Amr Elfizy

Grinding characteristics of a nickel-based alloy using vitrified CBN wheels

An experimental study is reported on the grinding of a nickel-based alloy using vitrified CBN wheels. This work was motivated by switching the grinding of fir-tree root forms of jet engine blades from creep-feed grinding with conventional abrasive wheels to vitrified CBN wheels. The objective is to explore process limits and practical grinding parameters for judging the switch in terms of overall costs and productivity. Straight surface grinding experiments were conducted with water-based fluid on rectangular blocks at a fixed wheel speed vs = 45 m/s, various depths of cut a = 0.05–1.0 mm, and workspeeds vw = 2–40 mm/s. Grinding and dressing power, forces, surface roughness, and radial wheel wear were measured. Specific material removal rate of 8 mm3/(mm.s) was reached in rough grinding using a wheel dressed for achieving surface roughness Ra = 0.8 μm in finish grinding. It was found that shallow depths of cut combined with fast workspeeds, or less creep-feed modes, are more suitable for achieving high ma...

Experimental Study on Grinding of a Nickel-Based Alloy Using Vitrified CBN Wheels

An experimental study is reported on the grinding of a nickel-based alloy using vitrified CBN wheels. This work was motivated by switching the grinding of fir-tree root forms of jet engine blades from creep-feed grinding with conventional abrasive wheels to vitrified CBN wheels. The objective is to explore process limits and practical grinding parameters for judging the switch in terms of overall costs and productivity. Straight surface grinding experiments were conducted with water-based fluid on rectangular blocks at a fixed wheel speed vs = 45 m/s, various depths of cut a = 0.05 - 1.0 mm, and workspeeds vw = 2 - 40 mm/s. Grinding power, forces, surface roughness, and radial wheel wear were measured. Specific material removal rate of 8 mm3/(mm.s) was reached in rough grinding using a wheel dressed for achieving surface roughness Ra = 0.8 µm in finish grinding. It was found that shallow depths of cut combined with fast workspeeds, or less creep-feed modes, are more suitable for achieving high material removal rates with vitrified CBN grinding. Rough grinding is restricted by high grinding temperatures with newly dressed wheels and by chatters with worn wheels.

Grinding of Chromium Carbide Coatings Using Electroplated Diamond Wheels

This paper reports an experimental study on grinding of chromium carbide coatings using electroplated diamond wheels. The work was motivated by machining carbide coatings in gas turbine engine applications. The objective is to explore the process conditions and parameters satisfying the ground surface quality requirements. Surface grinding experiments were conducted with water based grinding fluid on chromium carbide coated on flat surfaces of aluminum blocks for rough grinding at a fixed wheel speed vs = 30 m/s, and finish grinding at vs = 30, 60 m/s. The effects of depth of cut and workspeed on grinding power, forces, and surface roughness were investigated for each of the wheel speeds. Material removal rate Q = 20 mm3/s for rough grinding at a grinding width b = 101.6 mm was achieved. It was found that the maximum material removal rate achievable in rough grinding was restricted by chatters, which was mainly due to the large grinding width. The specific energy ranged from 27 to 59 J/mm3 under the tested conditions. Surface roughness Ra = 3.5- 3.8 µm were obtained for rough grinding, while Ra = 0.6 - 1.5 µm were achieved for finish grinding. Surface roughness was not sensitive to grinding parameters under the tested conditions, but was strongly dependent on the diamond grain sizes. Imposing axial wheel oscillations to the grinding motions reduced surface roughness by about 60% under the tested condition. It was proved that it is feasible to grind the chromium carbide coating with electroplated diamond wheels.