MATERIALS • PROCESSES • FINISHES
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for inexpensive design iterations, and therefore opens up design freedom and the ability to embrace trial and error without significant impact on product development schedules. It also makes the process equally attractive for development, prototype, and production volumes, and makes ramp up to high volumes simple and inexpensive. Te digital tooling also means that geometric complexity of designs is almost limitless, and the process is unique in that the link between increased complexity and increased costs is broken. Tis allows designers to innovate and experiment, and as such PCE is a truly disruptive technology. PCE also allows the production of different geometries at the same time on a single sheet of metal, which is a huge cost saver when using the process. PCE introduces no stresses or thermal degradation in parts being processed, meaning parts are free from damage and inconsistencies, and the process can be applied to a huge range of metals.
PROCESSING TITANIUM Processing titanium with traditional metal processing technologies is difficult and, in some instances, can be hazardous. Titanium
is very strong, exhibits low thermal conductivity, and can be chemically reactive with tool materials at high temperatures. Tis means that tools may not work the metal effectively and will wear out disproportionately quickly. In addition, the relatively low Young’s modulus of titanium alloys leads to spring-back and chatter when machining causing poor surface quality on the finished product. Also, if turning and drilling, long continuous chips are produced, which can lead to entanglement with the cutting tool, making automated machining nearly impossible. Conventional processing methods when applied to titanium can take up to 100 times longer to make components than is the case when processing alternative metals. Production methods for processing titanium need to be fast and minimise waste to be considered economical, and here PCE comes into its own. However, while PCE overcomes some of the issues faced by conventional metal processing technologies, standard etching chemistries do not work when applied to titanium, and so the focus is on adapting the science so that the inherent
NATURE INSPIRES NEW MATERIAL E
ngineers have developed a new material that mimics human cartilage – the body’s shock absorbing and lubrication system, and it could herald the development of a new generation of lightweight bearings. For years, scientists have been trying to create a synthetic material with the properties of cartilage. To date, they have had mixed results. But researchers at the University of Leeds and Imperial College London have announced that they have created a material that functions like cartilage. The research team believes a cartilage-like material would have a wide-range of uses in engineering.
Cartilage is a bi-phasic porous material, meaning it exists in solid and fluid phases. It switches to its fluid phase by absorbing a viscous substance produced in the joints called
synovial fluid. This fluid not only lubricates the joints but when held in the porous matrix of the cartilage, it provides a hydroelastic cushion against compressive forces. Because the cartilage is porous, the
synovial fluid eventually drains away and as it does, it helps dissipate the energy forces travelling through the body, protecting joints from wear and tear and impact injuries. At this point the cartilage returns to its sold phase, ready for the cycle to be repeated.
Dr Siavash Soltanahmadi, Research Fellow in the School of Mechanical Engineering at Leeds, who led the research, said: “Scientists and engineers have been trying for years to develop a material that has the amazing properties of cartilage. We have now developed a material for engineering applications that mimics some of the most important properties found in cartilage, and it has only been possible because we have found a way to mimic the way nature does it. “There are many applications in engineering for a synthetic material that is soft but can withstand heavy loading with minimum wear and tear, such as in bearings. There is potential across engineering for a material that behaves like cartilage.” l
For more information visit
www.leeds.ac.uk
www.engineerlive.com 33
characteristics of titanium that prohibit machining are overcome. One such issue is that when exposed to
air, titanium forms a protective oxidised coating which is extremely difficult to dissolve, and so etchant chemistries have been developed that cut through this layer and allow the processing of the base material. Most of the limited number of PCE suppliers that can process titanium turn to the use of hydrofluoric acid as an etchant material, but this is a hazardous and potentially environmentally damaging substance, and the requirements for chemical containment and extraction means that it is an expensive process and one that adds cost to finished parts. Micrometal (incorporating Etchform and HP Etch) is one of the only PCE providers that does not use hydrofluoric acid, and therefore customers can benefit from the strength, light-weight, heat and corrosion resistant attributes of titanium at a low cost and without the use of dangerous chemicals.
Dr Angel Lopez is with micrometal.
www.micrometal.de
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