CNC Milling Steel is a core capability at VT machining. We combine controlled machining with material-aware setup for Steel — an alloy that is strong, economical, widely available carbon/alloy grades — to produce parts that meet your specification first time.
Starting Parameters for CNC Milling Steel
| Cutting speed (carbide) | 190-330 m/min |
|---|---|
| Feed per tooth | 0.035-0.123 mm |
| Spindle speed, Ø10 mm end mill | 6050-10500 rpm |
| Insert / tool class | ISO P — CVD-coated carbide |
| Coolant | Emulsion (5-8%); dry is possible for interrupted cuts |
| Thermal growth, 100 mm part, +10 °C | 11.7 µm (CTE 11.7 µm/m·K) |
Shown for 1018 Steel, the most common Steel grade we see for CNC Milling. Starting values for 1018 Steel, Cold-drawn; optimised on the first article.
CNC Milling Capability for Steel
- 3-, 4- and 5-axis capability
- Tolerance to ±0.01 mm
- Pocket/slot/contour features
- Spindle speeds to 12,000+ rpm
Steel Material Data
| Density | 7.85 g/cm³ |
|---|---|
| Tensile strength | 585 MPa |
| Yield strength (0.2%) | 450 MPa |
| Hardness | 170 HB |
| Melting point | 1420–1460 °C |
| Thermal conductivity | 51.9 W/m·K |
| Thermal expansion | 11.5 ×10⁻⁶/K |
| Electrical conductivity | 9% |
| Machinability (C36000 = 100%) | 57% |
| Grades we run | 1018, 1045, 1215, A36, S45C, St37, 4140 (see alloy steel) |
Published typical values for 1045. Other grades in the family differ — the certificate supplied with your order carries the actual heat-lot figures.
Rust. Bare steel flash-rusts within hours in a humid container, so parts are oiled or passivated before packing unless you specify otherwise.
How CNC Milling Steel Works
Rotating multi-flute cutters remove material as the Steel workpiece is driven through programmed tool paths on 3-, 4- or 5-axis machining centres. Climb milling, step-over and depth-of-cut are set so chip load stays in the ideal band for the alloy.
We start from your supplied geometry and tolerance scheme. The setup is designed to minimise re-clamping, which protects positional accuracy across features. A first article is verified against the drawing before the balance of the batch is released.
Achievable Tolerances for CNC Milling Steel
| Feature | Standard | Precision |
|---|---|---|
| Linear dimension (< 100 mm) | ±0.05 mm | ±0.010 mm |
| Linear dimension (100–300 mm) | ±0.10 mm | ±0.025 mm |
| Hole diameter (reamed) | H9 | H7 |
| True position of hole pattern | ±0.10 mm | ±0.025 mm |
| Flatness over 100 mm | 0.05 mm | 0.015 mm |
| Perpendicularity | 0.10 mm | 0.020 mm |
| Surface finish, as machined | 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.
Working with Steel
Steel is strong, economical, widely available carbon/alloy grades. We translate those properties into a process plan: the right tooling, speeds, feeds and fixturing for the alloy.
Where the grade, temper or heat-treat condition matters to performance, we confirm it with you and can supply material certificates. Material is procured to recognised standards for consistent, repeatable results.
CNC Milling Tolerances & Surface Finish
For CNC Milling, dimensional and positional tolerances around ±0.01 mm are routine, tightening toward ±0.005 mm on precision setups. Surface finish on machined faces typically falls in the Ra 0.4–1.6 µm range depending on tooling and pass strategy.
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.
Design Tips for CNC Milling Steel
Small design adjustments often cut cost and lead time. Generous internal radii, sensible pocket depth-to-width ratios and avoiding very thin unsupported walls all reduce cost and improve accuracy in Steel. If you send your model early, we will return practical DFM feedback before you commit to production.
Applications of CNC Milling Steel
Steel parts made this way are found throughout aerospace, medical, automotive, electronics and industrial equipment. Prototype, bridge and production volumes are all welcome.
Typical Steel Parts for CNC Milling
Illustrative examples of CNC Milling 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.
Manifold block
- Material
- Steel
- Size
- 120 × 60 × 45 mm
- Key callouts
- Cross-bore intersection ±0.05 mm, ports G1/8", leak-tested to 10 bar
- Batch
- 80 pcs
Deburred internally with a brush tool; a burr at a cross-bore is what fails the leak test.
Heat sink base
- Material
- Steel
- Size
- 200 × 100 × 8 mm
- Key callouts
- Fin thickness 1.2 ±0.05 mm, base flatness 0.03 mm
- Batch
- 500 pcs
Fins cut with a slotting cutter in one pass to avoid the deflection a step-over leaves.
Vacuum chamber flange
- Material
- Steel
- Size
- Ø180 × 20 mm
- Key callouts
- Knife-edge seal Ra 0.4 µm, bolt circle ±0.05 mm
- Batch
- 60 pcs
Sealing face finished last, then handled in gloves and bagged straight off the machine.
Finishing Options for Steel
| Finish | Thickness / effect | Why it gets specified |
|---|---|---|
| Black oxide | 1–2 µm | Mild corrosion resistance, no dimensional change |
| Zinc plate + clear/yellow | 5–12 µm | ASTM B633, general corrosion protection |
| Nickel plate (electroless) | 10–25 µm | Uniform in bores, 500 HV after bake |
| Phosphate | 5–10 µm | Paint key, mild lubricity |
| Powder coat | 60–120 µm | RAL colours |
| 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 Milling 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 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 Milling
Other Processes for Steel
Send the drawing, the 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
Which industries use CNC Milling Steel parts?
CNC Milling Steel parts are used across aerospace, medical, automotive, electronics, semiconductor and general industrial sectors — anywhere precise Steel components are required.
What material thickness or size range suits CNC Milling Steel?
We machine Steel across a broad size range; share your part envelope for confirmation.
Why is Steel a good choice for CNC Milling?
Steel is strong, economical, widely available carbon/alloy grades, which makes it well suited to CNC Milling. We tune the process to the alloy so the finished Steel machining part meets your dimensional and functional requirements.
How clean are the edges produced by CNC Milling on Steel?
Machined Steel edges are clean and to specification; edge-break or deburring is added when your drawing calls for it.