The factors influencing surface roughness

4.6 The factors influencing surface roughness

Based on the ANOVA table that have been constructed, the model develop is in a single interactions. Hence, the 3D graph generated shows the effect of cutting parameters on the surface roughness. With using 3D graph also it can be determined the relationship and correlation between each cutting parameters used in the experiments. The graph below shows the interactions among the parameters using in the experiment consists of cutting speed and feed rate influencing the quality of surface roughness. The 3D graph show the interactions of each parameter and the interaction of cutting speed to the surface roughness most significant than the feed rate. As the cutting speed machining is increases, surface roughnesses are decreasing gradually. According to Aguiar et al. 2013, in milling operations, surface quality improves at higher cutting speeds. The interactions between cutting speed and feed rate to the surface roughness are show in figure 4.5. The slope of width of cut in the figure 4.5 show is not significant because the lines of the slope is not steep compared with the cutting speed and feed rate parameters. The graph also show the slope of feed rate with constant cutting speed that is set at minimum illustrate that the surface roughness is also decreasing. It will most significant when the cutting speed is set a maximum value. 61 Figure 4.5: Factor feed rate and cutting speed on surface roughness Figure 4.6: Factor width of cut and feed rate on surface roughness The figure 4.6 represents the width of cut versus feed rate, where a small width of cut produces a higher surface roughness although the feed rate is increasing. At 62 width of cut of 8mm with the feed rate of 0.1mmmin will produce a surface roughness approximately equal to 0.3 µm. while, the maximum surface roughness that can be obtained at width of cut of 2.0mm and the feed rate is set to 0.2mmmin is approximately 0.45µm. according to Toh 2005 finishing process generally requires the largest amount of machining time due to low depths of cut and feed rate. The finding from the research is that the combination between width of cut and the feed rate is not very significant because of pattern of chip formation influencing to the surface damage during the machining process Konada and Engineering, 2007. Figure 4.7: Cutting speed and width of cut on surface roughness Based on the figure 4.7, surface roughness is only affected when there is a fluctuation on the cutting speed rather than width of cut. At the cutting speed of 150 mmin and width of cut is set at 2.0 mm, the obtained surface roughness is close to 0.35µm. whereas surface roughness of 0.38µm can be obtained when using cutting speed 100 mmin and width of cut is set to 8 mm. from this graph it can be seen that surface roughness is increasing when the cutting speed is reducing although the width of cut 63 is varied. According to Cakir et al. 2009, an increasing cutting speed, the surface roughness will be decreases.

4.7 PURTUBATION PLOT