A short history of electrical discharge machining (EDM)
From Priestley's initial spark in 1770 to FastEDR
EDM has been proven in aerospace for decades: ‘The process is used in the original manufacturing of the most high-precision components of the whole engine,’ says Scintam’s Chief Technical Officer, Pete Woodsmith.
It’s well suited to working with hard materials, tight tolerances and high stakes – the exact environment Scintam’s solution, FastEDR operates in when removing seized fasteners from aircraft engines.
Removing a seized screw might sound simple in theory – but in aircraft maintenance, that’s rarely the case, and given the average price of a turbine jet engine and the current shortages, MRO mistakes can be costly.
EDM, a technology that’s been around since the 1940s, allows FastEDR to remove fasteners in a much safer and more predictable way than traditional methods. Here, we’re giving a brief outline of the history of EDM and how Scintam’s solution represents the latest stage in its evolution.
1770: The accidental discovery
In 1770, British physicist Joseph Priestley, better known for discovering oxygen, observed that electrical discharges have a corrosive effect on metal. He had no idea of the practical implications of this, and his accidental observation sat dormant for two centuries.
1943: The first EDM machine
In 1943, Soviet scientists Boris and Natalia Lazarenko made a discovery that birthed EDM. The husband-and-wife team based in Moscow were trying to find a way to prevent tungsten electrical switches from eroding, and while their experiments were unsuccessful, they did find that when electrodes are immersed in dielectric fluid (a liquid that resists electrical current until the voltage is high enough to jump the gap), the erosion becomes predictable, controllable and repeatable. They had uncovered a brand new way to cut extremely hard metals, marking a big leap forward in manufacturing.
Meanwhile, on the other side of the Atlantic, an American team made up of Jack Beaver, Harold Stark, and Victor Harding, also arrived at a working EDM machine, but through a completely different route. They wanted to remove broken drill bits and taps that had snapped off inside aluminium castings and couldn't be extracted any other way. Their machine used a relaxation circuit to generate controlled sparks, and it worked.
1950s-60s: Industrialisation
Throughout the 1950s and 60s, EDM technology continued to improve, and in 1956, researchers at General Electric developed a wire electrode machine that allowed more precise cutting of small holes. Wire EDM took off in the 1960s and was mainly used for making dies from hardened steel.
1960s onwards: The three types diverge
The three main variants – hole drilling (the original, oldest type), die sinker (the second branch) and wire EDM (the newest) – each matured into specialised industrial tools across the latter half of the 20th century, becoming central to aerospace, toolmaking, and precision manufacturing.
What all three types share is scale: they are large, static machines, and the workpiece comes to them. A wire EDM machine is roughly the size of a large desk and a die sinker is not much smaller. They live in machine shops, require specialist operators, and are built around the assumption that the part being machined can be brought to the machine, fixtured, submerged, and left to run.
Vacuum tube generators had powered the earliest EDM machines but in 1963, transistorised generators launched, which were smaller, faster and easier to control. The power supply also shrank in size, meaning the EDM machines themselves could be made much smaller, while giving the operator more control over the duration and frequency of each spark.
1970s onwards: EDM machines become more specialised
Next, numerical control came in, so the machine learned to follow instructions, following a programmed cutting path without an operator guiding it. This improved repeatability and precision. In 1976, the first fully CNC-controlled EDM machine was manufactured, which meant EDM could be programmed, automated, and repeated with tighter tolerances than an operator could achieve.
In the 1970s and 80s, EDM became the method of choice for creating the small cooling holes in turbine blades designed to prevent engines from overheating during flight. Engines typically had thousands of these holes, measuring between 0.3 and 0.5mm in diameter, that go through superalloys such as Inconel. EDM became known for its extreme precision and application on the most demanding materials in the engine.
The early 1990s saw one of the earliest applications of AI in EDM – the machine was starting to understand what it was doing, monitoring the sparking process and adjusting parameters to optimise the cutting speed and surface finish.
Today: FastEDR
Scintam’s FastEDR solution represents the latest advancement in EDM technology. It takes the core hole-drilling EDM principle and applies it to a maintenance rather than manufacturing context. Building on the latest developments such as CNC and portability, it has applications in MRO – while also introducing several unique innovations of its own, such as automatic decap detection, fastener-specific settings and a full audit trail.
From a large, messy, fixed workshop machine, to a controlled, portable system that’s purpose-built for a specific problem, it removes seized fasteners from very high value components.
This transition from manufacturing to MRO speaks to a broader trend that’s seeing aerospace maintenance become more sophisticated and data-driven – based on conditions rather than a set schedule.
For example, modern aircraft engines are fitted with sensors that monitor temperature and vibration throughout a flight, and the data is analysed to predict when a component needs maintenance before it actually shows obvious signs of wear.
Similar to this predictive maintenance and engine health monitoring is the creation of digital twins of individual engines to track their history – again, it means maintenance decisions can be based on real operational history rather than an average across a fleet. FastEDR’s automatic parameter logging and depth-versus-time recording is another example of this same shift, with data captured automatically as part of the process.
The Scintam team are now working on further innovations of FastEDR, having received funding from Innovate UK alongside the Aerospace Technology Institute to support a new project, FastEDR Expansion: Enhancing Aerospace Asset Dependability (FEEAD).
This will see a grant go towards scaling FastEDR for aerospace maintenance applications. The investment will support an 18-month R&D programme, focusing on three major areas: developing a universal fixturing system, laser guided surface plane detection and EDM parameter optimisation.