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Direct Manufacture of Biomedical Implants, Fixtures and Guides.

1. Introduction

The Rapid Prototyping and Tooling Department within the Warwick Manufacturing Group have recently taken delivery of an Arcam EBM S12 system, which is a unique Free Form Fabrication technology for direct manufacturing of fully dense parts from metal powder. This technology is based on Electron Beam Melting (EBM) and parts are constructed by melting metal powder and building up the parts layer-by-layer.

The EBM S12 system offers a high level of geometric freedom combined with excellent material properties. The CAD to Metal ® technology provides fully dense metal with material characteristics identical or close to the target metals used. The combination of electron beam melting in a vacuum results in a high power process (rapid build speeds) and a good environment, resulting in excellent material microstructure and properties.

The manufacturing industry is now under more pressure than ever to reduce the cost and time of introducing new products in order to compete in a global market. Rapid prototyping techniques, introduced in the late 1980’s, are now an established method of reducing product development costs and lead-times. More recently, rapid tooling methods are now making a commercial impact by reducing the cost and lead-time associated with prototype and production tool manufacture. Although these developments are undoubtedly important, the potential for a complete change in the way products are manufactured exists. By extending the use of rapid prototyping principles to the manufacture of end-use products, a revolution in the way products are designed, manufactured and even supplied to the end customer can be anticipated.

Direct Manufacturing employing additive methods has a number of significant benefits;

  • Elimination of the cost and lead-time associated with the manufacture of tools.
  • Complete flexibility allowing production of small batches and frequent product changes.
  • Removal of the geometry limitations associated with tools and with cutting processes.
  • Possibility of building assembled products “straight-off” the machine.
  • Opportunity for significant reductions in inventory.

The industries in which the majority of interest will be expected are the aerospace, automotive and medical. The system will support these three primary industries through the tool-less manufacture of high integrity components in a wide range of metals. Of particular significance is the potential to manufacture 100% dense titanium aerospace components, offering great savings in time and cost, and giving the designer the ability to design for use, rather than for manufacture. The direct manufacture of custom medical devices and implants is also an exciting application, having huge scope for exploitation.

The Arcam system offers the ability to produce high integrity components in an increasingly wider range of materials, with H13 tool steel and low alloy steel already commercially available, Titanium 6-4 ready for imminent release, and high nickel super-alloys being under development. The potential exists also for the manufacture of components having compositions not achievable using standard forming processes such as casting, opening up the potential for manufacture of components with mechanical properties superior to those currently achievable. Furthermore, the conditions under which the components are manufactured within the Arcam system offer easy and tight control over microstructural development during and after manufacture, allowing the final mechanical properties to be tuned.

2. Medical Applications

The medical industry represents one of the largest potential users of this technology, with a very wide range of application, including the manufacture of surgical tools, custom jigs and fixtures and internal and external implants and scaffolds.

The development of custom jigs and fixtures is currently a laborious and highly expensive process, and indeed, as a result, is not often practiced, despite the significant benefits to both the patient (shorter operating times, better outcome) and to society itself (shorter waiting lists, cost savings to the NHS). New techniques and processes need to be developed to allow the cost and time efficient manufacture of such devices, particularly as they become more sophisticated. Currently, advanced manufacturing techniques, involving CT / MRI scan data and layered manufacturing processes are limited to the indirect manufacture of the devices, which extends the lead-time and increases their cost. The Arcam system has the capability to directly manufacture the devices in biocompatible materials such as titanium.

The system offers a revolutionary means to manufacture custom implants and scaffolds in a cost and time-efficient manner, having the functionality to be applicable to all areas of traditional implant deployment. The potential for up-take of this technology is huge, within the EU itself there are an estimated 3,500 cancer cases, 900 trauma cases, 1500 facial deformity cases and between 100,000 and 200,000 orthopaedic cases that would benefit from custom surgical implants, which is estimated to be worth in excess of 250MECU by 2005.

This area has a wide application area, and huge scope for development. No other system has yet been able to produce fully dense titanium components form CAD. Further evaluation and development could be focused in areas such as:

 Efficacy and long-term durability evaluation of medical devices produced from the Arcam system and control of build parameters over micro / macrostructure and subsequent mechanical and other properties.

 Structural control over biocompatibility, which could include development of in-process build process parameter variation to allow the generation of graded structures.

 Development of novel materials, including metal matrix composites, potentially including the co-processing of biocompatible metals, bio-resorptive polymers and ceramics and bioactive materials to offer optimal implants and scaffolds. With the need for integrated projects, this topic is particularly interesting since optimally designed structures, developed using Knowledge Based Engineering and other automated design tools could be realised using the Arcam technology, and evaluated for efficacy with recourse to in-vitro evaluation (potentially in collaboration with the department of biology or the Warwick Leicester Medical School).

 Medico-legal issues: There may also be collaboration required between WMG and other departments, particularly concerning medico-legal issues, which, for the manufacture of bespoke, custom implants, will be of extreme importance.

We within the RP&T group are extremely keen to forge collaborative research links within the University and would encourage anyone with a potential requirement for the EBM technology or who would like to evaluate the process feel free to contact us.

For further information please contact:

Dr Greg Gibbons

024 7652 2524