While using threaded inserts for plastic it is very important to note the type of plastic for which it is being used. There are two types of plastics namely thermo and thermoset plastics. For the former, it is advisable to use the ultrasonic inserts because these plastics do not undergo a chemical change and hence can be shaped and reshaped at anytime according to the requirement. For the latter, where there is a chemical change happening, it is better to use the press inserts. These plastics change their shape only once and continue to be in the same state throughout, until they break.