No abstract

A new indigenous spin welding machine for thermoplastics with advanced mechatronic controls is conceptualised, designed in detail and a prototype is developed for joining of two thermoplastic parts in axis-symmetrical fashion. Manual spin welding machines for joining thermoplastic parts in axis-symmetrical manner are generally obtained by modifying drill type machines which causes the relative frictional rotation of parts under contact pressure exerted manually through a lever. The contact under relative motion causes the heat generation and results into fusion of parts. The joints from such machines exhibit inconsistency inherent in the manual process. The indigenous prototype machine is able to perform spin welding process with consistency. It enables the operator to choose and control the process parameters such as rotation velocity, time of rotation, spin pressure and cooling pressure.

The welding of thermoplastic pipes under a shear joint configuration using friction spin welding is investigated. The shear joint configuration consists of two cylindrical and concentric polypropylene plastic parts joined with each other at their interfacing cylindrical surfaces through frictional heat generation. The effects of welding pressure and rotational velocity on the joint overlap distance and joint strength between the parts of polypropylene plastic are evaluated. The study is of a specific application in making plastic pressure vessels and joining of pipes. The joint strength is tested by conducting the hydraulic pressure burst test. The burst test is conducted for welded specimens manufactured using different values of rotational velocity and welding pressure. It is observed that at the constant spin velocities, the welding pressure in the range 64.8 to 65.2 kPa produced better joint strength than the other values of welding pressure in the overall range 64–76 kPa. It is concluded that the suitable welding pressure range to manufacture polypropylene plastic pressure vessels in the shear joint configuration using friction spin welding is 64.5 to 65.2 kPa. Further, it is established that the user can control the joint overlap distance at 64.8 kPa welding pressure by selectively controlling the rotational velocity in the range of 700 to 2500 rpm.

Figure parts d and f were incorrectly labelled in Fig. 2 in the initial online publication. The original article has been corrected.