Abstract.Polymer are now widely used as substitute material for steel gear in low load devices. Its failure differs from gears made of steel, thus it is important to categorize the failures shown by polymer gears. Several previous studies noted that wear detection, microstructure surface condition monitoring, weight loss and temperature detection can be used in detecting failure of polymer gear. This article reviews the failure detection method mentioned above. Other researcher works were studied and their findings were extracted in order to identify the methods they used. The most common method used was wear detection and it was supplemented by other methods such as microstructure surface condition monitoring. Failures shown by polymer can be concluded to be tooth breakage, tooth deformation, material removal and surface fatigue.

Injection moulding process is one of the common processes to produce plastic parts from simple to complicated parts. This paper focuses on the injection process analysis of a 25 tooth spur gear. Three runner system are proposed for the gear and each system will be analysed using Autodesk Simulation Moldflow Advisor. The most suitable design will then be chosen based on the results obtained from the simulation. The design undergoes cooling quality, sink mark, fill + pack, and warp analysis. Based on these analyses, Design 1 gave the better results compared to Design 2 and 3. From there, Design 1 runner system is chosen for the injection moulding mould which will be fabricated later in the research.

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Plastic gear applications are rapidly increasing in transmission systems in automotive, domestic and kitchen machineries. Biopolymer gears are now being preferred over polymer gears due to its biodegradable properties. Hence, a comparative investigation of wear characteristics between polymer and biopolymer gears is studied. Injection molded biopolymer, PLA (polylactic acid) gear and polymer, ABS (acrylonitrile butadiene styrene) gear have been fabricated with appropriate properties. Gears are experimentally tested for the period of 3 h at three different rotational speeds (500, 1000 & 1500 rpm) with and without load (1 kg). Wear debris, material loss, thermal damage and microstructure surface condition monitoring have been investigated. PLA presents better adhesive wear resistance and shows thermal deformation and tooth breakage. Biopolymer gives better thermal and wear resistance than polymer gear. At low rotational speed of 500 rpm under no-loading condition, both PLA and ABS show higher weight loss and wear rate due to thermal damage occurred due to gear pump effect. Whereas when load is applied, PLA shows wear loss at all rotational speeds due to inferior thermal conductivity and ABS shows wear loss at high rotational speeds of 1000 rpm or 1500 rpm due to loading effect.