Development Of A Spur Gear From Carburised Cast Iron For Application In Bottling Machine

ABSTRACT

Spur gears are components used in power transmission in bottling machines. Bottling machine breakdowns are often the result of spur gear failure, and the cause of gear failure can stem from many issues, of which the most common is failure due to wear. This study, therefore, developed a spur gear with adequate mechanical properties that can function in such an environment. Pareto and metallurgical techniques were used to characterise the failure and its effects on the production process and equipment reliability. A mechanistic design approach was employed to simulate the casting process using proCAST software before the casting of the blank. The third stage involves the experimental casting, testing, and characterisation of the developed material and its comparative analyses with characterised mild steel results. The blank cast was sectioned into coupons for carburisation using palm kernel shell, coconut shell, and wood charcoal at different temperatures of 700oC, 800oC, and 900oC at different holding time of 60, 90, 120 and 180 minutes respectively using eggshell as an energiser. Optimised samples were characterised using spark spectrometer, scanning electron microscope integrated with energy dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD). The microhardness test was evaluated using Vicker’s hardness tester, while wear test was done using sliding wear tester, and the thermal gravimetric analyses were equally carried out. All tests and methods were carried out according to the American Society for Testing and Materials (ASTM). The result of the 3D surface analyser showed variation in wear distribution with some zones under intense material erosion. The result of the analysed failure data revealed that about forty-three thousand two-hundred products (43,200), which translates to a 100 % loss in operation for a day (24 hours). From the result of carburisation, all samples showed a homogenous absorption of carbon at the interface for each of the carburising media. The microstructures of each sample revealed the presence of iron and carbon at the interface, and chromium and nickel which improved the corrosion resistance of the developed material. More so, samples carburised using the three carburisers revealed improved hardness properties, with palm kernel shell having an improved hardness value of 355 HV against the as-received grey cast iron and other media. Improved wear and friction were demonstrated by each sample as well as excellent electrochemical characteristics with grey cast iron showing a lower corrosion rate and weight loss of 0.0007 and 0.0008 mg for samples tested in 28 % and 43 % ethanol blend concentration respectively. Results from the performance evaluation of the developed gear showed that there is a significant improvement in the machine reliability and productivity with 183.33 % output for total operating hours of 620. The improvement in the mechanical properties of developed samples due to the homogenous diffusion of carbon at the interface of surface asperities verified their suitability in engineering applications. Thus, organic carbon is an excellent enhancer of the mechanical properties of metals.