# CNC Turned 316 Stainless Steel Marine and Automotive Parts

Category: Precision CNC Machined Parts
URL: https://www.machined-parts-factory.com/products/precision-cnc-machined-parts/cnc-turned-316-stainless-steel-marine-and-automotive-parts/

These are CNC turned and milled stainless steel parts, mainly in 316, for marine hardware and automotive assemblies. Typical items are shafts, bushings, deck fittings, threaded studs and sensor housings. They are produced from bar on CNC lathes, finished on mills when needed, and passivated. They suit boat equipment makers and automotive buyers who need corrosion-resistant custom parts.

- 316 stainless for salt-water and road-salt exposure
- Both ends finished on sub-spindle lathes
- Passivated after machining to remove free iron
- Material certificates available on request

## Specifications
| Spec | Value |
|---|---|
| Process | CNC turning with sub-spindle and live tooling, CNC milling |
| Materials | Stainless steel 316, 304, 303 |
| Surface Finish | Passivation, polishing, bead blasting, brushing |
| Tolerance | ±0.05 mm standard; down to ±0.005 mm on critical features |
| MOQ | 1 piece; prototypes through mid-volume runs |
| Drawing Formats | STEP, IGES, X_T, STL, DWG, DXF, PDF |
| Lead Time | Prototypes typically 3–7 working days; production usually 10–20 |
| Inspection | FAI, in-process checks, 100% critical dimensions; CMM |

## How we make it
Round parts are turned from 316 bar on CNC lathes with sub-spindles, which allow both ends to be finished without re-chucking by hand. Flats, cross holes and slots are added with live tools or on a separate mill. Because 316 work-hardens, we use sharp inserts, steady feeds and avoid dwelling in the cut, which keeps surfaces clean and threads accurate.

316 contains about 2–3% molybdenum, which improves resistance to pitting in salt water compared with 304. For dry automotive interiors, 304 or free-machining 303 is often enough and costs less to machine. Passivation removes free iron after machining; electropolishing-style polishing gives a brighter, easier-to-clean surface. Avoid pairing stainless with aluminum in seawater without isolation, as galvanic corrosion will attack the aluminum.

Diameters, thread fit and runout are checked during the run and critical features are inspected on every part before shipping. Material certificates for 316 can be supplied on request. Common uses include propeller shaft sleeves, bilge pump fittings, cleat studs, steering components, exhaust sensor bosses and automotive brackets exposed to road salt.

## FAQ
### Is 316 stainless steel necessary for marine parts?
For parts in contact with seawater or salt spray, 316 is the usual minimum because its molybdenum content resists pitting much better than 304. For parts fully submerged long-term or in warm seawater, consider duplex or super-austenitic grades. For enclosed areas on a boat that stay dry, 304 can be acceptable and reduces cost.

### Do you passivate stainless steel parts after machining?
Yes, passivation is available and recommended for 316 marine parts. Machining can leave embedded iron particles from tools and fixtures, which rust and look like the stainless is corroding. Passivation removes that free iron and restores the chromium oxide layer. Specify the standard you need, such as ASTM A967, on the drawing.

### How do I get a quote for cnc turned 316 stainless steel marine and automotive parts?
Send a 3D model (STEP or IGES) and a 2D drawing with tolerances, material, finish and quantity through the quote form or by email. An engineer replies within 24 hours on business days with price, lead time and any DFM suggestions.

Request a quote: https://www.machined-parts-factory.com/contact/#rfq — inquiry@machined-parts-factory.com — WhatsApp +86 176 2154 1688