Ultrasonic plunge welding of polypropylene nonwovens

Polypropylene blown micro fibers with spun bonded cover web made from Polypropylene and polyester fibers were used for the experimental study of the ultrasonic plunge welding of nonwovens. A face centered central composite design of experiment (DOE) with 3 process variables and 3 levels was used to evaluate the effects of vibration amplitude, weld time and weld pressure. In addition to those settings, three different welding profiles were used resulting in forty-five different welding conditions with five specimens welded for each condition. Increasing the welding time generally improved the weld strength until it leveled off. For high welding pressures physical damage was observed around the welding area. Finally increasing the amplitude of vibration resulted in making the welding seam tougher with higher breaking forces.