4140 steel is tough, strong, and easy to heat‑treat. That is why many engineers pick it for hubs that carry high torque. At CNC Rapid we cut 4140 bar into finished hubs quickly and accurately.
Why Choose 4140 Steel?
- High strength – after heat treat it can reach 930 MPa or more.
- Good fatigue life – resists crack growth under repeated loads.
- Stable size – hardens through the whole part, so thin and thick areas stay aligned.
- Predictable heat treat – easy to hit 30‑32 HRC for normal work or 38‑42 HRC for very hard use.
- Our Machining Process
Rough Machining (Soft State)
We buy certified 4140 bar. While it is still soft (about 217 HB) we turn the outside, drill the center hole, and mill pockets. High‑pressure coolant keeps the steel cool and stops hard spots.
Heat Treat
The half‑finished parts go for oil quench and double temper. We leave 0.5 mm extra on key faces so we can clean them after heat treat.
Finish Machining
After hardening, we put the hubs back on multi‑axis machines. CBN tools let us keep the surface roughness under Ra 1.6 µm and run‑out under 0.01 mm. In‑process probes adjust offsets so we do not need many setups.
Inspection
Every hub ships with an inspection report, surface finish record, and material certs. You know exactly how the part was made.
Optional Surface Coatings
- Black oxide – basic rust guard, matte look.
- Phosphate + oil – better scratch resistance.
- Zinc‑nickel plating – over 720 h salt‑spray for offshore work.
- Gas nitriding – 58‑62 HRC case up to 0.4 mm deep.
Typical Lead Times
- Prototypes (1–5 pcs): 7 days incl. heat treat.
- Small batch (≤ 100 pcs): ~14 days.
- Production (> 500 pcs/month): reserved machines.
How to Order
- Send STEP file and PDF drawing (with tolerances).
- Tell us final hardness or say “default 30‑32 HRC”.
- List any keyway, spline, or balance grade.
- Pick a surface coating, if needed.
- Choose shipping terms (DAP or DDP).
Quick FAQs
Can hard 4140 be wire‑EDM cut? Yes, good for tight keyways.
What surface finish on bearing seats? After grind we can reach Ra 0.4 µm.
How long does DDP shipping clear customs? Most steel parts clear in 24 h. We give HS codes and pre‑docs to help.
Why Choose CNC Rapid
Making 4140 steel hubs takes careful steps—rough cut, heat treat, finish cut, and full checks. CNC Rapid has refined this flow so your hubs arrive fast and fit right the first time. Upload your files today and see how simple strong parts can be.
Contact CNC Rapid Today
We invite you to take advantage of our Metal & Plastic parts machining service, ideal for both prototypes and production needs. To receive a personalized quote, simply visit our website to get quote or reach out directly to our team at [email protected] with details of your project.
For the most accurate and speedy quote, kindly include the following in your communication:
- Part Name
- 3D Drawing
- Quantity
- Material
- Tolerance Range
- Surface Finish
We appreciate your interest and look forward to serving your machining needs. Thank you for your time!
