EDM Explained: Wire EDMs vs Sinker EDMs for Australian Workshops

What Is EDM and Why Does It Matter?

EDM stands for Electrical Discharge Machining. Instead of cutting with a physical tool, EDM removes material using controlled electrical sparks between an electrode and the workpiece, usually submerged in a dielectric fluid.

Because there is no mechanical contact between the tool and the workpiece, EDM produces no cutting forces, no deflection, and no mechanical stress. That means it can machine any electrically conductive material, regardless of hardness. Hardened tool steels, tungsten carbide, titanium, Inconel, and other superalloys that would destroy conventional cutting tools are all fair game for EDM.

For Australian workshops, EDM fills a specific gap. It handles jobs that milling and turning simply cannot do, such as intricate internal profiles, micro features, and high-hardness materials that need to hold tight tolerances.

The Three Types of EDM

There are three main types of EDM machine. Each one does a different job.

Wire Cut EDM (Wire EDM)

A wire EDM uses a thin, continuously moving brass or coated wire (typically 0.25 mm diameter, with fine wire options down to 0.05 mm) as the electrode. The wire cuts through the workpiece like a bandsaw cuts timber, except the “blade” never touches the material. The workpiece is submerged in deionised water, and controlled sparks between the wire and workpiece erode the material along a programmed path.

Wire EDMs cut 2D profiles through the full thickness of a workpiece. With U and V axes that tilt the wire, they can also produce tapered cuts and complex 3D geometries. All wire EDM machines are effectively 5-axis: X, Y, and Z for positioning, plus U and V for taper control.

Common applications: Stamping dies, extrusion dies, precision gears, aerospace components, medical device parts, and any profile requiring tight tolerances in hard materials.

Sinker EDM (Die Sinking EDM / Ram EDM / “Sparker”)

A sinker EDM uses a custom shaped electrode, typically made from graphite or copper, which is plunged into the workpiece submerged in dielectric oil. The electrode shape is replicated as a cavity in the workpiece with micron-level precision. Think of it like a reverse mould: the electrode’s shape becomes the cavity.

Sinker EDMs excel at creating complex 3D cavities, textured surfaces, and features that would be impossible or impractical to produce with conventional machining.

Common applications: Injection mould cavities, forging dies, turbine blade root forms, complex internal geometries, and surface texturing for moulds.

EDM Hole Drilling (Small Hole EDM)

An EDM drill uses a rotating tubular electrode to “drill” precise holes, often as small as 0.1 mm diameter, through extremely hard materials. It is commonly used to create start holes for wire EDM, cooling holes in turbine blades, and fuel injection nozzles.

Wire EDM vs Sinker EDM: Which One Do You Need?

The simple way to think about it: wire EDM cuts profiles through a workpiece; sinker EDM creates cavities into a workpiece.

Factor	Wire EDM	Sinker EDM
What it does	Cuts 2D profiles through the full thickness of material	Creates 3D cavities and complex shapes into material
Electrode	Thin wire (0.05 to 0.3 mm), continuously fed from spool	Shaped graphite or copper electrode, custom-made per job
Dielectric fluid	Deionised water	Dielectric oil
Typical accuracy	±1.5 to ±3 µm (depending on machine and number of passes)	±5 to ±10 µm (higher precision achievable on premium machines)
Surface finish	Ra 0.06 to 0.8 µm (depends on number of cutting passes)	Ra 0.1 to 0.8 µm (depends on electrode and process)
Best suited for	Punches, dies, profiles, gears, precision components	Mould cavities, forging dies, 3D contours, micro features
Ongoing consumable	Wire (brass or coated), deionised water, filters, resin	Electrodes (graphite or copper), dielectric oil, filters
Typical entry point	Most workshops start here	Primarily mould and die shops

For most general engineering workshops in Australia considering their first EDM machine, a wire EDM is the more versatile starting point. It handles a broader range of work, and the wire itself is a relatively low-cost consumable compared to custom-made sinker electrodes.

Sinker EDMs become essential when you are producing injection mould tooling, complex 3D cavity work, or surface texturing that cannot be achieved any other way.

How Wire EDM Compares Across Leading Brands

There are only about 10 wire EDM manufacturers in the world that design and build their own technology from the ground up, including the software and controller to run it. This is fundamentally different from the milling and turning world, where dozens of machine builders can buy a Fanuc or Siemens controller off the shelf and bolt it on. In wire EDM, every manufacturer develops their own proprietary controller, discharge technology, and software. You cannot buy a wire EDM “controller” separately: it is integrated into the machine’s core technology.

The key players globally are:

• Japan: Fanuc, Mitsubishi, Sodick, Seibu, Makino
• Taiwan: AccuteX, Chmer
• Europe: GF Machining Solutions (AgieCharmilles), ONA

Here is how some of the major brands compare on the factors that matter most to Australian workshops.

Controller and Ease of Use

Fanuc uses its own proprietary CNC system, the same family found in their robots and machining centre controllers. It is a proven, reliable platform, but it is not PC-based, which can make troubleshooting more involved. From our experience, the Fanuc controllers used in their EDM machines do not always have as many diagnostic sensors built in, so when a fault occurs, the controller may report that a problem exists without pinpointing exactly where it is.

AccuteX, Chmer, and Sodick all use PC-based controller platforms (Windows-based operating systems), which tend to offer more intuitive interfaces, easier diagnostics, and simpler connectivity. AccuteX’s latest controller includes built-in CAD/CAM software, allowing operators to draw and generate NC code directly on the machine without needing a separate computer or software licence.

Drive Systems: Linear Motor vs Ball Screw

This is one of the most significant technical differences between brands. There are two main drive technologies used in wire EDMs:

Ball screw drives are the traditional approach. A rotating screw turns to move the axis. They are proven and reliable, but they involve mechanical contact. Over time, ball screws wear, develop backlash, and require replacement or repair.

Linear motor drives are non-contact and magnetic. Because there is no physical contact, there is no wear, no backlash, and no degradation of positioning accuracy over time. Linear motors also provide faster servo response, which is important for maintaining consistent spark gaps during cutting.

AccuteX has been developing in-house shaft-type linear motors since 2013 and reports no faults or damage across their installed base since introduction. On AccuteX machines, linear motor drives improve cutting speed by 8 to 10% due to faster servo response in the discharge gap. Fanuc’s Robocut range on the other hand, uses ball screw drives.

Brand	Drive System	Controller Type
AccuteX (Taiwan)	Shaft-type linear motor (standard on higher models, optional on entry)	PC-based Windows, 64-bit industrial PC, built-in CAD/CAM
Fanuc (Japan)	Ball screw	Proprietary Fanuc CNC (not PC-based)
Chmer (Taiwan)	Ball screw (linear motors available as optional extra on some models)	PC-based Windows

Accuracy and Surface Finish

All leading wire EDM brands are capable of producing parts well within the tolerances required by most Australian workshops. The differences tend to emerge at the top end of precision:

Japanese machines (Sodick, Seibu, Mitsubishi) generally achieve the highest absolute accuracy, but at a significantly higher price point.

Taiwanese machines (AccuteX, Chmer) sit in the upper-middle tier for accuracy and offer strong value for money. AccuteX publishes data showing 95.45% of workpieces fall within ±1.5 µm accuracy when cutting 100 holes of 6 mm continuously in SKD-11 material at 30 mm thickness. Their top-end AP series achieves pitch accuracy of less than ±3 µm across a 400 x 300 mm cutting area.

Surface finishes of Ra 0.06 µm are achievable on premium AccuteX models with the MST (Micro Sparking Technology) option, and similarly fine finishes are standard capability on Sodick and Mitsubishi machines.

For the majority of work done in Australian workshops, the practical accuracy differences between a well-maintained Taiwanese machine and a Japanese machine are unlikely to affect the finished part.

Where Does Each Brand Sit in the Market?

Tier	Brands	Characteristics
Premium (highest accuracy, highest price)	Sodick, Seibu, GF (AgieCharmilles), Mitsubishi	Top-end precision, often specified for aerospace, medical, semiconductor. Price reflects brand premium and absolute accuracy.
Upper-mid (strong accuracy, strong value)	AccuteX, Chmer, Fanuc Robocut	Proven accuracy for general engineering, toolmaking, and mould work. Competitive pricing. In-house technology.
Entry (budget)	Various Chinese brands	Lower cost, lower accuracy, limited global support.

What to Look for When Buying a Wire EDM in Australia

If you are considering adding a wire EDM to your workshop, here are the key questions to work through:

1. What is the largest workpiece you need to cut? Check the X/Y/Z travel and the maximum workpiece weight. A 400 x 300 mm travel machine handles most general work. Larger moulds or dies may need 600 x 400 mm or above.

2. What accuracy and surface finish do you actually need? Be honest about this. Many workshops pay a premium for accuracy they will never use. If your typical work requires ±5 µm or better, a well-specified mid-range machine will serve you well.

3. Auto Wire Threading (AWT)? AWT is essential for unattended overnight operation. If the wire breaks at 2 am, the machine needs to re-thread automatically and resume cutting. All leading brands offer AWT, but the reliability and speed of the system varies.

6. What consumables are involved? Budget for ongoing wire costs (brass wire is the standard), deionised water and resin, and regular filter changes. These are modest costs, but they add up over time.

Frequently Asked Questions

Can a wire EDM replace a sinker EDM? No. They do different jobs. A wire EDM cuts profiles through material. A sinker EDM creates cavities into material. Some jobs can only be done by one or the other. Many mould and die shops run both.

How thick can a wire EDM cut? Most wire EDMs can cut workpieces up to 200 to 300 mm thick as standard. Larger machines like the AccuteX AU-1400 handle workpieces up to 800 mm in Z-axis height.

Is EDM safe? Yes. The process takes place submerged in fluid, enclosed behind guarding. There is no flying swarf, no heavy cutting forces, and no exposed moving parts during operation. EDMs are among the safest machine tools in a workshop.

What brands does QMT supply? QMT Machinery is the exclusive Australian distributor for AccuteX, offering wire cutting EDMs (GA, AU, AZ, AL, and AP Series), sinker EDMs (CM Series), and EDM drilling machines (AH Series). All machines are manufactured in Taichung, Taiwan.

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