Analysis of Gear Milling at Various Speeds, Time and Feed Rates
Spur gears are the most commonly used gears for mechanical power transmission. Form-milling the tooth of involute spur gear involves specification of the cutting speed for the work piece material and feedrate of the milling cutter. The speed and feedrate selection for such cutting has a strong link with the completion period of the machining exercise, which indirectly also determines the cost of producing the gears. This paper presents a study carried out in establishing a multiple linear regression model for determining time required for form-milling an involute spur gear tooth at varying speeds and feedrates on a milling machine. Five spur gears, of 15-teeth each, with pressure angle 200, and module 2.8mm, were experimentally milled on a universal milling machine, while the time for the completion of each tooth at different speeds and feedrates were recorded and analyzed on the platform of SPSS 12.0, where the data were subjected to t-test, ANOVA analysis and optimality test. The model generated t = f(s,f), gave coefficients β0, β1 and β2 as 0.281, -0.005, and -0.03 respectively. The test confirmed the coefficient as being significant to the adopted model and the ANOVA analysis showed the correlation between speeds and feedrates for cutting a tooth of a spur gear. Thus, as the cutting speed and feedrate increases, cutting time reduces. The model will serve as a useful tool in preparation of cost estimate in machining of involute spur gear.