But what changes are consumers, designers and manufacturers looking for in plastics? And, in a world increasingly aware of the need for environmental sustainability, can plastics adapt to future requirements? Designers and product managers from four manufacturing sectors talked to Curve about how they use plastics and how they see future trends developing.
Plastics may be responsible for that ‘new car smell’, but they’re doing a lot more besides. According to John Field, interior design manager at GM Holden, the auto industry relies on plastics to provide consistent, strong, lightweight, reproducible high-volume parts that are cost effective and often recyclable.
“A high proportion of parts for car interiors are moulded in plastic now,” he said. “This is less the case on exteriors but is increasing. Some manufacturers are using plastic body panels for mass reduction, but this is not necessarily the most cost-effective solution yet.”
As an example of the number of plastic components in an interior, Field points to the VE Commodore instrument panel pad.
“It has a TPO (thermoplastic elastomer polyolefin) skin with a TPO foam backing and polypropylene substrate, which can be ground up and recycled. TPO and poly-propylene are inexpensive materials that offer a great functional performance and appearance.
“The design flexibility plastic provides allows for complex and streamlined shapes, and decorative finishes can be easily applied. The TPO skin used on the instrument panel comes from rollstock. Combined with the foam backing and through a vacuum-forming process, it adds a high-quality, soft-feel appearance to the hard substrate underneath.
“Plastics have the ability to achieve complex shapes with tight radii for precision appearance, large depth of draw and some opportunity for undercuts. One example is the instrument panel centre facia on our VE sports models. This is a large and deep part with fine radii and complex hidden attachment details.
“Also, the rear bumper fascia that wraps a long way around the sides of the car would be difficult to make in one piece from steel due to the depth of the part and the amount of stretch required.”
The use of plastics can also lead to a reduction in the number of parts needed, which makes cars lighter and assembly easier.
“Plastics are lightweight compared to other materials, and when moulded can be used judiciously to provide material only where necessary. Overall vehicle mass has a direct impact on the fuel consumption and performance of the car, and plastics help keep the mass down.
“Plastics also provide potential for ‘live’ hinges and therefore part reduction. The VE child-restraint anchor on the parcel shelf has a live-hinged moulding to cover the metal bracket and bolt which the customer can pull back to remove if necessary.
"The chute from the passenger airbag module also operates as a live hinge. Laser perforations in the TPO instrument panel provide an invisible burst-through for the airbag, giving a seamless appearance and eliminating the need for a separate door.
“Many interior components are assembled without fasteners, using moulded-in clips instead. They provide a robust attachment but enable ease of assembly and repair, as well as mass and part savings.
“Plastic fibres and yarns in textiles such as carpet provide a plush feel while meeting automotive usage requirements such as durability, manufacturability, non-flammability and cost effectiveness.”
Field says the subtle use of colour is just one of many exciting trends taking place at the moment.
“Pliable plastics and plastics with memory are interesting new technologies that we’re looking at. Transparent and semi-opaque plastics that can be back-lit to create interesting illumination effects and matt resin-type effects are also of interest.
“On the VE Commodore we developed a new high-flow crystalline polypropylene material which provides low, consistent gloss levels, with rubberised fillers to meet ever-increasing safety requirements for impact absorption. We also worked with a new painting technology to improve the painting process, durability and paint adhesion to polypropylene.
“We are starting to see more polycarbonate being used decoratively in car interiors. Clear parts that can be used as light guides for ambient lighting effects are an upcoming trend.
“We are also seeing more combinations of materials through co-moulding and over-moulding. For example, vent thumb wheels with a soft rubber grip or, more decoratively, with a sandwich construction of transparent and opaque finishes.”
Tail lamp lenses are another example of this, with multiple colours (clear reds, ambers and whites) combined in one smooth, seamless moulding.
“Plastics suppliers are experimenting with new processes, some of which are making their way into automotive design – translucent tortoiseshell finishes, for example. Others are looking at laminating transparent and opaque plastics to create ‘second surface’ effects that provide an extra dimension to a part, or cutting them into sections to give a striped or layered appearance.
“TPO is popular for its ease of recyclability. Its other benefits include ductility, low gloss, lack of squeak, absence of chlorine (making it safer to manufacture and improving ‘new car smell’) and cost effectiveness. It’s also available in various grades, including mouldable, rollstock and foam.”
Field sees plastics coming more and more to the fore in car design, in innovative ways.
“Plastics are no longer being hidden. Designers are mixing different types of plastics together, such as poly-carbonate and acrylonitrile butadiene styrene (ABS) blends, to eliminate design restrictions.
"These are fantastic to use in decorative areas. Traditionally plastics get disguised as something else, but we are seeing them being used honestly as an interesting raw material in their own right.
“Personalisation and customisation are the way of the future and we are looking for polymers that give us this flexibility. We are dreaming up ways of using plastics with embedded electronics to operate switches or to collect and convert solar energy.”
Environmental impacts from plastics in automotive design can be seen in a positive light, given that lighter vehicles produce fewer greenhouse gas emissions. Eco awareness is also leading manufacturers to opt for less hazardous compounds.
“Using plastics helps reduce vehicle mass and thus fuel consumption and emissions. There are also environmental aspects to plastics production itself, such as the phasing out of chlorine-based PVC, which is hazardous to produce. Emissions in the vehicle interior are another concern, which we’re addressing with the phasing out of PVC and use of TPO instead.”
When it comes to passenger safety, plastics come into their own.
“Plastics are ideal for absorbing impacts in crash conditions in contactable areas such as glove boxes and door and pillar trims. The key to impact absorption in both interior components and exterior fascias is to maximise the deceleration time of the impact.
"The deformation properties of plastics and their ability to absorb impact and deflect energy without shattering make them ideal materials.
“Also, egg crate-style ribs can be moulded into the back of a part to further absorb impacts, without making the part bulky. Usually rubberised grades of polypropylene, which remain ductile at low temperatures without becoming brittle, are used for impact requirements to improve safety.”
With Holden’s global reach, the plastics used must comply with the safety regulations of outside markets and also suit a wide range of climatic conditions.
“Because Holden sells vehicles in many global markets, we have to ensure the specific legislative and other safety requirements of those markets are met, but also ensure the plastics function effectively in different environments.
"For example, plastics must remain stable and UV resistant in hot climates like the Middle East, but also not become brittle in freezing conditions like those experienced in parts of Korea.”
According to Rob Tigani, marketing manager at Schiavello in Melbourne, plastics are cheaper than traditional materials such as metals and woods when it comes to furniture manufacturing. And plastic parts can be rapidly reproduced with consistent sizing, colour and product performance.
“We find plastics perform well from a design point of view,” Tigani said. “They are easy to mould into complex forms, which reduces secondary process operations, and can be produced much faster than metal components.
“We use nylon in the structural components of our chairs, as it has excellent impact resistance and flexural strength, dimensional stability and the right load-bearing properties. It’s also lightweight compared to metal castings or fabricated metal.
“Other materials such as glass-filled nylon are used for our gear-box caps. ABS and polycarbonate (PC) are used in electrical power modules. Polycarbonate is used for its rigidity, heat resistance, clarity and impact resistance. The addition of flame retardants
on our power board and outlet range allows us to meet local and international requirements set by governing bodies.
"ABS is used as a relatively low cost, rigid material. It has excellent gloss levels when moulded in highly polished moulds and is a wonderful material for decorative components that are highly visible to consumers.
“Plastics have great colourability and it’s easy to create different feels, textures and surface finishes such as metallic effects and tints. We use translucent colours and etched matt finishes on some components. Soft-touch rubberised plastics are used to produce decorative, appealing and ergonomic products that compliment our range.
“Foams and leather substitutes are used in upholstery, and the colourability of these plastics can be easily adjusted to suit consumer preference. We are currently testing and evaluating plastics that can be powder coated.”
Schiavello also dabbles in recycled plastic, both buying it in and re-using scrap to create innovative new materials.
“Programs and trials have been implemented to re-use scrap generated within Schiavello, such as saw dust,” said Tigani. “The saw dust is compounded and incorporated into plastics.”
“We make sure that most of the resins we use are recyclable, and we also use some recycled plastics. As with all recycled materials a loss of performance can be a problem, so a part must be designed to suit the recycled material. If this is impractical then prime resin must be used.
"The other option is to purchase recycled materials that are manufactured against a specification. Adequate supply of recycled plastic can also be an issue, but physical properties and consistency are bigger concerns.”
Packaging can pack a punch, and plastics are at the core of its power. “Packaging can play a key role in creating a point of difference and supporting brand development,” said Teresa Aprile, marketing and business-development manager at Visy Industrial Packaging.
“Plastics offer the industrial designer the flexibility and freedom to create a package that not only protects the product but also communicates and supports key brand messages.”
The versatility of plastics leads to quite different applications and outcomes, depending on the qualities required. They can be rigid when protection is needed, or flexible when convenience is paramount.
“Soft finishes are often used in cosmetic applications to communicate the benefits of a product such as moisturiser,” said Aprile. “Metallic or high-gloss finishes are often used to differentiate a premium design. Transparent PET (polyethylene terephthalate) materials are used to communicate freshness.
"LDPE (low-density polyethylene) can be used to offer ‘squeezability’, in sauce applications for instance. Generally, tooling for plastic packaging is also less expensive than metal alternatives. This is why you see common can sizes but a plethora of plastic shapes.”
According to Aprile, ‘barrier protection’ is the latest packaging trend, with the emergence of polymers that protect against oxygen, light or the loss of carbonation.
“Barrier protection is the ideal solution for common packaging issues such as oxygen ingress, carbon-dioxide loss and UV protection,” said Aprile.
“The key driver is supply-chain flexibility and the solution is to extend product shelf life. Barrier packaging also has the potential to differentiate products and opens up enormous opportunities for consumables like juice, sauces, spreads, condiments and even pharmaceutical products.”
Environmental concerns are another driving force in the development of new plastic packaging, and bioplastics are creating a lot of interest.
“We are investigating biodegradable packaging using bioplastic materials, as part of our long-term drive towards sustainable packaging,” said Aprile. “At this stage there are valid arguments for and against the use of bioplastics.
“PLA (polylactic acid), made from corn starch, is one such bioplastic with similar characteristics to traditional thermoplastics. Cradle-to-factory-gate assessments show PLA uses 30-40% fewer fossil-fuel resources and emits 20-50% fewer greenhouse gases compared to PET, polystyrene, polypropylene and polyethylene.
“Despite the many benefits of PLA, uptake has been stalled by concerns about the product’s end of life. Many argue that composting bottles represent ‘downcycling’ and that it is better to recycle bottles back into bottles. There are also concerns that the introduction of ‘bio bottles’ could harm the existing recycling networks.
"PLA bottles will likely enter material recovery facilities intermingled with PET bottles. If not sorted out, they will contaminate the PET recycling stream. PLA cannot be separated from PET in float tests. Optical sorting can separate the two but is expensive.”
Despite concerns about mixed-up recycling streams, we are starting to see the emergence of bioplastics on the market.
“PLA is being used in fruit-and-vegetable packaging, and Belu Mineral Water, a British company, uses compostable bottles. Now that Belu is on supermarket shelves in New Zealand, Waitakere City (within the Auckland region) wants to introduce a third kerbside collection stream to collect bioplastics and other kitchen waste to send to commercial compost plants.
"And Sainsbury’s has announced it will replace 150 million plastic trays and bags with compostable packaging made out of maize, sugar-cane or starch.”
The use of plastics in appliances is well established, with selection of materials usually determined by consumer preferences and retail pricing pressures. At Sunbeam, appliances are made from various plastics, carefully chosen to suit the product, according to Brian Johns, the company’s design director.
“Depending on the application, polymers are critically analysed for performance as well as their impact on product cost,” said Johns. “Most Sunbeam appliances are moulded in polypropylene, ABS, PC or styrene acrylonitrile (SAN).”
“Depending on the final surface treatments required, we also include soft-touch materials such as thermo-plastic rubber and silicone. Aesthetics often dictate the choice of polymer; for example, ABS is the preferred option for chrome plating.
“Beyond the engineering aspects, polymer selection is dictated by price rather than aesthetics or consumer preference, as the designer can usually achieve a desirable effect regardless. But compromises sometimes have to be made.
“The decision to use a type of polymer is directly linked to function. If a plastic is going to be subjected to high heat or used to carry food, then plastic selection is very specific and cannot be compromised. Sometimes we use additives to ensure a plastic meets the appropriate standards.
“The use of soft-touch materials is very prevalent in our products, in design details that interact directly with the consumer such as tactile interfaces. Ergonomics can be loosely linked to these types of materials, as they provide grip and visual cues to the user.”
Johns reflects that current trends are led by price. “The latest trends, unfortunately, are to utilise the most cost-effective materials available and this sometimes compromises the final design requirement,” he said.
“This trade-off is very heavily debated, as recommended retail price and the ability to function, and actually sell, all need to be finely balanced.”
Special effects are getting a lot of attention these days. “Plastics are receiving more play, not necessarily with type specifics but with over-moulding more than one plastic type for different effects, or with moulded effects through in-mould film,” Johns said.
When it comes to specifying polymers, Sunbeam looks for longevity.
“Each product is reviewed on a case-by-case basis, but final function in regard to long-term performance is the key. This includes not only functional performance but aesthetic performance for colour fastness, gloss levels, staining and/or heat effects.
“Another key issue is taste. Consumers ask, ‘Will this plastic product transfer a taste into the food if I use it?’ We conduct trials during the design and prototyping stage, to ensure the best result is obtained.”
New plastics, new possibilities
Plastic injection moulding has much more to offer than most designers realise, according to Greg Pracy, managing director at Bestmould Plastics, an engineering component manufacturer specialising in complex resins and component designs that are difficult to tool and mould.
“The trends that excite us in plastics are those that allow us to replace metal and rubber,” said Pracy.
“Long glass–fibre reinforcing of resins such as polypropylene, polyamide and nylon has been around for a long time, but is finally being considered for the replacement of metal components. We are trialling several of these materials in existing tooling to demonstrate their suitability.
“Glass fibre coupled with glass bead has often been used to improve the performance of badly designed components in poor-quality tooling, but this has had the benefit of introducing this material to designers who are now specifying it in well-designed components.
"Dimensional stability, mechanical strength and surface finish benefit greatly from this combination and we encourage designers to keep this in mind at an early stage of design.”
New developments in established materials such as polyamides are providing solutions for complex applications.
“A new company in Europe has been successful in improving polyamides and we can now offer tailor-made polyamides to suit difficult applications,” Pracy said.
“Thermoplastic polyurethanes (TPUs) have recently been improved through the introduction of polyester polycaprol-actone and ether polycaprolactone elastomers.
"Materials developed through these technologies have high abrasion resistance, high tear strengths, faster moulding cycles, improved resistance to hydrolysis and improved chemical resistance compared to straight polyester TPUs.
"We have seen significant benefits in areas such as pump liners and castors. The ability to injection mould rather than cast also provides huge cost savings.
“Technologies in alternatives to rubber and thermoplastic vulcanisates (TPVs) have benefited from the development of styrenic block copolymers. These newly developed materials are easy to mould and have good aesthetics and strong welds.”
Strengthening thin walls
“Plastics are being used more and more as a substitute for metal”, said Barry Benger, managing director at Quality Plastics and Tooling, a component manufacturer for the plastics industry. “The trend is developing further to thin-wall section moulding that reduces weight and cost.”
“The drive towards thin-wall sections less than 0.5mm (even 0.3mm) has led to engineering grades of material that maintain the required impact properties,” said Benger. “This new technology means we can save materials, shorten cooling time, reduce cost and materialise miniaturisation of products, as seen in the continuing development of the mobile phone.”
Benger says the diverse range of new polymers now available makes product development simpler, whether the requirement is for thin walls, strength, impact resistance, electrical resistance or heat-tolerance.
“Design limitations have become less restrictive, with material suppliers able to provide assistance in the early design stage. There is an opportunity for designers and manufacturers to lead in new technology.
"Fillers such as glass and talc add strength to products featuring a rigid or load-bearing design. We have seen products specifically designed in load-bearing applications that exceed their metal counterparts.
“We are seeing a trend towards early supplier involvement with the manufacturer, which generates a partnering relationship.”