2.5D Surface Inspection for Automotive Engine Blocks
-
+ 60%Detection Stability
-
3xDefect Contrast
-
- 90%False Reject Rate
-
ObjecEngine block
-
RegionChina
-
ModelDS200
Content
-
Project Background
-
The Challenge
-
The Solution
-
Inspection Results
-
Customer Benefits
-
Project Background
In automotive powertrain manufacturing, the quality of the Engine block surface is critical. Any microscopic scratches, dents, or irregularities on this surface can lead to gasket sealing failures, resulting in oil leaks or cylinder pressure loss.
A leading automotive components manufacturer faced a significant bottleneck on their automated assembly line. The Enigne blocks, having undergone precision CNC machining, presented highly reflective metal surfaces. Furthermore, the production environment meant these surfaces were often contaminated with cutting fluids, residual oil, and complex machining textures, making automated inspection notoriously difficult.
-
The Challenge
Field testing with traditional imaging revealed three major pain points:
Severe Specular Reflection: The machined metal surface is highly reflective. Under standard lighting, this causes local overexposure (halations), hiding critical defect details behind glare.
Raw Image 2D Image (over exposured)
Interference from Oil & Texture: Residual oil stains and normal machining tool marks share similar grayscale values with actual scratches in 2D images. Traditional algorithms struggle to distinguish between a harmless oil spot and a functional defect.
Low Contrast: Shallow scratches often blend into the complex metallic background, making them invisible to standard vision systems.
-
The Solution
We deployed a 2.5D Hybrid Data Camera powered by Photometric Stereo technology. By utilizing high-speed, multi-angle sequenced lighting and onboard FPGA processing, the system separates surface color/reflectivity from physical topography.
The NZ Channel (Normal-Z Imaging):This is the core of the solution. The NZ channel maps the vertical component of the surface normal vectors. It is sensitive only to height changes (topography) and completely ignores surface color or flat contaminants. By setting a gray-level threshold, the system effectively filters out flat oil stains and background textures, retaining only the physical depth information of scratches and dents.
Nomal 2D Nz channel
Normal Mix Visualization:Using pseudo-color rendering, the system visualizes the surface orientation. Different colors represent different slopes, making even the slightest indentations pop out clearly against the background for easy verification.
NZ channel Normal Mix channel
-
Inspection Results
The 2.5D solution demonstrated superior performance where 2D systems failed:
Feature Traditional 2D Imaging 2.5D Hybrid Data Imaging Glare Handling Suffering from overexposure; data loss in bright areas. Uniform illumination; specular reflections are computationally removed. Interference Unable to distinguish oil stains from defects; high false positive rate. Oil stains are invisible in the NZ channel; only physical defects remain. Defect Contrast Defects blend into the background texture. Visual Proof:
Original / 2D View: Shows significant green oil residue and strong metal glare, making detection impossible.
2.5D NZ Channel: The oil stains vanish completely. The background becomes uniform, and the physical scratches are clearly extracted.
-
Customer Benefits
Enhanced Stability: Inspection performance is no longer affected by ambient light changes or varying levels of surface cleanliness.
Reduced False Rejects: Drastically lowered the False Reject Rate (FRR) by eliminating alarms caused by benign oil stains.
Simplified Integration: A single camera delivers 2D grayscale, 3D surface normals, and reconstructed texture maps, eliminating the need for complex external lighting arrays.
CONTACT US
-
Trusted by Global Industry LeadersProven in high-end production lines of top-tier companies.
MTBF ≥100,000 h certified. Get your rush orders covered in 72h.
-
Unmatched Service & Reliability GuaranteeSpeedy response within 4h, solutions within 7 days, everything from fault diagnosis, part replacement to validation report.
