OLA

Case Study: Monolithic Centrifugal Turbine Impeller

316L Stainless Steel | SLM | Aero-Engine / Gas-Turbine Impeller with 3D-Marked Blades

Metal 3D Printing Application

1. Background

An aero-engine component supplier was developing a high-speed centrifugal turbine stage for a small turbojet demonstrator. The legacy welded-impeller design suffered from blade-tip cracking at the weld seams and limited efficiency because the blade profile was constrained by the welding fixture. A fully monolithic impeller with optimized blade geometry and direct 3D-marked identification was needed to meet both the durability and the traceability requirements for the demonstrator program.

2. The Challenge

Design requirements included:

· 60+ radial blades with full aerodynamic profile, 100% monolithic — no welded blade roots

· Optimized 3D blade twist to deliver >88% stage efficiency

· Material-grade and serial number 3D-printed directly into the hub face (no adhesive label, no laser mark that can be removed)

· G2.5 dynamic balance at full operating speed (24,000 rpm)

· 316L stainless steel for high-temperature oxidation resistance and NDT compatibility

3. The Solution

The impeller was redesigned as a single monolithic part with CFD-optimized radial blades and a hub face pre-marked with the material grade and unique serial number, then manufactured by Selective Laser Melting (SLM) in 316L stainless steel. The blade backswept angles, leading-edge radii, and outlet wrap angles were tuned with CFD, and the hub was topology-optimized for stiffness-to-weight. The 3D-marked text on the hub face was printed as raised characters in the same build, eliminating any post-print marking process. After printing, the part was finish-machined at the shaft bore, dynamically balanced to G2.5, and run-in tested at full speed.

 

Figure 1: SLM-printed 316L turbine impeller — front view showing 60+ radial blades and 3D-marked material grade on the hub face

 

Figure 2: Same impeller from the back — monolithic hub, no welded blade roots, ready for shaft bore finish-machining

4. The Result

· 88% stage efficiency — +8 pts vs. legacy welded design

· 25% weight reduction — via topology-optimized hub

· Monolithic construction — no welded blade roots, no fatigue failure mode

· Built-in traceability — material grade + serial number 3D-printed in the same build

· G2.5 balance at 24,000 rpm — ready for direct engine installation

· Lead time: 4 weeks — from CAD to balanced, run-in-tested impeller

“We got a monolithic impeller with built-in traceability and an 8-point efficiency gain. The 3D-printed text is part of the part — it cannot fall off or be sanded away.”

 

Material: 316L Stainless Steel  |  Process: SLM / Metal 3D Printing  |  Application: Centrifugal Turbine Impeller