CNC Sinker EDM Alloy Steel is a core capability at VT machining. We combine controlled EDM machining with material-aware setup for Alloy Steel — an alloy that is high strength and hardenability for demanding parts — to produce parts that meet your specification first time.
Process Data for CNC Sinker EDM Alloy Steel
| Electrode | Graphite (roughing) / copper (fine finish) |
|---|---|
| Relative removal rate | High (vs tool steel = medium) |
| Best finish | VDI 12-18 (Ra 0.4-0.8 µm) |
Shown for 4140 Alloy Steel, the most common Alloy Steel grade we see for CNC Sinker EDM. Typical values for 4140 Alloy Steel, Annealed or pre-hardened (28-32 HRC); confirmed on the first part.
CNC Sinker EDM Capability for Alloy Steel
- Blind cavities & ribs
- Fine surface (VDI grades)
- Tolerance to ±0.005 mm
- Hardened tool steel
Alloy Steel material properties, finishing options and grade notes are on our CNC Wire EDM Alloy Steel page.
How CNC Sinker EDM Alloy Steel Works
Material is removed from the Alloy Steel workpiece by controlled electrical discharges across a dielectric gap, with no mechanical contact. Flushing, on/off pulse timing and electrode/wire feed are set to balance speed against surface finish.
Programming is driven directly by your 3D model or print. Work-holding, tool selection and the cutting strategy are planned around the critical features and the material before the first chip is cut. First-off inspection confirms the process is centred before production continues.
Achievable Tolerances for CNC Sinker EDM Alloy Steel
| Feature | Standard | Precision |
|---|---|---|
| Profile dimension | ±0.010 mm | ±0.002 mm |
| Internal corner radius | 0.15 mm | 0.05 mm |
| Taper control over 50 mm | 0.02 mm | 0.005 mm |
| Surface finish (skim passes) | Ra 0.8 µm | Ra 0.2 µm |
| Recast layer | 10 µm | 2 µm (fine skim) |
| Start-hole diameter | 1.0 mm | 0.25 mm |
| Workpiece hardness | no limit (conductive) | no limit (conductive) |
Standard is what a normal quotation assumes. Precision is available on nominated features and is priced separately, because it needs extra setups, in-process gauging and CMM verification. Call out only the features that need it — blanket-tightening a drawing is the single most common reason a quote comes back expensive.
Design Tips for CNC Sinker EDM Alloy Steel
We are happy to suggest design tweaks that improve manufacturability. EDM suits sharp internal corners, thin ribs and hardened Alloy Steel that cannot be milled; allowing a small corner radius where possible speeds the cut. If you send your model early, we will return practical DFM feedback before you commit to production.
CNC Sinker EDM Tolerances & Surface Finish
EDM holds tolerances to roughly ±0.002–0.005 mm with no cutting force on the Alloy Steel part, producing fine, controlled surface textures and sharp internal corners impossible to mill.
Exact achievable figures depend on the alloy, the feature size and the part geometry. Tell us which dimensions are critical and we will advise feasibility up front.
Applications of CNC Sinker EDM Alloy Steel
Customers order CNC Sinker EDM Alloy Steel components for everything from instrumentation to structural and functional assemblies. Whether you need a single prototype or recurring production volume, the same process discipline applies.
Typical Alloy Steel Parts for CNC Sinker EDM
Illustrative examples of CNC Sinker EDM Alloy Steel parts and the callouts that usually drive the process plan. They show the kind of work that fits this process; they are not specific customer orders.
Injection mould cavity rib
- Material
- Alloy Steel
- Size
- 0.25 mm wide × 8 mm deep
- Key callouts
- Width ±0.005 mm, VDI 21 finish
- Batch
- 45 pcs
Sinker EDM with a graphite electrode; a cutter that thin would break in the first pass.
Spline broach section
- Material
- Alloy Steel
- Size
- Ø28 × 40 mm
- Key callouts
- Involute profile ±0.005 mm, Ra 0.4 µm
- Batch
- 60 pcs
Wire EDM after hardening to 62 HRC — the profile would not survive being cut soft and heat-treated.
Extrusion die
- Material
- Alloy Steel
- Size
- 120 × 120 × 25 mm
- Key callouts
- Profile ±0.005 mm, internal corner R0.1 mm
- Batch
- 35 pcs
Cut in four skim passes; the first pass is speed, the last three are finish and accuracy.
No drawing yet? Build one in the browser.
Set the metal, dimensions and features, watch the 3D model update as you type, then switch to the 2D sheet to add dimensions and tolerances. Download it or send it straight to us with your RFQ.
What We Need to Quote CNC Sinker EDM Alloy Steel
- GeometrySTEP or IGES for the 3D model, plus a PDF drawing if you have tolerance callouts. A dimensioned sketch is enough to start.
- MaterialThe exact Alloy Steel grade and condition — temper, heat-treat state or hardness. If you are not sure, tell us the function and we will suggest one.
- QuantityPrototype count and the expected annual volume. Both change how the part is made and therefore what it costs.
- TolerancesWhich features are critical. Everything else runs to our standard tolerance, which is what keeps the price sensible.
- FinishSurface treatment, cosmetic requirements, and any faces that must be masked.
- DocumentsWhether you need a material certificate, dimensional report, FAIR or PPAP with the shipment.
Missing something from the list is not a problem — send what you have. We will come back with the specific questions rather than a generic form.
Other Metals for CNC Sinker EDM
Other Processes for Alloy Steel
Send the drawing, the Alloy Steel grade and the quantity. You get pricing, lead time and any DFM notes back — usually within one business day.
Request a QuoteFrequently Asked Questions
Why is Alloy Steel a good choice for CNC Sinker EDM?
Alloy Steel is high strength and hardenability for demanding parts, which makes it well suited to CNC Sinker EDM. We tune the process to the alloy so the finished Alloy Steel EDM machining part meets your dimensional and functional requirements.
What material thickness or size range suits CNC Sinker EDM Alloy Steel?
We machine Alloy Steel across a broad size range; share your part envelope for confirmation.
Can VT machining make custom Alloy Steel parts to my drawing?
Yes. Alloy Steel EDM machining is made to order from your CAD/2D drawing. Share your geometry, material grade, tolerance and quantity and we will confirm feasibility, lead time and pricing.
What is CNC Sinker EDM Alloy Steel and how is it done?
CNC Sinker EDM Alloy Steel refers to sinker (die-sink) EDM burns a shaped electrode into metal to form precise cavities and blind features. Applied to Alloy Steel — high strength and hardenability for demanding parts — VT machining produces each part to your CAD drawing, selecting parameters from your tolerance, finish and quantity requirements.
What surface finish is achievable on Alloy Steel with CNC Sinker EDM?
Surface finish on Alloy Steel is controlled to your specification; we confirm the achievable Ra against your callout.