Wire and die-sinking EDMWe will check feasibility and get back to you shortly.
Spark erosion and EDM – wire EDM and die-sinking EDM for maximum precision
When geometries are complex and very small, when materials are hard, or when tolerances move into the micron range, EDM – also called spark erosion or electrical discharge machining – is often the most economical and the most reliable manufacturing process. Sharp-edged internal contours are no exclusion criterion for us. Bonsack Präzisionstechnik supports you with wire EDM and die-sinking EDM as contract manufacturing – for precise contours, fine details and reproducible quality.
Whether tool components, active parts, functional components or spare parts: we manufacture eroded precision parts that hold up in series production and are convincing down to the last detail.
What does erode (EDM) mean?
In spark erosion, material is not removed by cutting, but by controlled electrical discharges between the electrode and the workpiece. Sparks are generated in a dielectric (insulating fluid), which remove tiny particles of material from the surface. This allows contours to be created that are difficult or impossible to produce reliably using milling or turning, especially in the case of hardened steels, carbide or alloys that are difficult to machine.
Important for practical application: Erosion is not a “replacement” for CNC machining, but rather a high-precision supplement – whenever internal contours, intricate details, sharp corners or very tight tolerances are required.
Wire erosion – precise cutting contours, fine radii, reliable repeat accuracy
Wire electrical discharge machining (Wire EDM)
is ideal for precise contour cut-outs and cutting geometries. A thin brass wire serves as the electrode and cuts the desired contour along a programmed path – without contact, with no mechanical force on the component. Two of our wire EDM machines work in a water bath with automatic wire threading; a wire break therefore does not interrupt the job. Taper cuts up to ± 30° are possible. Closed internal contours need a start hole – we erode those in house on two dedicated machines, Ø 0.5 to 3.0 mm. The process is particularly strong when:
- complex 2D contours or precise cutting profiles are required,
- Workpieces are already hardened (e.g. tool steels),
- close fits, defined edges and constant repeatability are required are,
- low cutting forces are important for low distortion machining).
Typical
applications
are active parts in toolmaking (e.g. cutting inserts, die and punch contours), precise guide and contour elements, and spare parts for existing tools. Multi-cut strategies allow surface finish and dimensional accuracy to be improved in a targeted way – depending on material, component thickness and contour complexity.
Die-sinking EDM –
3D contours,
filigree details and internal geometries
Die-sinking EDM
(Sinker EDM, Ram EDM) works with a shaping electrode (e.g. graphite or copper) that “sinks” the desired negative geometry into the workpiece. This process is the first choice when:
- 3D cavities, pockets or mould contours are required,
- Internal geometries with sharp corners/small radii are required to be,
- complex forms in mould making and tool making are to be created in,
- hardened materials must be reworked.
The strengths
Die-sinking EDM shows its strengths above all on tool and mould components – contour inserts, functional surfaces, structured cavities, and geometries that could be produced mechanically only at a high risk of tool breakage, distortion or burr formation.
Erosion vs. milling:
When is EDM the better choice?
Combination
In many projects the best solution is a combination of CNC machining, grinding and EDM. Eroding is typically used when one of the following applies: when one of the following requirements is in the foreground:
- Hardness and material: hardened tool steels, carbide or difficult-to-machine materials.
- Geometry: sharp internal corners, very small radii, delicate contours, deep and slender geometries.
- Process reliability: low forces and therefore less distortion – especially in thin-walled areas.
- Repeatability: reproducible results for series and spare-part production.
Economic efficiency
Milling is often faster for open geometries, large volumes, or when the contour is mechanically easy to reach. EDM becomes the economical choice when milling strategies get extremely complex – special tools, long running times, high tool wear – or when certain contours simply cannot be milled at all.
Materials, tolerances
and surfaces – what is possible with spark erosion ?
Erosion is particularly suitable for materials that are in machining are demanding are. Typical materials in the EDM contract manufacturing are:
- Tool steels (hardened and unhardened), hot-work steels and cold-work steels
- powder metallurgical steels
- carbide
- Stainless steels and high-alloy steels
- Other electrically conductive materials and special alloys
Specifically, on our machines: surface finishes down to Ra 0.1 µm, taper cuts up to ± 30°, workpieces up to 900 × 600 × 426 mm for wire EDM and up to 600 × 400 × 450 mm for die-sinking EDM. Six EDM machines are available for this – three for wire EDM, one for die-sinking EDM and two for start-hole EDM (complete machine list).
Which dimensional tolerance results from this depends on geometry, material, component thickness and the selected cutting and erosion sequence. For many applications in toolmaking, defined fits, repeatable contours and clean cut surfaces are what matter – and that is exactly what EDM is built for.
Important: We agree requirements such as fit dimensions, surface quality and function together with you (drawing, tolerance concept, application) in order to determine the most economical process route.
Typical areas of application:
toolmaking, active parts, precision parts and spare parts
EDM components are used wherever precision and service life are important. Frequent areas of application for our customers:
- Toolmaking and mould making: inserts, contour elements, cavities, slide and guide components
- Punching and forming technology: cutting contours, die and punch geometries, progressive-die and fine-blanking parts
- Near-series production: function-critical precision parts with demanding internal contours
- Maintenance and spare parts: reproduction of eroded components for existing tools
When it comes to spare parts in the tooling sector, the ability to precisely rework hardened components or reproduce them according to drawings is a real advantage – ensuring short downtimes and quick recommissioning.
Your project at Bonsack – From drawing to tested component
In order for EDM to function economically and reliably, it is essential to have a clear process plan in place. Typical procedure:
- Enquiry and data check: drawing, 3D data where available, tolerances, material, application.
- Feasibility and process coordination: choice of wire or die-sinking EDM, cutting strategy, electrode concept where required, target surface finish.
- Manufacturing: precise EDM machining, combined with CNC machining or grinding where required.
- Quality assurance: measurable inspection, documentation as agreed.
- Delivery: on time, securely packaged, with a measurement report on request.
The result is functional components, ready to assemble or ready to use, that integrate seamlessly into your tooling or production processes.
Quality assurance & documentation –
crucial for series production readiness
Particularly in the case of active parts and functionally critical tool components, it is not only dimensional accuracy that counts, but also process reliability and verifiability. Bonsack works with clear testing processes and documented quality. Depending on requirements, we provide support in areas including:
- measurable inspection of relevant characteristics (e.g. fit dimensions, contour accuracy, functional surfaces)
- measurement reports as agreed
- traceability for repeat production and spare parts
- packaging tailored to sensitive surfaces and contours
This means you receive not just a component but a reproducible result – in line with your quality and supply-chain requirements.
We prepare a robust offer with a realistic ramp-up.
FAQ – Frequently asked questions about
EDM, wire EDM and die-sinking EDM
What is the difference between wire EDM and die-sinking EDM?
In wire EDM a wire acts as the electrode and cuts the contour along a programmed path – ideal for precise cut profiles and openings. In die-sinking EDM a shaped electrode is used to create 3D cavities and internal geometries.
When is EDM more useful than milling?
EDM is particularly useful for hardened materials, for very tight tolerances, or where geometries are difficult to produce by milling – for example sharp internal corners, small radii or deep, slender contours. Often a combination of milling, grinding and EDM is the most economical solution.
Which materials can be spark eroded?
In principle any electrically conductive material – and regardless of its hardness. Typical materials are tool steels (including hardened), carbide as well as high-alloy steels and special alloys: precisely the materials that can barely be milled any more.
How precise is electrical discharge machining (EDM)?
In wire EDM we achieve surface finishes down to Ra 0.1 µm and taper cuts up to ± 30°. Workpieces up to 900 × 600 × 426 mm can be clamped. Which dimensional tolerance results from this depends on material, component thickness and cutting sequence – we define it with you in the tolerance concept before production starts.
What advantages does EDM offer for tool components and active parts?
EDM produces true-to-contour geometries with low mechanical load on the workpiece, which reduces distortion. It also makes contours and internal geometries possible that would be achievable mechanically only with high effort or high risk.
Can Bonsack manufacture complete tools?
Bonsack manufactures high-precision individual components for tools (e.g. inserts, active parts, spare parts), but not complete tools as overall assemblies for customers.
How long are typical delivery times?
Delivery times depend on geometry, material availability, inspection requirements and current capacity. For many projects fast implementation is possible – the best approach is to send us the drawing and your requirements so that we can propose the most economical route and a reliable date.
Do you also erode start holes?
Yes. For closed internal contours we erode start holes from Ø 0.5 to 3.0 mm on two dedicated machines, one of them CNC-controlled. Workpieces up to 650 × 300 × 200 mm are possible. Because the start hole is produced in house, the job does not lose a day to an external operation.