Additive Manufacturing / 3D Printing Guided by OCT
Physical Sciences : Mechanical
Available for licensing
- Thomas Milner, Ph.D. , Biomedical Engineering
- Austin McElroy , Biomedical Engineering
- Joseph Beaman, Jr., Ph.D. , Mechanical Engineering
- Scott Fish, Ph.D. , University of Texas at Austin
Selective laser sintering (SLS) is an additive manufacturing technology utilizing a high-powered laser to enable manufacturing of three-dimensional components in a layer-by-layer fashion from a powder such as plastic, metal, polymer, ceramic, or composites. The process—deposition of the powder onto previously sintered layers of the part in a continuous manner to feed the next sintering layer—creates a challenge for identifying and rectifying small defects that may occur during manufacturing. Current methods for "observing" the part during the build process provide limited feedback for the correction of layer defects. For example, infrared and visible imagery give information on the surface, but not on the previous layers below, where layer-to-layer fusion is critical to overall finished part quality.
Researchers at The University of Texas at Austin have developed a non-invasive method for visualizing the entire 3D part within the powder matrix of the SLS system in real-time during the manufacturing process. The OCT process enables not only a view of the visible surface of a build, but also a penetrating 3D view through the build’s layers for the evaluation of layer-to-layer bonding.
The method entails the use of optical coherence tomography (OCT), a process widely used in the medical field to produce 3D images from within optical scattering media, such as biological tissues. In addition to SLS, the proposed OCT system can be applied to any form of additive or subtractive manufacturing. The real-time aspect of the OCT method allows for monitoring of a build during any stage of additive printing, such as observation of the thickness of each layer before the fusing process and evaluating the dimensions of the surface. OCT allows for the detection of voids or other defects in the part as each layer is added and fused, which can potentially be remediated in-situ by adjusting process parameters.
- Continuous monitoring of layer-to-layer defects throughout the additive manufacturing process
- Monitors product quality without disturbing the fusion process
- Increases part yield while maintaining design specifications
- Provides several methods for comparing current build to a reference design of the desired product
- Applicable to any form of additive or subtractive manufacturing process
- Reduces production cost without reducing build quality
- Allows for non-invasive visualization of 3D printing product in real-time
- Signals provide feedback for process modifications necessary for improved product quality
- Detects and corrects defects before new layers are added to the product build
- Can derive a variety of signals, such as backscattered light intensity and the Doppler shift of a moving surface
- Provides feedback on layer thickness/roughness/homogeneity, layer fusing energy requirements, and layer fusing phase changes
- Measures part dimensions in-situ, allowing for comparison to a reference digital description
Persistence Market Research reports that the global additive manufacturing market value is expected to expand at a compound annual growth rate (CAGR) around 18% to 22% during the period 2015-2025. Additionally, an Allied Market Research’s report on 3D printing predicts that selective laser sintering and fused deposition modeling will be the most demanded additive manufacturing techniques in the future as markets grow and technology becomes cheaper. The increasing demand for additive manufacturing and 3D printing in automotive, manufacturing, and healthcare industries is attributed to the design of complex parts and finished goods. Enhanced additive manufacturing processes are ideal for fabricating these intricate products in that it is applicable to a variety of materials, such as plastics, metal alloys, rubber, and ceramics.
- 1 U.S. patent application filed