Non-Arc Welding Processes Resistive heating, chemical reactions, focused light and electrons, sound waves, and friction can also be used to join materials –Resistance welding –Oxy-Fuel Welding –Friction welding (&Solid State) –Laser and electron beam welding –Brazing and soldering –Plastics joining –Adhesive bonding Introduction

Joining Plastics Polymer - a single building block (mer) is repeated to form a long chain molecule –Thermoplastic polymers soften when heated, harden when cooled 2-liter bottles –Thermosetting polymers don’t soften when heated Car tires, caulking compound HHHH HHHH C=C H -C-C- H ··· add H 2 O 2 (Poly)ethylene Welding of Plastics

Hot Plate, Hot Gas, Infrared Advantages –Provide strong joints –Reliable –Used on difficult to join plastics Limitations –Slow –Limited temperature range T

Hot Plate, Infrared Welding Hot plate welding Welding of Plastics

Hot Gas Welding Thermoplastics (hotmelts) –Adhesive is heated until it softens, then hardens on cooling Hot gas softens filler and base material Filler is pulled or fed into the joint Welding of Plastics

Vibration Advantages –Speed –Used on many materials Limitations –Size –Requires fixturing –Equipment costly T

Ultrasonic Advantages –Fast –Can spot or seam weld Limitations –Equipment complex, many variables –Only use on small parts –Cannot weld all plastics T