Optimization of Thermal Weld Parameters for the Loading Neck of a Flexible Polyethylene Container

This study presents an experimental and numerical investigation of the sealing performance of welded joints in flexible polyethylene containers subjected to external pressure during vacuum compaction of forage material. The objective was to improve the reliability of welded seams under vacuum gauge pressures of up to 75 kPa. A three-dimensional transient heat-conduction model was developed to investigate the thermal behavior of polyethylene film during heat sealing. The governing heat-conduction equation was solved using ANSYS Fluent based on the finite volume method, employing a pressure-based transient solver and first-order implicit time discretization. Temperature distributions and their temporal evolution, T(t), were determined at selected locations within the film. The strength of welded joints in thin polyethylene films subjected to pressure loading of up to 75 kPa was experimentally evaluated as a function of weld-seam width and clamping force at a selected heat-sealing temperature of 175 °C. High-density polyethylene film (PE-180) with a thickness of 200 μm was used to carry out research specimens measuring 100 × 100 mm. The experimental results were analyzed using a design-of-experiments approach, and a regression equation was developed to describe the dependence of welded-joint strength on seam width and clamping force. The combined numerical and experimental findings provide a basis for selecting appropriate heat-sealing parameters to enhance the reliability of welded seams at the neck of flexible polyethylene containers subjected to vacuum-induced loading.