Precision in the cutting of tough materials is essential. Expertise is often required to determine parameter values in CNC machining processes. Occasionally, trial and error is used to determine the parameters, which raises the cost of the equipment and lengthens the production time. The depth of cut influences both surface quality and tool wear, which in turn influences the quantity of cutting tool tips that are used in the cutter. Since the complexity of constructing a specific tool for cutting complex profiles with a high surface quality varies with the depth of cut, the present research focuses on two kinds of tools: the four-flute bull nose cutter and the multi-tip facing cutter. We will optimise the surface finish in both cases by varying the depth of cut while maintaining the same feed and speed. We used a MEKINO 3-axis VMC with 4-tip cutters for our experimental investigation, and we adjusted the machine's parameters to get the optimum surface quality.