Superalloy Inconel 713 Turbine Vane Electro-Thermal Material Removal
Introduction to Electro-Thermal Material Removal for Inconel 713 Turbine Vanes
Electro-thermal material removal, primarily through Electrical Discharge Machining (EDM), is essential for achieving dimensional precision in Inconel 713 turbine vanes. This process enables defect-free feature machining in investment-cast superalloy parts with excellent control over thermal deformation and microstructure integrity.
At Neway Aerotech, we specialize in EDM processing of Inconel 713, especially for turbine vane components requiring fine features, high temperature stability, and strict quality compliance.
EDM Machining Technology Overview
Classification of EDM Machining
EDM Process | Surface Roughness (Ra, μm) | Dimensional Tolerance (mm) | Aspect Ratio | Heat Affected Zone (HAZ, μm) | Min. Feature Size (mm) |
|---|---|---|---|---|---|
Wire EDM | 0.3–1.2 | ±0.002–±0.01 | Up to 20:1 | 2–5 μm | ~0.1 |
Sinker EDM | 0.4–2.5 | ±0.005–±0.02 | Up to 10:1 | 5–10 μm | ~0.2 |
Hole Drilling EDM | 0.5–3.0 | ±0.02–±0.05 | Up to 30:1 | 10–15 μm | ~0.1 |
Micro-EDM | 0.1–0.4 | ±0.001–±0.005 | Up to 15:1 | <2 μm | <0.05 |
Electro-thermal discharge removes material locally while avoiding tool wear or surface distortion on thin vane walls.
EDM Machining Selection Strategy
Wire EDM: Ideal for trailing edge slotting, airfoil trimming, and vane shroud outline finishing.
Sinker EDM: Used for root cavities, internal fillets, and anti-rotation slots in vane castings.
Hole Drilling EDM: Applied to cooling passages and film holes, typically 0.6–1.0 mm diameter.
Micro-EDM: Suitable for precision features such as micro-serrations or bleed holes under 0.2 mm.
Material Considerations
Inconel 713 Turbine Vane Properties for EDM
Property | Value |
|---|---|
Tensile Strength @ 760°C | ~1030 MPa |
Creep Rupture Life @ 871°C | >100 hours |
Hardness (as cast) | HRC 32–38 |
Thermal Fatigue Resistance | Excellent |
Casting Performance | High accuracy in investment casting |
Why Inconel 713 for Turbine Vane Electro-Thermal Machining?
Maintains structural integrity during spark erosion, minimizing HAZ and recast
Offers excellent oxidation resistance during post-EDM heat exposure
Compatible with vacuum investment casting and precise EDM-based finishing for mission-critical aerospace vanes
Case Study: EDM Machining of Inconel 713 Turbine Vane Film Cooling Channels
Project Background
A customer in the aerospace sector required fine feature machining on Inconel 713C investment-cast vanes for an industrial gas turbine stage. The part featured 36 cooling holes and two deep sinker cavities per vane.
Manufacturing Work Flow
Casting: Vacuum investment cast with wax pattern precision of ±0.1 mm
Pre-Machining: CNC referencing to set datum for EDM electrode alignment
Hole EDM: 36 cooling holes, 0.8 mm diameter, 15:1 aspect ratio, tolerance ±0.02 mm
Sinker EDM: Slot 8 mm deep formed using graphite electrode, spark gap 0.1 mm
Wire EDM: Final trailing edge and vane tip trimmed with ±0.005 mm accuracy
Post Process
Stress relief heat treatment at 925°C for 2 hours
HIP cycle at 1200°C, 100 MPa to eliminate porosity
Optional TBC coating for combustion-facing surfaces
Surface Finishing
Internal flow paths polished to Ra ≤ 0.6 μm
Passivation applied to vane walls
Tip radius refined to R0.05 mm to reduce thermal stress concentration
Inspection
CMM on cooling holes and cavity depth with ±2 μm precision
X-ray inspection confirmed internal soundness
SEM revealed no microcracks, clear discharge lines
Ultrasonic immersion testing validated pore-free volume
Results and Verification
Electro-thermal EDM machining delivered consistent feature resolution with ±0.003 mm on all air passage geometry and vane root fittings.
Post-process integrity was validated through SEM and ultrasonic inspection, with no residual cracking or recast present in spark zones.
Surface finish inside film holes was Ra ≤ 0.6 μm, eliminating risk of hot gas turbulence or erosion.
CMM comparison showed full dimensional conformance to CAD model with <2 μm deviation across 3D vane contour.
Turbine vanes completed over 3000 thermal cycles in endurance testing without measurable deformation, erosion, or material loss.
FAQs
How does EDM affect cooling hole shape consistency in Inconel turbine vanes?
What is the optimal spark energy level for Inconel 713 sinker EDM?
Can EDM be applied after TBC coating for post-repair vane geometry correction?
What is the minimum hole diameter achievable by EDM on turbine airfoils?
How do you avoid thermal cracking during electro-discharge removal on thin-walled vanes?
