Connectors and cases to house electronic equipment for the automotive and electrical engineering sectors are the daily fare of Fischer GmbH & Co KG, based in Sinsheim, Germany. Erich Fischer, Head of Production at Fischer, is familiar with the challenges posed by injection molding thanks to his lengthy experience in this field. For ten years now, cavity pressure monitoring with sensors and systems from the Kistler Group has provided the reliable basis for his inspection work.
Erich Fischer and shift leader Martin Weinzettel, a qualified industrial specialist in plastics and rubber technology, accept no compromises when it comes to the quality of their injection-molded parts. They know that any defects will either cause problems when assembling components in their own operation, or complaints from the OEMs and Tier 1 suppliers who take delivery of millions of their products. Fischer has identified molds that are not completely filled (or 'short shots', as they are known) as the key criterion for the quality of injection-molded parts. Several years ago, Fischer introduced additional process monitoring based on cavity pressure to deal with this specific issue. So Fischer can rest assured its that molded parts meet the quality requirements:
Now we have reliable protection against spiraling costs thanks to cavity pressure monitoring."
Erich Fischer, Head of Production at Fischer
Consistent deployment of sensors and systems
Fischer now operates 60 process monitoring systems.. Over 300 molds are equipped with cavity pressure sensors. 'We equip virtually all of our new molds with sensors from Kistler,' Martin Weinzettel emphasizes, 'and we’ve already retrofitted many of our older molds as well.' CoMo Injection process monitoring systems (Type 2869A/B) from Kistler are installed to monitor pressure curves. All of these systems are permanently installed and networked to guarantee central storage of the production parameters. This data can be consulted when molds are changed. The benefits: simple data handling and shorter setup times.
However, quality monitoring isn't the only advantage that Fischer enjoys thanks to cavity pressure measurement. 'Cavity pressure measurement helps with process startup and optimization when we carry out trials on new molds. And on our multicavity molds, the process monitoring system tells us at a glance whether the hot runner balancing is right. Later on, we can even detect machine errors and signs of wear by looking at the cavity pressure curve,' Martin Weinzettel notes.
Networking saves valuable time
Most of types of machine at Fischer are networked, and there are multiple installations with identical equipment, control and automation. 'Kistler's process monitoring technology gives us problem-free mold interchangeability – so we save precious time,' Erich Fischer explains. Martin Weinzettel echoes his view: 'The pressure curves tell us very clearly whether the balancing is right.' Now, Fischer and Weinzettel are also eyeing MultiFlow, the new automated hot runner balancing system that Kistler has developed as an optional module for the process monitoring system. It synchronizes filling behavior in the cavities of a multi-cavity mold thanks to targeted control of the hot-runner tip temperatures. Weinzettel: 'This concept offers Fischer a good option for replacing manual hot runner balancing during setup and rebalancing in series operation in the future.'
Short shots massively reduced
Cavity pressure monitoring now gives Fischer reliable protection against spiraling costs due to complaints. 'If the machine, the mold, the hot runner and the material are already right, cavity pressure monitoring is an excellent tool for boosting quality and avoiding complaints.' The final word from Martin Weinzettel: 'We've seen a massive reduction in short shots since we've been working with Kistler systems.'