Charmilles' HSEDM cuts cycle times not quality

Charmilles' range of High-Speed Spark Erosion Machines (HSEDM) have faster axis acceleration and speeds and are equipped with with PILOT EXPERT software – intelligent software that adapts to the prevailing machining conditions. HSEDM capability is standard on Charmilles ROBOFORM 350 and 550 EDM machines. Faster speeds and higher acceleration result in a much more efficient cleaning of the spark gap (via a suction effect) and ensure that conditions in the gap between the workpiece and the electrode are optimised at all times. Increased speeds and acceleration obviate the need for flushing operations – which in themselves can be a barrier to speed and machining productivity… and can also cause cavity deformation. Most electrodes used in die-sinking operations have variable geometries (tapers or other free form shapes). These different shapes and features all create variable conditions in the spark gap. To control these variables Charmilles’ PILOT EXPERT system modifies the retraction distance of the electrode and adapts the power of the spark accordingly. During machining operations the frequency of the pulse and the retraction distance are variable – i.e. they change according to the depth of cut (shallow, medium or deep cavity). The PILOT EXPERT system adapts to these changing conditions and machining requirements by optimising both the spark duration and the timing between each spark - ensuring that during roughing operations more energy is directed to the surface contact area. As well as optimising the EDM machining process this adaptation also ensures less electrode wear. In an example using a graphite electrode (1 mm x 15 mm) with an undersize of 0.10 mm to machine 100 mm deep blade from steel to a surface finish of CH40 – the machining time recorded without HSEDM was 5 hours 13 minutes…with HSEDM the machining time was reduced to 4 hours 30 minutes. In another example using a copper electrode (20 mm x 0.28 mm) with an undersize of 0.10 mm to machine 18 mm fine blades from steel to a surface finish of CH27 – the machining time recorded without HSEDM was 3 hours 42 minutes…with HSEDM this was reduced to 2 hours 16 minutes.