Wexmar provides Inconel 625 CNC machining for fittings, valve trim, seal hardware, fasteners and components that must survive heat, seawater and aggressive chemicals. Alloy 625 (UNS N06625) is a nickel-chromium-molybdenum alloy strengthened by niobium in solid solution, so it is normally used in the annealed condition without an aging step. It is tough, corrosion resistant and demanding on tooling. We machine it from bar, plate and forgings at our Central New York shop in Canastota.
Inconel 625 machinability
Inconel 625 rates approximately 15 on the AISI 1212 = 100 scale. It keeps its strength at cutting temperature, work hardens rapidly and holds heat in the tool because of low thermal conductivity. Surface speeds run a small fraction of what carbon steel allows, and tool wear, notching at the depth-of-cut line and heat control drive the entire process plan.
Compared with 718, alloy 625 is softer in its usual annealed condition but more prone to gumminess and built-up edge, so it behaves somewhere between austenitic stainless and the age-hardened superalloys. Forgings and heavy plate can carry residual stress that shows up as movement after roughing. On tight-tolerance flanges and manifold blocks we rough all faces, let the part relax, then finish in a second setup on our horizontal machining centers.
Tolerances and surface finish
We typically hold plus or minus 0.0005 in. on turned diameters and plus or minus 0.001 in. on milled features in 625. Typical finishes are 63 Ra as machined and 32 Ra on sealing faces and bores, achieved with a fresh finishing edge and a single uninterrupted pass. Dimensional verification runs on our Brown and Sharpe CMMs, with reports available. These values are typical, not guaranteed.
Work hardening and tooling gotchas
- Never let the tool rub. A light pass over a work-hardened skin dulls the next edge, so feeds stay above a minimum chip thickness and finish allowances are sized to cut under the hardened layer.
- Vary depth of cut between passes to spread notch wear along the insert instead of concentrating it at one line.
- Use sharp, positive, coated carbide for finishing, and tougher grades or ceramic inserts for roughing when the setup is rigid enough.
- Flood or high-pressure coolant is mandatory for heat control, and drilling uses peck cycles with through-tool coolant where possible.
- Tapping 625 is slow and prone to breakage, so thread milling is often the safer route for internal threads.
- Burrs are tough and springy, and deburring is programmed rather than left to hand work.
Heat treat and finishing options
Because 625 does not rely on precipitation hardening, most parts are machined and shipped in the annealed condition. When a drawing calls for stress relief or a specific anneal, that work is done through qualified outside processors. Passivation, cleaning for chemical service and other surface treatments are also handled through qualified outside processors, with their certs returned with the parts.
Common Inconel 625 parts and processes
- Valve stems, seats and trim components: CNC turning on Mazak lathes
- Compression fittings, adapters and threaded bodies: lathes with live tooling and Y-axis
- Fasteners, pins and small bushings up to 32 mm diameter: Swiss-type machines with bar feeders
- Manifold blocks, flanges and brackets: 4-axis horizontal machining centers
- Seal rings and bellows end fittings for high-temperature service
Cost index versus 6061 aluminum
| Material | Approx. machinability (1212 = 100) | Cost index vs 6061 | Notes |
|---|---|---|---|
| Inconel 625 | ~15 | 7.0 | Solid-solution nickel alloy |
| Inconel 718 | ~12 annealed, ~8 aged | 8.0 | Age hardenable, higher strength |
| Hastelloy C276 | ~12 | 9.0 | Severe chemical service |
| Monel 400 | ~20 | 5.0 | Nickel-copper, seawater |
| Ti-6Al-4V | ~22 | 5.0 | Lighter, strong |
| 316 stainless | ~36 | 2.5 | Lower cost corrosion option |
| 6061-T6 aluminum | ~180 | 1.0 | Cost index baseline |
These values are typical and illustrative for a comparable part; actual quotes depend on geometry, quantity, tolerances and mill pricing.
Industries and applications
Precision Inconel 625 turned parts from our shop go to pump and fluid power manufacturers, instrumentation builders, aerospace hardware programs and defense build-to-print contracts. Typical service includes seawater systems, chemical processing equipment and hot exhaust or combustion hardware. Material certs, heat-lot traceability and FAI in AS9102 format are available. See the industries we serve, or compare Inconel 718 when higher strength is required.
Getting a quote
For alloy 625 parts, upload a drawing for an instant estimate or call (315) 400-2654. A human estimator confirms every quote and checks current nickel alloy availability and pricing before it is sent.