ABSTRACT: In metal machining, the selection of cutting parameters and cooling conditions affects thequality of the cutting process as surface roughness. For this purpose, the effect of cutting fluids(KEMECOLUBESS6120, AQUACUT125) and cutting parameters (cutting speed, depth- of-cut, and feedrate) and cutting tools are carbide tool and HSS tool on surface roughness was investigated during hardmilling of ALUMINUM HE15& HE30. Taguchi approach including L36 ORTHOGONAL ARRAY theexperiments were carried out by using the Taguchi method and the optimal values were introduced based onan analysis of the signal-to-noise response. The results of the present study indicated that the coolingcondition and the feed rate and cutting speed and cutting tool and depth of cut are the factors holding themost influence on surface roughness