The installation of cavity pressure measurement sensors and systems from Kistler has enabled thermoplastic injection moulder Polyfab to achieve a customer return rate of one part per million (PPM)


olyfab, a custom thermoplastic injection moulder, is using process

monitoring systems from Kistler, based on cavity pressure measurement, to sustainably optimise the high-volume production of plastic parts for various markets (medical, packaging, industrial and commercial). This has made it possible to reduce the number of faulty parts in injection moulding to a record- breaking 1 PPM (parts per million). For Polyfab to remain competitive in the

ever-changing plastic moulding industry, it has to continuously adapt its monitoring processes, with the ultimate goal of producing zero-defect quality assured parts. Brian Burhop, project engineer at the company, takes the quality of the moulded parts seriously. Monitoring the moulding process for suspect parts prior to packaging or assembly easily with guaranteed results is key. For nine years now, cavity pressure technology with sensors and systems of Kistler have provided an effective, reliable basis for automated inspection. Burhop said: “Our partnership with

Kistler came about because Polyfab Corp. is very much a moulder based on scientific principles which we employ to establish and monitor our moulding processes. Process monitoring and containment is very important for our high-volume jobs. Our decision was based on very important factors, such as how user-friendly the monitoring equipment is, how easy it is to acquire and interpret the data, how easily configurable it is with our machinery, and how easy it is to incorporate Kistler’s sensors into the mould itself. Kistler’s products were really hands down the best choice for us in all those categories. Approximately 66% of Polyfab machinery is now equipped with Kistler monitoring and sensor technology.” The first challenge Burhop and his team

faced was to improve the accuracy of short-shot monitoring for a dispenser lid with a living hinge. To reduce non-fills during the injection moulding process, the pressure at end of fill was monitored with a flush mounted sensor directly in the cavity. This allows for more accurate setting of the required minimum pressure which is affected by process variables including injection speed, and melt temperature. Burhop said: “Polyfab’s customer return score prior to implementing Kistler in

2009 was above 10,000 PPM (parts per million). In 2017, we moulded approximately 200 million parts and our rate for customer returns was 98 PPM, which is ‘world class’ performance. Our 2018 year-to-date PPM customer return rate is now ‘1 PPM’. This represents a drastic improvement after implementing Kistler’s process monitoring systems (ComoNeo/CoMo Injection), as well as Kistler’s direct and indirect cavity pressure sensors into our machinery.” Polyfab has also integrated Kistler’s

sensors into their automated assembly process, producing positive results. Burhop explained: “For automated assembly in terms of parts which have a lot of value added as they step through the assembly process, Kistler’s sensors ensure that we are not assembling parts with suspect (defective) plastic components. For example, we have a commercial inkjet cartridge that we have completely automated the assembly. “The cell incorporates two moulding

machines, six robots, and two 4-cavity moulds. We have placed a Kistler sensor in each one of those cavities so if there is a suspect or questionable shot, it segregates it so that those parts don’t enter the


A machine operator at Polyfab verifies the quality of the manufactured parts (top)

Process monitoring systems from Kistler were deployed to automate production of a dispenser lid with a living hinge. The benefits: time is saved, costs are cut and return on investment (ROI) is boosted (above)

assembly process. This has proven very beneficial and valuable to our automated assembly application needs.” Kistler’s process monitoring systems have

been saving time, reducing costs, and increasing the Return on Investment (ROI). Burhop said: “From my perspective: reducing re-validations was key. For instance, if we need to validate a tool in another press, either for capacity reasons or for risk mitigation for a customer, Kistler’s technology has made the process of duplicating a process much more straightforward and scientific in terms of the acquisition of data and the actual pressure curve data from the cavity.” Bob Hendricks, product sales manager

with Kistler, further explains this time- saving benefit: “When you have a reference curve that represents the part quality, and you need to move it from one machine to another, the benefit is you no longer have to revalidate the whole process every time because that reference curve remains valid on any machine.” According to Burhop, the set-up was

quick and easy to learn and use. He said: “The use of Kistler’s contact elements have greatly simplified our mould disassembly and maintenance process. At Polyfab, we focus on lean production, set-up reduction and quick-change. By utilising Kistler’s multi-channel connectors, it’s just one quick connection.” He continued: “Kistler’s piezoelectric

sensor technology, in my opinion, is much more straightforward and easier to use than a lot of the other sensors currently on the market. The installation of Kistler’s monitoring systems with our moulding machines couldn’t be any easier. We can pick up just one signal and that’s really all we need because it is so streamlined, and we are able to start collecting data quickly.” Burhop concluded: “We are very satisfied

with Kistler’s services and support. If an issue does arise, which is not often, Kistler’s support team responds very quickly and their services are fantastic.”

Polyfab’s production facility (right) operates the ComoNeo and CoMo Injection process monitoring systems as well as cavity pressure sensors from Kistler

All pictures courtesy of Kistler Group

Kistler Group


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