Is 3D scanning suitable for parts with complex internal structures?
The Fundamental Limitation of Optical 3D Scanning
For parts with complex, fully enclosed internal structures, traditional optical 3D scanning methods—such as laser triangulation and structured light scanning—are not suitable. These technologies function by capturing the external surface geometry that is directly visible to the scanner's camera and projector. They cannot see through solid material to capture hidden internal channels, voids, or undercuts. This makes them ideal for inspecting the external dimensions and surface contours of components produced through Precision Machining Service or Multi-Axis Machining Service, but they are ineffective for inspecting internal features.
The Solution: Industrial Computed Tomography (CT) Scanning
The definitive technology for non-destructively capturing both internal and external geometries is Industrial X-ray Computed Tomography (CT) Scanning. This method operates on the same principle as medical CT scanners but is specifically designed for engineering metrology, offering significantly higher resolution and accuracy.
How It Works: The part is placed on a rotary stage between an X-ray source and a detector. As the part rotates, hundreds to thousands of 2D X-ray images (radiographs) are captured. Powerful software then reconstructs these images into a precise 3D volumetric model, often referred to as a "voxel dataset."
Capabilities: CT scanning can reveal:
Internal passages and cooling channels.
Porosity and voids within castings or additive manufacturing parts.
The precise geometry and wall thickness of complex injection molds.
Assembly analysis without disassembly.
Practical Applications and Industry Use Cases
The ability to see inside a component without cutting it open is revolutionary for several industries and processes:
First-Article Inspection of Complex Parts: CT scanning is indispensable for validating the internal geometry of a first-run part from CNC Machining Prototyping, such as a fuel injector with intricate internal channels or a medical manifold, ensuring it matches the CAD model perfectly.
Additive Manufacturing Validation: It is the gold standard for verifying the internal integrity of parts made via 3D Printing, detecting internal voids, incomplete fusion, and porosity that external scanners cannot see.
Failure Analysis and Reverse Engineering: CT allows engineers to investigate internal failures, such as a cracked internal rib or a blocked channel, without the need for destructive sectioning. It also enables the reverse engineering of internal features for which no CAD data exists.
Casting Process Control: For parts produced through Rapid Molding, CT scanning can quickly identify internal shrinkage or gas porosity, allowing for rapid correction of the molding process.
Combining Technologies for a Complete Digital Twin
In many quality control workflows, optical scanning and CT scanning are used together to create a comprehensive digital record:
CT Scanning captures the complete internal and external geometry.
High-resolution optical scanning (e.g., using blue light or a laser) is then employed on the external surfaces to capture ultra-fine surface texture and color, or to inspect features where CT may have lower resolution at the very surface.
This hybrid approach provides the most comprehensive possible validation, which is critical for high-value components in sectors such as Aerospace and Aviation, as well as Medical Devices.
In conclusion, while traditional 3D scanning is limited to external surfaces, Industrial CT Scanning is perfectly suited and highly effective for parts with complex internal structures. It provides a non-destructive, thorough, and dimensionally accurate method for inspecting, analyzing, and reverse-engineering the hidden complexities within a component.
