Metal Cutting

The illustration of the above analyses indicates that cutting speed, feed rate, depth of cut and cutting tool material significantly affect the surface finish, diameter error and circularity of the end product.

From the experiment, the results in Figure 12 show that Parameter B (Feed rate) has significant effects on the surface finish. It is followed by Parameter D (Material), Parameter A (Cutting speed), Parameter C (Depth of Cut) follows and then (AxB) the interaction between the cutting speed and the feed rate has great effect on the surface finish. Pareto analysis of variance (ANOVA) as indicated in Table 5 shows that feed rate is a significant contributing factor affecting surface finish by 28.68%, followed by material with 16.58%. To obtain good surface finish, low feed rate should be applied. The reverse is true, when increasing the feed rate. The concept above confirms that surface finish is directly proportional to the feed rate as can be shown in the formula:

Surface Finish α Feed Rate

The results in Figure 13 show that Parameter D (Material) has significant effects on the diameter error. It is followed by Parameter A (Cutting speed), then Parameter C (Depth of Cut) follows, then Parameter B (Feed rate) and (AxB) the interaction between the cutting speed and the feed rate have great effect on the diameter error. Pareto analysis of variance (ANOVA) as indicated in Table 9 shows that material is a significant contributing factor affecting the diameter error by 19.39%. It is followed by cutting speed with 19.10%. This implies that the type of work material used contributes to the diameter error of the resultant product. The harder the work material, the higher the energy required to cut the material, increasing the work piece deflection resulting in increased diameter error.

Results in Figure 14 show that Parameter A (Cutting speed) has significant effects on the circularity. It is followed by Parameter D (Material), Parameter C (Depth of Cut) follows, and then Parameter B (Feed rate) and (AxB) the interaction between the cutting speed and the feed rate has great effect on the circularity. Pareto analysis of variance (ANOVA) as indicated in Table 13 shows that cutting speed is a significant contributing factor affecting the circularity by 24.31%, together with the material at 24.31%. The roundness of product parts is influenced by the speed and the composition of the material. The higher the speed of the cutting tool, the higher the circularity of the product, whereas the opposite is true for a slow cutting tool.

Ceramic and carbide cutting tools produce variations in the surface finish, diameter error and circularity of a product made. Ceramic tools have products with improved surface finish and diameter error. They have little or no circularity error. According to S/N ratio, ceramic cutting tools produce rough surface finishes, high diameter error and lower circularity in comparison to the carbide cutting tools. Overall, carbide cutting tools are highly encouraged for use as demonstrated above.