Material
Aluminum alloy comparable to 7075-T6, selected for the agreed strength and machining requirements.
Representative reverse engineering case · industrial compressors
Compressor Impeller Reverse Engineering: From Damaged Sample to a 0.02 mm Digital Baseline
A second-stage centrifugal compressor impeller with cracked, partially missing blades became the evidence set for a controlled replacement program—combining 3D scanning, design-intent recovery, five-axis CNC machining and inspection.
The challenge
A stopped compressor and an OEM wait of more than six months.
A critical centrifugal compressor at a Midwestern U.S. industrial gas plant was shut down after abnormal vibration. Inspection found multiple damaged inlet edges on the second-stage impeller, with two blades partially broken. The OEM could quote a replacement, but the stated lead time exceeded six months.
The impeller was a custom legacy design with no available CAD model and no recoverable original drawing. Used-part searches produced no viable alternative; local machine shops declined the work without drawings. The customer sent the damaged impeller to Mechonus for reverse engineering and replacement manufacture.
Material & specification
Requirements defined before manufacture.
The project brief defined an aluminum alloy comparable to 7075-T6, twelve pieces including spare parts, dynamic-balance grade G1.0 and surface finish Ra ≤ 0.8 μm. These requirements were reviewed alongside the recovered geometry before release.
Geometry capture
Industrial blue-light scan data with a 0.02 mm average point-spacing target for detailed blade and hub capture.
Surface & balance
Ra ≤ 0.8 μm surface finish and G1.0 dynamic-balance requirement specified for the replacement route.
Delivery
12 impellers including spares, with STEP data, controlled drawings and agreed inspection documentation.
The approach
Measure function first. Rebuild nominal geometry second.
Reverse engineering for compressor components requires both complete geometry capture and explicit engineering decisions for every area affected by damage, wear or missing data.
01
Capture geometry without copying damage
The returned impeller was cleaned, optically prepared and scanned from multiple orientations with an industrial blue-light system. A target average point spacing of 0.02 mm supported dense capture of the pressure side, suction side, hub passages and blade roots.
- Raw scan and measurement data retained for review
- Assumptions recorded before manufacturing release
- CAD, drawing and inspection requirements revision-controlled
02
Separate service damage from design intent
Two blades had partial edge loss and several inlet edges showed crack-related damage. Repeated blade features, hub geometry and intact regions were compared to recover the nominal relationships; missing sections were reconstructed from adjacent blade form and documented design assumptions.
- Raw scan and measurement data retained for review
- Assumptions recorded before manufacturing release
- CAD, drawing and inspection requirements revision-controlled
03
Rebuild editable CAD and an inspectable definition
Geomagic Design X was used to turn scan evidence into editable parametric CAD. The approved model was released to five-axis CNC programming together with functional datums, bore fits, blade form requirements and a defined dynamic-balance plan.
- Raw scan and measurement data retained for review
- Assumptions recorded before manufacturing release
- CAD, drawing and inspection requirements revision-controlled
Detailed engineering process
Eight controlled gates from physical sample to repeat order.
Every gate produces a specific engineering record. That is what turns a damaged legacy part into controlled manufacturing data rather than a one-time visual copy.
- 01
Sample intake & failure mapping
Photograph the impeller, record blade numbering and identify cracks, broken leading edges, rub marks and handling damage. Register bore, keyway, back-face, hub and mating-shaft evidence before cleaning changes the surface condition.
OutputDamage map + sample register - 02
Datum strategy & scan preparation
Establish the rotation axis from the bore and datum faces; apply matte scan spray and reference targets to reflective aluminum. Plan overlapping views for blade roots, narrow passages, pressure surfaces and suction surfaces.
OutputDatum plan + scan setup record - 03
Multi-view 3D data acquisition
Capture high-density mesh data from multiple orientations, align the data to the hub axis and inspect overlap quality. Targeted manual or CMM measurements confirm features that are inaccessible or critical to fit.
OutputAligned STL mesh + critical dimensions - 04
Mesh processing & damage separation
Remove noise without smoothing away blade edges, classify holes and broken zones, and compare each repeated blade against intact neighbours. The team does not use scan-fill alone to define missing aerodynamic geometry.
OutputWear and missing-geometry map - 05
Blade, hub & flow-path reconstruction
Build master sections, blade curves and hub surfaces in parametric CAD. Reconstruct repeated blade pattern, inlet and outlet edges, shroud-side relationships and the bore/attachment features around functional datums.
OutputEditable CAD + reconstruction assumptions - 06
Drawing, material & balance definition
Define critical dimensions, surface-finish requirements, bore fit, material condition, inspection points and dynamic-balance method. The customer reviews CAD, drawing and open assumptions before manufacturing release.
OutputApproved CAD, drawing + control plan - 07
Five-axis first article manufacturing
Create a machining sequence that protects the bore and datum features, roughs the blade volume, finishes blade surfaces with controlled toolpaths, deburrs edges and preserves stock for final balance correction where specified.
OutputFirst article + job traveler - 08
Inspection, balancing & release
Inspect datum features, bore, hub, blade profile checkpoints and surface finish against the approved definition. Complete the specified balance procedure, review results with the customer and freeze the released data package for repeat orders.
OutputFAI/CMM report + balance record + released baseline
Manufacturing & verification
First article approved, then a repeatable supply path.
After customer approval of the reconstructed CAD, the impellers were machined on a five-axis CNC route, finished, inspected and dynamically balanced to the project requirement before release.
Project result
- Reverse-engineered CAD compared against scan data with a controlled overall deviation of ≤ 0.02 mm
- Five-axis CNC replacement impellers manufactured from the approved data package
- Dynamic balance achieved to G1.0 project requirement
- First article fit validation completed before batch release
- STEP model, inspection report and revision-controlled data retained for future orders
“The compressor ran smoothly after restart. Mechonus did more than reproduce a damaged sample—they gave us a controlled replacement path without waiting for the OEM.”Maintenance Manager, Industrial Gas Plant
Customer-authorized publication
This case has been published with customer authorization. Customer name, plant location and selected technical details have been anonymized. For a similar reverse engineering project, submit your part information through our website; our engineering team will provide an initial assessment within 24 hours.
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