Wire EDM & Sinker EDM Services — Specs & Pricing

Introduction

Electrical Discharge Machining (EDM) is a non‑contact process that removes material using precisely controlled electrical discharges rather than mechanical cutting. In wire EDM the cutting electrode is an extremely fine wire, usually made from brass or copper, that moves along a pre‑programmed path through the workpiece. Deionised water acts as a dielectric to conduct the electrical charge and flush away debris. Typical wire diameters range from 0.1–0.30 mm (0.004–0.012 in), allowing very tight radii and slender slots that are impossible with conventional machining.

Die‑sinking EDM—also called sinker, ram or cavity EDM—works differently. Instead of a moving wire, a 3‑D electrode shaped to the desired geometry is plunged into the workpiece while both are immersed in a hydrocarbon oil dielectric. The shape of the electrode determines the cavity formed, making this process ideal for moulds, dies and components with deep ribs, blind cavities or sharp inside corners. BACH INDUSTRY AG supplies both wire and die‑sinking EDM equipment, along with expert services for customers across Switzerland, Germany, Austria, Liechtenstein, Belgium and Africa.

How wire EDM works

When a voltage is applied between the wire electrode and a conductive workpiece, electrons jump across the gap, vaporising tiny pockets of metal. Each spark leaves a microscopic crater and is immediately quenched by the dielectric fluid. Because the wire is continuously fed from spools, only the fresh segment is used for cutting. No mechanical force touches the part, so thin walls and delicate geometries are possible. The non‑contact nature also means there is almost no tool wear and the process can machine very hard materials—tool steels, titanium, Inconel, tungsten carbide and any metal harder than RC 38.

Precision and surface finish

Wire EDM is renowned for accuracy. Typical cutting tolerances are within ±0.002 in (0.05 mm), and with multiple skim passes they can improve to ±0.0002 in (0.005 mm). Lower power and slower cutting speeds allow tolerances around ±0.0002 in, whereas higher speeds yield ±0.001 in. Surface finishes are random rather than directional; with multiple skims they can reach about 5 RMS or ~4 μin Ra, and some sources quote finishes as fine as 3 μin Ra. Because the workpiece is not distorted by cutting forces, thin walls and internal corners with very small radii are possible.

Materials and applications

Any electrically conductive material can be cut by wire EDM, including aluminium, copper, brass, tungsten, titanium and hardened steels. The process excels on exotic alloys and heat‑treated parts because hardness has little effect on cutting rate. Modern machines use CNC control with diamond wire guides and can move the upper head in additional axes to create taper cuts or complex profiles. Industries such as aerospace, medical devices, precision tooling and electronics use wire EDM to produce extrusion dies, punches, gears and intricate medical implants.

Managing the recast (white) layer

Each EDM spark melts a small volume of metal. Not all the molten metal is flushed away—some resolidifies on the surface to form a recast or white layer. This layer is enriched with carbon because hydrocarbons from the electrode and dielectric break down and infiltrate the molten metal. Beneath the white layer is a heat‑affected zone where the structure is altered but not melted. If the white layer is too thick it can contain micro‑cracks, reducing corrosion and fatigue resistance. Finishing passes with lower spark energy minimize the white layer thickness, and post‑process steps such as electropolishing can remove it entirely to restore surface integrity.

Cost considerations

Wire EDM is a premium process because it is slow compared with milling or turning; however, it often becomes economical for hard materials or complex shapes where conventional tooling struggles. An industry comparison suggests that wire EDM costs typically range from US$15–100 per hour depending on part complexity and required surface finish. Shop rates generally fall between US$50–100 per hour and there is little setup expense, which makes small batches attractive. For volumes under about 15 parts, wire EDM can be more cost‑effective than CNC machining due to the absence of custom tooling and the ability to run unattended. As volumes approach 25 pieces the costs break even, while beyond 100 parts CNC usually becomes cheaper.

How die‑sinking EDM differs

In die‑sinking EDM (also known as ram, volume or plunge EDM) the tool is a block of copper or graphite shaped to the negative form of the cavity. The electrode and workpiece are submerged in oil, and controlled sparks erode the cavity shape. Because the electrode never cuts through the part, die‑sinking EDM can produce blind cavities, deep ribs and undercuts that wire EDM cannot. It is commonly used for injection‑moulding dies, forging tools, internal splines and pockets with sharp corners.

Advantages of die‑sinking EDM

Sinker EDM is versatile and efficient for complex 3‑D shapes. It is not limited by material hardness; it can shape tungsten, hardened steel and carbide. Because the electrode is shaped in advance, multiple identical cavities can be produced with consistent quality. Methods Machine Tools notes that sinker EDM offers high throughput, smooth finishes and tight tolerances, making it cost‑effective for high‑mix, low‑volume production. However, it may require multiple electrodes for roughing and finishing passes, which adds tooling costs. The electrode must be machined with conventional CNC or wire EDM beforehand, so lead times are slightly longer.

Comparing wire and die‑sinking EDM

Although both processes use electrical sparks to erode metal without physical contact, their capabilities differ:

• Tool geometry – Sinker EDM uses a shaped electrode that sinks into the workpiece, allowing complex 3‑D cavities. Wire EDM uses a spooled wire that cuts from the side; it excels at 2‑D profiles but cannot create blind recesses.

• Movement – Die‑sinking EDM primarily moves along the Z‑axis, while wire EDM moves along X–Y and can tilt for taper cutting.

• Dielectric – Sinker EDM uses hydrocarbon oil; wire EDM uses deionised water. Oil provides better flushing for deep cavities but requires fire safety measures.

• Applications – Sinker EDM is ideal for moulds, dies, deep ribs and blind keyways. Wire EDM is suited to punches, blanking dies, extrusion dies, medical implants and any part requiring tight tolerances without deformation.

BACH INDUSTRY AG can advise customers on whether wire or die‑sinking EDM (or a hybrid strategy) is best for a given part. Our engineers often rough bulk material using conventional milling and finish complex features with EDM to optimise cost and lead time.

Parts, consumables and tooling

Reliable EDM operation depends on quality consumables. BACH INDUSTRY AG stocks a full range of wire EDM machine parts, including wear components and wire EDM spare parts for obsolete models. Our wire EDM consumables include copper and brass wire spools, zinc‑coated wires for faster cutting, wire EDM filters and wire EDM resin or resin tanks to maintain dielectric purity. We offer wire EDM diamond guides for precise wire positioning and wire EDM workholding solutions such as System 3R and EROWA tooling. Modular wire EDM fixtures, V‑blocks, vises and V‑blocks ensure repeatable setups. If you require special workholding & tooling or wire EDM accessories, our application team will source or design custom solutions.

We also supply electrodes and tooling for die‑sinking EDM, including graphite blanks, copper electrodes, collet chucks and clamping systems. Our partnership with System 3R and EROWA allows us to provide quick‑change tooling that reduces setup time. For shops using both wire and sinker EDM, we offer integrated starter hole drilling (hole‑popping) machines and wire EDM drilling modules to create start holes efficiently.

Services: from prototype to production

BACH INDUSTRY AG operate a fully equipped EDM job shop. Our precision wire EDM services deliver tight‑tolerance parts for aerospace, medical, watchmaking and micro‑mechanics. We handle everything from single prototypes to small‑lot production runs (our production wire EDM capability). Our wire EDM machining service can rough‑cut features to ±0.002 in and finish to ±0.0002 in, and we can provide surface finishes down to 4 µin Ra. We routinely machine hardened steels up to 65 HRC—parts that might cost US$300 per hour on CNC due to tool wear. We also offer micro wire EDM services for tiny components and wire EDM hole popper drilling for starter holes.

For more complex geometries we combine wire and sinker EDM. For example, sinker EDM can produce blind cavities and deep ribs, while wire EDM can finish thin slots or narrow gaps. Our staff will review your design, propose process routes and provide a wire EDM quote or die‑sinking quote through our wire EDM online quote form. We provide quick turnaround and deliver across Switzerland, Germany, Austria, Liechtenstein, Belgium and Africa.

Designing for EDM

Designing for EDM requires an understanding of kerf, corner radii and wall thickness. Wire diameters determine minimum slot widths; a 0.3 mm target slot becomes ~0.4 mm actual width due to kerf. To avoid breakage when cutting multiple narrow slots, wall thickness should be at least three times the wire diameter. For thin walls in aluminium under 0.8 mm or steel under 1.2 mm, wire EDM eliminates deflection. Because wire EDM only cuts through profiles, features such as blind pockets require sinker EDM or a combination of processes.

Part tolerance mapping also affects cost. Tight tolerances under ±0.002 mm require more skimming passes and increase machining time. Designers should apply ±0.01 mm on non‑functional features, ±0.005 mm on most functional features, and reserve ±0.002 mm only for critical mating surfaces. Our engineers can assist with tolerance optimisation to minimise cost while meeting performance.

Conclusion

Wire and die‑sinking EDM are powerful tools for machining electrically conductive materials with exceptional precision. Wire EDM uses a thin moving wire and deionised water to produce 2‑D profiles and intricate outlines without part deformation, while die‑sinking EDM uses a shaped electrode and oil dielectric to create complex 3‑D cavities. Both processes leave a recast layer that must be managed through finishing.

BACH INDUSTRY AG offer a precision wire EDM services and die‑sinking EDM services. Contact us today for a detailed quotation and discover how EDM technology can sharpen your competitive edge.