Thermoplastic Materials

This is the second blog in a series of three outlining the background, properties and use of the plastic materials we at Merriott Group, use to provide our customers with diverse products here in the UK, Europe and worldwide. 

Engineering Plastics

This range of materials, of which 3 are detailed as below, are used for the majority of industrial products, as a result of their mechanical and environment use. As such they are higher cost than the commodity plastics but come into their own in specified applications where the end use is more demanding.

 

Acrylonitrile Butadiene Styrene (ABS)

One of the most common plastic that you are likely to encounter, as it is widely used for appearance parts, and is the number one choice for designers. Its smooth feel, appearance and cleanness of colours makes it very appealing, along with great properties for easier assembly. ABS can be assembled with adhesive, screws, clips, welded, inserted, painted, printed onto and chrome plated. The letter B is for Polybutadiene, which is a synthetic rubber, which improves the impact resistance of this vital material, along with allowing flex but strength for clip designs. All these options improve the product design along with improved assembly times and reduction of other fixings.

Using ABS with its excellent impact properties, toughness, rigidity, is further improved for temperature requirements by adding glass fibre, or being an alloy with PC (Polycarbonate), known as PC/ABS.

ABS has a relatively recent history, having been developed in the late 1940’s and came to market in 1954. The first company was Borg Warner to do so and was the market leader for many years. Their most notable grade was Cycolac T, and was used extensively for telephones of the non-digital type of the 60’s, 70’ and 80’s. With the wide colour range of both homes and offices at the time, thousands of tons of ABS material were converted into telephone housings.

Of course, the most widely known product using ABS is for the infamous child and keen enthusiast of Lego bricks. Known for its smooth clean finish, easy of manufacture/process, stability in temperature, but also the ‘clutch’ feel of both pushing and pulling apart is key to this wonderful imaginary toy worldwide.

Parts made in ABS have the re-cycle triangle and the letters ABS. The material is not re-cycled at the kerbside collections, but mainly at your main re-cycling centre or through the industrial waste reclamation facilities.

Merriott Group and both facilities use ABS for many products, such as Covers for air movement assemblies, agricultural Incubator parts, drainage parts for care home/domestic/NHS shower/wet rooms, to name but a few.

 

Nylon (PA)

Developed by DuPont in America at the tail end of the Great Depression and launched to market just prior to the start of WW2, this material is viewed as a major engineering material, but it has its difficulties, which we will come on to later.

At that time, ‘Nylons’ was in great demand as a lady’s garment, and very highly sought and fought over, for due to the feel/appeal and demand. Due to its importance and output, Nylon was used to support the war effort with parachutes and many items for the aircrafts being built rapidly.

Nylon material today is used extensively in many ‘under bonnet’ applications in automotive and many commercial vehicles, engine and electrical components. This is due to its strength, chemical and impact resistance, and temperature range, but also its impact/flexibility properties. It is these properties and weight savings that are key to reducing emissions of the vehicles of today and the future.

Also used widely in the electrical industry for its insulation, heat resistance and strength properties, enables the designer to build in complex forms and keep costs down.

Known in the trade as PA6, PA66 and now more options by linking other materials, and with the addition of glass fibres and beads, minerals, other additives to improve both fire resistance and smoke emissions, makes this material a key choice.

Producing products in Nylon requires much soul searching as the material shrinks after different rates according to the direct of flow within the mould tool. the choice and position of feed points is a critical decision by the tool designer, and requires detailed discussions with the tool designer, customer and tool maker at the outset. Processing Nylon is also key to quality products, with the most important being ensuring that the material is thoroughly dry at the outset, since Nylon absorbs moisture. This leads to poor quality parts that are brittle and of poor appearance. Process temperatures are closely monitored during the production, as well as having hot tools to ensure a quick mould fill. After moulding parts need to normalize by the absorption of moisture which improves the product impact. This can be achieved over a few days from the atmosphere or in some circumstances by placing the parts in very hot water for a period of time determined by the part section.

Parts made by Merriott Group are for electrical products in lighting and electric panels, under bonnet engine management plus many more. A recent development is the replacement for a steel spinning, which is then welded, that has been replaced with a complex design in glass filled and bead Nylon. This is a drum that is used in a macerator unit in hospitals and care homes. This is moulded on our 1,100t press due to the tool complexity and part height of 450mm. The material was selected for its weight reduction, impact, design requirements and ability to incorporate complex features to aid final assembly.

Polycarbonate (PC)

Yet another material that was developed following the Second World War in Germany in 1953 and then registered by the worldwide company Bayer, under the trade name of Makrolon. This was closely followed by General Electric with their trade name of Lexan. GE only commenced commercial selling of their material in 1960, following a trade agreement with Bayer. Both of these trade names are widely known and are even stronger in today’s market, as a result of further material developments for many applications.

Known for its natural fire retardancy that can be further enhanced to V0, being glass-clear, strong impact, is used widely both as a moulding material and as a forming material from sheet.

Critical to the processing of Polycarbonate, is oven dried material and very hot mould tools, typically 60-80°C, to ensure good fill of the mould using least pressure. Moulded parts not made under these conditions do suffer with internal stress which can lead to cracking of vulnerable features.

Typical applications are lighting, both commercial lights/diffusers thus replacing glass. Automotive light clusters, which can be enhanced with coatings to protect against road debris and scratches. Its biggest single use is CD’s, where cycle times are extremely fast as low as 3 seconds on multi-cavity tools. Your mobile phone is mainly built around polycarbonate covers, where the material is moulded to very thin sections, but offering the designer features to improve assembly along with pleasing appearance.

Widely used in the construction market as sheet materials, for roofs, like many conservatories, large roof lights where the weight is a factor.

One of Polycarbonates down falls is the link to Bisphenol A and use in food applications. Polycarbonate was the most used material for baby feeding bottles, and other food applications. The link was that when the container reached a certain temperature that the Bisphenol A would leach out of the Polycarbonate and contaminate the food stuff within. May studies were carried out at the time, and hence today more suitable food compliant Polycarbonates are used for food applications, like the large drinking water containers, plus many others.

The linking of Polycarbonate and ABS above, known as PC/ABS in the trade, is a widely used material in automotive, electrical and applications where the properties of the 2 materials enable designs to incorporate clips features, along with strength, impact and flex all at the same time.

 

Here at the Merriott Group, all of the above materials are processed daily, providing diverse customers with mouldings for many industries here in the UK, Europe and further afield. Our knowledge of the tooling requirements for these materials have been built up over many years of experience, along with processing and design input to bring many applications to market. If you need any further information, please do not to get in contact either vis the web site or by contacting us directly.