They’re using a linear friction welding machine which oscillates the sample at about 200hz. Their best guess is linen lignin cells within the wood are melting, interlocking and rejoining ...

Linear friction welding welds materials together using heat from friction. After placing two materials into a welding machine they are then pushed tightly together. One of the two materials moves ...

Here are a few more videos of friction welding: And linear friction welding is basically bananas: interesting Machinery Metal Recycling more of the copper, aluminum, and other minerals in our old ...