Ever expanding role for 3D printing

The 'sky's the limit' cliché is much used, but when it applies to 3D printing, it is a befitting phrase with huge potential for manufacturers.

3D printers can produce very complex parts that are beyond what traditional manufacturing techniques can do.

3D printers are capable of making parts that are nearly equivalent to machined or injection moulded parts strength-wise.

Latest machines are capable of 'manufacturing' large products cost-effectively are relatively quickly.

3D printing continues to expand its rapid growth, pushing the boundaries ever outwards. Already this year, an 83-year-old patient has had a 3D printed lower jaw surgically implanted with complete success. The titanium jaw was built by Belgian company Layer Wise in collaboration with scientists from the University of Hasselt.

Printing three dimensional objects with incredibly fine details is also now possible using "two-photon lithography". With this technology, tiny structures on a nanometer scale can be fabricated. Researchers at the Vienna University of Technology have now made a major breakthrough in speeding up this printing technique, opening up new areas of application, such as in medicine and electronics.

The 3D printer uses a liquid resin, which is hardened at precisely the correct spots by a focused laser beam. The focal point of the laser beam is guided through the resin by movable mirrors and leaves behind a hardened line of solid polymer, just a few hundred nanometers wide. This fine resolution enables the creation of intricately structured sculptures as tiny as a grain of sand.

Chris Peters, industrial designer and founder of 3d-printers.com.au, says there have been massive advances in 3D printing in recent years, coupled with prices falling to as low as a thousand dollars for a desktop 3D printer.

"Printers can now print tiny parts at the sub atomic level. And once they can do that repeatedly, at a rapid pace and to a point where they can print metal and plastics together, they will be able to print a complete working electronic part such as a mobile phone. This is where the real future of 3D printing is," Peters told Manufacturers' Monthly.

At present however, stereolithography (SLA) is the most commonly used 3D printing technology. The process builds 3D parts from a photopolymer liquid resin which is hardened by a UV laser.

The laser traces out the profile of each slice of the part and gradually builds a part layer by layer. After the laser has completed a slice, the build table lowers into the resin and the process starts all over again for the next layer.

"SLA machines produce the most accurate detailed parts with a broader scope of materials as well as resins. They can melt nylon plastics together to get some really strong functional production parts," Peters explained.

"Most parts are used for rapid prototyping, but there are companies using them for low-volume production."

Peters says the limitations on 3D printers are still the resolution, the surface finish, and the turn around time.

"For example, an iPhone case can take as long as two hours to print, but there are no initial tooling costs, so it's ideal for low-volume parts such as the aerospace industry which often need under 100 parts.

"They are often producing very complex parts that are beyond what traditional manufacturing techniques can do.

"Complex air conditioning ducts for example, using traditional injection moulding techniques would have to be manufactured using seven separate parts then screwed and sealed together somehow, can be produced using 3D printing in a single unit. As the parts aren't visual, surface finish and the colour are not an issue."

Peters says manufacturers should also be aware of Fuse Deposition Modelling (FDM) a process where the 3D part is built by extruding material (usually plastic) through a print head onto a build surface. The part is built up layer by layer and support material is used where ever there is an over hang.

"FDM uses real engineering grade plastics such as ABS, Polyethylenes, nylons and are melting and building parts out of layers.

"They are making parts that are nearly equivalent to machined or injection moulded parts strength-wise and they have the same colours. The only difference is the surface finish.

"Another exciting process is Selective Laser Melting (SLM) which allows users to print metals such as titanium, stainless steel, platinum, even gold which are as good as castings."

Peters says there is a lot of growth in this area, with the jewellery market using the technology for sculptures, and again in the aerospace industry.

"However, size is an issue here, with the metal printing machines presently going up to shoe box sizes, but they are costly. Most of the common metal printing machines will print something the size of a tennis ball. Unlike the SLA and SLS machines, printing in plastics, which can print parts the size of a car's bumper."

Peters also mentioned Direct Light Projection (DLP) where they use a vat of resins and a projected light to harden the layers instead of a laser.

"The advantage of this is they are printing a whole layer in one snapshot of the light, making the process much quicker.

"Really the only limitation with 3D printers is the resolution (lines) of what you are printing, but this is improving all the time as well as the speed," he said.

Peters is passionate about this exciting technology. "It's scalable and I can image being able to print a house one day.

"A machine might rock up on your block of land and start printing all the walls including plumbing, electrical wiring and everything."

If so, the sky is truly the only limit.

3D printing

Despite the fall in price of 3D printers, with many companies now having their own equipment, Jeff Condren, founder and director of SOS Components, one of Australia's leading 3D printing companies, says there is an increasing demand for product development and rapid prototyping projects.

"We have a broad range of equipment here including SLA, SLS, FDM, and 3D printing machines.

"SLA is often used for high precision presentation form fit models as master parts for other processes, while SLS can be used to produce one-off parts in nylon for vehicles, runners, rollers, guides, etc," Condren told Manufacturers' Monthly.

"We have a diverse range of applications for FDM where the parts are used for relatively medium stress componentry or electrical components to proof a concept before it goes into manufacture.

"But by far the most diverse machine we have here is the Z Corp 3D printer: we do everything on it. It uses a modified composite compound; a gypsum derivative material.

"Fine powder is solidified with a special type of glue applied from an ink jet print head creating full colour and rugged parts.

"We have a number of different ways we can finish that material to give it the strength and durability of what the client is looking for.

"We have created full colour terrain models from satellite data with this process several metres long. For prototypes this is a cost effective way to verify a part design," Condren said.

3D printers

There are a wide range of 3D printers on the market. Two of the leading companies in the market are Objet and 3D Systems.

Objet's inkjet-based 3D printing systems and materials are said to be ideal for any company involved in the manufacture or design of physical products using 3D software or other 3D content.

Peters says by using Objet's Polyjet technology, users can combine two types of materials on the fly. So if you have soft and hard materials, you can combine a ratio of these materials to give you different densities and different properties for that part.

"It uses the same technology as the commercial machines, but is scaled down and way more portable. Users can get the machine up and running in a matter of hours," Peters said.

The company's Connex line of multi-material 3D printers is said to be the world's only technology to simultaneously jet two materials. With this, users can print many different materials into a single part and print various mixed parts on the same build tray.

According to Kathryn Hay, 3D Systems marketing manager, the company's ProJet 3000 range produces excellent quality parts with the finest features.

"Plastic parts can be drilled, machined, painted or metal plated to produce life-like product mock-ups without extra finishing or sanding.

"The best thing users like about these machines is the easy removal of support material from the model.

"Other 3D printers require the support to be physically scrapped away from the model. This is time-consuming and can damage the part. The ProJet HD 3000 uses a non-toxic wax support that easily melts away," Hay said.

[Image: smh.com.au]