Measuring Cavity Pressure Is Key to Optimizing Molding Process

Norbert Sparrow | Nov 14, 2022

Measuring cavity pressure during the injection molding process is an effective way to optimize production. This requires the use of sensors to capture data and, perhaps more importantly, interpreting the data in a meaningful way. That's one area where things get complicated, according to Christian Streili, field service development manager at Kistler, a global developer and supplier of advanced measurement systems.

The complexity actually begins with the injection molding process itself and the many parameters — part size, material consistency, and ambient temperature as well as the temperature of the plastic itself — that have an impact on the finished product. "Many injection molders underestimate these influences or know little about how seemingly minuscule changes in the process can affect the quality of the molded part," said Streili. Cavity pressure is an indicator of part quality — a part-specific fingerprint, as Streili puts it — and measuring it can play a crucial role in overcoming several challenges.

Piezoelectric sensors help injection molders find and maintain the optimal process for each mold, regardless of the materials that are being processed, explained Streili. "The sensors measure and analyze cavity pressure during injection molding. Based on these measurements, manufacturers can control the injection molding process, balance the hot runner system in line, as well as automatically sort out bad parts," said Streili. But making the best use of the data that is generated is no easy task, he added. It requires deep knowledge of the injection molding process and expertise in deployment of measurement systems. Kistler is perfectly positioned to provide that technical support, he added.

A simulation program developed by Kistler can determine how many sensors will be needed and where they should be placed before the injection mold is even built.

The company also has MoldValidation packages to verify sensor and cable installation and ensure that the injection molding process is achieving peak performance. "Every mold and process is different. There are so many contributing factors that it can be difficult to detect the correlations between faulty processes and external factors," explained Streili. "This is where our expertise truly pays off."

Based in Switzerland with more than 60 facilities worldwide, Kistler partners with industrial customers and researchers to optimize products and processes. Its core area of expertise is in dynamic pressure, force, torque, and acceleration measurement technology. Kistler's innovations in sensor-based systems are applied in automotive, industrial automation, and many emerging sectors.

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