automotive, and military markets have relied on prepregs. Prepregs enable manufacturers to closely control resin-to-fiber ratios. Prepregs require less cleanup and waste (no over spray). Q23: ULTRASONIC WELDING? ULTRASONIC WELDING: Vibrations move parts at a minimum of 20,000 hertz, causing friction that melts metal and plastic parts. Ultrasonic can be used to spot weld, change adhesives to molten material, and melt films and fabrics together. Used for sealing and staking—melting thermoplastic studs