Custom Steel CNC Machining Services
Carbon, alloy, stainless and tool steel machined to ±0.02mm for shafts, housings, valve bodies and wear parts. Turning, milling, drilling and tapping with heat treatment and surface finishing coordinated under one purchase order, from a single prototype to 10,000 pieces.
Free Consultation24h
Rapid Quote
1 pc
MOQ
±0.02mm
Dimensional Tolerance
Ra 0.8μm
Surface Roughness
Materials
| Grade | Properties | Typical Applications |
|---|---|---|
| 1045 Carbon Steel | Tensile strength 585 MPa normalized, hardness 170-210 HB, good machinability and weldability, responds well to induction hardening | Shafts, plates, gears, sprockets, fixture bodies, general machine parts |
| 4140 Chromoly Steel | Tensile strength 655 MPa annealed to 1000 MPa quenched and tempered, 28-32 HRC in the common condition, high fatigue resistance | Drive shafts, connecting rods, mold bases, clamps, high-load brackets |
| 304 Stainless Steel | Tensile strength 505 MPa, austenitic, non-magnetic, good corrosion resistance in food and general chemical exposure, gummy chip control requires sharp tooling | Food equipment parts, shafts, brackets, fasteners, sanitary fittings |
| 316L Stainless Steel | Tensile strength 485 MPa, molybdenum bearing for chloride and marine exposure, low carbon to limit sensitization at weld zones | Marine hardware, pump and valve components, chemical process parts, medical equipment frames |
| 17-4PH Stainless (630) | Tensile strength up to 1310 MPa in H900 condition, 40-44 HRC after precipitation hardening, excellent strength with moderate corrosion resistance | Valve stems, aerospace fittings, high-strength shafts, pump rods, locking pins |
| P20 Mold Steel | Pre-hardened 28-34 HRC, uniform hardness through section, good polishability and machinability without further heat treatment | Mold bases, cavity blocks, jigs, fixtures, inspection gauges |
| H13 Tool Steel | Hot work grade, 48-52 HRC after quench and temper, high hot hardness and thermal fatigue resistance, machinable in the annealed state only | Die inserts, extrusion tooling, punches, wear plates, hot shear blades |
Process Parameters
| Parameter | Standard Range |
|---|---|
| Dimensional Tolerance (Critical Features) | ±0.02 mm, ±0.01 mm on request |
| General Tolerance (ISO 2768-m) | ±0.1 mm |
| As-Machined Surface Roughness | Ra 1.6 μm, Ra 0.8 μm finish pass |
| Part Size (3-Axis Milling) | up to 1000 x 600 x 500 mm |
| Part Size (CNC Turning) | up to Ø500 x 1000 mm |
| Hardness After Heat Treatment | up to 58 HRC |
| Thread Range | M2 to M30, UNC/UNF, BSP, NPT |
| Concentricity (Turned Parts) | 0.01 mm |
| Minimum Feature Size | 0.5 mm slot, 0.5 mm wall |
| Material Stock | Bar, plate, tube, forging, cast billet |
Surface Finishes
Passivation (Stainless)
Citric or nitric acid passivation per ASTM A967 removes free iron and shop contamination from 304 and 316L surfaces. Restores the chromium oxide layer so corrosion resistance in service matches the alloy grade, and leaves no dimensional change.
Black Oxide
Conversion coating 2-4 μm for carbon and alloy steel, applied after machining to give mild corrosion protection and a matte black appearance. Often paired with light oil for tooling, fixtures and machine parts that stay indoors.
Electroless Nickel Plating
Uniform 5-25 μm nickel phosphorus deposit on complex steel geometry, including bores and threads, with hardness up to 500 HV after baking. Chosen for wear resistance and chemical protection where electroplating throws unevenly.
Zinc Plating
Alkaline or acid zinc 5-15 μm with clear, blue or black trivalent passivation for carbon steel hardware. Gives a low-cost corrosion barrier with predictable torque behaviour on threaded parts.
Bead Blasting and Polishing
Glass bead blasting produces a uniform satin surface that removes tool marks and blends transitions, while mechanical polishing reaches Ra 0.4 μm for sealing faces or visible stainless parts.
Heat Treatment
Quench and temper, case hardening, nitriding and stress relief coordinated with machining. Critical dimensions are cut after hardening so distortion does not eat the tolerance band.
Electropolishing
Electrochemical removal of 5-25 μm from stainless parts to level micro peaks, improve Ra and leave a bright, easy-clean surface for food, pharma and semiconductor hardware.
Design for Manufacturing (DFM)
- Machine critical dimensions after heat treatment, since quench and temper moves features 0.05 to 0.3 mm depending on section size
- Avoid sharp internal corners; specify fillets at least one third of the pocket depth to reduce tool wear and stress risers
- Keep tapped holes at least one diameter deeper than the thread length so taps do not bottom out
- Design walls of 0.8 mm or thicker on stainless to avoid chatter and work hardening during the finish pass
- Specify hardness only on surfaces that need it; through-hardening a whole block raises cost and slows machining
- Put ground finish callouts on sealing and bearing fits rather than across the whole part
- Allow 0.2 to 0.5 mm stock on faces that will be ground after hardening
- Avoid deep narrow slots in 316L; the material work hardens and small end mills wear quickly below 3:1 depth to width
- Provide flat datums for fixturing so second-operation setups repeat without indicating every part
- Upload STEP, IGES or DXF files and get a free DFM report within 24h covering stock size, setups, tolerances and heat treat sequence
Tooling & Capacity
| Type | Lead Time | Suitable For |
|---|---|---|
| No Tooling (Direct Machining) | 3 - 5 working days | 1 to 100 pcs covers prototypes, replacement parts and one-off fixtures on direct machining |
| Dedicated Fixture or Soft Jaw | 1 - 2 weeks | 100 to 10,000 pcs for repeat orders where setup time dominates the cost |
| Production Machining Cell | Integrated with order | 10,000+ pcs with bar feeder or pallet changer, stable annual demand |
| Heat Treatment and Finishing Line | 3 - 7 days added | Hardened parts, passivated stainless, plated carbon steel, all coordinated in house |
Quality Assurance
- Incoming stock is verified against the mill certificate, and the grade and heat number are recorded for each lot
- EN 10204 3.1 material certificates are issued with every production batch on request
- Hardness checked on heat treated lots with calibrated testers before finish machining
- First Article Inspection report carries the full dimensional data measured against the 3D model
- CMM measurement of critical features including true position, concentricity and profile
- Surface roughness on sealing and bearing faces is verified with a calibrated profilometer
- Thread gauges confirm go and no-go limits on production threads
- Inspection is done at every setup change, not only at final inspection
- SGS, Bureau Veritas or TUV third-party inspection is available at any stage of steel machining on request
- Each steel lot ships with a dimensional report, material certificate and Certificate of Origin
Applications
- Industrial shafts, spindles and drive components
- Valve bodies, stems and pump housings
- Jigs, fixtures, gauges and inspection tooling
- Mold bases, cavity blocks and die inserts
- Food processing and sanitary stainless parts
- Marine and chemical handling hardware
- Automotive brackets, mounts and structural links
- Hydraulic manifolds and cylinder components
- Machine tool wear plates and guide parts
Why Choose FHY Precision
One supplier covers carbon, alloy, stainless and tool steel, so grade selection advice comes with the quote
Critical features are held to ±0.02mm and backed by CMM data rather than a catalogue claim
Heat treatment and finishing coordinated in the same schedule, so hardened parts do not bounce between vendors
MOQ of 1 piece lets you validate a design before committing to a production batch
Free DFM report within 24h covering stock, setups, tolerances and heat treat sequence
Our quality system is documented and controlled, with third-party inspection and EN 10204 3.1 material certificates available on request
Machined in our own China plant, priced factory-direct with no trading layer
Stable capacity exists for repeat orders from a 1 pc prototype to 10,000 pc annual release
FAQ
1. What is your minimum order quantity for steel CNC machining?
MOQ is 1 piece for machined steel parts. There is no tooling charge because CNC machining cuts directly from bar or plate, so a single prototype is quoted on the same basis as a production order. Most first orders run 1 to 50 pieces, and repeat orders typically settle between 200 and 5,000 pieces per release once the drawing is fixed.
2. Which steel grades do you machine?
We machine 1045 and 4140 carbon and alloy steel, 304 and 316L stainless, 17-4PH precipitation hardening stainless, and P20 and H13 tool steel. Aluminum, brass and titanium are also available when a project mixes materials. If you are unsure which grade fits the load and corrosion conditions, send the application notes and we will recommend two options with the cost difference.
3. What tolerance can you hold on steel parts?
Critical features are held to ±0.02 mm, and ±0.01 mm is possible on short turned features and ground diameters. General dimensions follow ISO 2768-m at ±0.1 mm. On hardened parts, we machine after heat treatment so quench distortion does not consume the tolerance band, and we report actual CMM values rather than nominal targets.
4. Can you machine parts after heat treatment?
Yes. We finish machine or grind critical features after hardening, which is the usual route for 4140 at 28-32 HRC, 17-4PH in H900, and H13 at 48-52 HRC. Hardness up to 58 HRC is workable with carbide and CBN tooling. Where a part needs both soft features and hard features, we split the operations and mask the finished surfaces.
5. How long does a steel machining order take?
Prototypes and small batches ship in 3 to 5 working days after drawing approval. Orders requiring heat treatment add 3 to 7 days because the parts travel through quench, temper and finish machining in sequence. Repeat orders with a dedicated fixture typically run 7 to 12 days for 1,000 to 5,000 pieces, depending on the number of setups.
6. Do you provide material certificates?
Every lot ships with a mill certificate showing grade, heat number and chemical composition. EN 10204 3.1 material certificates are issued on request, and hardness test results are recorded for heat treated lots. If your quality plan needs the certificate before parts ship, we can send the scan with the inspection report so you can release the order in advance.
7. What surface roughness do you achieve as machined?
Standard as-machined surfaces are Ra 1.6 μm, with Ra 0.8 μm on a finish pass for sealing and bearing faces. Mechanical polishing reaches Ra 0.4 μm when a gasket or O-ring needs a finer surface. Surface roughness is checked with a calibrated profilometer and reported alongside the dimensional data on the inspection sheet.
8. Can you supply a free DFM report before we order?
Yes. Upload a STEP, IGES or DXF file and we return a DFM report within 24 hours. For steel parts the review covers stock size versus part size, the number of setups, whether tolerances are achievable in the specified grade, where heat treatment will move the part, and which features should be ground rather than milled. The report is free and carries no obligation to order.
9. How do you prevent stainless steel from work hardening during machining?
We use sharp carbide tooling with positive rake geometry, high feed per tooth and constant coolant flow, and we avoid dwelling in the cut. For 304 and 316L, a light finish pass after the semi-finish removes the hardened skin instead of cutting through it. Deep narrow slots in 316L are the main risk, so the DFM report flags any feature deeper than three times its width.
10. Do you machine 17-4PH stainless steel?
Yes. 17-4PH is machined in the solution treated condition at roughly 30 HRC and then precipitation hardened to H900 or H1025, reaching tensile strength up to 1310 MPa and hardness of 40-44 HRC. We plan the process so aging happens before the final finish pass on critical diameters, which keeps the 0.02 mm tolerance intact after the part grows slightly during aging.
11. What threads and special features can you produce?
We cut and form threads from M2 to M30, plus UNC, UNF, BSP and NPT, with go and no-go gauge verification on production threads. Cross holes, keyways, splines, serrations, knurls and fine boring are all handled in house. Thread callouts should include depth and class, since a 6H versus 6G fit changes the tap and the inspection method.
12. Can you machine large or long steel parts?
Three-axis milling covers parts up to 1000 x 600 x 500 mm, and CNC turning handles diameters up to 500 mm and lengths up to 1000 mm. Longer shafts can be machined between centers in multiple setups with a steady rest. Parts beyond these envelopes are quoted with a partner shop and managed under the same inspection plan rather than declined.
13. How are steel parts protected for shipment?
Carbon and alloy steel parts receive a rust preventive oil film or VCI paper, with edges protected by foam or plastic caps. Stainless parts are passivated and wrapped individually where appearance matters. Every carton carries a packing list and batch report, and sea freight shipments add desiccant and an inner liner so humidity does not reach bare steel during transit.
14. Do you offer third-party inspection?
Yes. We arrange inspection by SGS, Bureau Veritas or TUV at any stage you specify, from incoming material verification to pre-shipment dimensional and hardness checks. You receive a neutral report from an inspector you did not appoint, which is often what an end customer or auditor requires before accepting a first lot from a new supplier.
15. What information do you need to quote a steel part?
A 3D model in STEP or IGES, a 2D drawing with tolerances and surface callouts, the steel grade, quantity per release, and any heat treatment or finishing requirement. If the drawing is incomplete, tell us the function of the part and we will propose tolerances for the features that matter. Quotes come back within 24 hours on working days.
16. How do you handle repeat orders and consistency?
Drawings, CAM programs, fixture designs and inspection plans are archived against the part number, so a repeat order runs on the same setup and tooling as the first lot. We keep the first article report on file and compare new lots against it, which is why dimensions stay stable across releases even months apart. Fixtures are stored for two years at no charge.