Using solid ultra-fine grain tungsten carbide ball end mills with TiAlN coating

45 hardened steel at 43HRC was machined at the constant spindle speed of 20000 revolutions per minute with workpiece inclination angles ranging from 10° to 60°.The effect of inclination angles on machined surface roughness was investigated.The results show that the surface roughness decreases with increase of the inclination angles within the range of 10° to 30°.After the angle approaches to 30°

increase of the inclination angle causes increase of the surface roughness.Furthermore

the effect of inclination angles on cutting speed was investigated.The conclusion is that variation of the surface roughness is primarily due to enormous change of the cutting speed.