Guides / Materials
Inconel Machining: A Buyer's Guide to Nickel Superalloy Parts
September 20, 2026
Inconel is a family of nickel-chromium superalloys built to hold strength and corrosion resistance at temperatures that would soften or oxidize most metals. That is exactly why it ends up in turbine sections, exhaust systems and downhole tools, and exactly why it is a different machining job than aluminum or standard stainless.
What makes Inconel hard to machine
Three properties drive almost every problem a shop runs into:
- Work hardening. The material hardens where the tool just cut, so a light finishing pass can be harder to cut than the rough pass before it.
- Low thermal conductivity. Heat stays concentrated at the cutting edge instead of transferring into the chip, which shortens tool life if speeds are not adjusted for it.
- High strength at temperature. The property that makes Inconel useful in a turbine also means it resists deformation under the cutting tool, so the machine needs rigidity and the fixturing needs to hold the part without letting it move.
A shop that runs Inconel regularly has already solved these with the right tooling grade, coating and speeds. A shop new to the alloy is usually rediscovering them on your part.
The grades buyers ask for most
| Grade | Why it gets specified | Machining note |
|---|---|---|
| Inconel 718 | Age-hardenable, high strength after heat treatment. The default for aerospace and gas turbine parts. | Machined easier before aging, harder after. Sequence matters. |
| Inconel 625 | Solid-solution strengthened, not age-hardenable. Chosen for corrosion resistance and weldability. | Slightly more forgiving than 718, still work-hardens fast. |
| Inconel 825 | Stress corrosion cracking resistance in sour, chloride-heavy environments. | Common in oil and gas downhole tools and valve trim. |
| Inconel 600 / 601 | High-temperature oxidation resistance for furnace and heat-treat fixtures. | Lower demand, fewer shops stock it, expect a longer quote cycle. |
If the grade is not yet chosen, start with our guide to nickel alloy selection. If the part runs hot, start with our guide to high temperature nickel alloys.
What drives the quote
Setup and tooling cost dominate small orders. A shop pricing 718 has to account for tool wear that would be unusual on steel, plus the raw material itself, which runs many times the cost of mild steel by weight. Tolerance matters more here than on easier alloys: every finishing pass fights work hardening, so a tolerance tighter than the part actually needs adds real machine time, not just inspection time.
Material certification is its own line item. Inconel stock from an unfamiliar mill without a verified certificate is a real risk on aerospace and energy parts, since a substitute alloy can look similar to the eye. Positive material identification (PMI) testing on incoming stock catches this before it becomes a delivered part with the wrong material behind it.
Writing an RFQ that gets a real quote
The fastest way to a usable quote is giving a shop everything it needs to price the job without a back-and-forth first:
- Grade and any spec standard (AMS, ASTM) the part must meet
- A STEP or IGES model plus a PDF drawing with tolerances called out
- Quantity, including realistic annual volume if this repeats
- Any FAI, mill cert or PMI requirement, stated up front
- Whether an NDA is needed before the drawing moves further
Qualifying a shop before you commit
Ask what alloy it runs most, not just whether it can run Inconel. A shop that names 718 or 625 by grade and can speak to typical cycle times has almost certainly run real production, not one prototype. Ask how it verifies incoming material and whether FAI is standard or an add-on. A shop that treats these as routine, not exceptional, is usually the one that will hold your tolerance on the second run as well as the first.
If you have a drawing ready, send it and we will match it with shops that already do this work.
Frequently asked questions
Is Inconel hard to machine?
Yes, compared with aluminum or standard stainless. It work-hardens as the tool passes over it, holds heat at the cutting edge instead of carrying it away in the chip, and stays strong at temperatures that would soften most steels. Shops without the right tooling and speeds burn through carbide fast and still miss tolerance.
Which Inconel grade should I specify?
If you are not sure, describe the application (temperature, corrosion exposure, whether the part is welded) and let the shop or your RFQ match confirm the grade. 718 dominates aerospace and turbine work. 625 is common where weldability and corrosion resistance matter more than strength at high temperature.
Can a general CNC shop machine Inconel?
Some can machine small, simple Inconel parts adequately. Complex geometry, tight tolerance or aerospace paperwork usually needs a shop that runs the alloy often enough to have the tooling, speeds and inspection process dialed in.
Need a quote for this part?
Send the drawing. We match you with up to 3 Inconel-capable shops and reply within 24 business hours.
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