When rapid prototyping first started to emerge from research establishments and become a commercial reality, the cost, complexity and limitations of the various processes meant that their use was limited.
But with further development, the processes improved and designers and engineers allowed themselves the luxury of dreaming about the day when a three-dimensional printer (or 3D printer) would be as commonplace in a design office as a laser or inkjet printer.
Although 3D printers have been available for a few years now, the market is maturing to a stage where there is a real choice, with reasonably-priced machines available that produce detailed models with the mechanical properties and accuracy that makes them genuinely useful for more than just presentations to senior managers or clients. Depending on the machine, of course, 3D printers are now suitable for concept modelling, presentation models, functional testing and FEA (finite element analysis) visualisation. In addition, 3D printed models can be used as master patterns for investment casting and silicone rubber moulding.
Numerous industries already use 3D printing routinely, including consumer products, packaging, electronics, medical devices, fashion accessories, footwear, automotive, aerospace, surgical, jewellery and architecture.
Finely-detailed models can typically be built with wall thicknesses down to 0.6mm and tolerances of 0.1mm. Multi-coloured models can be built, and removable support structures enable the accurate creation of shelled structures. Remarkably, all of this is achievable with desktop or benchtop machines that can be installed in an office or modelmaking environment with no need for special electrical supplies, fume extraction or materials handling procedures.
One of the leading companies in the field is Z Corporation of the USA. Tom Clay, the company’s CEO (chief executive officer) has said: “We want to make high-quality 3D printing affordable enough to be on every desk of every design engineer.” Without a doubt, Z Corporation’s latest machines – as well as some from other suppliers – are now extremely close to that goal, with cost and speed being two areas perhaps needing further refinement. Although model build times are continually being reduced, 3D printers take a considerable time to build a model. One supplier, for example, recently announced that its latest machine is capable of operating unattended for a full 72hours – or over a weekend. But with today’s communications technologies enabling ‘instant’ communication and sharing of data on a global basis, anything longer than an hour feels like a long time.
In October 2005 Z Corporation unveiled its Zprinter310Plus, which was described as incorporating high-end 3D printing capabilities in an entry-level product (Fig.1). The machine’s resolution of 300x450dpi (dots per inch) is 50percent finer than the Zprinter 310system, which the Zprinter 310Plus replaces. A heated build chamber, combined with a new zp130 material, enables users to print more complex geometries and thinner-walled parts up to 25percent faster than with the previous machine. Despite its upgraded capabilities, the new Zprinter310Plus is priced the same as its predecessor at E21600(US$25900).
Z Corporation quotes a build time for the Zprinter310Plus of two to four layers per minute, each layer being user-selectable from 0.089 to 0.203mm. The build envelope is 203x254x203mm and material options are high-performance composite, snap-fit, elastomeric, direct casting or investment casting materials.
Launched at the same time as the Zprinter310Plus machine, zp130 is a high-performance composite powder material that enables faster printing, greater detail and richer colours when used with machines having a heated build chamber. Richer colour is particularly advantageous to users of the Z Corporation Spectrum Z510 printer – said to be the only multi-colour 3D Printer on the market.
The Spectrum Z510 system produces high-definition models using a 24-bit colour inkjet printing technology. Colour models communicate more information than any other type of rapid prototype, such as for the visualisation of finite element analyses (Fig.3).
This machine has four print heads, a build speed of two layers per minute, each layer being user-selectable from 0.089 to 0.203mm, and a resolution of 600x540dpi. The build envelope is 254x356x203mm and material options are a high-performance composite, elastomeric or direct casting materials.
For larger appearance models suitable for design review, mock-ups and for casting applications, Z Corporation offers the Z810 system. Models can be created in plaster or starch-based materials and can be infiltrated to produce parts with a variety of material properties, satisfying a wide spectrum of modelling needs. .
Another company at the forefront of 3D printing is 3D Systems. Its latest offering is a new generation of its Invision LD benchtop 3D printer that is able to produce parts 30 per cent faster than the previous version. When it was launched in January 2006, the new Invision LD printer was priced at E19 100(US$22900). Models are built by fusing, masking and trimming layers of Visijet LD100, a tough, translucent amber sheet material that is supplied on a roll 215mm wide and 0.15mm thick; once the model is built, it can be drilled, sanded and painted. The build envelope is 160x210x135mm.
In comparison, the company’s Invision HR 3D printer builds models using multi-jet modelling (MJM) technology with UV (ultraviolet) curing of an acrylic photopolymer material – in black, blue, grey, red or white. A separate low-melt material is used to support the model as it is being built. The build envelope is 298x185x203mm and the resolution is 328dpi with a 0.04mm layer thickness.
The Invision SR also uses MJM technology and therefore has more in common with the Invision HR machine than the Invision LD. However, this machine has a smaller build envelope (127x178x50mm) with a higher resolution of 656dpi and a reduced layer thickness of 0.03mm.
Both of the latter two machines are best used in conjunction with the Invision Finisher, a separate unit for the automated removal of the wax support material.
The Dimension 3D Printing Group, a business unit of Stratasys, announced a price reduction for its Dimension BST and SST 3D printer in January 2006. While the Dimension BST is now priced at E15800(US$18900), the Dimension SST 3D printer sells for E20 800(US$24900), which represents a discount of 24percent and 17percent, respectively.
Dimension BST and SST 3D printers build functional 3D models from the bottom-up, one layer at a time, with durable ABS material in white, blue, yellow, black, red or green (custom colours can also be supplied). Whereas the Dimension BST (breakaway support technology) requires the manual removal of supports, the Dimension SST (soluble support technology) utilises a separate ‘cleanstation’ that with hot water and soap to remove the supports.
Both the Dimension BST and SST have a build envelope of 203x203x305mm and a layer thickness of either 0.245 or 0.33mm.
Many of the machines described so far – including the Dimension BST and SST – are freestanding, whereas others are benchtop or desktop units. Other examples of the compact format are the T612 Benchtop and T66 Benchtop modelmaking systems from Solidscape. These combine a proprietary thermoplastic ink jetting technology, high-precision milling, and proprietary Modelworks graphical front-end software to build models or patterns with an accuracy as good as 0.025mm (0.001in) per 25.4mm (1inch) in the X, Y, and Z dimensions and a completed model surface finish of 0.8 to 1.6microns (32 to 63micro-inches). Interestingly, Solidscape announced towards the end of 2005 that the build speed for its benchtop machines had increased by 100percent.
The T612 Benchtop and T66 Benchtop build in layers as small as 0.013mm (0.5thousandths of an inch), which is described as an order of magnitude better than many other rapid prototyping systems. These machines are therefore suitable for the creation of accurate models or patterns that need little or no finishing.
While the T66 Benchtop has a build envelope of 152.4x152.4x152.4mm, the T612 Benchtop has a build envelope of 304.8x152.4x152.4mm. Prices for the two machines are E38100 and E46500.
Objet Geometries claims that it was the first company to successfully jet photopolymer material. The company introduced its patented Polyjet technology in early 2000 and, since then, has continually enhanced its 3D printing process, leading to smaller machines, more accurate builds, and improved cost effectiveness. With non-contact resin handling and water-jet removal of support material, Polyjet is suitable for use in office environments.
Objet’s Polyjet technology works by jetting photopolymer materials in ultra-thin layers (0.016 mm) onto a build tray, layer by layer, until the part is complete. Each photopolymer layer is cured by UV light immediately after it is jetted, producing fully cured models that can be handled and used immediately, without post-curing (Fig.4). The gel-like support material is specially designed to support complicated geometries and is easily removed by hand and water-jetting.
Precise jetting, in combination with the properties of the photopolymer material, enables the modelling of fine details, walls as thin as 0.6mm or less and typical tolerances of 0.1mm, depending on the geometry and materials selected. A wide variety of Fullcure materials is available from Objet for building parts with different geometries, mechanical properties and colours.
The latest machine from Objet Geometries, announced in January 2006, is the Eden250. As with all previous Eden printing systems, the Eden250 is based on Objet's Polyjet technology. It has a build envelope of 250x250x200mm and offers users a choice of High Quality or High Speed printing modes, so the printing process can be optimised to suit the specific quality and timing requirements of each model being built. High Quality mode prints 0.016mm layers with a resolution of 600x300dpi. High Speed mode prints 0.030mm layers at the same resolution.
The Eden250 operates with four different model materials: Fullcure720 transparent, Veroblue, Verowhite and Veroblack. The system also supports the universal Fullcure Support material. This wide choice enables a broad range of applications, as it means users can produce models and parts with varying properties, in terms of flexibility, elongation at break, and colour. All materials can achieve the same high accuracy, detail and surface quality.
At the end of 2005, Objet Geometries introduced the Eden350V and Eden350 3D printers, which were based on the Eden platform that was first used on the company’s Eden500V large-format 3D printer launched in the autumn. As with the Eden500V and the latest Eden250 (Fig. 2.), the Eden350 and Eden350V build in 0.016mm layers and are capable of producing wall thicknesses as thin as 0.6mm, though the intermediate machines have a build envelope of 350x350x200mm.
While all of the systems described above are likely to be suitable for installing within an office environment, not all are desktop or benchtop units. Clearly the size of the machine depends, to some extent, on the size of the build envelope, but the underlying technology is also a major factor. Prices are falling rapidly, and, while there is only a limited number of players in this market, competition appears to be fierce. This article has not considered the cost of ownership, and this is bound to vary from one supplier to another in exactly the same way as it does for laser printers or inkjet printers. Nevertheless, there is now a broad choice of machines capable of building high-quality models, whatever the application.