When you hear the word welding, you usually think of metal and hot flying sparks. You don’t think of plastic welded to another piece of plastic.
If you are working with a plastic such as HDPE, LDPE, HMWPE, a traditional glue/super glue will not work. These materials do not react with the plastic to do what it needs to do to make it stick. If you have a low volume, a one-off project, or a very large tray or project, regular thermal forming methods will not work nor are they cost-effective in money and time.
Plastic welding works a similar process as metal welding. The areas to join are heated just enough to accept a filler material that is injected between the two pieces, and when the area cools, they are joined together. For example, we do a large amount of custom trays. We have made custom trays to catch drips for under sinks, mini-fridges, aquariums, hot tubs, and even to catch drips from a leaky roof in a state penitentiary.