Comparative Evaluation of Hot Air and Ultrasonic Sealing in Paper Cup Manufacturing

Abstract

Consistent heat sealing is a critical aspect of paper cup manufacturing, ensuring both liquid tightness and a visually appealing finish. Given the high production volumes in the disposable cup industry, optimizing energy consumption while maintaining good seal quality is critical to minimize waste and resource use. A mechanical testing device for quantifying the side seal strength of finished cups was developed to replace the subjective hand-peel method. Unlike laboratory testing with pre-sealed samples, the proposed test method accounts for stresses imposed on the seal area during the converting process. The device allowed for the objective comparison of cup side seals produced from two different materials sealed using two different technologies: ultrasonic and hot air. The experiments yielded largely consistent results and offered insights into material-specific behaviors in the cup manufacturing process, which involves shorter heating, cooling, and forming cycles than those in other coated paperboard conversion processes. In addition, ultrasonic sealing was shown to have an advantage in sealing consistency over hot-air sealing. The developed test method showed potential as a repeatable evaluation tool for side seal strength in finished paper cups, facilitating quality control across high-speed production lines.