Prediction of injection molding parameters for symmetric spur gear

Polymer gears pose major advantages, like noiseless operation, resistive against corrosion, low weight, ability to damp vibrations, ease of manufacturability, and ability to operate without lubrication like in printers, household appliances, etc. In order to enhance mechanical properties of gear materials, various reinforcing materials are added such as glass and carbon fibers. The orientation of these fibers and distribution are critical parameters at the microstructural level for polymer reinforced with short fibers, which defines the strength and life of gears. The geometric accuracy and precision of molded gears are improved by the injection molding technique. The fiber orientation prediction is a new and novel aspect for high performance and life, as these injection-molded gears have complex patterns of fiber orientation. This also affects material properties such as elastic modulus, strength, and gear geometrical dimensional properties shrinkage and warpage. In this present work, an attempt is made to develop 3D symmetric spur gear tooth geometry using Autodesk Fusion 360. The injection molding parameters such as fiber orientation tensor, volumetric shrinkage at ejection, weld lines, deflection, and confidence in filling are studied for modeled gear having symmetric teeth profile for unreinforced and 20%, 30%, 40%, 50%, and 60% glass fiber-reinforced nylon 6/6 (PA66) by using Autodesk Moldflow Adviser 2017. The result obtained from mold simulation tool indicates that fiber orientation tensor for varying glass fiber contents was close to unity. The volumetric shrinkage considerably reduced from unreinforced PA66 to glass-reinforced PA66.Graphical abstract.