Equiaxed Crystal Castings Multi-Axis Superalloy Precision Machining
Precision Milling and Turning for Equiaxed Superalloy Components
Equiaxed crystal castings are widely used for complex, high-temperature turbine parts where isotropic mechanical properties are required. These superalloys, when processed via equiaxed crystal casting, demand multi-axis CNC machining to deliver precise tolerances, aerodynamic contours, and secure mechanical interfaces for blades, vanes, nozzles, and housings.
Neway AeroTech offers high-accuracy multi-axis CNC machining of equiaxed-cast superalloy parts made from Inconel 713C, Hastelloy X, Rene 77, and Nimonic 90.
Core Capabilities for Equiaxed Casting CNC Machining
Machining equiaxed-cast components requires precise surface control, consistent material removal, and positional accuracy across complex 3D geometries.
5-axis simultaneous CNC milling for blade airfoils and curved housings
Multi-axis turning-milling for concentric interfaces, flanges, and bore alignments
Toolpath optimization using scanned casting profiles and CFD-derived geometry
Coolant-through tooling for heat management in hard-to-machine alloys
Machining solutions follow AS9100D, NADCAP, and customer-specific turbine tolerance requirements.
Superalloys Commonly Machined from Equiaxed Castings
Alloy | Max Temp (°C) | Yield Strength (MPa) | Typical Application |
|---|---|---|---|
950 | 760 | Nozzle guide vanes, turbine wheels | |
1175 | 790 | Combustor rings, exhaust frames | |
1040 | 960 | Stator segments, transition ducts | |
920 | 1265 | Valve guides, turbine segments |
These superalloys provide good weldability, oxidation resistance, and strength uniformity for multi-directional loading.
Case Study: CNC Machining of Rene 77 Nozzle Segment Set
Project Background
An industrial turbine OEM contracted Neway AeroTech to finish-machine a batch of Rene 77 equiaxed cast nozzle segments with inner vane curvature and precision platform geometry. Required tolerances: ±0.008 mm on profile surfaces, Ra ≤ 0.5 μm, and trailing edge radii of 0.2 mm.
Typical Equiaxed-Cast Components and Applications
Component | Alloy | Tolerance | Industry |
|---|---|---|---|
Nozzle Segment | Rene 77 | ±0.008 mm | |
Turbine Shroud | Inconel 713C | ±0.010 mm | |
Combustion Liner | Hastelloy X | ±0.012 mm | |
Turbine Stator Ring | Nimonic 90 | ±0.006 mm |
Each part requires multi-axis access to achieve precise fitment, sealing, and flow characteristics.
CNC Machining Challenges in Equiaxed Superalloy Parts
Surface tolerance within ±0.008 mm on variable-thickness airfoils
Tool wear control in alloys above 40 HRC hardness
Holding Ra ≤ 0.5 μm on sealing faces with barrel tools
Maintaining bore alignment across cast surfaces in multi-feature housings
Removing post-cast excess while preserving critical datum points
Multi-Axis Machining Solutions for Equiaxed Castings
Toolpath generation from 3D-scanned surfaces ensures precise removal from net-shape castings
Probing after roughing resets reference frames to hold positional tolerances under ±0.005 mm
Coolant-fed carbide cutters improve surface finish and reduce burrs in alloy cuts
Secondary EDM machining used for micro-channels and high-radius trailing edges
Post-machining heat treatment stabilizes geometry before inspection
Results and Verification
Manufacturing Methods
Parts were machined from vacuum cast equiaxed blanks using 5-axis machining centers. Toolpaths were adjusted using optical scan data to match as-cast deviations.
Precision Finishing
Ra ≤ 0.4 μm finish was achieved on sealing and airflow surfaces. Blending tools removed any transition ridges, and radii on leading/trailing edges were maintained at 0.2 mm.
Post-Processing
All parts underwent HIP and stress-relief heat treatment. Optional TBC coatings applied to gas-facing surfaces per spec.
Inspection
CMM inspection confirmed surface and geometric tolerances. X-ray checked internal structural continuity. SEM validated edge quality and microstructural soundness.
FAQs
What is the typical machining tolerance for equiaxed-cast turbine parts?
Can you machine sealing surfaces to Ra ≤ 0.5 μm?
What alloys are most common in equiaxed-cast turbine parts?
Do you support both rough and finish machining in one setup?
How are cast surface deviations handled during final CNC milling?
