CNC Swiss Machining 4340 Alloy Steel is part of VT machining's grade-specific capability. 4340 Alloy Steel is high-strength and hardenable, and we combine controlled turning with material-aware setup to produce parts that meet your specification.
CNC Swiss Machining Capability for 4340 Alloy Steel
- Cr-Mo / Ni-Cr-Mo grades
- High strength & hardenability
- Tolerance to ±0.01 mm
- Heat-treatable to 30–55 HRC
4340 Alloy Steel Material Data
| Density | 7.85 g/cm³ |
|---|---|
| Tensile strength | 655–1020 MPa |
| Yield strength (0.2%) | 415–900 MPa |
| Hardness | 197–302 HB |
| Melting point | 1416 °C |
| Thermal conductivity | 42.6 W/m·K |
| Thermal expansion | 12.3 ×10⁻⁶/K |
| Electrical conductivity | 8% |
| Machinability (C36000 = 100%) | 65% (annealed) |
| Grades we run | 4140, 4340, 8620, 20CrMnTi, 42CrMo4, 20MnCr5 |
Published typical values for 4140 (Q&T). Other grades in the family differ — the certificate supplied with your order carries the actual heat-lot figures.
Heat treatment moves the part. Anything held tighter than ±0.02 mm is machined soft, hardened, then ground or hard-turned to final size.
Machining 4340 Alloy Steel with CNC Swiss Machining
The machinability of 4340 Alloy Steel is good in annealed condition; machined soft then heat-treated to final hardness. For CNC Swiss Machining we select tooling, feeds, speeds and coolant to match, keeping the 4340 Alloy Steel workpiece stable and the result accurate.
Because we machine 4340 Alloy Steel regularly, proven settings shorten setup and keep quality repeatable across reorders.
Achievable Tolerances for CNC Swiss Machining 4340 Alloy Steel
| Feature | Standard | Precision |
|---|---|---|
| Outside diameter | ±0.05 mm | ±0.005 mm |
| Bore diameter | H9 | H6 |
| Length / shoulder position | ±0.10 mm | ±0.020 mm |
| Concentricity OD to ID | 0.05 mm TIR | 0.010 mm TIR |
| Roundness | 0.02 mm | 0.005 mm |
| Thread class | 6g / 2A | 4h / 3A |
| Surface finish, as turned | Ra 1.6 µm | Ra 0.4 µm |
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.
CNC Swiss Machining Quality & Inspection
Consistent quality comes from disciplined process control. Critical dimensions on 4340 Alloy Steel parts are checked in-process and verified at final inspection using calibrated instruments and, where required, CMM measurement. Full documentation — dimensional reports, mill certs, FAIR — is available when your programme needs it.
Design Tips for CNC Swiss Machining 4340 Alloy Steel
A few design choices make a real difference to cost and quality. Consistent diameters, standard thread forms and avoiding extremely long, slender features help 4340 Alloy Steel turned parts stay concentric and economical. If you send your model early, we will return practical DFM feedback before you commit to production.
CNC Swiss Machining Tolerances & Surface Finish
Turned 4340 Alloy Steel holds diameter tolerances to about ±0.005 mm with concentricity within 0.01 mm and good roundness. Turned finishes of Ra 0.4–0.8 µm are achievable with finishing passes and sharp tooling.
The tightest tolerances are reserved for the features your drawing flags as critical. Share your tolerance scheme and we will confirm what is realistic before quoting.
Secondary Operations & Finishing
We complete 4340 Alloy Steel components with the secondary steps your drawing calls for. We arrange heat treatment, surface treatment, marking and assembly as needed. Tell us the final spec and we will plan the full route so parts arrive ready to use.
Why 4340 Alloy Steel?
Specifying 4340 Alloy Steel for CNC Swiss Machining 4340 Alloy Steel is usually about its properties: high-strength and hardenable. Tell us the condition you need and we machine to it.
Applications of CNC Swiss Machining 4340 Alloy Steel
CNC Swiss Machining of 4340 Alloy Steel supports parts across aerospace, medical, automotive, electronics, semiconductor, energy and general industrial sectors. We scale from one-off prototypes to ongoing production while holding the same quality.
How to Order CNC Swiss Machining 4340 Alloy Steel
Ordering 4340 Alloy Steel parts is straightforward. Provide the drawing, material, quantity and any certification needs. Our engineers reply — in English — with feasibility, pricing and a realistic lead time, usually within one business day.
Finishing Options for 4340 Alloy Steel
| Finish | Thickness / effect | Why it gets specified |
|---|---|---|
| Through hardening | — | 30–55 HRC, ground afterwards for tight sizes |
| Case hardening (carburise) | 0.3–1.2 mm case | 58–62 HRC surface, tough core |
| Nitride | 0.1–0.5 mm | 900–1100 HV, minimal distortion |
| Black oxide | 1–2 µm | Cosmetic + light corrosion protection |
| Zinc / nickel plate | 5–25 µm | Corrosion protection |
| Deburr / edge break | 0.05–0.3 mm | All parts unless the drawing says otherwise |
| Bead blast | Ra 1.6–3.2 µm | Uniform matt finish, hides tool marks |
| Laser marking | — | Part number, lot code, data matrix |
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 Swiss Machining 4340 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 4340 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.
4340 Alloy Steel in Other Processes
Related
Send the drawing, the 4340 Alloy Steel condition and the quantity — pricing and lead time come back the same or next business day.
Request a QuoteFrequently Asked Questions
Which industries use CNC Swiss Machining 4340 Alloy Steel parts?
CNC Swiss Machining 4340 Alloy Steel parts are used across aerospace, medical, automotive, electronics, semiconductor and general industrial sectors — anywhere precise 4340 Alloy Steel components are required.
How clean are the edges produced by CNC Swiss Machining on 4340 Alloy Steel?
Machined 4340 Alloy Steel edges are clean and to specification; edge-break or deburring is added when your drawing calls for it.
What material thickness or size range suits CNC Swiss Machining 4340 Alloy Steel?
Turned 4340 Alloy Steel parts are produced from bar or chuck stock across a wide diameter range.
What is CNC Swiss Machining 4340 Alloy Steel and how is it done?
CNC Swiss Machining 4340 Alloy Steel refers to swiss-type machining guides bar stock through a sliding headstock for high-accuracy small, slender parts. Applied to 4340 Alloy Steel — high-strength and hardenable — VT machining produces each part to your CAD drawing, selecting parameters from your tolerance, finish and quantity requirements.
Does CNC Swiss Machining 4340 Alloy Steel require dedicated tooling?
Most 4340 Alloy Steel turning work uses standard cutting tools and CNC programs; dedicated fixtures are made only when geometry or volume requires them.
What surface finish is achievable on 4340 Alloy Steel with CNC Swiss Machining?
Surface finish on 4340 Alloy Steel is controlled to your specification; we confirm the achievable Ra against your callout.