Injection Moulding Machines Upgraded With the Latest Generation Plastic Material Conveying System

Injection Moulding Machines Upgraded With the Latest Generation Plastic Material Conveying System

We at Polymermedics operate dozens of injection moulding machines from some of the leading machine manufacturers. Our company serves some of the world’s biggest medical and pharmaceutical brands – working collaboratively to create solutions, finalise mould designs and bring safe & efficient products to the market. We are constantly investing in the latest equipment, skills and techniques to maximise quality, efficiency and precision of manufacturing. However, bumps on the road do occasionally appear: once we determined a rising quality issue, we were able to conquer it by upgrading our moulding machines with Piovan’s plastic conveying and blending system.

Project description: the highlight of the main challenges we had

Each year, Polymermedics produces billions of plastic components. A segment of these produced components are the flip-off seals for drug vials. The colour of the flip-off is used to indicate the type of drug contained in the vial, so colour consistency of these plastic parts is critical. We produce parts in a large number of different colours and shades, so to cater for this variety, we use colour masterbatches blended with a virgin plastic material. This gives us an amazing production flexibility, but there was a risk of violating the colour’s integrity, which in the very worst case could cause the death of a patient.

“Polymermedics performs in excess of 1650 colour changes per year, so ease of cleaning of the equipment is very important”

Polymermedics performs in excess of 1650 colour changes per year, so ease of cleaning of the equipment is also very important. Since the moulding area is a clean production area, all equipment should be removed from the mould shop to be cleaned. Equipment cleaning is a very time-consuming procedure. That is why the time needed to clean it was also an important metric to consider when choosing the supplier. To speed up the process of colour changes, we had spare equipment always ready to move into the mould shop.

The moulds we have are mostly multi-cavity, and some of them are fast cycling. Almost all new moulds are full hot-runner. All of the moulding machines were equipped with granulators, mainly auger type, positioned under the mould to directly granulate the sprues and runners. Accordingly, each machine had to potentially process virgin, masterbatch and regrind materials. Moreover, some products also require a slip additive to be added to the mix. The existing blending and conveying equipment was outdated, so we decided that we needed to upgrade our injection moulding process to ensure that we continue to offer our customers the latest technology.

Key steps that were taken to reach our goals

Polymermedics and Piovan have a long-standing relationship based on a trust, which spans over 25 years. Piovan’s product portfolio includes storage, drying, conveying and blending equipment for plastic granules. The moulding process temperature control (in terms of both heating and cooling) combined with high energy efficiency is also an important part of their products’ portfolio. This background enabled the two companies to work closely together. Through the years, Piovan developed a detailed understanding of exactly what moulding needs Polymermedics has. This was vitally important, as we had started to experience issues with one of our main customers due to quality performance. We called Piovan in to look at the areas that could be improved. Following numerous interactions, it was agreed that the following areas would be the key drivers to eliminate the issues faced:

  • 1Reduction of the airborne dust and noise in the mould shop. The existing hopper loaders on the injection moulding machines had integrated single phase motors, with a filter, which is needed to be cleaned with compressed air after each cycle. The single phase motors are noisy and the motor’s brushes can produce carbon dust, which is not the greatest thing for a clean production area. And even more: the compressed air filter cleaning could potentially release and spread the dust. It was therefore decided that the new system shouldn’t use any single phase hopper loaders. Instead, we had to employ system loaders with the patented technology that doesn’t need any filters at all. Due to some moulding machines running with granulators, our employees were spending hours cleaning filters. So the decision to replace filters alone resulted in direct labour saving and reducing the maintenance costs.
  • 2Colour consistency. Previously employed gravimetric blenders had integrated mixers, which mixed the plastic before it was conveyed to the moulding machines’ hoppers. Therefore, the mixed material could potentially be divided between the blender and machine hopper, due to the different bulk densities and flow properties of the virgin, masterbatch and regrind materials. In addition, because of the mixers being a part of the gravimetric blenders, the regrind also had to be re-introduced by the blender, as it was important for the regrind to be thoroughly mixed with the virgin and masterbatch plastic materials. If the regrind was not mixed evenly with the virgin and masterbatch, colour variation could result, as the regrind already contains its own colour. It was agreed that the mixers should be separated from the blenders and installed on the moulding machine throats. This would mean that the plastic would be mixed immediately prior to being processed. This change enabled the regrind to be conveyed directly back to the moulding machine hopper without going through the gravimetric blender. The design change released a labour savings benefit of over 550 hours annually and resulted in the 90% reduction in colour-related issues complaints from our customer.
  • 3Control and traceability. For product traceability, we at Polymermedics need to record any system alarms and plastic material deviations. Previously, one of the possible risks was that the wrong recipe could be uploaded to a blender, which could cause the wrong colour plastic parts to be produced. It was agreed that a SCADA production management system should be installed to properly manage recipes and capture plastic material usage. We requested to customise our WinFactory system: in addition to managing material recipes, we wanted the system to also set the virgin conveying time, material type, material source and regrind conveying % automatically. This decision minimized the need for human intervention. Additionally, a “tagging manifold” was installed to check the virgin material connection, eliminating the risk of conveying the wrong plastic to the moulding machines.

gravimetric blenders machines

Once the requirements and recommendations were finalised, it was decided that the next step should be for a part of Polymermedics’ employees to visit the Piovan factory in Italy. They had to examine the proposed equipment and ensure that it would meet their needs. As a result of the visit, a number of bespoke adjustments were made. We agreed for Piovan to supply the “trial” equipment for one of the moulding machines so that the operators and technicians at Polymermedics could also give their feedback and take part in the decision-making process. Our employees carried out the report that highlighted all further changes required to meet the company’s needs. The equipment was then manufactured according to the agreed design, which resulted in a fully signed-off URS: a “full package” consisting of dozens of gravimetric blenders with remote mixers, numerous hopper loaders and several new vacuum systems.

“A team of engineers were deployed and worked continuously for a 14 day period, working 12 hours a day, to meet the deadline for production to restart”

Very soon it became evident that due to the fact that Polymermedics operates a clean production area running 24/7, the installation could only be done during a shutdown period: we had to stop the machines to place the equipment. Polymermedics had an annual shutdown planned in August 2016, it meant that the Piovan UK engineers had a vast amount of work to do in a relatively short period of time. Therefore a team of engineers were deployed and worked continuously for a 14 day period, working 12 hours a day, to meet the deadline for production to restart. Once the system was up and running, an engineer was left on-site for two weeks to iron out any initial problems. He had to train all Polymermedics’ team to ensure a smooth transition from one system to another.

The results of the partnership

The relationship between Polymermedics and Piovan represents a true partnership. Piovan’s engineers were eager to understand what problems we had, in order to design a system that was capable of solving them. The equipment was re-engineered to meet our exact requirements and the success which followed was evident: the maintenance costs were reduced, colour-related complains dropped by 90%, control process was automated. A full engineering support was provided to guarantee the expected results: the planned upgrade of injection moulding machines was performed in a very smooth manner. This attention to the details led to a seamless transition from an ageing system to a state of the art, full material track, trace and handling system that delivered benefits in excess of our expectations.

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