electrically conductive or a ferromagnetic workpiece. In an electrically conductive workpiece, the main heating effect is resistive heating, which is due to induced currents called eddy currents. Induction welding of carbon fiber reinforced thermoplastic materials is a technology commonly used in for instance the aerospace industry. In a ferromagnetic workpiece, plastics can be induction-welded by formulating them with metallic or ferromagnetic compounds, called susceptors. These susceptors absorb electromagnetic energy from an induction coil, become hot, and lose their heat energy to the surrounding material by thermal conduction. Injection welding Injection welding is similar/identical to extrusion welding, except, using certain tips on the handheld welder, one can insert the tip into plastic defect holes of various sizes and patch them from the inside out. The advantage is that no access is needed to the rear of the defect hole. The alternative is a patch, except that the patch can not be sanded flush with the original surrounding plastic to the same thickness. PE and PP are most suitable for this type of process. The Drader injectiweld is an example of such tool. Ultrasonic welding In ultrasonic welding, high frequency (15 kHz to 40 kHz) low amplitude vibration is used to create heat by way of friction between the materials to be joined. The interface of the two parts is specially designed to concentrate the energy for the maximum weld strength. Ultrasonic can be used on almost all plastic material. It is the fastest heat sealing technology available. Friction welding In friction welding, the two parts to be assembled are rubbed together at a lower frequency (typically 100–300 Hz) and higher amplitude (typically ) than ultrasonic welding. The friction caused by the motion combined with the clamping pressure between the two parts creates the heat which begins to melt the contact areas between the two parts. At this point, the plasticized materials begin to form layers that intertwine with one another, which therefore results in a strong weld. At the completion of the vibration motion, the parts remain held together until the weld joint cools and the melted plastic re-solidifies. The friction movement can be linear or orbital, and the joint design of the two parts has to allow this movement. Spin welding Spin welding is a particular form of frictional welding. With this process, one component with a round weld joint is held stationary, while a mating component is rotated at