Agie Charmilles EDM, 5-axis milling and laser ablation technology developments

Following the biennial international manufacturing technology show, EMO, in Italy last October, GF AgieCharmilles held an event at its World Applications Centre (WAC) in Schorndorf, near Stuttgart, Germany, to further underline the "world novelties" that the company unveiled at the Milan event. But the WAC itself is the company's showpiece centre where its whole range of technologies can be seen – laser ablation, EDM, milling, as well as workholding and automation technology from sister company System 3R. The company's technology highlights at the event were: HPM 800U, 5-axis machining centre with full access from the front, with pallets loaded from the rear; the all linear motor HSM/XSM 400/400U 5-axis machining centres; the CUT 1000 Oiltech wire-cut EDM – EDM without compromise; the Form 1000 – "the most accurate die-sink machine you can get"; and the most novel of all, the 3/4/5-axis fibre laser ablation machine – technology "you will not see anywhere else". Taking the most novel first, Dino Paganelli, business development manager, explained the technology of the laser ablation machine. These machines are capable of creating a textured surface in repeatable fashion via a program. This would allow, for example, an insert in another part to have a surface that would match in with the host part's surface. The target is decorative finishes, not highly accurate machined features, it was stressed, with specific examples highlighted: watch cases; bottle moulds; plastic bottle top logos; weapons engraving (shotguns); jewellery punches and dies; graphite electrodes; texturing of embossing rolls (for leatherwork, for example); hard metal parts; tyre mould logos; and shoe moulds, with that last one an area where "work can be won back from China", where it is currently a labour-intensive activity. Image: Laser ablated texturing There are four machines – L500, L600, L1000 and L1200 (the number is X-axis travel), capable of handling workpieces of up to 700 by 700 by 700 mm in size and up to 1700 kg in weight. Apart from a 5-axis head – a patented design - a rotary table can also be fitted, at least to the largest machine, which can support the engraving of moulds up to 900 by 900 mm. Mr Paganelli highlighted that 70 per cent of the mould tools in the automotive industry would fit within the envelope of the largest machine. The system is centred around a 20 or 50 W pumped diode Ytterbium fibre laser, with the beam defected and controlled by moving two galvo-mirrors that direct the beam onto a workpiece, via a so-called F-theta lens. This type of laser source has a life of 100,000 hours, it was offered. The laser can be focused to a spot size of 30, 50 and 70 microns, according to model – FL100, FL160, FL254 – with these having corresponding height tolerances (distance over which that spot size is achieved), as well as area over which the surface can be textured. For the former, these are 0.3, 1 and 2 mm, respectively; for the latter, the figures are 50 by 50, 90 by 90 and 120 by 120 mm, respectively – the part is moved via machine axes to position areas under the laser head, of course. The minimum area that can be ablated is about 1 mm2, Mr Paganelli states. There are up to five patterns that can be achieved, and these are: outline around area; outline plus horizontal lines (limited engraving); outline, plus horizontal and vertical lines (surface engraving); outline, plus horizontal, vertical and 60° (deep engraving); and no outline, horizontal, vertical and 60° (outline useless for small sweep areas). The distance between laser spots centres is a default 0.040 mm, meaning that spots overlap. The machines are driven by a CAD image-derived grey-scale bitmap, with the black areas taken as the deepest; white, highest. Maximum depth that can be ablated is between 4 and 5 mm, Mr Paganelli explains, with a depth-to-width ratio of 2:1, meaning that a 2 mm slot could be up to 4 mm deep, but there would be 5-6° of taper, in any event. The minimum grove width groove is 100 microns. Moving on to EDM, and the CUT 1000 Oiltech wire-cut EDM is aimed at the highest accuracy applications, Mr Magistra points out.That means geometry accuracy requirements of between ±1-4 microns; position accuracy of between ± 1-3 microns; surface finish of Ra 0.08 to 0.3; and taper of 0-15°. The machine can use 0.02 to 0.20 mm diameter wire and it can, Fernando Magistra, product manager and marketing support, explained, deliver surface finishes better than Ra 0.05, in carbide, and offers ±1 micron accuracy in x, y and z anywhere in the machine. Important in this is the separation of the x and y axes, this giving no interference, one to the other – this is part of a patented monobloc structure. Image: CUT 1000 Oiltech wire-cut EDM The CUT 1000 Oiltech is an evolution of the CUT 1000, with the use of oil catering to those applications where absolutely no corrosion, including surface discolouration, is allowed. The Swiss watchmaking industry is a particular instance where parts that are cut may undergo no further processing. The use of oil also allows for a smaller gap between part and wire, this offering the ability to make smaller internal radii or employ larger wire to get same radii – larger wire is more productive, due to the higher power it can transmit. The CUT 1000 was modified with new seals able to withstand the oil's action, while a new generator was also designed, due to its different characteristics to water. Cutting speed is the same or faster as with water for wire diameters of 0.1 and below, but slower for diameters above that and up to the maximum 0.20 mm. The machine features twin-wire capability, however, which boosts productivity, allowing fast cut with large wire and finish with fine. Moving to sink EDM and the Form 1000, which joins the FORM 2000 HP and For 3000 HP, and here the requirements fulfils by this machine are: accuracy requirement between ±2-7 microns; position accuracy ±1-5 microns; surface finish Ra 1-0.1; with minimum radius 5-50 microns. The FORM 2000 HP and 3000 HP are based on the FORM 2000, while the FORM 1000 is based on the CUT 1000 and is aimed at micro-machining applications. This means, said Mr Magistra, the production of features that fall within a cube of 1 by 1 by 1 mm, and that accuracy must be within a cube of 5 by 5 by 5 microns, anywhere in the machine and in a workshop environment. Supporting this, the control offers special cycles for micro-erosion. X, Y and Z travel are 220 by 160 by 250 mm in X, Y and Z, respectively, while maximum workpiece size is 550 by 330 mm. Image: Form 1000 Another major feature of this machine is the use of IQ technology, launched last year for graphite electrodes, but which is now also offered for use with copper electrodes. This technology minimises electrode wear (see Machinery website - http://tinyurl.com/yje3elm). Turning to milling, and the claim for the HPM 800U is that it is the most compact machine of its type. It can feature 7, 9 or 12 pallets of 500 by 630, 500 by 500 and 400 by 400 mm, respectively, and has a capacity of up to 210 tools, including long tools. The pallet magazine sits at the rear of the machine so that there is good access from the front. Machine travels are 800 by 800 by 550 mm, with the HPM 800U available in standard and HD (high dynamic), high speed, mode. This means that the accelerations and rapid travels in all axes are greater. So, for A-axis, 24 rads/sec2 becomes 34, with top speed of 25 rpm becoming 50 rpm; for B-axis the figures are 30/45 rads/sec2 and 35/60 rpm; for X, Y and Z-axis, the figures are 6/10 m/sec2 and 45/60 m/min. So that's an acceleration rate of 1.7 G for the HD version. Spindle units available offer 20,000 or 30,000 rpm maximum speed. Image: HPM 800U In conjunction with the performance, the machine's control features OSS (Operator Support System), which allows users to adjust a program for best accuracy, quality (surface finish) or cycle time. By moving a selection point within a triangle having these three corners, some 20 machine parameters are adjusted. This is further supported by the user being able to highlight workpiece weight and worpiece complexity level, both in three stages. An example of a workpiece that is able benefit from this machine in standard version is a spiral bevel gear of 1,800 mm diameter and weighing 4,000 kg. This high alloy, case hardened steel (8CrNiMo7-6, 61 HRc) part was machined to a quality level of DIN3965 Q2/Q3, runout was under 6 microns, the result being that this can be considered a 'master gear', said product manager, high performance 5-axis milling, Stefan Fahrni. Normally, to reach this quality level, grinding would be required. For finishing, a 5-axis strategy was used; it required two tools; maximum spindle speed was 6,000 rpm; maximum federate was 1,800 mm/min; cycle time was 7 min 9 secs per tooth (17 teeth); tool life was over 200 mins. An aluminium turbocharger for a ships' engine (21,000 hp) was an example given of 5-axis machining on the HPM 800U HD. Diameter of the part is 660 mm and a high quality surface is required to permit smooth airflow. The material is (AlCu2Mg1.5Ni); maximum spindle speed was 18,500 rpm; 5 tools were employed; maximum feederate was 7,700 mm/min; and the cycle time was 6 hours 20 mins, a large reduction on the previous time of 9 hours. Also launched at EMO, 2009 and highlighted at the Schorndorf event were the company's linear motor machines, HSM/XSM 400, 400U LP (Linear Performance) for high speed machining – the first machines designed by GF AgiCharmilles in every axis, underlined Georg Scheiba, product management and market support. The HSM/XSM 400 are 3-axis machines, with the 400U model supporting 5-axis machining. The 3-axis machines have travels of 500, 450 and 360 mm, in X, Y and Z axes; for the 5-axs machine they are 500, 235, and 360 mm with 220° (±110°) in B-axis and 360° in C-axis. XSM machines have more powerful linear motors fitted than the HSM, which means that the XSM must be bolted to the floor. The XSM also comes, as standard, in high accuracy guise, with this an option for the HSM. Image: XSM 400U The new machines are based on the HSM series but the structure has been redesigned to make room for the linear motors, with a new lower structure of polymer concrete in the working envelope. The company has also made sure that there are no surfaces on which swarf can collect, with good swarf clearance out of the working area. The latter gives more weight in the base, allowing for faster acceleration than before. As with the HPM 800U, there's automation via pallet pool. Customer benefits in surface quality, accuracy and speed are delivered by the new machine. In terms of accuracy, reduced thermal drift is a factor in this, while linear motors demonstrate no reversal error in standard circularity tests, as compared with ballscrews, which do. In addition, there's a novel CCD (Charge-Coupled Device) unit is used to measure tools, rather than a laser, called Intelligent Tool Measurement (ITM). This takes 1,000 pictures of a tools rotating up to 54,000 rpm to establish diameter and length, and is able to 'digitally clean' any swarf that is sticking to the tool, ignoring its influence – laser systems cannot do this. In operation, the difference between ITM and laser is revealed by visible surface finish improvements that are startling. Image: ITM Other developments include: a new high speed spindle with higher torque – 42,000 rpm with 8.8 Nm up to 13,000 rpm; chip-to-chip time is now 5.5 secs versus 12.5 secs; pallet changing time is 75 secs versus 95 secs; and rapid traverse rate (X, Y, Z) is 60 m/min versus 42 m/min (HSM) and 100 m/min versus 80/min (XSM). Box item Customer experiences with GF AgieCharmilles Ceramic dies and low-cost spectacles Holland-headquartered ART – Always Right Tooling – specialises in the manufacture moulds and dies for a wide range of industries, and has locations in China and Hong Kong. Simon van den Berg, managing director, dies, highlighted how GF AgieCharmilles technology helped the company, first, in the manufacture of ceramic dies, via EDM technology, and, second, through a third-world project for the manufacture of low-cost glasses, using Mikron high speed milling machines. As an opening statement, Mr van den Berg highlighted ART's speciality – reduced time to market and cost reductions in the order of 20-30 per cent. This is achieved by offering fully integrated services: design; rapid prototyping/tooling; tool design, production and validation; short runs; turnkey processes and automation; preventative and corrective maintenance; continuous improvement; product life cycle partner shift. His first example was the manufacture of ceramic dies for the production of integrated chip carriers for the semiconductor industry, made from copper alloy 0.2 mm thick. The current method of manufacture employed carbide dies to produce product at the rate of 650 million/month. Grinding intervals, to remove burrs, were every 1.2 million parts, with tool life 60 million. The challenge was to improve the process by increasing tool life; decreasing copper dust during stamping; decrease use of oil and, hence, cleaning; reduce maintenance costs; and increase the stamping speed. Switching to ceramic dies, already tested within the company, was not a simple solution. Ceramic punches are fragile. Part of the answer was to update its wire-cut EDM facilities with new GF AgieCharmilles technology, with GF AgieCharmilles die-sink technology also part of the equation. Able to manufacture the required parts, the final outcome was that, for an updated tool regrind interval became 2 million and tool life, 70 million parts; but for a completely new tool, these figures became 7.5 million and 350 million. A second example from ART concerned the manufacture of glasses and lenses for third world countries, having adjustable dioptre values. The volume was to be 100 million/year and the manufacturing cost target was €1/pair. The main challenge was the moulding of the lenses, which had to be made to a precision of 3-4 nanometres and come out the mould ready to use, so highest surface finish was a must. The outcome was a pair of glasses of the required function at under €0.84/pair. Latest GF AgieCharmilles milling technology was employed to produce the mould tools. Better plastic boxes Injection moulder Mundomold of Spain, as part of a strategy, wanted to reduce production cost (hours) by 18 per cent, while increasing unmanned running by 20 per cent, explained the company's Jorge Novella . The company makes plastic crates, bins and some furniture, and some 80 per cent of its products are exported, most to South America. To achieve its ambitions, it investigated the benefits of manufacturing mould tools using 5-axis continuous machining technology, moving from 5-axis positional. The first example was an agricultural crate mould tool, 600 by 400 by 250 mm and weighing 700 g. The mould tool weighs 5 tonnes and cycle time for each crate is 17 sec. The tool is comprised of several parts – core, bottom, cheek/slide, and guide cheek. The production processes for the parts was analysed to see where time is being wasted. Working with partners – machine tools, tooling, software companies – the company established a team to review the processes and targeted to reduce overall time by 50-60 per cent. GF AgieCharmilles Mikron HPM 1000U with 5 pallets was chosen. Results for the standard mould showed that production time was cut by 51 per cent, with unmanned running increased by 170 per cent, reducing the manufacturing cost significantly. Across its whole production in year one, the company achieved a reduction of 16 per cent in production hours and an increase of 22 per cent for unmanned hours, so very nearly meeting its objectives in the first year. In another project, involving a bottle crate mould for 20 litre bottle and which also involved a mould redesign, the achievement was a 43 per cent reduction in production hours, with a 217 per cent increase in unmanned production hours.