Experimental and theoretical investigations on ultrasonic insertion process for manufacturing applications

Abstract

Increasing the usage of plastics in various fields of engineering necessitated the suitable technique for joining the metallic parts with plastic components. When the plastic parts are joined by self tapping screws or bolts, it may get damaged due to plastic creep. In this circumstances, a technique is needed which has to join the plastic components without degrading them. Many techniques are available to join the plastic components with metal inserts like pre-moulding, cold pressing, thermal insertion and ultrasonic insertion. One of the preferred techniques is ultrasonic insertion process, because of shorter cycle time, minimum induced stress and automation possibilities for mass production. Ultrasonic insertion is the process of embedding an internally threaded metal insert into the thermoplastic component. In this process, metal insert is placed on pre-moulded hole in the thermoplastic component which is lesser in diameter than metal insert. The ultrasonic vibration produced from horn presses and transfers the ultrasonic energy to the metal insert. Friction between the metal insert and thermoplastic component generates heat energy which softens the thermoplastic component for encapsulating the metal insert to produce the joints. Metal inserts are the mechanical fasteners which are used to assemble and disassemble the components with other parts. Inserts provide resistance to both axial and angular movement by endow with knurls, grooves and undercuts on the external surface of the insert. The dimensions of pre-moulding hole in which metal insert to be encapsulated are determined by functional requirements of the joints. newline