Developing a Bespoke Incremental Sheet Forming Machine for Cranioplasty

Cranioplasty is a surgical procedure for the repair of deformity of a human skull due to brain tumour, stroke or traumatic injuries. Among all available materials, titanium continues to be a main stream material used in cranioplasty surgeries because of its excellent biocompatibility, resistance to infection, excellent material properties and lightweight. However, in spite of the popular use of titanium in cranial reconstruction, there is a wide variety of methods including casting, manual shaping and rubber press forming commonly used in cranial plate manufacture. Even with the assistance of advanced CAD/CAM (computer-aided design and manufacture) and computed tomographic (CT) and magnetic resonance imaging (MRI) technologies, currently the process for manufacturing customised cranial plates by conventional methods normally takes up to two weeks to completion mainly due to the time required for the manufacture of dies and tools. Recent advances in 3D printing or additive manufacturing based techniques make it possible to complete the 3D printing of a cranial or a maxillofacial prosthetic part within several hours. However, there are still a number of impediments including material property and cost issues to be overcome before its wide clinical applications.

This project proposes a novel alternative solution for an even faster and more cost effective method for the manufacture of personalised cranial plates by using the incremental sheet forming (ISF) technique. Our recent work has shown that a typically large size cranial plate can be made satisfactorily by using the ISF process in 7~8 minutes rather than hours or days. This outcome has considerable implications in potential technological advances and economic benefits as well as improvement to quality of life. In this project we aim to develop the new ISF based cranioplasty manufacturing technique, to design and build a bespoke desktop ISF machine for cranial reconstruction with full CT/MRI and CAD/CAM software integration and ISF process automation. By using the developed bespoke ISF machine, we will conduct a series of ISF benchmark testing and cranial reconstruction pre-clinical trials of 3 demonstration case studies using the developed bespoke ISF machine. The project will demonstrate its technical viability, economic benefit and potential improvement of quality of life. By the end of the project we aim to achieve up to 95% manufacturing lead time reduction with associated cost benefits as compared to the conventional methods. We also plan to show that the bespoke ISF machine can be used as a new and viable medical device for cranial manufacturing and there is a niche market place for speedy commercial exploitation.

The proposed project outcomes will not only benefit the involved project partners but also relevant research communities in ISF and materials processing technologies, UK's high value manufacturing and healthcare technology providers and SMEs as well as cranial and maxillofacial prosthesis end users. The following outlines the key impacts of the project:

Contribution to knowledge creation: The proposed research will develop in-depth understanding of the material deformation and failure mechanisms for ISF based titanium cranial manufacturing and to establish optimised operational windows with given material, size and dimensions of a cranial plate. Important research results are also expected from developing novel ISF machine concepts and reconfigurable tooling solutions as well as new computational methods for CT/MRI based cranial shape reconstruction and CAD/CAM software integration and ISF machine hardware automation. Positive outcomes will not only make a contribution to knowledge in ISF focused research but also demonstrate its viability and suitability for cranioplasty and maxillofacial related applications.

Impact on UK's high value manufacturing: The development of the bespoke ISF machine will require the integration of CT/MRI and CAD/CAM programming and ISF process for the niche application of cranioplasty and maxillofacial prosthesis. Successful development of the bespoke ISF machine will bring a step change to the current practice of largely skill based craftsmanship process to an integrated process design, optimisation and manufacturing automation. The implementation of the bespoke ISF machine to cranioplasty surgery will enhance its affordability and usability by NHS and private hospitals. The change in the ways of cranial reconstruction will have considerable impact to the capability and competiveness of UK's high value manufacturing in the healthcare technology sector in lead time reduction and associated cost savings. The commercialisation of such a machine will allow UK's high value manufacturing technology providers and SMEs to explore technical innovation and develop new business opportunities in the niche market.

Impact on quality of life: Conventional methods of cranial manufacturing are time consuming due to the need for the design and manufacture of necessary tools and dies. As a specific example of commonly used press forming technique, a number of steps are necessary in the design and manufacture of male and female dies/moulds before actual forming of the cranial plates. Without the need for specific tooling and dies, the bespoke ISF machine can be deployed to make cranial plates in significantly shorter time and reduced cost. By using the developed bespoke ISF machine, it is envisaged that up to 95% lead time reduction could be achieved from currently 10~14 days to 2~4 hours. Such a lead time and associated cost reduction will have a considerable impact to the quality of life especially in situations where urgent cranioplasty surgeries are needed as suggested in UCL NHS hospital's Statements of Support.

Impact on training and skills: In close collaboration with all project partners, this project will allow the involved researchers to have the opportunity to understand the industrial need and the current and future challenges and to develop specialist knowledge, skills for innovative solutions in the interdisciplinary fields of high value manufacturing and healthcare technologies. The experience gained from R&D and dissemination activities of the project will play an important part for them to become future generation of research leaders.