Prototypes have traditionally been either functional - in which the appearance is usually different to that of the proposed design - or visual 'look alike' models with limited functionality. The first generation of rapid prototyping processes were also restricted in terms of the physical properties of the components they output, resulting in a compromise that was better but still fell short of the ideal. Unless the rapid-prototyped parts were subsequently used to create moulds for investment castings, the opportunities for rapid manufacturing were even fewer.
However, advances in equipment and materials have changed all this. Improvements in rapid prototyping processes - which includes stereolithography (SLA), selective laser sintering (SLS) and fused deposition modelling (FDM) - combined with sophisticated materials means that prototypes are now closer than ever to the final part. In some cases, the techniques are also used rapid manufacturing of short-run production parts.
At the 2009 TCT show in the UK, Laser Lines showed how the latest generation of Fortus 400mc and 900mc '3D production systems' from Stratasys can make finished parts in polyetherimide (PEI) resin. The Ultem 9085 grade of PEI, from Sabic Innovative Plastics, is a new addition to a range of materials - such as ABS, PC-ABS, PC and PPS - that can be used on Fortus machines to produce finished parts. Like many similar systems, it does this using digital data to 'print' 3D parts. While the PEI grade was launched specifically for aerospace applications, Laser Lines says it is also suitable for use in other industries that can benefit from its high resistance to heat and chemicals, as well as its tensile and flexural strength. This grade is certified for FST (fire, smoke and toxicity), which sets it apart from most other materials developed for rapid prototyping and rapid manufacturing.
Fortus machines are based on the principle of fused deposition modelling (FDM) in which thin layers of powdered material are laid down and fused by a laser. Both the 400mc and 900mc systems can produce Ultem parts with a layer thickness of 0.254 mm (0.01 inch), though the 400mc also works in increments of 0.33 mm (0.013 inch) if preferred. In terms of build envelope, the 900mc builds parts as large as 914 x 610 x 914 mm (36 x 24 x 36 inches), while the 400mc's offers 356 x 254 x 254 mm (14 x 10 x 10 inches). Owners of older 400mc and 900mc models can upgrade their software to build Ultem parts.
Even Victrex Peek - one of the highest specification plastics, often used in sterilisable medical components - can now be used in rapid prototyping and rapid manufacturing. The design of the Eosint P800 high-temperature laser sintering machine was adapted from that of the Eosint P730 by EOS of Germany, raising the operating temperature to 385°C. This means it can make parts using Victrex Peek for the first time - courtesy of the new EOS Peek HP3 powder. EOS reports that products made with this material achieve tensile strengths up to 95 MPa and a tensile modulus of 4400 MPa. An EOS manufacturing partner, FKM Interethnic of Germany, is the first company to buy an Eosint P 800. It sees potential in typical Peek applications such as rotor vanes and tank lids.
For more generalist applications, the new Connex350 3D printer from Israeli company Objet Geometries enables designers to create multi-material prototypes combining rigid and flexible characteristics. Developed as an entry-level version of the larger Connex500, this machine has a build tray of 350 x 350 x 200 mm so can print multiple small objects or single large ones. It prints 16 micron layers by jetting UV-curable polymer with its patented Polyjet Matrix technology. Chris Baker, the UK sales manager, says that the system is aimed at "manufacturers, industrial designers or their suppliers who want to reduce to the cost of product development cycles. Customers want to make more variation of prototypes, which are closer to the end product." In one interesting non-product application the machine has been used to create medical models in which a transparent material represents the 'flesh' yet provides a clear view of the white 'bone' inside.
Objet's range of 'digital materials' can be mixed on the machine to create different effects - such as varying the hardness of the material. Up to 11 materials can be combined in a single part. Furthermore, the company recently launched 18 new 'digital materials' in its Vero and Tango ranges; Vero materials are hard, while Tango materials are elastomeric. Connex machines can blend these materials, enabling stiffness and flexibility to be combined in a single part. Objet has used the machine to create a one-piece air vent for a car: the main body of the vent is made in a rigid material and the perimeter seal is formed from a flexible material.
Production parts from prototyping machinery
The quest to produce 'production' parts from 'prototyping' machinery looks set to continue, plus it is creating opportunities for new markets. The latest Wohlers Report, which tracks worldwide developments and trends in these technologies, says that direct part production is now the second most popular application after modelmaking. Terry Wohlers, the report's principal author, comments: "Methods of additive manufacturing are creating new markets for one-of-a-kind products." Respondents to Wohlers' survey said that making parts using these techniques will represent one-third of their business in five years - and just over half within 10 years.
Indeed, the market for these prototyping techniques is expected to double by 2015, despite a recent slowdown: the Wohlers Report says the market for 'additive manufacturing' products and services grew to $1.183 billion in 2008 - an annual increase of just 3.6 per cent - which was some way down on the 16 per cent growth of the previous year.
Many small companies will be put off by the price of conventional prototyping machinery, viewing it as an unaffordable luxury. But, in response, Z Corporation has launched an entry-level machine - the low-cost, monochrome Zprinter 350 - to complement its existing range.
The company claims the entry-level machine still provides high-end functionality, with features such as: automatic material loading and recycling; self-monitoring operation; control from either desktop or printer; 20 mm/hour vertical build speed; a build area of 203 x 254 x 203 mm; and the use of office-safe build materials with no liquid waste.
The quoted price for a machine is a 'package price' and includes training, consumables, software and delivery charges. Whereas a 650 machine would cost around EUR40,000 ($55,000) the 350 is nearer EUR17 500 ($24000).
At the same time, the company has developed a new powder for the Zprinter series of multi-colour 3D printers. Parts made from its ZP150 can be cured by water and Epsom salt (a magnesium sulphate) - which is more straightforward than the usual methods. Another advantage is that the part's 'green' strength - the initial strength it has once it is removed from the machine - is around 40 per cent higher than with the company's previous materials.
SLA machines without lasers
Huntsman' Digitalis system uses a new laser-free principle to make parts using stereolithography. The machine works on a different principle to other SLA machines in that it still uses focused light beams to cure a liquid chemical into a solid but it does not use a single-beam laser. Instead the Digitalis cures the material with a 'micro light switch' (MLS) with 40,000 tiny, simultaneous UV light sources. It is claimed that the ability to focus multiple micron-sized points of light on the surface simultaneously will lead to shorter build times. It is also possible to build multiple parts concurrently.
Ole Hangaard, a project manager at Huntsman, explains why the company has developed new materials for the Digitalis: "We think the properties of SLA materials have reached a plateau - so we have decided to develop our own system." These new materials - designated the Araldite MLS 7000 series and launched at the recent Euromold show in Frankfurt, Germany - are specifically designed for use in the Digitalis system and will not work with other SLA systems. Huntsman has sold two Digitalis machines and previously supplied the customers with specially designed resins. These resins are now available commercially.
The company has also continued with its traditional range of SLA materials, adding Renshape SL7840, a colourless liquid resin that cures to a pearl white appearance. Parts made with the material have a fine PP-like surface, with high elongation strength and flexibility.
Another Euromold exhibitor, Hofmann Innovation, says its Hofmann Medea 1500 is the world's largest SLS system for plastics, with a usable volume of up to 1500 x 500 x 500 mm. This can therefore produce large components such as instrument panels and interior/exterior automotive parts with no adhesive joints or welded seams. As an alternative to making large components, the system can build thousands of different components at the same time - in a single process. Peter Mischke, head of the rapid prototyping technologies department, says: "We can produce a wider range of component sizes. At the same time, we can influence and actually configure the process much better than we could with conventional sintering systems."
In a similar vein, Materialise's Mammoth process uses SLA to create very large single-piece prototypes. The technique - which is said to have gained wide approval in the automotive industry - uses a machine with a build length of more than 2 m. Materialise says that the idea of producing large components arose from the increasing demand for extremely fast and large prototypes of superior quality.
Materialise's machine park in Belgium houses ten Mammoth machines. Parts are built using an SLA process with a patented 'curtain recoating technology' that ensures there is less dead time between layers - hence production is faster.
Rapid inspection crucial to R&D
Inspection is a crucial part of research and development processes, including reverse engineering. Wenzel Group's recently introduced exaCT computed tomography (CT) workstation for industrial applications makes contactless 3D measurements of external and internal structures to complement existing co-ordinate measuring machine (CMM) methods. According to Wenzel, it enables non-destructive inspection for processes such as quality control, test engineering and reverse engineering, at a price that is affordable for small and medium-sized companies.
The exaCT's control software optimises image acquisition, while its reconstruction software enables 3D voxel (volumetric pixel) data to be evaluated. Data analysis is performed with Quartis software from Wenzel Metromec and Pointmaster from Wenzel Knotenpunkt. Accurate free-form surfaces can therefore be generated and processed from the CT data.
Currently the exaCT is used to inspect and measure small and medium-sized parts and assemblies made from plastics, composites, ceramics, aluminium or magnesium. There are also plans to develop systems that can inspect larger parts and those made from other materials.
Despite the cost-reduction in rapid prototyping and rapid manufacturing, investing in equipment is not always necessary, as there are numerous companies offering bureau services. USA-based 3D Systems has now extended its rapid prototyping and manufacturing service to Europe: 3Dproparts, which launched in the USA in October 2009, supplies a wide range of metal and plastic parts made using the company's SLA and SLS technologies. As part of the European launch, 3D Systems has set up a 3Dproparts website in German and intends to extend this to other European languages in the near future.
Greg Elfering, vice president of European sales and marketing, comments: "We expect the latest generation of Pro systems and materials to provide our European customers with all their design, prototyping and manufacturing needs."
The new service has been launched on the back of several acquisitions, including Acu-Cast Technologies and Advatech Manufacturing, the latter of which has particular expertise in rapid prototyping and manufacturing for the aerospace, defence and motorsports industries.
At the same time, 3D Systems has developed a large-format 3D production printing system. This Projet 5000 3D printer has a build volume of 55 x 393 x 300 mm and utilises the company's multi-jet modelling (MJM) technology.
The Projet 5000 3D printer will use the Visijet MX plastic material to produce durable, high-definition parts and is aimed at applications in automotive, aerospace, footwear and appliances.
Changing back to two dimensions
Moving from 3D to 2D prototyping may seem a retrograde step, but Roland DGA's VersaUV LEC-330 combines printing and cutting in order to produce packaging prototypes and short-run labels. Roland says that the VersaUV series is the world's first LED-UV inkjet printer/cutter line, and the only production tool that can print CMYK (cyan, magenta, yellow and black) + White + Clear Coat and contour-cut designs - all in one device in a seamless workflow. It can also print on a range many substrates, including metallic surfaces for labels, decals, point-of-sale displays and posters, as well as semi-rigid sheet stocks - such as card stocks for folding cartons, and thicker polycarbonate sheets for membrane switch applications.
In addition, the machine can print on offset paper stock, BOPP, PE and PET film for highly accurate proofs and prototypes, and can be used to create original patterns and 3D domed corporate logos directly on synthetic and natural leathers. Low-heat UV LED lamps allow printing on heat-sensitive media such as shrink wrap.
The LEC-330 is described as a versatile pre-press and proofing device that can save commercial printers many of the costs associated with press downtime. VersaUV shops can also eliminate outsourcing for short production runs for customised graphics and wraps of virtually any shape, size and texture.
Six high-precision print heads deliver a maximum print speed of 10m2/hr (101 ft2/hr). An 'intelligent ink circulation system' optimises ink usage and minimises waste. The built-in ventilation hood supports third-party air filtration systems and enables printing on both flexible and semi-rigid sheet stocks.