The use of thermoplastics in various fields like aerospace, automotive, medical and packaging industries is growing day by day, due to their light weight and compactness. In some instances, the plastic components are required to be welded. In this research study, process parameters used for the ultrasonic welding of thermoplastics, produces highest weld strength which is highly preferred for their complex use in the above said applications. Also, the possibility of welding dissimilar plastics is also tested. Tensile testing of above welded samples fabricated through injection moulding was carried out for all possible welds and the ultimate tensile strength was calculated in each case. Of all the welded specimens, at given parameters (weld time, weld pressure and energy director) it is observed that Ultimate Tensile Strength of ABS (8.89 N/mm2) is highest. Injection moulded thermoplastics can be carried out with other suitable testing techniques like Hardness testing and Flexural testing so that these thermoplastics can be used in various Automobile, Aerospace, electrical, Medical, Packaging industries and under the hood components.