Surface roughness optimization on steel fiber reinforced geopolymer fly ash by CNC milling operation

Geopolymer is a material that has been widely used in engineering applications particularly in construction industry because its friendliness to environment. This time, our work tries to explore the potential use of geopolymer in machining process. However, limited machining activity reported on geopolymer fly ash. Hence, this study attempt to find the best combination of machining parameters suitable for steel fiber reinforced geopolymer fly ash and the most significant parameter influencing the output evaluated which is surface roughness. The machining parameters involved are cutting speed, feed rate and depth of cut. Orthogonal arrays by using L9 of Taguchi method, Signal-to-Noise ratio (S/N Ratio) and analysis of variance (ANOVA) employed in investigating the best combination machining parameters and the parameters contribution to surface roughness. The best combination parameters obtained is 50 m/min of cutting speed, 0.12 mm/rev of feed rate and 0.4 mm of depth of cut. From the analysis, the average surface roughness recorded is 2.193 µm that is the least and the best surface roughness obtained. The most significant contributing factor affecting the surface roughness of steel fiber reinforced geopolymer fly ash is cutting speed with 68.97 % of contribution.