(12) Other machining methods such as Electrical Discharge Manufacturing (EDM) is useful in sustainable manufacturing; one example is that it leaves a good surface finish making finishing processes unnecessary saving time, energy and money. Although this method is more costly to set up, you will end up saving money as you don’t need finishing processes and you will not need to use other machining methods to get it to a correct tolerance as EDM is a very accurate process as it can produce a tolerance of (13) +/- 0.005mm and a surface finish of Ra 0.1?m. During the cutting process a wire is used in order to cut through the material instead of using cutting tools making it more sustainable in terms of cost as well as energy because when maintenance occurs, the wire is easier and cheaper to replace whereas a cutting tool requires either replacing or sharpening using a grinder. Both of these methods require more money and time proving that maintenance is better in Electrical Discharge Manufacturing.
During Gear Hobbing, a hob tool is used in order to cut the gears to give them their shape and correct dimensions. But the hob tool would eventually get blunt or even break after a period of time. To extend that period of time, the hob tool is coated making the whole process more efficient. The reason for this is because it manages to extend the lifetime of the hob tool due by enhancing its properties of the metal coating it. The Titanium doped Aluminium-Chromium-Nitrate (as mentioned before) gives the tool more toughness and compressive strength which makes sure that it will not break easily during use and makes the layers corrosion resistant allowing you to use coolant to get successful cuts and produce gears to their correct dimensions. If a hob tool is broken, a number of processes must be used to create a new one making it a very wasteful process in comparison to coating the hob tool.