Reasons to use graphite electrodes

There has been a long-standing debate about whether graphite or copper is a better EDM electrode material for aerospace applications.

For this reason, Erodex has taken a closer look at the differences between the two materials and outlined reasons why graphite is likely to be the most appropriate for aerospace EDM needs.
Due to the wide range of graphite materials available, it is proven that some EDM grades are more economical than copper. Furthermore, most comparisons do not consider the cost of machining the electrode. Significant cost savings can be made choosing graphite over copper, generated through reduced machining times and speed of cut, less production time to create electrodes, faster EDM times and better throughput from EDM machines.
Graphite also offers a wide range of material characteristics in order to allow matching of the electrode material properties to the EDM application.
In addition, it should be noted that copper does not have the ability to handle current density as effectively as graphite, which performs exceptionally well at a high current density (even with complex geometry), allowing for various intricate machined details to be designed on the same electrode. The result is that the number of electrodes required to perform a job is reduced significantly.
Further reasons to select graphite over copper electrodes for aerospace applications include EDM performance, whereby graphite is able to achieve electrode wear of less than 1% in relation to the depth of cut, while working to more aggressive machine parameters. Moreover, fine-grain graphite electrodes are able to deliver similar surface finishes to that of copper, while offering much faster speeds and less wear.
For further information www.erodex.com

Wire EDM designed for ultra precision

Makino, which is represented in the UK by NCMT, has released its UP6 HEAT wire EDM for ultra-precision machining. The machine is capable of achieving workpiece positional accuracies of 1 µm, while providing XYZ travels of 650 x 470 x 320 mm.

Designed for precision stamping and fine-blanking applications, the machine is suitable for electric motor stator die tooling. The Makino UP6 HEAT features a stationary work table design that helps improve positional accuracy, as the machine is moving the same mass regardless of workpiece weight. A programmable rise and fall three-sided work tank is deployed that provides ergonomic access to the work zone; a configuration that also simplifies requirements for automation.
The machine contains several features that are designed to provide high levels of long-term thermal stability, such as integrating the water di-electric reservoir into the base casting of the machine, which also minimises floor-space requirements. Makino’s UP6 HEAT employs active thermal cooling of the entire structure, whereby chilled di-electric fluid is circulated through the casting to maintain a constant machine temperature.
Hyper-i control, with its 24” HD touch screen, operates like a common smartphone or tablet. The Hyper-i control delivers a common interface that is used on both Makino wire and die-sink EDM machines, and contains many helpful advanced functions that support the needs of the operator to boost productivity. UP6 HEAT also comes as standard with the HyperConnect IIoT network connectivity function for remote machine monitoring and interconnectivity of all manufacturing information.
For further information www.ncmt.co.uk

EDM for aero-engine production

TEK4 recently introduced what it describes as a world first, an EDM machine dedicated to producing aerospace engine blades and vanes. As a specialist in cooling hole drilling technology for jet engines and gas turbines, TEK4 has launched its 6G FHD SA (Small Aerospace), a fast-hole EDM drill specifically for industrial turbine production.

The TEK4 6G FHD SA incorporates full six-axis simultaneous machining and intelligent probing, as well as pre-breakthrough and breakthrough tool detection. These features are essential for machine shops in this sector as it enables them to avoid the risk of back wall impingement. The machine is fitted as standard with an automatic electrode guide changer and automatic electrode changer, which can accommodate electrodes up to 600 mm long for extended autonomy.
According to TEK4, the EDM generator works in combination with the in-house developed software. This compatibility allows for excellent metallurgical results, says the company, which is another critical parameter for this high-tech industry. In addition, the TEK4 6G FHD can be integrated in an autonomous robot cell with automatic part loading for unmanned operation. A laser ablation head can be incorporated in TEK4 FHD machines for the removal of the ceramic protective barrier. Having the EDM head and laser head on the same platform avoids positioning issues and offers reduced capital investment.
The TEK4 5G FHD machine has an X, Y and Z axis of 300 x 300 x 400 mm, with 360° rotation in the A (±180°) and C axes (360° continuous), a 600 mm drill stroke, and a maximum work part weight of 20 kg. This flexibility enables the machine to process holes from 0.25 to 10 mm diameter, and up to 200 mm deep.
For further information www.tek4.co.uk

EDM used on live nuclear reactor pipeline

Machining specialist Hydratight says it has become the first company to use EDM for maintenance work on a live nuclear reactor pipeline system.
The company completed the technically challenging campaign for a major energy company at a US power station as part of post-Fukushima upgrades.

Using EDM avoided an expensive unplanned shutdown of the reactor, and took 48 hours off the reactor outage schedule.
The process used a heated solid electrode to cut a hole (featuring 0.05 mm tolerance) within the reactor feed water line. Microscopic cuttings were then removed using back-flushing and vacuums. Hydratight’s process prevented 99.5% of foreign material exclusion particles, such as drill cuttings and debris, from entering the reactor.
Mike Riordan, Hydratight’s nuclear speciality services manager, says: “This was a milestone achievement on a live nuclear reactor pipeline system, and resulted in safety enhancements in line with the industry’s post-Fukushima requirements. The work has created another way to feed water into the main line if there is ever a power loss to the reactor.”
The line had water pressure of 8.3 bar and electrical conductance exceeding 3,500 micro-siemens. Hydratight’s speciality services deployed customised tooling to negotiate a 380 mm long, 25 mm wide pipe as an entry point to reach the spot where the 19 mm EDM penetration was to take place.
“Material contaminations are a major concern for most facilities, and EDM is a highly accurate and safe way of machining,” says Riordan. “Tool pressure was also a concern on this particular project, so we were able to use a method which was completely contactless.”
Hydratight has offered its services to the nuclear and power-generation industries for more than 30 years.
For further information www.hydratight.com

A&M EDM showcases engineering

Greg Clark, Secretary of State for Business, Energy and Industrial Strategy, recently visited precision engineering company A&M EDM in Smethwick, West Midlands to understand what drives growth and the issues facing a manufacturing SME.

The Business Secretary met some of A&M’s current and recent apprentices, speaking to individuals about their motivation to take up an apprenticeship, the work they undertake and the skills they are developing by working with experienced engineers. All of A&M’s apprentices study for academic engineering qualifications at Dudley College.
Mark Wingfield, managing director of A&M EDM, said: “We had an informed discussion with the Business Secretary on how the Industrial Strategy can accelerate West Midlands manufacturing and A&M’s initiative to develop its own apprentices.”
Added Clark: “The Industrial Strategy for the West Midlands will harness its distinctive strengths to unlock greater growth and earning power across the region’s cities and towns.”
A&M showcased engines and components manufactured for aerospace and automotive customers. In addition, Clark saw a new high-speed CNC machining centre and handheld alloy analyser in action; these were part funded by a Black Country Local Enterprise Partnership (LEP) grant to create new manufacturing jobs.
The Business Secretary discussed the practical implementation of the Industrial Strategy with senior representatives of the Black Country Chamber of Commerce, Black Country LEP, Dudley College and the EEF.
A&M has grown from a two man start-up in 2002, to 67 staff and sales of over £6m in 2018. This has been achieved using EDM and CNC machining to design and manufacture precision components and tooling for a range of UK and international customers.
For further information www.amedm.co.uk