EDM — Electrical Discharge Machining
Sinker and wire EDM machining in Gdańsk. Mitsubishi EA machines with ±0.005 mm accuracy. We machine materials that cannot be milled — hardened steel 60+ HRC, cemented carbides, titanium.
What is EDM and when is it indispensable?
EDM (Electrical Discharge Machining) is a method of machining electrically conductive materials using controlled electrical discharges. Unlike CNC milling, the tool never contacts the workpiece — machining takes place in a dielectric fluid (oil or deionised water) through thousands of micro-sparks that remove material layer by layer with ±0.005 mm accuracy.
EDM is indispensable wherever conventional cutting methods fail: materials harder than 55 HRC (hardened steels, cemented carbides), complex 3D shapes with sharp internal corners, deep narrow slots, and micro-holes below 0.5 mm diameter. At the MAJ-PLAST toolroom in Gdańsk, EDM is a key technology in the production of injection molds — it enables us to reproduce cavity, core, and slide geometries in hardened steel that cannot be achieved by milling.
Our toolroom in Gdańsk is equipped with Mitsubishi EA EDM machines — among the most advanced EDM systems in the world. These machines combine the precision of Japanese engineering with reliability and machining speed. We offer two types of EDM: sinker EDM — a graphite or copper electrode reproduces its shape in the workpiece, and wire EDM — a thin brass wire cuts the profile like a precision saw.
Sinker EDM vs wire EDM — method comparison
Sinker EDM (die-sinking EDM) uses an electrode shaped as the inverse of the desired cavity. We manufacture electrodes from graphite or copper on a CNC milling centre. Thousands of electrical discharges cause the electrode to "imprint" its shape into the workpiece. This method is ideal for machining injection mold cavities, dies, and 3D shapes. Accuracy ±0.005 mm, surface roughness Ra from 0.1 µm (mirror finish).
Wire EDM uses a thin brass or molybdenum wire (∅ 0.10–0.30 mm) to cut profiles like a precision saw. The wire is stretched between two guides and travels along a programmed path. This method is ideal for cutting punches, dies, shaped holes, and profiles from hardened steel. Accuracy ±0.003 mm, with taper cutting capability up to ±15°.
At the MAJ-PLAST toolroom in Gdańsk we employ both EDM methods — selecting the right technology for each project. For clients in the Tri-City area and Pomerania, we offer machining for our own injection molds as well as contract EDM services. Simply send your technical drawing or 3D model to majplast@majplast.com.
Toolroom with EDM in Gdańsk — applications and capabilities
EDM at the MAJ-PLAST toolroom is an integral part of our production process. Every injection mold we manufacture requires electrical discharge machining at some stage — whether for precision cavity machining in hardened H13 steel or for cutting complex punch and slide geometries. EDM enables us to reproduce shapes that are impossible to achieve with CNC milling: sharp internal corners (0 mm radius), deep narrow grooves, micro surface textures (leather grain, matte, sand finishes).
EDM applications at MAJ-PLAST: machining injection mold cavities in hardened tool steel (P20, H13, 718, S136), cutting punches and dies for stamping and blanking tools, machining cemented carbide and titanium components (aerospace and medical), producing micro-holes ∅ 0.1 mm and grooves 0.05 mm (micro-machining), removing broken tools (drills, taps) from workpieces.
Why is EDM superior to milling in certain applications? EDM generates no mechanical forces — there are no vibrations, stresses, or thermal distortions in the workpiece. This is a critical advantage when machining thin walls, precision turbine blades, and medical components. Furthermore, material hardness does not affect machining speed — we machine 20 HRC and 62 HRC steel with equal ease. EDM also delivers mirror-finish surfaces (Ra 0.1 µm) without additional polishing.
The MAJ-PLAST toolroom in Gdańsk offers EDM services not only for our own mold production but also as a contract service for external companies in Gdańsk, Gdynia, Sopot, the Tri-City area, and across the Pomeranian region. We accept orders from toolrooms, machine shops, manufacturing companies, and research institutes. Lead time from 3 business days — express turnaround available for urgent projects.
Our Mitsubishi EA EDM machines operate in fully automatic mode — auto electrode change, automatic wire threading, 24/7 process monitoring. This enables unattended (overnight) machining, reducing lead times and lowering costs. Every part after EDM is measured and documented — we provide measurement reports and macro photographs of the surface.
Need EDM machining?
Send your drawing — we quote within 24h. Lead time from 3 business days.
Frequently asked questions
What materials can be machined with EDM?
Any electrically conductive material: hardened steel (up to 65 HRC), tool steel, cemented carbides, titanium, copper, aluminium, Inconel, tungsten, graphite. Material hardness does not affect machining speed — this is the key advantage of EDM.
When is EDM better than CNC milling?
When the material is harder than 55 HRC, when the part has sharp internal corners (zero radius), deep narrow slots, micro-holes, or complex 3D geometries. EDM generates no mechanical forces — ideal for thin walls and precision components.
How much does EDM machining cost?
The price depends on complexity, material, accuracy, and machining time. Simple operations start from a few hundred PLN, complex mold cavities from several thousand. We provide individual quotes based on your drawing — free of charge within 24 hours.
Do you provide EDM services for external clients?
Yes. In addition to machining for our own injection molds, we fulfil external orders for companies across the Tri-City area and Pomerania region. Simply send your technical drawing to majplast@majplast.com.