The bond is very effective and permanent. This is a process developed by two US firms which is extremely effective for Coroplast but somewhat restrictive in application. A simplified explanation of the process is that a tape of polypropylene type material which has been extruded with fine metal fillings is placed between the two pieces to be joined, in exactly the places that the bond is desired. The material is clamped and a magnetic field is induced. This field excites the filings and they get hot enough to melt the tape which then fuses as on piece with the two sheets.
Initial investment is high, but the tooling can be designed in many shapes.
For volume applications, this may turn out to be a very effective technique. For example, a box could be set up to weld four corners simultaneously. Set correctly, the bond is permanent and the material becomes one piece. The bond is not visible on the outside of the sheets. If you feel you have an application for this process we would be pleased to put you in contact with suppliers.