What is EDM drilling?
EDM drilling is a form of spark erosion in which a thin, tubular electrode creates small round holes in electrically conductive material by means of electrical discharges. The technique achieves hole diameters of approximately 0.2 to 3 mm with a high length-to-diameter ratio, including in hardened and exotic metals. EDM drilling is often used to create a start hole for wire EDM.
EDM drilling: where conventional methods fall short
EDM drilling makes it possible to create holes that cannot be achieved with conventional drilling tools: micro-holes, deep holes with a high aspect ratio and precise holes in the hardest materials. Without mechanical contact, without cutting forces and with minimal thermal load.
Tumag carries out EDM drilling as part of a complete spark erosion process, from start hole to finished precision component.
EDM drilling integrated into the production process
At Tumag, EDM drilling rarely stands alone. In most projects, EDM drilling is one step within a broader machining process. Thanks to our fully in-house production capacity, we seamlessly combine EDM drilling with complementary techniques, without losing time, tolerance or traceability.
- Wire EDM: for complex contours and start holes after EDM drilling
- Sinker EDM: for deep cavities and fine surface structures
- CNC milling and HSM milling: for pre-machining and finishing operations
- Quality control: measurement and reporting for every component
Industrial application in demanding sectors
EDM drilling is used in sectors where tolerances are tight and material failure is not an option:
- Healthcare: micro-holes in medical instruments, implant components and pharmaceutical precision parts where hygiene and dimensional stability are crucial
- High-tech industry: cooling channels, spray openings and start holes in semiconductor and electronics applications with extremely tight tolerances
- Aeronautics & defence: holes in titanium, Inconel and other lightweight yet hard alloys for structural and functional components
Applications of EDM drilling: micro-holes and deep drilling
EDM drilling excels where holes need to be small, deep or precise and where conventional drilling falls short. The technique creates holes with a high aspect ratio, from a few tenths of a millimetre to several millimetres in diameter, without compromising hole quality or positioning accuracy.
Typical applications:
- Cooling channels in moulds and tools
- Start holes for wire EDM, EDM drilling creates the hole through which the wire is inserted
- Spray openings in injection moulding systems and fluid technology
Diameters range from a few tenths of a millimetre to several millimetres, while maintaining hole quality and positioning accuracy.
Suitable for hard and exotic materials
EDM drilling is ideally suited for machining hardened steel, carbide, titanium, Inconel, and other exotic alloys. Since material hardness has no influence on the process, machinability remains constant regardless of the material selected. This makes EDM drilling especially attractive for applications where strength, wear resistance, and heat resistance are essential, and where conventional machining methods quickly reach their limits.
Minimal thermal load and deformation
Although the process is based on heat, the thermal load is highly localized and controlled. As a result, the rest of the workpiece remains unaffected and deformation is minimized. No mechanical stresses caused by cutting forces are introduced, which benefits dimensional accuracy and structural integrity. This is particularly important for precision components and complex geometries.
Your partner in precision machining
Are you looking for a reliable partner for high-precision EDM drilling, or would you like to know whether this technique is suitable for your specific application? Tumag is happy to work with you—from technical feasibility through to the final product.
Curious to find out what we can do for you? Get in touch with us today.
Frequently asked questions about EDM drilling (FAQ)
What is the difference between EDM drilling and wire EDM?
Both techniques are forms of EDM, but they work in fundamentally different ways. Wire EDM uses a tensioned wire to cut contours. EDM drilling uses a rotating tubular electrode to create cylindrical holes, often as preparation for the wire EDM process. Tumag offers both techniques and can determine which method is suitable for your application.
What are start holes and what are they used for?
In wire EDM, a tensioned metal wire is used to accurately cut contours and shapes from a workpiece. However, the wire needs a starting point; it cannot simply enter a closed contour from the outside of the material. This requires a start hole: a small, precisely drilled hole through which the wire is threaded before the EDM process begins.
Start holes are preferably made using EDM drilling, because:
- the hole can be drilled in hardened material after the workpiece has already undergone its final treatment
- the diameter can be very small and matched to the wire thickness
- the position is extremely precise, which is essential for the dimensional accuracy of the final contour
- no mechanical stresses or deformation occur that could affect the tolerance of the wire EDM process
Tumag performs EDM drilling of start holes and the subsequent wire EDM entirely in-house, improving accuracy and lead time.
Does the surface quality of the hole require post-processing?
After the EDM drilling process, the surface has a typical EDM structure. Depending on the functional requirements, post-processing may be desirable, for example to achieve a very high surface quality or a close-tolerance fit. Tumag reviews this with you and can carry out the finishing in-house.