FEATURE ADDITIVE MANUFACTURING/ 3D PRINTING Plastic or metal 3D printing: Which is best?

AM in metals is gradually becoming a more popular method for some major manufacturers, particularly in high-value, low-volume industries, opening up the question as to which is best: plastic or metal 3D printing? Michael Wilson*

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dditive Manufacturing (AM), more commonly referred to as 3D printing,

has been around since the 1980s, with the commercialisation of stereolithography (SLA) in 1987, followed by fused deposition modelling (FDM) in 1991 and selected laser sintering (SLS) in 1992. Today, 3D technology is transforming

the world we live in. The ability to innovate and manufacture something new and cheaper, but without sacrificing quality, or something which meets the individual client’s needs, is a technology that businesses cannot afford to ignore. If businesses put off evaluating the impact of 3D printing on them and their customers, the more difficult it will be to maintain and grow their market share. Sometimes referred to as rapid prototyping, 3D printing accelerates the product development cycle and allows the manufacturer to respond to changing demands quickly and in an innovative manner. Not only does 3D printing permit forms and functions to

be combined in ways impossible to achieve using traditional methods, it allows for a degree of customisation to meet the challenge of changing markets and individual customers. It also offers the possibility of streamlining the supply chain, distribution and manufacture of spare parts by permitting the distribution of ‘items’ as electronic files that can be printed elsewhere and even by the end user.

3D PRINTING IN PLASTICS Despite metals taking the lead with durability, plastic 3D printing still has its use – especially in product development, where an initial affordable prototype can be made in plastic, tested for any inaccuracies and adapted. While the final product can then be printed in metal, there may be no need for it to be replaced if the plastic version is robust enough and fit for purpose. We recently worked with a military uniform manufacturer with a 100-year

heritage when a Leesona winder part broke. Made out of cast iron, spares were impossible to come by, but the part needed to be identical to fit the 70-year old machinery. Although a small part, without it the machine wouldn’t work and production would come to a halt. So, our in-house design team scanned the broken winder part, produced the CAD files and then additively manufactured a replacement part in polymer that was lightweight yet potentially strong enough to undertake the same function and fit. The winder part is currently on a trial period and the intention is to print a replacement in stainless steel and

Originally made in cast iron, the winder part was replaced with an additively manufactured polymer version

* Michael Wilson is general manager of the 3M Buckley Innovation Centre (3M BIC) and director of the

Huddersfield Innovation and Incubation Project (HIIP)

introduce other improvements if the polymer version is the correct form but does not wear well in regular use.

THE RISE OF METAL AM AM in metals can create products that would be difficult or impossible to achieve with casting or subtractive techniques, such as machining. It can produce complex structures such as webs and honeycombs where the physical properties of the object are retained, but with a large saving in mass. It is particularly beneficial to the

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