Alternative Titanium Machining Methods
The ways in which companies machine titanium have been growing. Many old problems are simply not a factor any more thanks to technological advancements like lasers and 3D printing. These new machining methods can create opportunities and help companies find the best ways to tackle their unique problems. The most exciting new machining techniques are electrical discharge milling, laser cutting, laser etching, titanium 3D printing and water cutting.
Electric Discharge Milling
Electrical discharge milling or (EDM) uses a tiny wire filament that carries an electric charge. When it comes into contact with a conductive material like titanium it generates a white hot spark that removes tiny particles of the material. This method can make cuts 2 microns or smaller. When EDM is used, parts can be made with incredible precision but an electric discharge milling machine works like a band saw. It must be able to feed the wire through a part so, in essence, it is only good for cutting, not material removal. EDM machines use deionised water called dielectric to cool the process, control the spark and flush away any removed material. The dielectric is special because it does not conduct electricity and therefore does not inhibit the process.
Laser cutting is a great way to cut titanium plate. It is highly precise and requires no coolant. Lasers also have no possibility of tool wear so they cut down on cost and have a long lifespan. A laser cutter uses stimulated emissions of radiation focused into a tight area to melt through titanium. The drawback of using laser cutting is that it usually cuts all the way through a material. Lasers simply are not suited to material removal and they may struggle on complex 3D parts. Laser cutting also consumes a great deal of power which can make it expensive compared to other cutting and milling methods. Finally, reflective material can pose a problem for laser cutters as it reflects light and resists cutting.
Laser etching is a very common way to create detailed reliefs in titanium. It is often used by companies to mark their products and is even used at trade shows to create bespoke pens for potential clients. Laser etching works in much the same way as laser cutting. A laser is given a very precise focal length and is able to remove the tiniest layer of material to create intricate designs or details. The benefits of laser engraving are precision and speed. The disadvantages are the high energy costs of running a laser and its limited applications. Lasers are not economically practical for removing large amounts of material, which means they are often used only for putting brand logos on finished parts.
Titanium 3D Printing
Titanium 3D printing, or direct metal laser sintering, is an additive metal fabrication process. A 3D model of the desired part is created on a computer. The part is then broken down by a computer programme into thin layers. This layered model is then sent to the 3D printer, which uses a powerful optic laser to fuse titanium. The titanium is dispensed using a recoating blade and slowly but surely, the object is created. The benefits of titanium 3D printing are its versatility and ability to make complex pieces with working gears or moving parts. The drawbacks are cost and speed. Lasers are expensive to run and laser printing can take longer than conventional machining.
Water cutting uses water sprayed at around 60,000PSI to slice through titanium and other metals. The water jet contains a mixture of water, silicon and carbide to give it enough abrasion to blast through titanium. This method of cutting is cheap, fast and efficient, plus it is capable of doing detailed work in tight spaces. The benefits of water jet cutting focus on speed, heat and price. Water jets can cut fast, they never overheat and water is cheap to use as a cutting medium. The downside of water jet cutting is versatility. Water jets, like laser cutting, must go all the way through the medium, which means they cannot be used for many types of machining.
These machining techniques can complement, but not replace traditional methods. They are best used to make traditional machining processes faster and more affordable. In particular they can help by cutting waste and improving turnaround time. The high cutting speeds of water cutting, laser cutting and EDM in particular are allowing businesses to employ near net shape methods to use the least titanium and save money. Once these techniques have been employed, traditional machining can quickly turn out high finish products. If you want to learn more ways to save on your machining costs, visit our waste reduction page.