||CNC turning of the metal removal is the important system regulation, in cutting behavior aspect also along with processing demand day by day severe, but more hastens slightly.More than one quality characteristic must be simultaneously considered to enhance the product quality in light of the increasing complexity of modern product design. Surface roughness, tool wearing, cutting force, CNC turning noise are considered as major objectives in modern CNC （computerized numerical control）maching industry. This research uses Grey relational analysis conformity the question,of multi-quality to discover the optimum parameter.
This research is proposed to experimentally perform various turning operations with different cutting tools on an ECOCA-3807 CNC lathe under the concerns of multiple objectives. The Taguchi method is commenced through selection of orthogonal array for four machining parameters （cutting depth, feed rate, spindle speed） with three different levels （low, medium,and high）.
This research the main purpose is according to the Taguchi method plan experiment, inducts Grey relational analysis, simultaneously weighs the preferred plan and ideal solution and negative ideal solution characteristic, undergoes the Grey relational, can find a group of best cutting parameter truly, and carries on the actual cut on the numerical control lathe, confirms its most cuts serviceability of the parameter. In order to confirm that Grey relational analysis result, carries on 81 groups according to four factor and three standards to test, tests 81 groups obtains the data completely by way of the lathe actual cut, obtains again this data of analysis program by the Grey relational, best cutting parameter A1 B2 C1 D2 which obtains this research in posts 81 groups to test again the comparison, confirms its Grey relational is biggest, therefore it truly for best factor standard combination.
Though the results of the proposed project, an economical insight of the competitive Taguchi method in analyzing the optimum machining parameters for multiple objectives is contributed, and the orientation of the database system for the machining industry is also developed. Thus, the setup time of machining operation, machining cost, and competition of the industry are deemed to be improved.