Title: Low Constant Pressure Injection Molding for Lighter Weight Automotive Plastics

Authors: Steven Prascius, Shane Skop, Patrick Blanchard

DOI: 10.33599/nasampe/c.25.133

Abstract: Throughout the automotive industry, there is growing momentum to reduce the carbon emissions associated with internal combustion engine and electric vehicles. Low constant pressure injection molding is a processing technology that shows promise for reducing the thickness and weight of injection molded automotive plastics through minimizing the molding tonnages required to produce these parts. This method for injection molding differs from conventional injection molding as it is does not rely on a two-phase process with a velocity-controlled fill phase and a pressure-controlled pack phase. In contrast, low constant pressure injection molding operates with a single pressure-controlled phase that uses closed loop feedback to maintain a melt pressure setpoint that is below what is seen in a conventional process. This study evaluated the low constant pressure process on a production representative automotive door panel part in comparison to conventional injection molding. When comparing the molding processes, it was determined that the low constant pressure process was able to decrease the peak pressure observed during the cycle by 27%, reduce the required tonnage by 32%, and reduce the number of active valve gates by two. When comparing the molded parts, it was evident that the parts produced with the low constant pressure process had reductions in tiger stripping, less prominent sink marks, and less significant warpage than did the conventional parts. Based upon the pressure and tonnage reductions observed during the evaluation, simulations were conducted in Moldex3D to determine the feasibility of reducing the thickness of the door panel parts while still retaining the ability to mold within the maximum tonnage of the machine used in the study. These simulations showed the ability to reduce the thickness of the door panel parts by up to 12%, yielding a potential weight reduction of 8%. This evaluation showed the ability of low constant pressure molding to reduce the required tonnage needed to mold automotive door panel parts and showed the potential to translate those reductions to thinner wall stock parts. Further studies are required to understand the benefits that can be achieved with other automotive parts.

References: 1. Gene Altonen. (2020). Low-Pressure Injection Process Facilitates “Green Molding.” Plastics Technology, 66(8). 2. Gene Altonen. (2019). Advancing “Autonomous Molding” with a Uniform-Low-Pressure Process. Plastics Technology, 65(9).

Conference: CAMX 2025

Publication Date: 2025/09/08

SKU: 133

Pages: 15

Price: $30.00