Monel 400 (UNS N04400) is a difficult-to-machine material that we run regularly for export customers. It has a density of 8.80 g/cm3, a tensile strength of 550 MPa and a typical hardness of HB 150. Those numbers make it the right choice for seawater valves and pump shafts, and a poor choice when cost or corrosion resistance matters more than mechanical performance.
On our machines we hold +/-0.02 mm on turned and milled features and reach Ra 1.6 um where the drawing calls for it. Standard lead time for Monel 400 parts is 4-8 working days, including material procurement, machining and any finishing operation you specify.
Monel 400: key properties
| Property | Value |
|---|---|
| UNS / designation | N04400 |
| Density | 8.80 g/cm3 |
| Tensile strength | 550 MPa |
| Hardness | HB 150 |
| Machinability | Difficult |
| Suggested cutting speed (carbide) | 40-60 m/min |
| Relative material cost | 5 of 5 |
Machining Monel 400: what to plan for
- Work hardens readily
- Gummy chips
- Magnetic-free requirement
Cutting speed for Monel 400 with carbide tooling sits around 40-60 m/min. Going faster burns the edge; going much slower causes rubbing and a poor surface. Flood coolant is not optional here. If your part has thin walls or a lot of stock to remove, say so in the RFQ — we plan roughing, stress relief and finishing as separate operations when the geometry demands it.
Parts we machine in Monel 400
- Seawater valves
- Pump shafts
- Marine fasteners
- Heat exchanger tubes
Most Monel 400 work arrives as 2D drawings with a mix of critical and non-critical features. Loosening tolerance on the non-critical ones is the fastest way to cut cost, and we will tell you which features those are before we quote.
Tolerances, finish and lead time
| Item | Capability |
|---|---|
| General tolerance | +/-0.02 mm |
| Achievable surface finish | Ra 1.6 um |
| Minimum wall thickness | 0.8 mm (aluminium) / 1.0 mm (steel and stainless) |
| Typical lead time | 4-8 working days |
| Prototype quantity | 1 piece |
| Production quantity | 10 to 50,000 pieces |
Frequently asked questions
What is the lead time for Monel 400 parts?
Standard is 4-8 working days from drawing release, assuming the material is in stock. Exotic grades and cast forms can add 5 to 10 days. Finishing such as anodizing or plating adds 3 to 5 days.
What tolerance can you hold in Monel 400?
+/-0.02 mm is routine on turned and milled features. Tighter than that is possible on specific features by grinding or lapping, but it is quoted separately because it changes the process.
Do you keep Monel 400 in stock?
We hold common sizes of Monel 400 and buy mill-certified stock for everything else. Material certificates are supplied with the parts on request.
Can you supply Monel 400 parts with a certificate of conformity?
Yes. We issue a dimensional report, a material certificate and a certificate of conformity as standard for production orders, and full PPAP or AS9102 paperwork when the programme requires it.
Related pages
- Materials — the full index for this section.
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- Inconel 718 CNC Machining: Cost, Tooling, Lead Time
- PPS CNC Machining for High-Temperature Parts
- Instant CNC quote
- Tolerance quick reference
- Frequently asked questions
Get a price for your part
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