Processing is a process (yep, it is), where a material changes its shape to the shape we want. But how to do this? There are a number of methods to reshape things, such as hammering, breaking or molding.
But how to do it with a plastic? We can not just break it or push it to change its shape. Fortunately, there are a lot of ways to change a plastics shape permanently, but mostly all the methods are based on the same principle.
That is, we have to change the state of the material and then with a help of some tool, create a new desirable shape. The state can be changed by using heat, pressure or both at the same time.
In the liquid state (or semi-liquid state) the plastic material has to be in the tool, which has the desired shape. Then, by cooling down, the plastic changes the state again, but this time from liquid to solid. This way the new shape of the plastic has been achieved.
Simple, isn’t it?