What to know about CNC machining Inconel?
Inconel is a nickel alloy with excellent mechanical properties that produces CNC machined parts that exhibit high-strength and corrosion resistance.
What is Inconel CNC machining?
Inconel CNC machining is the computer-controlled cutting of an Inconel workpiece—using CNC mills, lathes, drills, or multi-axis machines—to make precise parts such as turbine components, valves, manifolds, fasteners, and heat-resistant structural features.
Inconel is typically selected when strength is key, and the component will be exposed to high heat, oxidation, and corrosion. These mechanical properties make Inconel a go-to material for aerospace, chemical, and marine applications.
What are the advantages of CNC machining Inconel?
CNC machining makes Inconel practical for precision parts that must survive extreme heat, corrosion, and sustained mechanical stress. The main payoff is repeatable precision in a costly, difficult-to-cut material, helping protect both part quality and expensive raw stock.
The main advantages include:
- Extreme-service performance
- Longer component life
- Tight tolerances and consistency
- Ideal for complex geometries
- Yields better process control than other alloys
What are the challenges of CNC machining Inconel?
For all of its advantages, Inconel is difficult to machine because it's prone to work hardening, retains heat at the tool edge, and shortens your cutting tool's tool life.
The main challenges include:
- Work hardening
- Heat concentration
- Requires high cutting forces
- Sees rapid tool wear
- Chip control
- Raw material and process cost
What are the most common Inconel grades?
The two most common Inconel grades used for CNC machining are Inconel 718 and Inconel 625.
Inconel 718 is widely used in aerospace and other high-strength applications, while Inconel 625 is typically selected when corrosion resistance and weldability are essential.
| Grade | Tensile (KSI) | Yield (KSI) | Hardness | Machinability | Weldability | Corrosion Resistance |
| Inconel 718 | 185 | 150 | 38 HRC | Poor | Excellent | Good |
| Inconel 625 | 130 | 70 | 22 HRC | Moderate | Excellent | Excellent |
| Inconel 600 | 80 | 30 | 75 HRB | Moderate | Excellent | Good |
| Inconel X-750 | 180 | 140 | 350 HB | Poor | Moderate | Good |
| Inconel 617 | 110 | 51 | 173 HB | Moderate | Excellent | Excellent |
| Inconel 690 | 86 | 35 | 85 HRB | Moderate | Good | Excellent |
*Please note that these are estimates and intended to be used as a reference for engineers
How to pick the right Inconel grade?
Choosing the right Inconel grade for a machined component depends on identifying the most critical service requirement, whether that's high-temperature, corrosion resistance, strength, or fabrication method.
Quick Decision Guide
- Need maximum strength, fatigue resistance, and creep resistance in high-temperature environments? Inconel 718
- Need corrosion resistance or welding? Inconel 625
- Need general heat, oxidation, or corrosion resistance? Inconel 600
- Need extreme heat resistance? Inconel 617
What are the best surface finish options for Inconel?
For most Inconel parts, the best post-process is no coating at all: use a controlled as-machined or ground finish, then clean and deburr.
Inconel is selected because its base alloy already provides strong corrosion and high-temperature oxidation resistance; conventional anodizing is for aluminum, not a standard or useful finish for Inconel.
Inconel components are compatible with electroplating, bead blasting, electroless nickel plating, powder coating, anodizing, hand polishing, and passivation.
Important surface finish considerations:
- Specify finish only when and where it supports function
- Consider roughness as a fatigue design variable
- Define the required machining lay on sealing and sliding faces
- Prioritize tool sharpness and rigidity, as Inconel is prone to smearing
- Avoid grinding burn, excessive polishing, and uncontrolled abrasive blasting
What are best practices for designing Inconel parts?
Designing Inconel parts for CNC is about keeping the cut stable. Small geometry choices—like corner radii, pocket openness, and wall thickness—control tool access, chip evacuation, and sequence, and determine whether the tool can cut cleanly or ends up rubbing and work‑hardening the surface.
Good DFM practices for machined Inconel parts include:
- Keep sections stiff and avoid long-reach features because HRSA stays strong at high temperatures and quickly work-hardens, increasing heat and load on the cutting edge
- Use generous internal radii and avoid sharp inside corners
- Avoid straight plunges and thick-chip exits; use geometry that supports smooth tool entry and exit
- If a part needs to be aged or hardened, do as much machining as possible in the soft state
