| The purpose of this research is to determine the effect of various weld and machine parameters on ultrasonic weld strength. Specifically, welds with six different triple-layer coextruded polyethylene and metallized polypropylene films were examined. These materials were welded in separate experimental studies using a bench top weld system and a high production volume packaging machine.;The first study investigated the effect of a range of weld forces, energies, and amplitudes in a lap joint geometry using a bench top ultrasonic plunge welding system. Weld strength was determined by measuring resistance to tearing and peel and shear strength. It was observed that low energy and low weld force had a significant effect on shear strength welds for all materials. High peel strength was observed at relatively high weld forces and energies, and high tear resistance was observed at relatively high forces, high amplitudes, and mid-range energy levels.;The second study determined the suitability for the same materials to be sealed as bags for packaging applications in a vertical "form fill seal" machine. This machine was equipped with an ultrasonic end seal jaw. The machine factors tested in this study include energy, amplitude, and production rate (the rate at which bags are created/welded) to determine the effect on peel strength. It was observed that low energy and amplitude correlated with high strength for the top weld (top of bag) of one material and low production rate resulted in high strength for the top weld of two materials as well as the bottom weld for two materials. Data for the sixth material was inconclusive. |
