Many modern products are made of plastics. We encounter this basic but highly complex range of materials throughout our daily lives. However, they are not simplistic, nor are the decisions about whether consumer goods have certain components made from metal for example whilst the majority appear to be in plastic.
In the past, (and hopefully again in the future) an engineering student would ‘time serve’, spending up to five years as an apprentice, learning and understanding how products are manufactured before turning his or her hand to the complexities of design and material choice. Our current further education system has embraced CAD and the ability to solid model, constructing components and assemblies on screen, and in some cases ‘testing’ the capability of the model.
Usually these powerful tools are able to draw upon the databases of materials provided by manufacturers such as Bayer, BASF, Dupont, and GE Plastics , who are continually developing & marketing new and more sophisticated polymers. Any designer will undoubtedly be able to expound the differences between a myriad of commodity, engineering and performance thermoplastics, yet many will probably have only a relatively superficial knowledge of metals, quite unaware that there are, for example, hundreds of stainless steels to choose from, with subtly different properties for various applications. Buy Ambien Online India is a good example of a stainless steel web site, but you need to be a metallurgist to understand it!
Yet we encounter metal probably more than any other material is our lives, our cars are mostly steel and aluminium, our houses whilst being predominately brick built rely on numerous metal widgets such as brick ties, window fixings, handles, hinges, locks. The list is endless.
And all of these examples have one thing in common, we EXPECT them to be metal, it’s in the field of consumer products where the designer and his CAD system is King, and thanks to the changes in education, and perception is it any wonder that so many of today’s products are constructed of plastics?
The film, The Full Monty showed the sad decline of steel manufacturing in its Sheffield, UK, heartland, whilst there has been a modest recovery in steel, with rare exceptions the metals industry overall is perceived as reactive and encumbered by the dyed-in-the-wool, producer-orientated attitudes of yesteryear. Meanwhile, the plastics industry is seen as proactive, ready to listen and help.
It is perfectly possible to buy almost any type of metal required, but you need to know exactly what you want, and be prepared to wait a few weeks for delivery and order a large quantity unless a local stockist happens to have just what it is you require. This is quite different to the plastics industry, which often offers tryout quantities for prototyping and addressing fresh applications.
Yet there is most definitely a place for metals if only we take the time to investigate, and recognise that as a society we value metal.
Consider costume jewellery, it can be very expensive, carry a designer label and be highly valued, yet it is tainted by the word ‘costume’. In some cases it can even be more expensive than bijouterie in precious metal but we still prefer gold, silver or platinum.
Product designers are more aware in some areas than in others of the benefits of the intrinsic value, solidity and aesthetics of metals. No matter how technically advanced a plastic watch may be, it’s still plastic. Other watches are advertised on the basis that they are made from titanium. There is no great design or technical benefit in manufacturing a watch from such a material, but it is the image of titanium as aerospace and ‘high tec’ that makes it desirable.
At a technical level, many plastics are inferior to metal components, they can shrink, & there must be joint lines? In RFI/EMI applications they do not provide a natural shield as metals do, they are less dimensionally stable and can be degraded and discoloured over time by heat, sunlight and ultraviolet rays. Plastics are hydroscopic (absorb water) and most significantly are subject to the whim’s of the petrochemical industry which provides the basic raw material. We must not ignore either their major carbon footprint. Metals, unlike plastics, are recyclable in more than 95% of cases, with plated metals and bimetals being more difficult but not impossible to recycle.
A stronger argument in favour of metals is that plastic mouldings have a lower perceived value than metals owing to less weight and an inferior feel. A favourite example being a lipstick, a superb use of the highest quality plastics for cosmetic appeal. Yet, to enhance that appeal, and increase the perceived value, a zinc die cast weight is carefully concealed within the mechanism. The more expensive the product, the bigger the weight.
For more visible products many modern consumer goods offer many more examples: Plastic food processors, kettles, mixing bowls and kitchen utensils are considered more downmarket and cheaper than the professional, all stainless steel versions seen in a TV chef’s kitchen, where stainless steel implies cleanliness and hygiene too. When was the last time you saw Gordon Ramsay, Jamie Oliver or Rick Stein with a plastic serving spoon?
A low cost MP3 player will be housed in a flimsy, economy plastic case whilst the top of the range will almost certainly feature some metal in its construction.. Indeed, for marketing purposes, many hand-held devices, although encased in plastics, are coated to simulate metal. Such products would be better enclosed by a metal pressing to absorb electromagnetic interference (EMI) and physical shocks. The metallising of plastics for mobile phone housings is an expensive process with environmental drawbacks, Nokia, Samsung and Apple promote stainless steel & aluminium cased mobile phones as premium products.
Design icons of the 21st century in metal including the Maglite torch, Rayban aviator sunglasses, even Adidas Predator football boots market the fact that metals are used in their construction. Better quality pens and spectacle frames all come in metal. The Zippo lighter has always been stainless steel and is preferable to a bagful of throwaway plastic lighters. Even when plastics are used for reasons of appearance, such as on a Sky HD box, they are concealing a metal substrate that houses and protects the sensitive electronics.
Plasma or LCD high-definition TV sets embody superb electronics as well as outstanding product design, and can be wall-mounted. There are over 30 individual metal pressings in such home entertainments equipment, many of them structural. After all, would you trust a plastic bracket to secure your large and valuable TV to the wall?
It has often been predicted that automotive engineering companies would design and develop a completely plastic car for the mass market, but it’s never happened.
Vehicles as diverse as a Caterham seven and the latest Audi Coupe share some common composite materials for body panels, but when it comes to the floor pan, it’s metal all the way. The use of metal in such an application is quite clear, and mirrors the use of structural steels within buildings; In a direct comparison metal is stronger, safer and more reliable. As consumers we pay little attention to the materials all around us, but when asked about the structure of a car we know what it is that we understand, and trust.
So, yes, we do value metal over plastics, just look at the news in recent months, theft of all manner of metals has become a national issue with hundreds of tonnes of scrap metal simply disappearing, when was the last time you heard of someone stealing a couple of tonnes of nylon 6! Sadly there have been and are times when the metals manufacturing and supply industry falls well short in terms of information, promotion and service in the face of the intense and innovatory competition from plastics. Metals are crying out for a 21st century approach to meet the challenges of modern products. We work at the forefront of metal manufacturing, yet cannot honestly give an example of the last time the industry offered us a new innovation. It’s no wondered that some many things end up in plastic.