Tim Sercombe is an Associate Professor at UWA's School of Mechanical and Chemical Engineering, with expertise in the 3D printing of metals using Selective Laser Melting.
He has been working in the field of 3D Printing since 1996 and describes the 3D printing process as ‘additive manufacturing’ through the layer-wise addition of material to create a part. This process largely frees the designer from the constraints imposed by traditional manufacturing.
By removing these constraints 3D Printing is set to revolutionise diverse sectors ranging from medicine (implants and 3D-printing of living cells, to produce an organ ready for transplant) to the mining support industry: mining companies will be able to make their own parts on site, in remote locations, which translates into big time- and transport cost savings. 3D Printing has put ‘mass customisation’ and‘parts on demand’ into the realms of the possible.
In addition, the process of Selective Laser Melting allows for superior material properties to be engineered. Using selective laser melting of metal powders, Tim and his team are currently working on five material development projects of particular interest to UWA:
- Titanium structures: the researchers have developed isotropic high specific strength and stiffness titanium structures by 3D printing using Selective Laser Melting. The result has been a ‘topological structure’ made up of ‘upside-down pyramids joined at their vertices’. These structures can be scaled in size according to the requirements and can carry 1,000,000 times their own weight;
- Low modulus titanium: the current state of the art medical implants are produce from a titanium alloy that is at least five times stiffer than bone. This can lead to a process called stress shielding, which is a leading cause of implant loosening. When this occurs, the implant must be replaced, which requires painful revision surgery. We are working on the Selective Laser Melting of the next generation of orthopaedic titanium alloys. These alloys have a stiffness of less than half that of conventional titanium and are therefore are much more compatible with bone.
- An aluminium-12% silicon alloy: The very rapid cooling that occurs in additive manufacture allows up to 10% silicon to be trapped in solution, combined with a very fine grain size. This can yield a material with higher strength (50% higher) and improved ductility. In addition simple heat treatment can result in a ductility of ~25%
- Metallic glass: Additive manufacture by selective laser melting has the potential to allow largescale metallic glass structures. The point by point processing and rapid cooling of each of these points removes the normal requirement to rapidly cool the entire structure in order to avoid crystallisation. This means that an amorphous components can be produced without size of geometric limits.
- Antibacterial and antimicrobial materials: We are developing special materials that have been shown to have excellent antibacterial properties as well as successfully minimising corrosion that results from microbial attack. These materials have potential in a wide range of applications from implants to prevent post-operative infections to subsurface structures where microbial attack or fouling are an issue.