturing and cycle time are considerable with the Makino solution.
Further reading
VIPER quadruples Inconel grinding rate
Continuous dress , high-speed VIPER grinding of a 700mm long, industrial turbine blade made from Inconel 718 was demonstrated to quadruple stock removal rate to 200cm3/min.
VIPER grinding replaces turn/mill on big parts
How the VIPER grinding process can machine features on big nickel alloy components - like a 1.1m diameter jet engine casing - demonstrated the replacement of milling and lathe-turning.
The second component demonstration involved grinding the fir tree root form for a high-pressure turbine blade from solid nickel alloy in a cycle time of 3.5 min.
Normally, such components are ground from a closer-to-form forging on a dedicated grinder.
The most usual production process for this popular aerospace component is in a 'Nagare' cell comprising, say, 10 separate machines tended by five operators to clamp every part once on each machine.
On a Makino VIPER machining centre, parts generally come off complete in two operations, drastically reducing production costs.
Grinding of a radial seal slot, 2.6mm wide by 7.3mm deep over a 200mm chordal length, formed the third demonstration.
Instead of being produced in Inconel, the part was of a less expensive steel, which in this application is more challenging to grind.
Two small, aluminium oxide wheels were used, rather than traditional cubic boron nitride, one for the outside radius and another for the inside radius to achieve perpendicular groove sides.
Dressing was by NC profiling, avoiding the expense and long lead time of full-form dressing (ideal for fast-make situations).
Two-axis control of the grinding wheel plus B-axis positioning of the component achieved the required contouring of the slot.
Another aspect of this demonstration was the manual-assist loader at the front of the machine.
Components were fixtured outside the machining area and transferred with minimal effort to a zero point fixture on the table ready for machining.
Instead of the loader, a 6-axis industrial robot can be used for component load / unload, and many Makino VIPER machines have been thus configured. Request a free brochure from NCMT ...
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