**6.4 Production of small/medium series of value-added biomedical products**

EBM technology can also be used for the production of small/medium series of implants with a competitive price, since it offers an interesting alternative to other manufacturing processes where previous investment in tooling is necessary. A variety of industrial sectors use tooling for manufacturing of large series (millions of units) where the cost of the tooling is included in the final price of each produced part. The larger the production, the smaller the cost fraction included in each part. This is not economically viable in the case of small-medium series, since the cost fraction derived from tooling increases as the number of parts decreases. The case of a customized implant is the low end of small series production (Figure 26).

Fig. 26. Comparison of the cost per part using manufacturing processes with tooling and AM technologies.

Additive Manufacturing Solutions for Improved Medical Implants 173

loosening by means of telemetry. For this application this tibial prosthesis was manufactured in 6 hours by EBM in Ti6Al4V, consisting of two parts: the main body and a

Fig. 27. LAFITT case. Upper row: radiography of a Hip prosthesis implanted; 3D image of the design of a Total Hip prosthesis for special indications; Virtual preparation of batch for building in Magics®; Middle row: 10 prototypes manufactured by EBM and complete batch

of 10 prostheses finished ready for testing; Downer row: Comparison between Hip

prosthesis before and after polishing.

cover for the introduction of sensors inside (Figure 30).

In the case of manufacturing implants with EBM technology, there is no need of tooling, since EBM uses the digital file of the implant (3D CAD) for its direct fabrication as described in section 2. As a consequence, EBM makes profitable the production of small/medium series production because the cost of the batch remains always the same (for a determined geometry and batch size) without depending on the size of the whole production (Figure 26). All these economical aspects have several positive implications for EBM:

	- Make costly tooling corrections in order to improve some features and keep product competitive and up-to-date or
	- Keep producing parts with the original implant design until the mould is paid off by a determined number of sold units. Then, the design of the implant can be updated by corrections on the mould. The fact that for standard implants there are several sizes implies one mould for each size. More demanded sizes can be updated earlier than the others because of moulds investment depreciation.

## **6.5 Rapid prototyping for the research in the biomedical field**

EBM is being widely used for Research & Development in the biomedical field due to its production speed and design freedom which permits shortening the development periods. For this reason it is used for manufacturing prototypes in order to validate new products and concepts. As an example, the Spanish company SURGIVAL has developed a hollow tibial prosthesis for knee arthroplasty. The prosthesis has sensors for detecting osseous

In the case of manufacturing implants with EBM technology, there is no need of tooling, since EBM uses the digital file of the implant (3D CAD) for its direct fabrication as described in section 2. As a consequence, EBM makes profitable the production of small/medium series production because the cost of the batch remains always the same (for a determined geometry and batch size) without depending on the size of the whole production (Figure

 For manufacturing of greater variety of implant sizes on EBM, unlike traditional manufacturing processes, it is not necessary to have a huge stock of moulds and tooling, since 3D models of different sizes are stored electronically and manufactured on

 Semi-customization of standard products is also viable on EBM. Small modifications can be introduced in the standard implant model in order to treat specific pathologies with special requirements. The Spanish company LAFITT designed and manufactured a Total Hip Prosthesis with special indications (ASTM, 2010). Ten prototypes were manufactured by EBM in Ti6Al4V ELI in 36 hours. These prototypes are being evaluated by several tests. If results from tests are positive LAFITT may consider EBM technology as a production method for medium-small series, case of prostheses with

 The gradual evolution of the implant design and the addition of improvements between a fabrication and the next one are possible, due to the feedback and experience from already implanted cases, new findings, competitors, etc. At this point implants manufacturers that use conventional manufacturing techniques have two options: Make costly tooling corrections in order to improve some features and keep

 Keep producing parts with the original implant design until the mould is paid off by a determined number of sold units. Then, the design of the implant can be updated by corrections on the mould. The fact that for standard implants there are several sizes implies one mould for each size. More demanded sizes can be

updated earlier than the others because of moulds investment depreciation. As mentioned before, AM favours manufacturing batches in which every part is different in size, shape, special features, etc. This is possible because lots of parts can be packed inside EBM process chamber which has a capacity of 200x200x350 mm. One example is the case developed by the Spanish company SURGIVAL. This company has designed osteosynthesis plates for the treatment of different fractures in the human body (Radius distal, Proximal and Proximal Humerus plates). In total, 21 plates (different models and sizes) were manufactured in 7.5 hours by EBM in Ti6Al4V ELI fulfilling the standard ASTM F136 (grade 23). These plates are shown on

EBM is being widely used for Research & Development in the biomedical field due to its production speed and design freedom which permits shortening the development periods. For this reason it is used for manufacturing prototypes in order to validate new products and concepts. As an example, the Spanish company SURGIVAL has developed a hollow tibial prosthesis for knee arthroplasty. The prosthesis has sensors for detecting osseous

26). All these economical aspects have several positive implications for EBM:

demand.

special indications (Figure 27).

Figures 28 and 29.

product competitive and up-to-date or

**6.5 Rapid prototyping for the research in the biomedical field** 

loosening by means of telemetry. For this application this tibial prosthesis was manufactured in 6 hours by EBM in Ti6Al4V, consisting of two parts: the main body and a cover for the introduction of sensors inside (Figure 30).

Fig. 27. LAFITT case. Upper row: radiography of a Hip prosthesis implanted; 3D image of the design of a Total Hip prosthesis for special indications; Virtual preparation of batch for building in Magics®; Middle row: 10 prototypes manufactured by EBM and complete batch of 10 prostheses finished ready for testing; Downer row: Comparison between Hip prosthesis before and after polishing.

Additive Manufacturing Solutions for Improved Medical Implants 175

Fig. 29. SURGIVAL case. 21 customized radius distal, proximal and proximal humerus

Fig. 30. Sensorized Tibial prosthesis manufactured by EBM in Ti64 for detection of osseous

loosening. INTELIMPLANT CDTI's Project (Courtesy of SURGIVAL).

plates manufactured in a single EBM build (Courtesy of SURGIVAL).

Fig. 28. Virtual preparation of batch for EBM building: case of 21 customized radius distal, proximal and proximal humerus plates manufactured in a single build (Courtesy of SURGIVAL).

Fig. 28. Virtual preparation of batch for EBM building: case of 21 customized radius distal,

proximal and proximal humerus plates manufactured in a single build

(Courtesy of SURGIVAL).

Fig. 29. SURGIVAL case. 21 customized radius distal, proximal and proximal humerus plates manufactured in a single EBM build (Courtesy of SURGIVAL).

Fig. 30. Sensorized Tibial prosthesis manufactured by EBM in Ti64 for detection of osseous loosening. INTELIMPLANT CDTI's Project (Courtesy of SURGIVAL).

Additive Manufacturing Solutions for Improved Medical Implants 177

As a proof of the improvement potential of this technology, recently a new manufacturing beam strategy named MultiBeam® has been developed and released. This strategy allows EBM to produce finer details and obtain better surface finish, splitting the high energy electron beam in multiple finer beams (less power/beam) so the energy input in every location on each layer can be accurately controlled. MB strategy opens the possibility of manufacturing implants with better surface finish and finer scaffolds (Figure 12). Some attempts with finer beams and powders are being performed in order to achieve higher

Great efforts in different areas are being made in software developments since AM

 New 3D CAD (Computer Aided Design) tools will permit more freedom in design, since most commonly used commercial 3D CAD tools are conceived for conventional manufacturing processes and don't allow to design easily new concepts with complex geometries, i.e. scaffolds, fractals or bionic features. There are several commercial software tools available, i.e. 3-Matic® which allows common Computer Aided Design (CAD) operations on 3D anatomical data (STL format), Magics®, Netfabb® or AutoFab® which permit automated design of scaffolds structures. Further improvements are

 KBE tools. Expert systems for process planning automation which will permit the automated orientation and location of a batch of different parts in the building virtual platform in order to obtain desired features or properties on each part, surface finish,

 Specific CAE tools, for scan to part reconstruction (Mimics®), automatic guidance in implant design in STL format (3-Matic®), assisted an automated topological optimization of lattice structures (Within®), etc. Further improvements are being

Authors would like to show their sincere gratitude to CIMA research group from University of Vigo, Veterinary Clinic FAUNA from Vigo, medical device manufacturers LAFITT and SURGIVAL from Valencia. Without their collaboration, this manuscript would not be

AIMME. (2009). MEDIFUTUR Project: Informe de inspección de vertebras – AIMME,

AIMME. (2009). Puesta en marcha de una línea de investigación para la fabricación de

piezas con aleaciones no férricas mediante técnicas de conformado de material

Unidad de análisis 3D, AIDO, November 2009.

**7.2 EBM technology** 

resolution with the EBM process.

technologies work with digital files of parts.

being developed in these commercial tools.

mechanical properties, etc. (Petrovic, 2010).

developed in these commercial tools.

**8. Acknowledgments** 

possible.

**9. References** 

**7.3 Software developments** 
