Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Monel 400 Machinability - UNS N04400 and R-405 Machining Parameters
Monel 400 machinability (also Monel 400 turning, Monel 400 drilling, Monel N04400 machining) is rated 22 on the AISI B1112 = 100 scale, the same band as 304 stainless. The alloy work-hardens aggressively, so cuts must be uninterrupted, tools sharp, setups rigid. For screw-machine production specify the free-machining variant Monel R-405 (UNS N04405) at 0.025 to 0.060 percent sulphur per ASTM B164 Table 1. Monel® is a registered trademark of Special Metals Corporation; TorqBolt is not authorized by, affiliated with or endorsed by Special Metals. TorqBolt supplies N04400 round bar and finished fasteners machined to drawing from Mumbai stock.
Monel 400 Machinability Rating
Machinability is reported against free-cutting steel AISI B1112 = 100. Monel 400 (UNS N04400) sits at ~22 percent; Monel R-405 (UNS N04405) reaches ~45 percent. The gap is sulphur: 0.024 max in N04400 versus 0.025 to 0.060 in N04405, where MnS inclusions break the chip and lubricate the interface.
| Alloy | UNS | Rating (B1112 = 100) | Chip | Use case |
|---|---|---|---|---|
| Free-cutting steel B1112 | G12144 | 100 | Short broken | Reference |
| Free-cutting brass C36000 | C36000 | ~100 | Short broken | Reference |
| 304 stainless | S30400 | ~45 | Stringy | General fab |
| Monel R-405 | N04405 | ~45 | Short broken | Screw machine, CNC bar |
| Monel 400 | N04400 | ~22 | Long stringy | Weldable parts, pressure |
| Monel K-500 (age-hardened) | N05500 | ~16 | Stringy | High-strength shafting |
| Inconel 600 | N06600 | ~12 | Stringy | High-temperature |
Annealed bar at the soft end of the tensile band machines easier than cold-drawn bar at the hard end.
Monel 400 Turning Parameters
Turn UNS N04400 with positive rake C-2 carbide (uncoated or TiAlN-coated) at 65 to 90 sfm, feed 0.010 to 0.020 ipr, depth of cut 0.060 inch minimum to engage virgin metal below the work-hardened skin. HSS-Co (M42, T15) is acceptable for prototype at 25 to 35 sfm but tool life drops sharply on production. Side-cutting-edge angle 15 degrees, top rake 6 to 10 degrees positive, nose radius 0.030 inch. Hold constant feed; tool dwell hardens the skin and the next pass ploughs.
| Operation | Tool | Speed (sfm) | Feed (ipr) | Depth (in) |
|---|---|---|---|---|
| Rough turn N04400 | C-2 carbide | 65 - 80 | 0.015 - 0.020 | 0.125 - 0.250 |
| Finish turn N04400 | C-2 carbide | 80 - 90 | 0.005 - 0.010 | 0.060 - 0.125 |
| Rough turn N04400 | HSS-Co M42 | 25 - 35 | 0.010 - 0.015 | 0.100 - 0.200 |
| Rough turn R-405 | C-2 carbide | 120 - 150 | 0.015 - 0.025 | 0.125 - 0.250 |
| Form / cut-off | C-2 carbide | 40 - 60 | 0.002 - 0.005 | tool width |
Flood sulphochlorinated mineral oil or a 10 percent water-soluble emulsion at the tool-chip interface. Coolant on the workpiece alone leaves the cutting edge dry.
Monel 400 Drilling and Tapping
Drill UNS N04400 with cobalt HSS split-point drills (M42 or M35) at 25 to 35 sfm, feed 0.005 ipr at 0.250 inch dia scaling to 0.012 ipr at 1.0 inch dia. Peck the cycle at one diameter to clear chips before the drill packs and work-hardens the hole bottom. Solid carbide drills run at 60 to 80 sfm in CNC with through-coolant.
| Operation | Tool | Speed (sfm) | Feed | Notes |
|---|---|---|---|---|
| Drill 0.250 in dia | Cobalt HSS split point | 25 - 35 | 0.005 ipr | Peck 1D |
| Drill 0.500 in dia | Cobalt HSS split point | 25 - 35 | 0.008 ipr | Peck 1D |
| Drill 1.000 in dia | Cobalt HSS split point | 25 - 35 | 0.012 ipr | Peck 1D, pilot |
| Drill (CNC carbide) | Solid carbide TiAlN | 60 - 80 | 0.004 - 0.008 ipr | Through-coolant |
| Tap 1/4-20 UNC | 2-flute spiral-point HSS | 10 - 15 | NPT pitch | Drill 75 percent thread |
| Tap 1/2-13 UNC | 3-flute spiral-flute HSS | 10 - 15 | Pitch | Sulphurised oil |
| Ream | HSS-Co or carbide | 15 - 25 | 0.005 ipr | 0.005 - 0.015 stock |
Tap to 75 percent thread engagement with a spiral-point or spiral-flute tap at 10 to 15 sfm; faster invites tap breakage on the work-hardened pilot wall. Form taps are not recommended on standard N04400.
Monel R-405 Free-Machining Variant
Specify Monel R-405 (UNS N04405) for small fasteners, nuts, fittings, ferrules or instrument components on CNC screw machines, multi-spindle automatics or Swiss-type lathes. R-405 is identical to N04400 except sulphur is held at 0.025 to 0.060 percent per ASTM B164 Table 1. MnS stringers act as in-grain chip breakers; turning feed roughly doubles and tool life triples against standard N04400.
Do not specify R-405 for welded, brazed or hot-formed parts (sulphur causes hot-shortness and weld cracking), for ASME pressure-containing parts (ASTM B564 excludes the high-sulphur variant), or for NACE MR0175 / ISO 15156 sour service. Use N04400 for those; reserve R-405 for chip-driven volume production where the part is not welded or pressure-rated.
Monel 400 vs R-405 vs K-500 vs 316L Machinability
The four reference grades for nickel-alloy and stainless-steel machine shops:
| Property | Monel 400 (N04400) | Monel R-405 (N04405) | Monel K-500 (N05500) | 316L (S31603) |
|---|---|---|---|---|
| Machinability (B1112 = 100) | 22 | 45 | 16 (aged) | 45 |
| Sulphur | 0.024 max | 0.025 - 0.060 | 0.010 max | 0.030 max |
| Annealed hardness HB | 110 - 150 | 110 - 150 | 140 - 175 | 149 max |
| Aged hardness HB | n/a | n/a | 250 - 315 | n/a |
| Work-hardening rate | High | High | High | High |
| Carbide turn sfm | 65 - 90 | 120 - 150 | 40 - 60 | 200 - 300 |
| Weldable | Yes | No | Yes (pre-age) | Yes |
| Pressure parts | Yes (ASTM B564) | No | Yes | Yes |
| NACE MR0175 sour service | Yes | No | Yes (HRC 35 max) | Conditional |
316L runs faster than Monel 400 (lower density, higher nickel equivalent). K-500 runs slower (gamma-prime precipitate raises hardness, cuts tool life). R-405 is the only one that returns a short broken chip in standard turning.
Frequently Asked Questions
Is Monel 400 hard to machine? Yes. UNS N04400 rates near 22 on the B1112 = 100 scale, comparable to 304 stainless. It work-hardens aggressively, so setups must be rigid, edges sharp, feed positive and uninterrupted. Production runs C-2 carbide at 65 to 90 sfm with 0.010 to 0.020 ipr feed; depth of cut stays 0.060 inch or greater to engage virgin material.
What is Monel R-405? Monel R-405 (UNS N04405) is the free-machining variant of Monel 400, identical to N04400 except sulphur is raised to 0.025 to 0.060 percent per ASTM B164 Table 1. MnS chip breakers cure the stringy chips. R-405 is the grade for CNC screw-machine production of nuts, fittings and small fasteners; it is not weldable, not pressure-rated and outside NACE MR0175.
Why does Monel 400 work-harden so much? Monel 400 is a single-phase FCC nickel-copper solid solution with low stacking-fault energy. Plastic deformation at the cutting edge multiplies dislocations faster than recovery removes them, so the freshly cut surface is harder than the bulk. If the next pass rides on that hardened skin, the tool ploughs and the work hardens further. Fix: positive rake, sharp edges, feed >= 0.010 ipr, depth of cut deep enough to engage virgin material below the prior pass.
Request a Quote
For machined Monel 400 (UNS N04400) or Monel R-405 (UNS N04405) parts against drawing - bolts, nuts, fittings, instrument components, custom turned parts - send drawing, quantity and certification class (EN 10204 type 3.1 or 3.2) to info@torqbolt.com or WhatsApp +91-22-66157017. Ex-Mumbai price plus heat-numbered MTC inside one working day. Domestic India 3 to 7 working days; export through JNPT.
Related: chemical composition, mechanical properties, density, heat treatment, forging, ASTM B164, ASTM B564, ASTM F468, UNS N04400, vs Monel K-500, round bar, bolts, hex nuts.
References
- ASTM B164 Nickel-Copper Alloy Rod, Bar, and Wire (UNS N04400 and N04405)
- ASTM B564 Nickel Alloy Forgings, Table 1, UNS N04400 Class A
- ASTM F468 / F468M Nonferrous Bolts, Hex Cap Screws, Socket Head Cap Screws, and Studs
- AISI B1112 = 100 free-cutting steel machinability reference scale
- Special Metals Corporation datasheet, MONEL alloy 400 and MONEL alloy R-405
- DIN 17743 Wrought Nickel-Copper Alloys, NiCu30Fe, Werkstoff 2.4360
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