Bright spark developments

First up is the ingenious 7-axis die-sink machine development from Japan's Sodick (Sodi-Tech EDM). Demonstrated on a new range of EDM die-sinkers, specifically the AG60L, two extra axes are delivered by a Jauch Schmider head. This controls the movement of a twisted electrode, so that it penetrates the workpiece in a corkscrew-like motion – an increasingly frequent requirement for advanced applications, particularly in the aerospace, power and medical sectors. Image: Corkscrew motion from Sodick via the Jauch Schmider head The claim made by Sodick is that no other EDM manufacturer is able to create the twisted, closed-channel, helix geometries, as demonstrated at EMO. This is attributed to the fact that Sodick develops its own control systems, which has ensured that it maintains the expertise and speed of innovation to stay ahead of the competition. The machining of components with this type of complex, cork-screw geometry has, up to now, only been possible with 5-axis milling applications – and then only in the open-channel form, it is asserted. Sodick's latest innovation opens up a wide range of manufacturing opportunities. MANUFACTURING CHALLENGES The design of the latest generation of turbine and pump rotors poses many manufacturing challenges, including the resolution of the conflicting pressures of simultaneously increasing power output, while reducing emissions. This has resulted in designs incorporating the transportation of more aggressive and higher volumes of gas and steam, which has therefore driven the development of ever-more resistant alloys – which are, naturally, more difficult to machine. Using closed-channel form designs, the loading on turbine blade walls is reduced, while the wear on pump rotors and seals is similarly reduced, all at a fraction of the cost of milling, particularly when working with 'super-alloys' and when the 'nano-wear' capability of the Sodick generator is taken into account. This 'nano-wear' strength is related to the new SGF2 generator, which provides much increased machining speed – up to twice the previous rate with graphite electrodes – and a significant reduction in electrode wear, to levels Sodick describes as 'nano-wear'. The AG60L itself is part of the new 5th generation of linear EDM solutions from Sodick, which includes a range of both wire and sink machines. The new die-sinking range incorporates a new active control system that simultaneously performs both discharge control and motion control through its high speed communications controller, and the new SGF2 generator is also a highlight. Moving to wire-cut EDM and one of Swiss firm GF AgieCharmilles' EDM highlights is the new CUT 1000 OilTech, a variant of the CUT 1000. The use of oil supports capabilities that will be of interest to those in the micro-machining field, in areas such as the watch industry, a particular focus in Switzerland, of course, as well as carbide stamping dies. Image: Cutting with oil supports micro-machining The machine can use wire diameters over the range 0.20 mm to 0.02 mm; deliver surface finishes of the order of 0.05 Ra; and deliver radii of 0.010 mm. To achieve such results, GF AgieCharmilles has equipped the CUT 1000 OilTech with a completely new generator. In the case of carbide stamping tools, surface finish and cutting edge quality are perfected with no affected layer or micro-cracking, resulting in extended tool life. The CUT 1000 OilTech also boasts positioning accuracy of 1 µm over all travel paths, with all axes regulated to within a 0.1 µm, further underlining its micro-machining credentials. Working envelope is 220, by 160, by 100 mm in X, Y and Z, respectively. For conical cutting, the upper wire guide head is offset against the lower guide; as a result, a cross slide for U and V axes fits above the wire guide and, thanks to their small travel paths, causes no tilting errors. A 3D setup system with a touch probe located on the Z axis detects the position of the workpiece and the VISION 5 machine control responds by transposing the progam to suit. During the machining process, the generator constantly checks the process parameters, detects the state in the spark gap and optimises the cut ,if necessary. GF AgieCharmilles' unique Variocut function continuously records the cutting cross section and automatically adjusts the power to changing conditions. Mitsubishi Electric (HK Technologies) also unveiled a high precision wire-cut EDM series, the NA Essence, 1200 and 2400 models. The NA1200 Essence has X, Y and Z travels of 400, 300 and 220 mm, respectively, and the NA2400 Essence's figures are 600, 400 and 310 mm. REAL-TIME COMMUNICATION The new high precision units use what is described as a 'Swift Optic Communication System', which allows real-time communication between all components. Together with the use of tubular direct drives, used first time in an EDM machine, this sets a new benchmark for precision, process adoption and energy efficiency, claims the company. Image: Mitsubishi's NA Essence range uses tubular direct drives Tubular direct drives offer the benefits of ballscrew drives and conventional linear drives, but avoid both the interfering magnetic-power influence of linear drives on the guidance system and unnecessary heat generation. One result is optimised energy consumption efficiency. Additionally, a new construction approach for the NA Essence avoids unnecessary heat, which helps to improve energy. The NA Essence series is "a highest precision wire-cut EDM, setting new standards in quality and productivity in the market", says the company, but the machines are not "special machines" with limited usage, it is underlined. Both NA machines are designed for a wide range of application, using wire diameters from 0.05 up to 0.30 mm as a standard. The best surface quality, achievable with the Digital FS generator (standard for NA Essence series), is up to 0.05 µ Ra. This depends on workpiece material and cutting height, but can be achieved with brass wire. Due to this, the NA Essence series is not only efficient, but also has low running costs. In addition to the mentioned D-FS generator, Digital AE generator also features, which controls the vertical position of sparks, supporting the achievement of best possible parallelism. The NA Essence is equipped with Mitsubishi's ADVANCE CNC, and numerous automatic functions, optimised for the new Optical Servo Drive system, are said to make daily work easier, without irritating the machine user. First published in Machinery, November 2009