Pentagon Plastics – UK Technical Plastic Injection Moulding Experts

Plastic injection moulded components are designed with various levels of complexity from small and very simple products right through to the highly complex components used in industries such as Aerospace, Marine and Medical.

Pentagon has been producing bespoke technical plastic mouldings for over 45 years, having started out simply catering for small batch mouldings they now provide production runs from 1-2 off right up to 150,000 off batch sizes. Injection moulding machine at Pentagon Plastics - UK Plastics News

The level of engineering and manufacturing capabilities at Pentagon allows them to serve those customers with technically challenging one shot injection moulding requirements whilst still looking after the needs of those with more simplistic designs or concepts.

Boasting a comprehensive mould shop of 10 moulding machines ranging in press size up to 280 tonne locking pressure the company is well placed to provide a proactive service.

The smaller 22 up to 50 tonne presses are predominantly dedicated to single impression products for the Medical sector.  The wide range of medical products that Pentagon manufacture are not invasive to the body and therefore cleanroom moulding is not required, however very strict clean practices are in place to ensure that contamination does not occur to the manufactured components.  To allow additional cooling time for these products conveyors are often used to draw the parts away from the moulding machine, this also ensures that parts remain flat before packing. The good working practices are rolled across the full range of products supplied delivering a very high quality level supported by their ISO9001 accreditation.

The mid-range moulding machines from 90 to 130 tonne are very versatile with a mix of electric and hybrid machines for greater efficiency. They take on a diverse spread of bespoke product manufactured for many industries including, electrical, security, aerospace and marine.

The biggest machines on site range from 150 to 280 tonne with a mix of electric and hydraulic presses that run the bulk of the multi-cavity medical jobs as well as products for construction and automation industries.

Process capabilities include high engineering materials such as Polycarbonate (PC), Polyamide (PA), Polyphenylene Oxide (PPO), Polyphenylene Sulphide (PPS) and Polyetheretherketone (PEEK) in filled and unfilled grades as well as more standard materials like Polyethylene (PE), Acrylonitrile Butadiene Styrene (ABS) and Polypropylene (PP) as well as a wide range of additive materials. To mould thermoplastics Pentagon are required to hold strict temperature and process control to ensure that the product does not distort, that the tool functions efficiently and the molecular integrity of the material is maintained to meet or exceed the product requirements.

Pentagon Plastics mould shop is able to cater for various temperature control requirements including water, oil and electric which is vital when processing such a wide variety of materials and is supported by a vast array of dedicated material dryers to ensure that the material is dried to the manufacturers recommendation on every production run.

Many thermoplastic materials provide their own processing challenges, having a vast experience in a wide range of materials certainly makes Pentagon stand out from the crowd.

There is so much variation when it comes to processing thermoplastics; for example Ethylene Vinyl Acetate (EVA) is moulded with a cold tool around 10ᵒc controlled by water, Polycarbonate (PC) would require a hot tool around 90ᵒc controlled by water or oil and Polyetheretherketone (PEEK) requires a very high tool temperature between 170ᵒc and 200ᵒc controlled with oil or electrically. Too cold and the material “sets” before the mould is full, causing loss of material properties and visual defects. Too hot and the parts can be too soft too eject and extend the cycle causing a higher cost per component. This tolerance band can be as little as 10ᵒc and is usually controlled by localised thermocouples built into the tool, or by the experienced setters monitoring the temperature through the run.

PEEK’s tend to be used by Aerospace manufacturers as they offer excellent dimensional stability throughout the wide range of temperatures they are subjected to while the plane is in flight or on the ground.

Softer materials such as EVA and Low Density Polyethylene (LDPE) are often found in medical products such as Stoma care, Colostomy and Urostomy systems forming the coupling flanges and drain taps for emptying the pouches. They offer the end user a soft feel and flexible product. The Vinyl content in the EVA dictates the softness and makes them weldable to the pouch materials.

EVA requires a much lower tool temperature to get them to harden off sufficiently for ejection and the surface finish of the tool also has an effect on the moulding process. During the warmer months condensation can form on the tool and all associated pipework so additional care is taken in the selection of a suitable tooling material to prevent long term issues.

Compressed air is often used to assist the ejection of soft parts; this in turn can lead to issues with mouldings coming into contact with greasy areas of tools and machines or wet pipes, so they have to be controlled as they “fly out” of the press.  Those that think plastic injection moulding is a straight forward process would be surprised by the number of challenges todays moulders face!

An average day in Pentagon’s mould shop will see 3-4 mould changes being carried out on average, each taking around an hour and a half to complete including setting the conditions ready for production start approval. The shop is run over a two shift work pattern with 2 experienced setters per shift lead by the mould shop manager.

Pentagon Plastics not only mould the products for tomorrow but offer a full mould tool package from the manufacture of new tools through to the service, repair and modification of existing moulds; providing a range of mould tooling solutions from small modular insert systems right through to complex multi-cavity tooling. All produced on one site in the UK Pentagon do truly provide a full turnkey solution for many customers who rely on their knowledge and expertise. They are focused on providing optimum tooling and production parts for the life of a product and create partnerships built on mutual trust.

If you are looking to source a new UK supplier for your injection moulded components or have a new project that you would like to discuss call the team 01403 264397 or email

Pentagon Plastics logo - UK Plastics News

Pentagon Plastics
01403 264397

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