Precision EDM for moulds, dies and precision-engineered components
In today’s precision industry, components are becoming increasingly complex and tolerances ever tighter. Especially when manufacturing injection moulds, mould inserts, dies and functional precision components, conventional milling or turning is not always sufficient. In such cases, sinker EDM offers an extremely precise and reliable solution.
At Tumag in Turnhout, we master this EDM technique down to the smallest detail, from electrode design to final inspection.
What is Sinker EDM?
Die-sinking EDM, also known as sinker EDM, is a form of spark erosion, a machining technique in which material is removed by means of electrical discharges between a shaped electrode and the workpiece. The electrode (or combination of multiple electrodes), which has exactly the desired negative shape, is controlledly “sunk” into the workpiece. Through spark discharge, the material melts away locally and is removed, allowing the shape to be reproduced with very high precision.
Production technique for complex geometries
One of the greatest advantages of sinker EDM is the ability to create shapes that are difficult or impossible to achieve with conventional machining techniques. Examples include sharp internal corners, deep cavities, fine rib structures, micro-details and complex 3D contours.
Because complex shapes can be easily produced using sinker EDM, this process is particularly suitable for:
- mould inserts and form components for injection moulds;
- cutting tools and die components;
- fine structures in hardened materials;
- precision components with high requirements for dimensional stability.
Because there is no direct mechanical contact between the tool and the workpiece, even delicate geometries can be machined in a controlled manner without any additional risk of deformation.
Machining hard and sensitive materials
Sinker EDM is often used for materials that are difficult to mill or turn due to their hardness, toughness or wear resistance. Examples include hardened tool steel, carbide, stainless steel and high-performance alloys for demanding industrial applications.
Because the process is based on electrical discharge, the hardness of the material is not a limiting factor. This makes sink EDM highly valuable for:
- hardened mould components;
- wear-resistant die components;
- thin-walled or delicate workpieces;
- components where stress build-up or deformation must be avoided.
For sectors such as healthcare, high-tech, aeronautics & defence and packaging, this process reliability is essential. It is not only the shape that matters, but also the reproducibility of every detail.
In-house electrode production
The quality of EDM spark erosion is largely determined by the electrode. That is why Tumag designs and produces die-sinking EDM electrodes in-house. This gives us maximum control over dimensional accuracy, geometry, material selection and surface quality.
Tight tolerances and repeatable quality
At Tumag, sinker EDM is always closely linked to quality control. During and after the process, we inspect dimensions, form details and surfaces using precise measuring equipment. Where required, measurement reports are provided, giving customers complete certainty about the final result.
Thanks to the high level of process control, sinker EDM can achieve very tight tolerances and fine surface qualities. This is important for moulds and precision components that need to function reliably over the long term in production environments.
For customers, this means: a lower risk of production defects, more stable processes and components that fit within a broader technical system.
Part of integrated precision production
Tumag combines sinker EDM with other techniques within high-precision production, allowing us to produce and finish complex components entirely in-house.
This combination is especially valuable in mould making and precision engineering, where different machining operations must be precisely aligned. By contributing early in the project to manufacturability, electrode design, clamping and post-processing, we achieve a more efficient production process with a lower risk of deviations.
40 years of mould expertise translated into sinker EDM
Whether your project requires a prototype, a specific mould insert or small to medium series production, our production site in Turnhout is fully geared towards flexibility. Here, more than 40 years of mould-making experience seamlessly come together with the latest generation of EDM technology and ISO-certified processes.
Do you have a complex geometry that requires a well-considered machining strategy? Our engineers are happy to support you from an early stage. We optimise the process from the initial design sketch through to the final precision component.
Frequently asked questions about sinker EDM (FAQ)
When should I choose sinker EDM instead of CNC milling?
Sinker EDM is particularly useful when a shape cannot be milled efficiently or accurately enough. This applies, for example, to deep cavities, sharp internal corners, fine details, narrow ribs or very hard materials. In addition, sinker EDM is sometimes deliberately chosen to create a specific surface texture: the so-called EDM texture. Sinker EDM is often combined with milling to achieve the best technical and economical result.
Which materials can be machined using sinker EDM?
Sinker EDM is suitable for electrically conductive materials, including hardened steel, carbide, stainless steel and various wear-resistant alloys. The technique is often used when the material is too hard or too sensitive for conventional cutting operations. Material hardness is not a major limitation in EDM.
Why is the electrode so important in sinker EDM?
The electrode determines the negative shape that is transferred into the workpiece. A precise electrode is therefore essential for the dimensional stability, shape quality and surface finish of the final result. Because Tumag designs and produces electrodes in-house, the entire process remains optimally controlled.
Is sinker EDM suitable for mould making?
Yes, sinker EDM is very often used in mould making. The technique is ideal for form components, inserts, deep cavities, rib structures and technical details in hardened mould steels. Especially for complex injection moulds, sinker EDM offers a high degree of precision and reproducibility.
How do I know which areas need to be EDM machined and which can be milled?
This depends on the geometry, tolerances, material hardness, desired surface quality and accessibility with milling tools. At Tumag, we assess already during the engineering phase which areas are best milled, HSM milled or sinker EDM machined. This allows us to avoid unnecessary operations and choose the most accurate and cost-efficient production method for each detail.
