Rapid/additive manufacturing is catching the popular mood, or at least 3D printing is – the term that the general press has picked up and which is becoming common parlance.
As a general solution to the manufacture of metal parts, we are a way off, in terms of the size of parts that can be produced and the rate at which they can be manufactured, however. Many applications of rapid manufacturing are in the dental, medical or jewellery fields, it seems, although heavier industrial use is gaining ground.
For example, Concept Laser's X line (ES Technology, 01865 821818) has been developed for tool-less manufacturing of large functional components and technical prototypes. Featuring a high power laser in the kilowatt range, productivity is better by a factor of 10, compared with standard metal additive manufacturing machines currently available on the market, it is claimed.
The new machine was specifically configured to cater for fellow German company Daimler AG's special requirements for automotive applications. Daimler AG's aim is to replace costly sand-casting and die-casting applications, used in the early phases of development. In addition, the LaserCUSING process, as Concept Laser calls it, will, in future, support production of lightweight structures featuring high rigidity. This will permit the production of weight-optimised geometries, with almost no restrictions on the design, which at present cannot be produced.
The project partners worked together as part of the 'Alu generative research and development project (German Ministry of Education and Research)'. The Fraunhofer ILT, together with several industry partners, including Daimler AG, evaluated laser melting technology for production applications involving aluminium components outside of the dental and medical areas that are typical.
The results of this exercise were appraised by Daimler as a fundamentally new way of looking at manufacturing options, with the aim of creating innovative and environmentally friendly products. They are also seen as providing a solid basis for tackling production cost pressures and safeguarding Germany's long-term future as a location for high-tech manufacturing.
Daimler AG's demands included a significant increase in build rates, an improvement in the quality of the surface finish, reproducibility and reliability of the machine as a result of appropriate process monitoring, together with the qualification of further aluminium series alloys for a range of applications. And to deliver the process required the support of an experience additive manufacturing technology specialist, Concept Laser.
Frank Herzog, managing director of Concept Laser, explains: "This really was uncharted territory for us. The development of a machine concept of these dimensions in close collaboration with Daimler AG and the Fraunhofer ILT, based on our LaserCUSING technology, clearly illustrates our claim to be the technology leader in the field of laser melting. This patented, top-class machine technology from Concept Laser has been exported throughout the world since 2000. As a result of the cooperation project with Daimler and the Fraunhofer ILT, we hope that the generative machine technology will meet customers' requirements on a broad basis and that it can be employed profitably," Turning to more established areas of application, however, and the creation of metal parts is gathering momentum in the dental, medical and jewellery sectors.
Rapid manufacturing of dental parts hit the news in the UK in 2010 when Renishaw (01453 524524), the world's largest supplier of in-lab CADCAM scanning machines, opened a new facility for the manufacture of low-cost CADCAM frameworks, using pure, certified medical-grade cobalt chrome metal.
The new copings and frameworks are be produced via Direct Metal Laser Sintering (DMLS) and allow dental laboratories to offer a high quality, lower cost alternative to ceramic restorations. Reporting last year, the company said that production of parts at the facility was "at record levels". And towards the end of its last financial year (30 June, 2012), the company introduced a new process to dental laboratories that allows them to design dental abutments, which are then produced using an additive manufacturing process. Renishaw's 'LaserAbutments' are metal structures that connect to a dental implant and to which are attached a crown or bridge. Across its dental additive business, the company is now making "many thousands of units per month", according to Ben Taylor, assistant chief executive.
(Renishaw acquired a UK additive manufacturing technology company (MTT) in 2011. The development of additive manufacturing systems with faster processing capability is a stated aim of the company, as well as the delivery of solutions, not just technology, as indicated above.)
A MANUFACTURING JEWEL
Moving to the jewellery sector, last November Germany's EOS (01926 623107 ) and the UK's Cookson Precious Metals (CPM) showcased precious metal parts made of 18 ct yellow gold manufactured on a new, small prototype metal laser-sintering system Previous M 080 at EuroMold. CPM now offers a service that employs the technology to manufacture bespoke 18 ct yellow gold (3N colour) jewellery (pictured - www.cookson-emanufacturing.com
). But the pair is also planning to develop a bespoke solution for high volume jewellery production.
In the UK, a current jewellery project involves High Wycombe-based CRDM (0845 051 4900). The additive manufacturing specialist was approached by watchmaker Richard Hoptroff of Hoptroff Ltd, a leading British manufacturer of electronic watch movements for luxury watchmakers.
Image: Rapid manufacturing aids watchmaking
Mr Hoptroff was looking for a flexible technology to manufacture cases for high-end, British-made watches. Working with CRDM, which employed EOS Direct Metal Laser Sintering (DMLS), watch cases in 316L stainless steel have been produced (picture, top, p25).
Returning to the medical sector, and last year EOS tied up with the USA's Innovative Medical Device Solutions (IMDS) to offer industry-leading orthopaedic and spine surgeons and implant companies product development resources for creating novel metal additive manufacturing (AM) designs.
"Until now, using AM for medical devices was considered a high-technology novelty done on a few implants, but mainly used to make quick metal prototypes," explains Dan Justin, chief technology officer for IMDS. "However, recent advances – such as increased materials choices, enhanced manufacturing precision and faster build speeds—have made medical product developers worldwide more willing to co-invest in developing implants made by laser-sintering systems. This partnership marks the most comprehensive resource alignment between contract medical device development and metal additive manufacturing expertise available to our industry."
At Chicago's IMTS exhibition last September, GF AgieCharmilles (024 7653 8666) and, again, EOS showcased an innovative start-to-finish manufacturing process chain for titanium tibial trays for surgical knee implants. The manufacturing process started with an FEA/CAD design, developed using WITHIN Medical software, of a lightweight, yet strong, tibial tray. The part's complex geometry involves variable pore sizes on one side (to promote osseointegration) and a smooth surface on the other (to support loads on the tibia). An EOSINT M 280 direct metal laser-sintering (DMLS) system then automatically built the component as a single near-net piece, layer by layer. The final step was surface machining, first on a Mikron HPM 450U 5-axis milling machine, then with a CUT 20P wire EDM machine, both from GF AgieCharmilles.
More established is the production of mould tool inserts with conformal cooling channels. And last year, German company W. Fassnacht Werkzeug- und Formenbau, Bobingen, supplied its 1,000th mould insert featuring conformal cooling. Within the space of five years, the company's LaserCUSING technology (ES Technology, 01865 821818) has developed to become an important process, used alongside traditional manufacturing processes like, turning, milling and EDM. And by using conformal cooling, realistic reductions in moulding cycle times of up to 40% are achieved, says the company.
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Laser sintering design guidelines
Design Guidelines, published by CRDM, the UK's longest established provider of rapid prototyping and tooling services, offers product and tooling designers an invaluable insight into the design considerations for the Direct Metal Laser Sintering (DMLS) process. http://is.gd/9r7jxv
First published in February 2013