Preparatory works for all welding process are very similar, so also for plastic welding. So you need a clean surface so there are no contaminations that might affect or alter the result of the plastic welding. In addition, the equipment used has to be the best possible and suitable for that particular plastic welding process. This means the correct head for the welder and the appropriate air pressure; also the most appropriate filter and tip are necessary for proper plastic welding. 

The specialty of plastic welding is that each plastic used has extremely different characteristics and need the most suitable level of head and pressure according to that uniqueness. The plastics used can be divided into two groups: thermoset that is thicker and thermoplastic that is easier to use when heated and welded. Thus, it is very important to know what kind of plastic is being used for plastic welding and its heat and pressure requirements.

Actually, all the preparatory works named previously have to have a lot of attention paid to them and done properly if you want have the best plastic welding. Thus, try to look over all the details and so you do not have to weld plastic over and over again.