What is a thermoplastic polymer?
A thermoplastic polymer is a type of plastic that becomes soft when heat is applied and turns into a smooth hard finish when cooled with significant structural strength. In order to meet specific applications, thermoplastic polymer can be mixed with other components like plasticizers that will keep the material flexible even at very low temperature. Thermoplastic polymers can be heated and cooled repeatedly which make them an ideal material for Plastic Welding.
Plastic Welding processes
Ultrasonic welding – is a method of Plastic Welding that makes use of high frequency mechanical vibrations to form a joint. The parts are assembled and held together under pressure between the oscillating horn and immobile anvil before it is subjected to ultrasonic vibrations of frequency up to 20 to 40 KHz at right angles to the contact area. A good quality weld is generated from alternating frequency stresses at the joint interface. However, the drawback of this type of Plastic Welding is its expensive price which makes it applicable to large volume production runs so that the investment can be recovered.
Friction welding – is based on the principle used when welding metals where one of the substrates is fixed while the other is rotated with a controlled angular velocity. When the parts are pressed together, frictional heat causes the polymers to heat and a weld is created when cooled. The advantages of friction welding are high quality weld and the simplicity and reproducibility of the Plastic Welding process. However, friction welding is only suitable for applications in which one of the components is circular and requires no angular alignment.
Vibration welding – is also called as linear friction welding wherein two thermoplastic parts are rubbed together under pressure and at a suitable frequency and amplitude until enough heat is generated to melt the polymer. After the vibrations are stopped the parts are aligned and the molten polymer is allowed to solidify to create a strong weld. This Plastic Welding process can weld a number of components simultaneously with simplicity of tooling that is suitable for applications in the automobile and appliance industry.
Hot plate welding – is the simplest welding process for mass production. A heated plate is clamped between the surfaces to be joined until they soften. When the plate is withdrawn the surfaces are brought together under controlled pressure for a specific period. The fused surfaces are allowed to cool to form a weld.