The demand from many sectors of industry today is for the use of light-weight but strong metals for a variety of applications. As such, titanium is often the material of choice for components used in end-use medical and aerospace products due to its high strength-to-weight ratio, its biocompatibility, corrosion resistance, extensive temperature range, and low thermal expansion co-efficients. But titanium is a notoriously difficult to process metal, due in no small part to its inherent attributes. It is time-consuming and extremely awkward to machine, and abrasion-based technologies produce a lot of waste, which with such an expensive metal is to be avoided. Even when considering the use of next generation metal processing technologies like photo-chemical etching (PCE) — which is a “corrosive” process — anti-corrosive titanium presents issues that have to be overcome by an intelligent and well-informed focus on etchant chemistries. Very few etching companies possess the know-how and understanding of the PCE process to be able to produce such etchant chemistries, which explains why so few PCE companies can produce titanium parts with the required geometric complexity and accuracy at volume.

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. This 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 characteristics of titanium which 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. micometal (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.

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