New platform for VIPER grinding is faster

i-Grinder G5 is designed to exploit VIPER* grinding technology to the full. Until now, the platform used was a standard horizontal machining centre, albeit extensively modified with very high-pressure coolant delivery to the vitrified aluminium oxide wheel via programmable nozzles and through the high-speed spindle. The purpose-built, 7-axis machine is 10 per cent quicker at machining nickel alloy components than the modified Makino A55 machining centre that it supersedes. Metal removal rate is of the order of 80 cc/min. The machine accepts parts nominally up to 300 mm in dameter. Probably the most critical improvement, however, is in the design of the programmable coolant nozzles. They are more versatile on the i-Grinder G5, as they may be positioned by two rotary NC axes anywhere through 360 degrees around the periphery of the grinding wheel, rather than through just 180 degrees, as was the case with the A55. To achieve this greater degree of freedom, power and coolant supplies are built-in, rather than being delivered through an umbilical cord. Nozzle positioning speed is faster and therefore more responsive when changing position to direct coolant accurately towards the point of cutting. The i-Grinder G5 has a 60-tool magazine capable of holding 20 grinding wheels up to 220 mm diameter. Any number of wheels can be sacrificed to allow conventional milling or drilling tools to be deployed, allowing full advantage to be taken of the machine’s multi-functionality. As with all VIPER-specification machining centres, i-Grinder G5 has three linear axes and two rotary axes as well as the two axes for positioning the coolant nozzles. Reinforced guarding, specially designed covers, pressurised rather than grease lubrication of the slideways, a double coolant filtration system, and positively pressurised electrical cabinets are all standard features to prevent ingress of dirt and contaminants. Related technologies that have been developed by Makino-NCMT to achieve world class process capability and throughput include EasyGrind and EasyGear programming software, flexible fixturing, and manual or in-cycle part measurement, verification and truing. * VIPER grinding, a production process patented by Rolls-Royce that employs a machining centre for creep feed grinding of nickel alloy components for the ‘hot’ end of gas turbine engines, has been an international success since its introduction in 2001. It has proved to be much faster than all of the machining techniques it was introduced to replace, namely CBN grinding, broaching, milling and turning.