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Biomedical applications are perhaps the most interesting field for 3D printing technology. Digitally constructed models of human organs are already being used in the field of medicine to allow for ‘practise run’ surgical operations where extreme delicacy is required. These replica organs are printed using two materials; the outer layer is transparent so the inner structures are visible. Having the benefit of a prototype assisted test run allows for better decision making when it comes to the real operation. In the biomedical field, 3D printing has the potential to expand far beyond models and prototypes however. Research is in progress to create new organs from scratch. The first printed human vein has already been a success; however the technology could potentially be used to print much larger organs. Instead of having to transfer organs from the dead (and having to deal with the body’s natural rejection issues) scientists will be able simply to print one on demand.
The Wake Forest Institute for Regenerative Medicine printed new bladders for seven patients in 2006 and continue to produce new innovations in this field. The process works by taking a tissue sample from the patient’s own bladder, extracting the precursor cells that can form muscle on the bladder exterior and the specialised cells within it. The cells are then cultured in a laboratory and painted on a body temperature biodegradable scaffold. Once the cells have matured and multiplied six to eight weeks later, you are left with a fully functional bladder ready to be installed in the patient. Dr. Anthony Atala of the Wake Forest Institute recently presented a 3D printed kidney at the TED conference in Long Beach, California. While the kidney was not functional due to lack of blood cells, estimates suggest scientific advances will lead to the first 3D printed fully functional kidney within the next decade.
As demands for highly personalised products increases 3D printing has become beneficial in more and more applications. Using the layer by layer additive manufacturing process, a printing machine has been designed to extrude chocolate into customised 3D edible structures. This project is in progress at the University of Exeter and according to lead scientist, Dr. Liang Hao, they hope to introduce the technology to the market within the next one or two years. Eventually there are plans to launch a website for the printer, linking it to social networking websites where people will be able to submit their chocolate designs and pay to have them printed.
Custom jewellery can also be 3D printed. Using the CAD design, the structure is additively printed in wax. Next, the age old technique of investment casting is deployed to turn the wax structure into one of metal. Plaster is poured on either side of the wax structure and metal is poured into the wax. The metal melts the wax, taking its place within the plaster bracing, leaving a personalised item of jewellery. Since such objects are often small and require minimal materials, 3D printing is economical as well as aesthetically pleasing. The production of unique figurines is also vastly more economical using 3D printing technology rather than traditional injection moulding techniques. Figureprints is a company which focuses on 3D printing World of Warcraft and Xbox Live avatars for gaming enthusiasts. The process used is 3D inkjet binder printing, with depowdering and artistic decorating taking place after construction of the object is complete. Although these models are significantly more expensive than higher print quality mass market models, consumers are prepared to pay extra to see their characters come to life.
Rapid prototyping is particularly useful in the automotive industry. Plastic prototype components can be created cheaply to see how they will fit in and interact with the vehicle’s other parts. These easily producible prototypes are very useful for perfecting the component’s dimensions before production takes place. A lot of time and money has to be invested in tooling to create the final part; if there is even a minor error with the design it will be a major waste of resources. This also has implications for individuals who seek to restore old cars and have trouble finding rare parts. A part can simply be created through 3D printing and then given to a machinist to finalise.
In the aerospace industry, final parts are often already 3D printed. For example, at BAE Systems in Filton a machine is used to print small but complex titanium landing-gear brackets. Using traditional subtractive manufacturing methods, aeroplane parts have to be machined from solid billets; meaning up to 90% of the material is cut away and thus rendered unusable. With 3D printed parts, there is no material wastage. Additionally, 3D printed aeroplane parts are generally lighter but equally sturdy, which saves money in fuel and also benefits the environment. In the future, entire aircraft wings could be 3D printed.
3D inkjet technology could prove to be revolutionary in the field of architecture. A giant machine to produce entire buildings made out of stone (and one day possibly moon bases out of moon dust) has been created by Italian inventor Enrico Dini. The process works by extruding magnesium based glue from the machine’s hundreds of printing nozzles onto a thin layer of sand, binding it into rock. The rock is then additively manufactured layer by layer until the structure is complete. The process has been used for both artistic as well as architectural purposes; Dini believes his machine is the leading contender in the market to undertake the task of completing Gaudi’s Sagrada Familia in Barcelona (a construction which began in 1882 but remains incomplete to this day). While production speed and lack of wastage has been touted by Dini as some of the advantages over traditional building techniques, the key advantage is the ability to create unusual curved structures effectively.
For low volume runs and highly customised objects, it is clear that 3D printing presents major advantages with the potential to expand dramatically in the future. However, it is questionable whether the technology can ever compete with traditional methods when it comes to mass manufacturing. Such methods need not be mutually exclusive; certain companies already have 3D printers working alongside established machinery so they are equipped for whatever kind of job presents itself. Industry expert Terry Wohlers believes that over 20% of 3D printers are already being used to produce final products (rather than prototypes) and this figure could rise to 50% by 2020.
NASA have tested a 3D printing machine on the international space station with the intention of producing spaceship parts and the US Army have done the same with a truck mounted 3D printer to produce vehicle components in the battle field. Braille printing might not strictly be classified as 3D printing, but the process involves creating a raised profile on the print surface so it is worth mentioning nonetheless. Braille can be inkjet printed with a standard 2D printer and UV curable ink - the raised effect results from controlling the dot gain on the substrate. As the potential applications for 3D printing continues to expand, it is no wonder that the industry has been growing since it started over 20 years ago and continues to grow rapidly today.
Tim Phillips, Catenary Solutions