Wire EDM

What wire EDM does that a cutter cannot

Carbides, titanium alloys and hardened tool steels are very difficult to machine conventionally, and the reference says electrical discharge machining can machine them precisely (source 1). Wire EDM does it with discharges between a thin wire, usually brass, and the workpiece, submerged in a dielectric fluid, typically deionized water, and without high cutting forces (source 1). That is why a profile can be cut in a punch that is already hard, and why carbide, which is very difficult to machine conventionally, can be profiled (source 1).

A2 is described as a common general-purpose tool steel and the most commonly used air-hardening variety, used for blanking and forming punches and trimming dies (source 2), and an A2 data sheet lists punches and dies among its typical applications (source 7). D2 carries 1.5% carbon and 11-13% chromium, is very wear resistant but not as tough as lower-alloyed steels, and is widely used for shear blades and industrial cutting tools (source 2). M2 is a high-speed steel; the reference puts high-speed steels above 60 HRC when hardened, with more abrasion resistance than common carbon and tool steels (source 4). Cemented carbide is carbide particles bound in a metal binder, used for wear parts and metal-forming tools, and the reference says it suits situations where other cutting tools would wear away faster, such as high-quantity production runs (source 5). The grade and the hardness go on the print, and steel parts covers the family.

Kerf, corners, and taper: the numbers

The wire leaves a slot, the kerf, that is wider than the wire itself because of the spark gap. With 0.25 mm (0.0098 in) brass wire the reference gives an average kerf of 0.335 mm (0.0132 in), described as the best balance of cost and machining time, and with 0.02 mm wire a kerf of 0.021 mm (0.00083 in) (source 1). Corners follow from the wire. A design-rule article gives the rule that the wire diameter has to be less than double the minimum internal corner radius, so a smaller inside radius calls for a finer wire, and it notes that the wire dwells at an inside corner and leaves a slight overcut (source 3). If a mating part needs a particular inside radius, put it on the print and the quote answers it.

Taper is possible because the upper guide can move independently of the lower one, which allows tapered and transitioning shapes, a circle at the bottom and a square at the top for example (source 1). Call the angle and the land depth out on the drawing and the taper is quoted from the print.

What a profile is quoted to

Profiles are quoted to ±0.0002 in on the critical dimensions you call out. The general profile can carry a wider tolerance, so mark the tight features and leave the rest at a general tolerance. Surface roughness is called out on the print; ASME B46.1 is the standard that defines surface texture, roughness included (source 6). Put a roughness callout where it matters and leave it off where it does not. A finish called out on the print is quoted with the part.

State the material and the hardness on the print. Where a ground diameter, a flat face, or a ground hole to the print’s tolerance sits alongside the EDM profile, that is precision grinding, quoted with the part. CNC machining tolerances covers how to choose the band for each feature.

Punch and die work, and the other parts that come here

The bread and butter is tooling: pierce and form punches profiled to match an existing die, die buttons and cavities, trim blades, and matched punch-and-die sets quoted together. A replacement punch for a die whose drawings are long gone is a normal request; send a new sample part and it gets measured and drawn first, quoted as its own line. Send a new part, not the worn one. Wear changes the sizes that matter. The sample ships back with the parts.

Beyond tooling: gauges and checking-fixture details with profiled openings, splined bores and keyways in hardened shafts, thin stainless or titanium parts that would distort under a cutter, and carbide wear strips and inserts. Most of these are a milled or turned part with one wire-cut feature, and they are quoted as one job.

Single pieces and tight tolerance

One punch is a normal order, and so is one carbide blade or one hardened keyway plate. There is no minimum, and a single hardened part with a tight profile is a one-off that a person reads and prices step by step. Ask for more than one quantity, such as 1, 25 and 100, and the quote shows each. Quotes come back in 24-48 hours. Lead time starts at order approval. Put your need date in the part description and the quote answers it.

From request to inspected part

1. Send a STEP file and a PDF drawing through the quote form, or a DXF with the material and thickness for a simple profile. State the material and the hardness.

2. A person reads the print, checks the internal corners against the wire, and flags any callout tighter than the function needs. That is the free DFM review.

3. A quote comes back in 24-48 hours: material, price, lead time, and a matched-set or spare-set price alongside a single piece when useful.

4. On approval the order covers the wire-cut profile and any ground features the print calls out, and parts come back finished and inspected.

5. Every part is inspected against your print before it ships. Shipping is quoted as its own line, or ships on your carrier account.

Sources

All accessed 4 October 2026. Where a figure here differs from your print, the print governs.

1. Wikipedia, "Electrical discharge machining": en.wikipedia.org/wiki/Electrical_discharge_machining (wire usually brass, dielectric typically deionized water, no high cutting force; carbides, titanium alloys and hardened tool steels machined precisely; average kerf 0.335 mm with 0.25 mm brass wire, 0.021 mm with 0.02 mm wire; independent upper-guide motion cuts taper).

2. Wikipedia, "Tool steel": en.wikipedia.org/wiki/Tool_steel (A2 as the most commonly used air-hardening variety, used for blanking and forming punches and trimming dies; D2 composition, wear resistance and lower toughness, use for shear blades and industrial cutting tools).

3. Wikipedia, "Rule-based DFM analysis for electric discharge machining": en.wikipedia.org/wiki/Rule-based_DFM_analysis_for_electric_discharge_machining (wire diameter less than double the minimum internal corner radius; overcut at a sharp inside corner).

4. Wikipedia, "High-speed steel": en.wikipedia.org/wiki/High-speed_steel (M2 named as a high-speed steel; high-speed steels above 60 Rockwell C when hardened, with more abrasion resistance than common carbon and tool steels).

5. Wikipedia, "Cemented carbide": en.wikipedia.org/wiki/Cemented_carbide (carbide particles cemented by a metal binder; wear parts and metal-forming tools among the uses; suits situations where other cutting tools would wear away faster, such as high-quantity production runs).

6. ASME B46.1-2019 (R2026), "Surface Texture (Surface Roughness, Waviness, and Lay)": asme.org/codes-standards/find-codes-standards/b46-1-surface-texture (the standard defines surface texture and its constituents: roughness, waviness and lay).

7. Hudson Tool Steel, "Data Sheet - A2", hudsontoolsteel.com/technical-data/steelA2Knife, undated (punches and dies among the typical applications of A2).