お使いの3Dプリンタに最適な3Dスキャナの選び方

A 3D scanner expands the capabilities of a 3D printer, allowing you to replicate the shape of almost any object. Together, the two technologies create a powerful, digital workflow that can simplify and sophisticate processes in a range of industries.

Engineers, product designers, and researchers use 3D scanners as a faster and more efficient way to start constructing digital models, including: 

• Reverse engineering to create replacement parts, products with custom ergonomics, and more.

• Replication and restoration of parts, especially in art and jewelry.

• Consumer audio for creating custom earpieces.

• Dental and medical applications for the creation of patient-specific devices. 

• Metrology to validate and measure the accuracy of manufactured objects.

3D scanning can also help to reverse engineer physical parts and, after fabrication, 3D scanning can support quality control and help to verify the accuracy of a 3D printed part. Many factors affect 3D print accuracy, and metrology-grade 3D scanners provide a clear picture of how a material performs for demanding applications; a scan of a deformed part can show you where to reinforce the design in the next revision.

The output from a 3D scanner is a mesh of triangles representing the surface of an object at a real-world scale. In some cases, the scan can be used directly to replicate objects without any CAD work. A hybrid workflow can also be powerful, where solid CAD models are combined with scanned 3D models. For example, customized ergonomics capture a physical imprint of a part of the human body, and integrate them with a mechanical design.

There are multiple scanning technologies currently on the market, all offering their own advantages and weaknesses, from handheld scanners to desktop 3D scanners. The best 3D scanning system for you will depend on your application and budget. 

Laser triangulation uses light projected onto the object to take up to millions of measurements (dots) per second. The light reflected from the dots back into the scanner’s sensor to help it capture the geometry of the object. These types of scanners are often the most accurate, and are great for highly detailed parts that have opaque surfaces.

Laser triangulation scanners do have limitations. For example, this technology is not used in most portable scanners because the laser dots need to project from a stable source, and the source has to be kept a close distance from the scanned object. Laser triangulation scanners don’t always work on transparent or shiny surfaces either. Typically, they require reflective markers to be applied onto the object, which need to be removed after use and can be an obstacle depending on the object being scanned.

Finally, the laser dots can be harmful to human eyes, so it is important to use extra safety precautions when scanning body parts with a laser triangulation system, or to check with your scanner manufacturer to make sure the device is eye-safe.

Structured light scanners (also known as white light scanners or blue light scanners) generally use a projector with two cameras at angles on either side. A pattern of light is projected and laid over the component being scanned, the cameras capture the ways in which the object deforms the light pattern, and then multiple images are integrated into a single 3D snapshot.

Structured light scanners are available in both stationary and portable format the technology is the most commonly used process for handheld 3D scanners. Structured light scanners are far more common in medical applications, since it is safe to use on both humans and animals and excels when an object is not perfectly still. Traditional white light scanners have been slower to scan than laser triangulation scanners.

Depth-sensing cameras project a field of dots in infrared (IR) to sample a 3D scene. Depth-sensing cameras are simple to use and are the least expensive scanning option, but their accuracy and resolution are low, and fine details are sometimes lost. Large objects may be captured with depth-sensing cameras, but accuracy declines with increased distance from the subject and at steeper angles to the camera.

Photogrammetry means the act of deriving precise measurements from photographs. It involves taking a set of overlapping photos of an object, building, person, or environment, and converting them into a 3D model using a number of computer algorithms. This is the most commonly used method when creating a 3D scan with a smartphone, since modern phone cameras are capable of capturing and combining a large number of photos. Photogrammetry should be considered the least expensive and least accurate method for creating 3D prints, and is not suitable for serious business applications.

LiDAR (light detection and ranging) sensors can be found on some higher-end smartphones and tablets, such as the latest versions of the iPhone Pro and the iPad Pro. This has made the iPhone and iPad viable scanners for those with only occasional scanning needs, offering performance a step above devices that only have access to photogrammetry. Applications that generate 3D mesh files via your smartphone’s or tablet's camera should be seen as the floor for entry-level scanning; users should expect additional work in their CAD software to remove gaps in meshes and improve the 3D model for applications like sending it to a professional 3D printer. Smartphones use fewer light points when scanning objects, resulting in less detail than a true, stand-alone scanner. iPhones are good substitutes for scanners if you have significant CAD design ability or need to transfer basic models into a digital space.

3D scanning is a valuable tool for creating parts that reference or incorporate older designs, where the original CAD design isn’t accessible. Once a part is designed, it can then be 3D printed as needed in a variety of high-performance materials. Create replacement parts that match the original design of damaged existing pieces, or use reverse engineering processes to integrate complex surfaces from existing objects into 3D printable jigs, which are useful when modifying mass manufactured and handcrafted products.

Learn more about reverse engineering parts here. 

Applied metrology is the measurement of part dimensions, and is essential to all manufacturing processes, including 3D printing. One way Formlabs uses 3D scanning during product development is to measure and validate the accuracy of new SLA materials. 3D scanning is the most versatile metrology tool for 3D printed parts, which tend to have more complex surfaces than could be easily measured with a micrometre, or even a CMM (contact measuring machine).

Metrology-grade scanners and scan software allow you to measure accuracy by comparing the scan output to the source model. The models are aligned based on selected reference points and the software performs a deviation analysis, identifying areas where the printed surface differs from the source file.

Deviation analysis paints a statistical picture of part accuracy. However, accuracy is not always perfectly consistent across a 3D-printed part. For instance, supported surfaces are less accurate than top surfaces, and post-curing shrinkage has a greater effect on a part across large spans.

3D scanners and 3D printers are essential parts of digital workflows across industries, empowering a variety of workflows in engineering, product design, and more.

Learn more about bringing your designs to life with 3D printing; explore stereolithography (SLA) and selective laser sintering (SLS) 3D printing technologies or request a free sample part to evaluate Formlabs materials for yourself.