VT machining offers CNC Milling for 440C Stainless Steel (UNS S44004 / 1.4125 / SUS440C), typically supplied annealed or hardened. Highest hardness/wear resistance of stainless; hardened parts are finish-ground.
CNC Milling Notes for 440C Stainless Steel
440C Stainless Steel mills well with conventional strategies; finishing passes are planned to meet flatness and finish callouts.
For estimating, a 100 × 100 × 10 mm block of 440C Stainless Steel weighs about 0.77 kg.
Starting Parameters for CNC Milling 440C Stainless Steel
| Cutting speed (carbide) | 90-165 m/min |
|---|---|
| Feed per tooth | 0.028-0.088 mm |
| Spindle speed, Ø10 mm end mill | 2860-5250 rpm |
| Insert / tool class | ISO M — positive-rake PVD/CVD carbide |
| Coolant | Flood emulsion (8-10%) or high-pressure coolant |
| Thermal growth, 100 mm part, +10 °C | 10.2 µm (CTE 10.2 µm/m·K) |
Starting values for 440C Stainless Steel, Annealed or hardened; optimised on the first article.
440C Stainless Steel Data Relevant to CNC Milling
| Equivalent designations | UNS S44004 / 1.4125 / SUS440C |
|---|---|
| Key composition | Cr 16-18%, C 0.95-1.2% |
| Typical supply condition | Annealed or hardened |
| Hardness (typical) | Up to ~58-60 HRC |
| Machinability rating | 40% (AISI B1112 = 100%) |
Typical values; we work to your drawing and mill certificate.
How 440C Stainless Steel Differs
Highest hardness/wear resistance of stainless; hardened parts are finish-ground.
Typical applications: Bearings, valve seats, nozzles, knives.
440C Stainless Steel vs Similar Grades
| 440C Stainless Steel | 431 Stainless Steel | 430 Stainless Steel | 17-4 PH Stainless Steel | |
|---|---|---|---|---|
| Key composition | Cr 16-18%, C 0.95-1.2% | Cr 15-17%, Ni 1.25-2.5% | Cr 16-18% | Cr 15-17.5%, Ni 3-5%, Cu 3-5%, Nb |
| Hardness | Up to ~58-60 HRC | ~25-40 HRC | ≤88 HRB | ~28-44 HRC by condition |
| Tensile (MPa) | ≥760 annealed | ~860 (H&T) | ≥450 | 930-1310 |
| Machinability % | 40 | 45 | 54 | 48 |
| Typical use | Bearings, valve seats, nozzles, knives | Pump shafts, marine fittings, aircraft fasteners | Appliance panels, trim, magnetic parts | Aerospace, oil & gas, medical instruments |
More on CNC Milling Stainless Steel
Finishing options, quality documentation and general cnc milling guidance for all stainless steel grades are on our CNC Milling Stainless Steel page.
No drawing yet? Sketch the part in our free 3D + 2D builder and send it with your RFQ.
Quoting CNC Milling 440C Stainless Steel
Send a STEP/IGES model or PDF drawing, confirm 440C Stainless Steel and its condition (we usually see it supplied annealed or hardened), the quantity, critical tolerances and any finish or certificate requirements.
440C Stainless Steel in Other Processes
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Send the drawing, the 440C Stainless Steel condition and the quantity — pricing and lead time come back the same or next business day.
Request a QuoteFrequently Asked Questions
Can VT machining make custom 440C Stainless Steel parts to my drawing?
Yes. 440C Stainless Steel 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 surface finish is achievable on 440C Stainless Steel with CNC Milling?
Surface finish on 440C Stainless Steel is controlled to your specification; we confirm the achievable Ra against your callout.
Does CNC Milling 440C Stainless Steel require dedicated tooling?
Most 440C Stainless Steel machining work uses standard cutting tools and CNC programs; dedicated fixtures are made only when geometry or volume requires them.
What tolerances can you hold for CNC Milling 440C Stainless Steel?
Achievable tolerances for 440C Stainless Steel machining depend on the alloy, geometry and feature size. Milling holds positional and dimensional tolerances to around ±0.01 mm, tighter with precision setups. Exact figures are confirmed against your drawing callouts.