Machining turbine disc fir-tree roots

The AV35 is one of ONA’s most ambitious projects in recent years: it represents the company’s technological development of WEDM technology applied to the manufacture of highly demanding parts.

One of the machine’s virtues is that it is a standard model, offering a basic structure to which modules/accessories can be added depending on the type of component to be manufactured. This configuration allows for fully automated machining.
One of ONA’s greatest challenges has been to develop EDM technology adapted to the process in order to convert electrical discharge machining into a competitive and high-quality machining process, even when compared with some of the most common processes in industry, such as milling or broaching. An example of the latter is the cutting of fir-tree roots for turbine discs, which are mainly manufactured by broaching.
A successful project to highlight is the work carried out in collaboration with a company in the aerospace industry, a project in which ONA manufactured fir-tree roots for aviation turbines on its AV35 wire-cutting EDM machine (WEDM). This work is, without a doubt, one of the most important and ambitious projects ONA has partaken in recent years. On the one hand, the company had to undergo a cultural change, since different departments had to work closely on the development of the machine. On the other hand, thanks to the hard work of staff and the technology developed, the application was successful and the manufacturing process of highly demanding parts was validated.
“The most complicated part was co-ordinating with different departments, as well as with the client,” says an ONA technician. “We had to use state-of-the-art software tools to comply with the traceability requirements.”
For further information

U6 HEAT Extreme now available

Now available in the UK from NCMT is the Makino U6 HEAT Extreme wire EDM, which uses the largest diameter wire – 0.4 mm – of any machine on the market, says the company.

The wire is coated and distinct from the 0.25 mm uncoated brass wire that is commonly used in industry. This extra wire thickness, together with the use of a second booster generator in the machine, allows two-to-three times higher feed rates and heavier duty machining, coupled with a slower un-spool speed, so there is no increase in wire consumption rate. At MACH 2020 (now postponed to January), NCMT was set to highlight the roughing of a turbine blade’s fir-tree root form, assisted by dual pumps delivering high flushing pressure and volume.
Comprising part of Makino’s U-series wire EDM machine platform, the U6 HEAT Extreme uses a newly developed Bedra copper core wire with a double layer coating featuring controlled zinc donation. The wire has been optimised for use with Makino’s generator and is exclusive to the machine. Areas of application include aerospace and medical component machining, separating additively manufactured parts, machining tall moulds and dies, and tackling tough nickel alloys.
Makino’s U6 HEAT Extreme also features the company’s HyperDrive Extreme wire control, which employs servomotor tensioning to facilitate both jet and jet-less automatic threading modes, and expands the range and stability of wire tension to overcome the difficult job of reliably threading high tensile and stiff 16-micron wire.
A cutting conditions library has been developed to provide an optimum combination of speed, accuracy, surface finish and wire consumption for both sealed and poor flush applications. Settings for two-pass machining have also been created to provide optimal productivity.
To reduce maintenance costs, the machine features long-life energisers that extend the service life of this consumable. Moreover, to improve ease of-use and productivity, the U6 HEAT Extreme comes with the intuitive Hyper-i twin-screen control that includes functions to support the needs of operators at all skill levels.
For further information

Precision machinist opts for Mitsubishi

In the face of shrinking demand for rubber injection moulds, AMB near Paris has been adding precision prototypes and mechanical components for a wide variety of industries to its portfolio.”

To aid this transition, the company began searching for a new wire EDM, as Jacques-Henri Miguet, second-generation managing director, explains: “We needed a new machine because our existing wire EDM from another manufacturer was unreliable and caused excessive maintenance costs.”
Initially there were discussions with three different suppliers, but the choice quickly narrowed down to the Mitsubishi Electric MV1200R offered by local agent Delta Machines. One important reason was that the system accommodates a working height over 200 mm.
Ultimately, a wire EDM system type MV1200R was purchased along with an EA8S die-sinking EDM system.
“Our Mitsubishi wire EDM machine works perfectly and delivers everything we expected of it,” says Miguet.
The MV1200R achieves an accuracy of 1/100 mm when used with wire diameters from 0.1 to 0.25 mm, usually with two passes to achieve the best possible quality. In two-shift operation and with an average spool life of 20 hours, jobs can usually be planned so that the next change falls within an employee’s working hours and the machine runs largely around the clock. In this context, the automatic re-threading of the wire after a breakage, even in the narrowest kerfs, is also very useful.
“If I should ever need another EDM system, I know exactly who to contact,” says Miguet, summing up his experience.
For further information

Output climbs

Manufacturing output across the UK increased significantly in May from its record low level as factories started to emerge from the coronavirus lockdown, according to figures from the latest BDO Business Trends report.

BDO’s Manufacturing Output Index jumped by 16.58 points to 69.55 in May, regaining around half of the losses sustained between March and April as manufacturers benefited from the easing of UK lockdown measures. Kaley Crossthwaite, Partner at BDO LLP, say: “Output remains drastically below where it would be in ordinary times, but the latest readings suggest we have passed the rock bottom of this crisis.”
For further information

Cost-effective tool grinding and erosion

Walter has announced two new entry-level machines for re-sharpening and manufacturing a wide range of carbide, PCD and HSS tooling in the most cost-effective way.

These include the ‘two-in-one’ eroding/grinding Helitronic Raptor Diamond, which is designed for PCD tools up to 400 mm diameter and 270 mm long (also end face operations).
The machine can be configured with, for instance, a Walter Top Loader (which accommodates up to 500 tools), glass scales, torque drive on the A axis, wheel probe and manual support steady rest.
Walter’s ‘two-in-one’ Helitronic Raptor Diamond, which uses an HSK interface for electrode/grinding wheel mounting, also features an 11.5 kW spindle, while its Helitronic Tool Studio software embraces integrated erosion functionality for the fast and easy programming of ‘what you see you can grind and erode’.
In addition, the machine boasts Fine Pulse Technology, a Walter innovation that is said to set new standards in terms of PCD tool surface and edge quality, as well as process reliability and speed of erosion. Fine Pulse Technology is the result of progressive improvements to the machine’s generator, as well as the erosion software.
With Fine Pulse Technology, there are marked differences to PCD tools of standard grain type that have been eroded by other machines. Indeed, the differences can be seen with the naked eye – the surface finish is like that of a polished (ground) tool and even coarse-grained PCD
types can be fine-finished with perfect surface qualities, reports the company.
Fine Pulse Technology is the result of progressive improvements to the machine’s generator, as well as the erosion software.
For further information