Tag Archives: 3D

Tell me what a 3D Scanner is.

3D Scanner
From Wikipedia, the free encyclopedia
3D computer graphics
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Basics
Primary Uses
Related concepts

3-D scanning at a Maker Faire

3D scanner is a device that analyzes a real-world object or environment to collect data on its shape and possibly its appearance (i.e. color). The collected data can then be used to construct digital, three dimensional models.

Many different technologies can be used to build these 3D scanning devices; each technology comes with its own limitations, advantages and costs. Many limitations in the kind of objects that can be digitized are still present, for example, optical technologies encounter many difficulties with shiny, mirroring or transparent objects.

Collected 3D data is useful for a wide variety of applications. These devices are used extensively by the entertainment industry in the production of movies and video games. Other common applications of this technology include industrial designorthotics and prosthetics,reverse engineering and prototypingquality control/inspection and documentation of cultural artifacts.

Functionality

3D scanning of a fin whale skeleton in the Natural History Museum of Slovenia(August 2013)

The purpose of a 3D scanner is usually to create a point cloud of geometric samples on the surface of the subject. These points can then be used to extrapolate the shape of the subject (a process called reconstruction). If color information is collected at each point, then the colors on the surface of the subject can also be determined.

3D scanners share several traits with cameras. Like cameras, they have a cone-like field of view, and like cameras, they can only collect information about surfaces that are not obscured. While a camera collects color information about surfaces within its field of view, a 3D scanner collects distance information about surfaces within its field of view. The “picture” produced by a 3D scanner describes the distance to a surface at each point in the picture. This allows the three dimensional position of each point in the picture to be identified.

For most situations, a single scan will not produce a complete model of the subject. Multiple scans, even hundreds, from many different directions are usually required to obtain information about all sides of the subject. These scans have to be brought into a commonreference system, a process that is usually called alignment or registration, and then merged to create a complete model. This whole process, going from the single range map to the whole model, is usually known as the 3D scanning pipeline.[1]

Technology

There are a variety of technologies for digitally acquiring the shape of a 3D object. A well established classification[2] divides them into two types: contact and non-contact 3D scanners. Non-contact 3D scanners can be further divided into two main categories, active scanners and passive scanners. There are a variety of technologies that fall under each of these categories.

Contact

A coordinate measuring machine with rigid perpendicular arms.

Contact 3D scanners probe the subject through physical touch, while the object is in contact with or resting on a precision flat surface plate, ground and polished to a specific maximum of surface roughness. Where the object to be scanned is not flat or can not rest stably on a flat surface, it is supported and held firmly in place by a fixture.

The scanner mechanism may have three different forms:

  • A carriage system with rigid arms held tightly in perpendicular relationship and each axis gliding along a track. Such systems work best with flat profile shapes or simple convex curved surfaces.
  • An articulated arm with rigid bones and high precision angular sensors. The location of the end of the arm involves complex math calculating the wrist rotation angle and hinge angle of each joint. This is ideal for probing into crevasses and interior spaces with a small mouth opening.
  • A combination of both methods may be used, such as an articulated arm suspended from a traveling carriage, for mapping large objects with interior cavities or overlapping surfaces.

CMM (coordinate measuring machine) is an example of a contact 3D scanner. It is used mostly in manufacturing and can be very precise. The disadvantage of CMMs though, is that it requires contact with the object being scanned. Thus, the act of scanning the object might modify or damage it. This fact is very significant when scanning delicate or valuable objects such as historical artifacts. The other disadvantage of CMMs is that they are relatively slow compared to the other scanning methods. Physically moving the arm that the probe is mounted on can be very slow and the fastest CMMs can only operate on a few hundred hertz. In contrast, an optical system like a laser scanner can operate from 10 to 500 kHz.

Other examples are the hand driven touch probes used to digitize clay models in computer animation industry.

Non-contact active

Active scanners emit some kind of radiation or light and detect its reflection or radiation passing through object in order to probe an object or environment. Possible types of emissions used include light, ultrasound or x-ray.

Time-of-flight

This lidar scanner may be used to scan buildings, rock formations, etc., to produce a 3D model. The lidar can aim its laser beam in a wide range: its head rotates horizontally, a mirror flips vertically. The laser beam is used to measure the distance to the first object on its path.

The time-of-flight 3D laser scanner is an active scanner that uses laser light to probe the subject. At the heart of this type of scanner is a time-of-flight laser rangefinder. The laser rangefinder finds the distance of a surface by timing the round-trip time of a pulse of light. A laser is used to emit a pulse of light and the amount of time before the reflected light is seen by a detector is measured. Since the speed of light c is known, the round-trip time determines the travel distance of the light, which is twice the distance between the scanner and the surface. If t is the round-trip time, then distance is equal to  \textstyle c \! \cdot  \! t / 2. The accuracy of a time-of-flight 3D laser scanner depends on how precisely we can measure the t time: 3.3 picoseconds (approx.) is the time taken for light to travel 1 millimeter.

The laser rangefinder only detects the distance of one point in its direction of view. Thus, the scanner scans its entire field of view one point at a time by changing the range finder’s direction of view to scan different points. The view direction of the laser rangefinder can be changed either by rotating the range finder itself, or by using a system of rotating mirrors. The latter method is commonly used because mirrors are much lighter and can thus be rotated much faster and with greater accuracy. Typical time-of-flight 3D laser scanners can measure the distance of 10,000~100,000 points every second.

Time-of-flight devices are also available in a 2D configuration. This is referred to as a time-of-flight camera.

Triangulation

Principle of a laser triangulation sensor. Two object positions are shown.

Triangulation based 3D laser scanners are also active scanners that use laser light to probe the environment. With respect to time-of-flight 3D laser scanner the triangulation laser shines a laser on the subject and exploits a camera to look for the location of the laser dot. Depending on how far away the laser strikes a surface, the laser dot appears at different places in the camera’s field of view. This technique is called triangulation because the laser dot, the camera and the laser emitter form a triangle. The length of one side of the triangle, the distance between the camera and the laser emitter is known. The angle of the laser emitter corner is also known. The angle of the camera corner can be determined by looking at the location of the laser dot in the camera’s field of view. These three pieces of information fully determine the shape and size of the triangle and gives the location of the laser dot corner of the triangle. In most cases a laser stripe, instead of a single laser dot, is swept across the object to speed up the acquisition process. The National Research Council of Canada was among the first institutes to develop the triangulation based laser scanning technology in 1978.[3]

Strengths and weaknesses

Time-of-flight and triangulation range finders each have strengths and weaknesses that make them suitable for different situations. The advantage of time-of-flight range finders is that they are capable of operating over very long distances, on the order of kilometers. These scanners are thus suitable for scanning large structures like buildings or geographic features. The disadvantage of time-of-flightrange finders is their accuracy. Due to the high speed of light, timing the round-trip time is difficult and the accuracy of the distance measurement is relatively low, on the order of millimeters.
Triangulation range finders are exactly the opposite. They have a limited range of some meters, but their accuracy is relatively high. The accuracy of triangulation range finders is on the order of tens of micrometers.

Time-of-flight scanners accuracy can be lost when the laser hits the edge of an object because the information that is sent back to the scanner is from two different locations for one laser pulse. The coordinate relative to the scanners position for a point that has hit the edge of an object will be calculated based on an average and therefore will put the point in the wrong place. When using a high resolution scan on an object the chances of the beam hitting an edge are increased and the resulting data will show noise just behind the edges of the object. Scanners with a smaller beam width will help to solve this problem but will be limited by range as the beam width will increase over distance. Software can also help by determining that the first object to be hit by the laser beam should cancel out the second.

At a rate of 10,000 sample points per second, low resolution scans can take less than a second, but high resolution scans, requiring millions of samples, can take minutes for some time-of-flight scanners. The problem this creates is distortion from motion. Since each point is sampled at a different time, any motion in the subject or the scanner will distort the collected data. Thus, it is usually necessary to mount both the subject and the scanner on stable platforms and minimize vibration. Using these scanners to scan objects in motion is very difficult.

Recently, there has been research on compensating for distortion from small amounts of vibration.[4]

When scanning in one position for any length of time slight movement can occur in the scanner position due to changes in temperature. If the scanner is set on a tripod and there is strong sunlight on one side of the scanner then that side of the tripod will expand and slowly distort the scan data from one side to another. Some laser scanners have level compensators built into them to counteract any movement of the scanner during the scan process.

Conoscopic holography

In a conoscopic system, a laser beam is projected onto the surface and then the immediate reflection along the same ray-path are put through a conoscopic crystal and projected onto a CCD. The result is a diffraction pattern, that can be frequency analyzed to determine the distance to the measured surface. The main advantage with conoscopic holography is that only a single ray-path is needed for measuring, thus giving an opportunity to measure for instance the depth of a finely drilled hole.

Hand-held laser scanners

Hand-held laser scanners create a 3D image through the triangulation mechanism described above: a laser dot or line is projected onto an object from a hand-held device and a sensor (typically a charge-coupled device or position sensitive device) measures the distance to the surface. Data is collected in relation to an internal coordinate system and therefore to collect data where the scanner is in motion the position of the scanner must be determined. The position can be determined by the scanner using reference features on the surface being scanned (typically adhesive reflective tabs, but natural features have been also used in research work [5][6]) or by using an external tracking method. External tracking often takes the form of a laser tracker (to provide the sensor position) with integrated camera (to determine the orientation of the scanner) or a photogrammetric solution using 3 or more cameras providing the complete Six degrees of freedom of the scanner. Both techniques tend to use infrared Light-emitting diodes attached to the scanner which are seen by the camera(s) through filters providing resilience to ambient lighting.

Data is collected by a computer and recorded as data points within Three-dimensional space, with processing this can be converted into a triangulated mesh and then a Computer-aided design model, often as Nonuniform rational B-spline surfaces. Hand-held laser scanners can combine this data with passive, visible-light sensors—which capture surface textures and colors—to build (or “reverse engineer“) a full 3D model.

Structured light

Structured-light 3D scanners project a pattern of light on the subject and look at the deformation of the pattern on the subject. The pattern is projected onto the subject using either anLCD projector or other stable light source. A camera, offset slightly from the pattern projector, looks at the shape of the pattern and calculates the distance of every point in the field of view.

Structured-light scanning is still a very active area of research with many research papers published each year. Perfect maps have also been proven useful as structured light patterns that solve the correspondence problem and allow for error detection and error correction.[24] [See Morano, R., et al. “Structured Light Using Pseudorandom Codes,” IEEE Transactions on Pattern Analysis and Machine Intelligence.

The advantage of structured-light 3D scanners is speed and precision. Instead of scanning one point at a time, structured light scanners scan multiple points or the entire field of view at once. Scanning an entire field of view in a fraction of a second generates profiles that are exponentially more precise than laser triangulation. This reduces or eliminates the problem of distortion from motion. Some existing systems are capable of scanning moving objects in real-time. VisionMaster creates a 3D scanning system with a 5-megapixel camera – 5 million data points are acquired in every frame.

A real-time scanner using digital fringe projection and phase-shifting technique (a various structured light method) was developed, to capture, reconstruct, and render high-density details of dynamically deformable objects (such as facial expressions) at 40 frames per second.[7] Recently, another scanner is developed. Different patterns can be applied to this system. The frame rate for capturing and data processing achieves 120 frames per second. It can also scan isolated surfaces, for example two moving hands.[8] By utilizing the binary defocusing technique, speed breakthroughs have been made that could reach hundreds of [9] to thousands of frames per second.[10]

Modulated light

Modulated light 3D scanners shine a continually changing light at the subject. Usually the light source simply cycles its amplitude in a sinusoidal pattern. A camera detects the reflected light and the amount the pattern is shifted by determines the distance the light traveled. Modulated light also allows the scanner to ignore light from sources other than a laser, so there is no interference.

Volumetric techniques

Medical

Computed tomography (CT) is a medical imaging method which generates a three-dimensional image of the inside of an object from a large series of two-dimensional X-ray images, similarly Magnetic resonance imaging is another a medical imaging technique that provides much greater contrast between the different soft tissues of the body than computed tomography (CT) does, making it especially useful in neurological (brain), musculoskeletal, cardiovascular, and oncological (cancer) imaging. These techniques produce a discrete 3D volumetric representation that can be directly visualized, manipulated or converted to traditional 3D surface by mean of isosurface extraction algorithms.

Industrial

Although most common in medicine, Computed tomography, Microtomography and MRI are also used in other fields for acquiring a digital representation of an object and its interior, such as nondestructive materials testing, reverse engineering, or the study biological and paleontological specimens.

Non-contact passive

Passive scanners do not emit any kind of radiation themselves, but instead rely on detecting reflected ambient radiation. Most scanners of this type detect visible light because it is a readily available ambient radiation. Other types of radiation, such as infrared could also be used. Passive methods can be very cheap, because in most cases they do not need particular hardware but simple digital cameras.

  • Stereoscopic systems usually employ two video cameras, slightly apart, looking at the same scene. By analyzing the slight differences between the images seen by each camera, it is possible to determine the distance at each point in the images. This method is based on the same principles driving human stereoscopic vision[1].
  • Photometric systems usually use a single camera, but take multiple images under varying lighting conditions. These techniques attempt to invert the image formation model in order to recover the surface orientation at each pixel.
  • Silhouette techniques use outlines created from a sequence of photographs around a three-dimensional object against a well contrasted background. These silhouettes are extruded and intersected to form the visual hull approximation of the object. With these approaches some concavities of an object (like the interior of a bowl) cannot be detected.

User assisted (image-based modeling)

There are other methods that, based on the user assisted detection and identification of some features and shapes on a set of different pictures of an object are able to build an approximation of the object itself. This kind of techniques are useful to build fast approximation of simple shaped objects like buildings. Various commercial packages are available likeD-SculptoriModellerAutodesk ImageModeler or PhotoModeler.

This sort of 3D scanning is based on the principles of photogrammetry. It is also somewhat similar in methodology to panoramic photography, except that the photos are taken of one object on a three-dimensional space in order to replicate it instead of taking a series of photos from one point in a three-dimensional space in order to replicate the surrounding environment.

Reconstruction

From point clouds

The point clouds produced by 3D scanners can be used directly for measurement and visualization in the architecture and construction world.

Most applications, however, use instead polygonal 3D models, NURBS surface models, or editable feature-based CAD models (aka Solid models).

  • Polygon mesh models: In a polygonal representation of a shape, a curved surface is modeled as many small faceted flat surfaces (think of a sphere modeled as a disco ball). Polygon models—also called Mesh models, are useful for visualization, for some CAM (i.e., machining), but are generally “heavy” ( i.e., very large data sets), and are relatively un-editable in this form. Reconstruction to polygonal model involves finding and connecting adjacent points with straight lines in order to create a continuous surface. Many applications, both free and nonfree, are available for this purpose (e.g. MeshLab, PointCab, kubit PointCloud for AutoCAD, JRC 3D Reconstructor, imagemodel, PolyWorks, Rapidform, Geomagic, Imageware, Rhino 3D etc.).
  • Surface models: The next level of sophistication in modeling involves using a quilt of curved surface patches to model our shape. These might be NURBS, TSplines or other curved representations of curved topology. Using NURBS, our sphere is a true mathematical sphere. Some applications offer patch layout by hand but the best in class offer both automated patch layout and manual layout. These patches have the advantage of being lighter and more manipulable when exported to CAD. Surface models are somewhat editable, but only in a sculptural sense of pushing and pulling to deform the surface. This representation lends itself well to modeling organic and artistic shapes. Providers of surface modelers include Rapidform, GeomagicRhino 3D, Maya, T Splines etc.
  • Solid CAD models: From an engineering/manufacturing perspective, the ultimate representation of a digitized shape is the editable, parametric CAD model. After all, CAD is the common “language” of industry to describe, edit and maintain the shape of the enterprise’s assets. In CAD, our sphere is described by parametric features which are easily edited by changing a value (e.g., centerpoint and radius).

These CAD models describe not simply the envelope or shape of the object, but CAD models also embody the “design intent” (i.e., critical features and their relationship to other features). An example of design intent not evident in the shape alone might be a brake drum’s lug bolts, which must be concentric with the hole in the center of the drum. This knowledge would drive the sequence and method of creating the CAD model; a designer with an awareness of this relationship would not design the lug bolts referenced to the outside diameter, but instead, to the center. A modeler creating a CAD model will want to include both Shape and design intent in the complete CAD model.

Vendors offer different approaches to getting to the parametric CAD model. Some export the NURBS surfaces and leave it to the CAD designer to complete the model in CAD (e.g.,Geomagic, Imageware, Rhino 3D). Others use the scan data to create an editable and verifiable feature based model that is imported into CAD with full feature tree intact, yielding a complete, native CAD model, capturing both shape and design intent (e.g. Geomagic, Rapidform). Still other CAD applications are robust enough to manipulate limited points or polygon models within the CAD environment (e.g., CATIA, AutoCAD, Revit).

From a set of 2D slices

3D reconstruction of the brain and eyeballs from CT scanned DICOM images. In this image, areas with the density of bone or air were made transparent, and the slices stacked up in an approximate free-space alignment. The outer ring of material around the brain are the soft tissues of skin and muscle on the outside of the skull. A black box encloses the slices to provide the black background. Since these are simply 2D images stacked up, when viewed on edge the slices disappear since they have effectively zero thickness. Each DICOM scan represents about 5mm of material averaged into a thin slice.

CTindustrial CTMRI, or Micro-CT scanners do not produce point clouds but a set of 2D slices (each termed a “tomogram”) which are then ‘stacked together’ to produce a 3D representation. There are several ways to do this depending on the output required:

  • Volume rendering: Different parts of an object usually have different threshold values or greyscale densities. From this, a 3-dimensional model can be constructed and displayed on screen. Multiple models can be constructed from various thresholds, allowing different colors to represent each component of the object. Volume rendering is usually only used for visualisation of the scanned object.
  • Image segmentation: Where different structures have similar threshold/greyscale values, it can become impossible to separate them simply by adjusting volume rendering parameters. The solution is called segmentation, a manual or automatic procedure that can remove the unwanted structures from the image. Image segmentation software usually allows export of the segmented structures in CAD or STL format for further manipulation.
  • Image-based meshing: When using 3D image data for computational analysis (e.g. CFD and FEA), simply segmenting the data and meshing from CAD can become time consuming, and virtually intractable for the complex topologies typical of image data. The solution is called image-based meshing, an automated process of generating an accurate and realistic geometrical description of the scan data.

Applications

Material processing and production

Main article: Laser scanning

Laser scanning describes the general method to sample or scan a surface using laser technology. Several areas of application exist that mainly differ in the power of the lasers that are used, and in the results of the scanning process. Low laser power is used when the scanned surface doesn’t have to be influenced, e.g. when it only has to be digitized. Confocal or 3D laser scanning are methods to get information about the scanned surface. Another low-power application are structured light projection systems that are used for solar cell flatness metrology enabling stress calculation with throughout in excess of 2000 wafers per hour.[11]

The laser power used for laser scanning equipment in industrial applications is typically less than 1W. The power level is usually on the order of 200 mW or less.

Construction industry and civil engineering

  • Robotic Control: e.g., a laser scanner may function as the “eye” of a robot.[12][13]
  • As-built drawings of Bridges, Industrial Plants, and Monuments
  • Documentation of historical sites
  • Site modeling and lay outing
  • Quality control
  • Quantity Surveys
  • Freeway Redesign
  • Establishing a bench mark of pre-existing shape/state in order to detect structural changes resulting from exposure to extreme loadings such as earthquake, vessel/truck impact or fire.
  • Create GIS (Geographic information system) maps and Geomatics.
  • Subsurface Laser Scanning in mines and Karst voids.[14]
  • Forensic Documentation [15]

Benefits of 3D scanning

3D model scanning could benefit the design process if:

  • Increase effectiveness working with complex parts and shapes.
  • Help with design of products to accommodate someone else’s part.
  • If CAD models are outdated, a 3D scan will provide an updated version
  • Replacement of missing or older parts

Entertainment

3D scanners are used by the entertainment industry to create digital 3D models for moviesvideo games and leisure purposes. They are heavily utilized in virtual cinematography. In cases where a real-world equivalent of a model exists, it is much faster to scan the real-world object than to manually create a model using 3D modeling software. Frequently, artists sculpt physical models of what they want and scan them into digital form rather than directly creating digital models on a computer.

Reverse engineering

Reverse engineering of a mechanical component requires a precise digital model of the objects to be reproduced. Rather than a set of points a precise digital model can be represented by a polygon mesh, a set of flat or curved NURBS surfaces, or ideally for mechanical components, a CAD solid model. A 3D scanner can be used to digitize free-form or gradually changing shaped components as well as prismatic geometries whereas a coordinate measuring machine is usually used only to determine simple dimensions of a highly prismatic model. These data points are then processed to create a usable digital model, usually using specialized reverse engineering software.

Cultural heritage

There have been many research projects undertaken via the scanning of historical sites and artifacts both for documentation and analysis purposes.

The combined use of 3D scanning and 3D printing technologies allows the replication of real objects without the use of traditional plaster casting techniques, that in many cases can be too invasive for being performed on precious or delicate cultural heritage artifacts.[16] In the side figure the gargoyle model on the left was digitally acquired by using a 3D scanner and the produced 3D data was processed using MeshLab. The resulting digital 3D model was used by a rapid prototyping machine to create a real resin replica of original object.

Michelangelo

In 1999, two different research groups started scanning Michelangelo’s statues. Stanford University with a group led by Marc Levoy[17] used a custom laser triangulation scanner built by Cyberware to scan Michelangelo’s statues in Florence, notably the David, the Prigioni and the four statues in The Medici Chapel. The scans produced a data point density of one sample per 0.25 mm, detailed enough to see Michelangelo’s chisel marks. These detailed scans produced a huge amount of data (up to 32 gigabytes) and processing the data from his scans took 5 months. Approximately in the same period a research group from IBM, led by H. Rushmeier and F. Bernardini scanned the Pietà of Florence acquiring both geometric and color details. The digital model, result of the Stanford scanning campaign, was thoroughly used in the 2004 subsequent restoration of the statue.[18]

Monticello

In 2002, David Luebke, et al. scanned Thomas Jefferson’s Monticello.[19] A commercial time of flight laser scanner, the DeltaSphere 3000, was used. The scanner data was later combined with color data from digital photographs to create the Virtual Monticello, and the Jefferson’s Cabinet exhibits in the New Orleans Museum of Art in 2003. The Virtual Monticello exhibit simulated a window looking into Jefferson’s Library. The exhibit consisted of a rear projection display on a wall and a pair of stereo glasses for the viewer. The glasses, combined with polarized projectors, provided a 3D effect. Position tracking hardware on the glasses allowed the display to adapt as the viewer moves around, creating the illusion that the display is actually a hole in the wall looking into Jefferson’s Library. The Jefferson’s Cabinet exhibit was a barrier stereogram (essentially a non-active hologram that appears different from different angles) of Jefferson’s Cabinet.

Cuneiform tablets

In 2003, Subodh Kumar, et al. undertook the 3D scanning of ancient cuneiform tablets.[20] Again, a laser triangulation scanner was used. The tablets were scanned on a regular grid pattern at a resolution of 0.025 mm (0.00098 in).

Kasubi Tombs

Photo overlaid atop laser scan data from a project held in early 2009 at Uganda’s Kasubi Tombs, which were destroyed by fire in early 2010; the data is slated for use in the building’s reconstruction.

A 2009 CyArk 3D scanning project at Uganda’s historic Kasubi Tombs, a UNESCO World Heritage Site, using a Leica HDS 4500, produced detailed architectural models of Muzibu Azaala Mpanga, the main building at the complex and tomb of the Kabakas (Kings) of Uganda. A fire on March 16, 2010, burned down much of the Muzibu Azaala Mpanga structure, and reconstruction work is likely to lean heavily upon the dataset produced by the 3D scan mission.[21]

“Plastico di Roma antica”

In 2005, Gabriele Guidi, et al. scanned the “Plastico di Roma antica”,[22] a model of Rome created in the last century. Neither the triangulation method, nor the time of flight method satisfied the requirements of this project because the item to be scanned was both large and contained small details. They found though, that a modulated light scanner was able to provide both the ability to scan an object the size of the model and the accuracy that was needed. The modulated light scanner was supplemented by a triangulation scanner which was used to scan some parts of the model.

Other projects

The 3D Encounters Project at the Petrie Museum of Egyptian Archaeology aims to use 3D laser scanning to create a high quality 3D image library of artefacts and enable digital travelling exhibitions of fragile Egyptian artefacts, English Heritage has investigated the use of 3D laser scanning for a wide range of applications to gain archaeological and condition data, and the National Conservation Centre in Liverpool has also produced 3D laser scans on commission, including portable object and in situ scans of archaeological sites.[23]

Medical CAD/CAM

3D scanners are used in order to capture the 3D shape of a patient in orthotics and dentistry. It gradually supplants tedious plaster cast. CAD/CAM software are then used to design and manufacture the orthosisprosthesis or dental implants.

Many Chairside dental CAD/CAM systems and Dental Laboratory CAD/CAM systems use 3D Scanner technologies to capture the 3D surface of a dental preparation (either in vivo orin vitro), in order to produce a restoration digitally using CAD software and ultimately produce the final restoration using a CAM technology (such as a CNC milling machine, or 3D printer). The chairside systems are designed to facilitate the 3D scanning of a preparation in vivo and produce the restoration (such as a Crown, Onlay, Inlay or Veneer).

Quality assurance and industrial metrology

The digitalization of real-world objects is of vital importance in various application domains. This method is especially applied in industrial quality assurance to measure the geometric dimension accuracy. Industrial processes such as assembly are complex, highly automated and typically based on CAD (Computer Aided Design) data. The problem is that the same degree of automation is also required for quality assurance. It is, for example, a very complex task to assemble a modern car, since it consists of many parts that must fit together at the very end of the production line. The optimal performance of this process is guaranteed by quality assurance systems. Especially the geometry of the metal parts must be checked in order to assure that they have the correct dimensions, fit together and finally work reliably.

Within highly automated processes, the resulting geometric measures are transferred to machines that manufacture the desired objects. Due to mechanical uncertainties and abrasions, the result may differ from its digital nominal. In order to automatically capture and evaluate these deviations, the manufactured part must be digitized as well. For this purpose, 3D scanners are applied to generate point samples from the object’s surface which are finally compared against the nominal data.[24]

The process of comparing 3D data against a CAD model is referred to as CAD-Compare, and can be a useful technique for applications such as determining wear patterns on molds and tooling, determining accuracy of final build, analyzing gap and flush, or analyzing highly complex sculpted surfaces. At present, laser triangulation scanners, structured light and contact scanning are the predominant technologies employed for industrial purposes, with contact scanning remaining the slowest, but overall most accurate option.

3D Extruders

The Darwin and Mendel Repraps were designed to extrude PLA plastic. People have developed many ways of improving on the original extruder. It didn’t take long before people starting trying to make them extrude other pastes, including ABS and even delicious frosting: Frostruder[1]. RepRap forums: “Frostruder MK2 = Granular extruder?”[2].

To extrude plastic filament, you need to force the raw material (usually a 1.75mm or 3mm diameter filament) with the drive of the “Cold End” out of the extruder. The filament should then go through the “Hot End” of the extruder with the heater and out of the nozzle at a reasonable speed. The extruded material falls onto the build platform (sometimes heated) and then layer by layer onto the part as it is built up.

The “Cold End” is usually the bulk of the extruder. It is often the actual carriage on one axis and supports the rest of the parts. In some designs, the “Cold End” is split into two parts; one part does the driving of the filament that is stationary and connected to the carriage portion, of a lighter weight design for easier movement, with aflexible tube. The drive is a motor that rotates a knurled, hobbed, or toothed pinch wheel against a pressure plate or bearing with the filament forced between them. Usually, the motor is geared to the pinch wheel to increase available torque and extrusion control (smoothness). The gearing can be a 3D printed pinion and gear, stock worm wheel and gear, or a more expensive integral motor gearbox. Stepper motors are used almost universally after initial trials with DC motors did not achieve the required repeatability. Servo motors are an option, though they are not seen in the literature yet. The final function, some form of cooling, keeps the “Cold End” cold. With the close proximity to the “Hot End” and possible heated build platforms and enclosures, it is sometimes necessary to have additional passive or active cooling of the cold end parts. Heat sinks and fans are often used; water and Peltier effect cooling is also discussed. Much of this bulk is usually made from 3D printed parts and the temperature is maintained within safe limits.

The “Cold End” is connected to the “Hot End” across a thermal break or insulator (the Bowden tube if used is on the cold side of this thermal break). This has to be rigid and accurate enough to reliably pass the filament from one side to the other, but still prevent much of the heat transfer. The materials of choice are usually PEEK plastic with PTFE liners or PTFE with stainless steel mechanical supports or a combination of all three.

The “Hot End” is the active part of the 3D printer that melts the filament. It allows the filament to exit from the small nozzle to form a thin and tacky bead of plastic that will adhere to the material it is laid on. Usually, the “Hot End” is made of brass. However, sometimes glass or aluminium is used. It consists of a barrel with a melting zone or chamber near the tip closed off with a fixed or removable nozzle with a diameter of between 0.3mm and 1.0mm with typical size of 0.5mm with present generation extruders. Outside the tip of the barrel is a heating means, either a wire element or a standard wire wound resistor. The heat required is of the order of 20W with typical temperatures around 150 to 250 degrees Centigrade. For feedback control of the nozzle temperature, a thermistor is usually attached close to the nozzle, though a thermocouple may serve with suitable control hardware. High temperature materials are needed here. These include metals, cements and glues, glass and mineral fibre materials,PEEKPTFE and Kapton tape.

IMG_0356

What is 3D Printing?

Additive manufacturing or 3D printing[1] is a process of making a three-dimensional solid object of virtually any shape from a digital model. 3D printing is achieved using an additive process, where successive layers of material are laid down in different shapes.[2] 3D printing is also considered distinct from traditional machining techniques, which mostly rely on the removal of material by methods such as cutting or drilling (subtractive processes).

A materials printer usually performs 3D printing processes using digital technology. The first working 3D printer was created in 1984 by Chuck Hull of 3D Systems Corp.[3] Since the start of the 21st century there has been a large growth in the sales of these machines, and their price has dropped substantially.[4] According to Wohlers Associates, a consultancy, the market for 3D printers and services was worth $2.2 billion worldwide in 2012, up 29% from 2011.[5]

The 3D printing technology is used for both prototyping and distributed manufacturing with applications in architecture, construction (AEC),industrial design, automotive, aerospace, military, engineering, civil engineering, dental and medical industries, biotech (human tissue replacement), fashion, footwear, jewelry, eyewear, education, geographic information systems, food, and many other fields. It has been speculated[6] that 3D printing may become a mass market item because open source 3D printing can easily offset their capital costs by enabling consumers to avoid costs associated with purchasing common household objects.[7]

Terminology

Although scientists and technicians have long been fascinated with the idea of replicating technology, it was not until the 1980s that the concept of 3D printing really began to be taken seriously.[8]. The man most often credited with inventing the language of ‘modern’ 3D printer is Charles W. Hull, who first patented the term ‘stereolithography’ (defined as “system for generating three-dimensional objects by creating a cross-sectional pattern of the object to be formed”) in 1984.[9][10]

The term additive manufacturing refers to technologies that create objects through a sequential layering process. Objects that are manufactured additively can be used anywhere throughout the product life cycle, from pre-production (i.e. rapid prototyping) to full-scale production (i.e. rapid manufacturing), in addition to tooling applications and post-production customization.

In manufacturing, and machining in particular, subtractive methods are typically coined as traditional methods. The very term subtractive manufacturing is a retronym developed in recent years to distinguish it from newer additive manufacturing techniques. Although fabrication has included methods that are essentially “additive” for centuries (such as joining plates, sheets, forgings, and rolled work via riveting, screwing, forge welding, or newer kinds of welding), it did not include the information technology component of model-based definition. Machining (generating exact shapes with high precision) has typically been subtractive, from filing and turning to milling and grinding.

General principles

3D model slicing.

Modeling

Additive manufacturing takes virtual blueprints from computer aided design (CAD) or animation modeling software and “slices” them into digital cross-sections for the machine to successively use as a guideline for printing. Depending on the machine used, material or a binding material is deposited on the build bed or platform until material/binder layering is complete and the final 3D model has been “printed.”

A standard data interface between CAD software and the machines is the STL file format. An STL file approximates the shape of a part or assembly using triangular facets. Smaller facets produce a higher quality surface. PLY is a scanner generated input file format, and VRML(or WRL) files are often used as input for 3D printing technologies that are able to print in full color.

Printing

To perform a print, the machine reads the design from an .stl file and lays down successive layers of liquid, powder, paper or sheet material to build the model from a series of cross sections. These layers, which correspond to the virtual cross sections from the CAD model, are joined or automatically fused to create the final shape. The primary advantage of this technique is its ability to create almost any shape or geometric feature.

Printer resolution describes layer thickness and X-Y resolution in dpi (dots per inch),[citation needed] or micrometers. Typical layer thickness is around 100 micrometers (µm), although some machines such as the Objet Connex series and 3D Systems’ ProJet series can print layers as thin as 16 µm.[11] X-Y resolution is comparable to that of laser printers. The particles (3D dots) are around 50 to 100 µm in diameter.

Construction of a model with contemporary methods can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems can typically reduce this time to a few hours, although it varies widely depending on the type of machine used and the size and number of models being produced simultaneously.

Traditional techniques like injection molding can be less expensive for manufacturing polymer products in high quantities, but additive manufacturing can be faster, more flexible and less expensive when producing relatively small quantities of parts. 3D printers give designers and concept development teams the ability to produce parts and concept models using a desktop size printer.

Finishing

Though the printer-produced resolution is sufficient for many applications, printing a slightly oversized version of the desired object in standard resolution, and then removing material with a higher-resolution subtractive process can achieve greater precision.

Some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts. Some are able to print in multiple colors and color combinations simultaneously. Some also utilize supports when building. Supports are removable or dissolvable upon completion of the print, and are used to support overhanging features during construction.

Additive processes

Rapid prototyping worldwide 2001[12]

The Audi RSQ was made with rapid prototyping industrial KUKA robots.

Several different 3D printing processes have been invented since the late 1970s. The printers were originally large, expensive, and highly limited in what they could produce.[13]

A number of additive processes are now available. They differ in the way layers are deposited to create parts and in the materials that can be used. Some methods melt or soften material to produce the layers, e.g. selective laser melting (SLM) or direct metal laser sintering(DMLS), selective laser sintering (SLS), fused deposition modeling (FDM), while others cure liquid materials using different sophisticated technologies, e.g. stereolithography (SLA). With laminated object manufacturing (LOM), thin layers are cut to shape and joined together (e.g. paper, polymer, metal). Each method has its own advantages and drawbacks, and some companies consequently offer a choice between powder and polymer for the material from which the object is built.[14] Some companies use standard, off-the-shelf business paper as the build material to produce a durable prototype. The main considerations in choosing a machine are generally speed, cost of the 3D printer, cost of the printed prototype, and cost and choice of materials and color capabilities.[15]

Printers that work directly with metals are expensive. In some cases, however, less expensive printers can be used to make a mould, which is then used to make metal parts.[16]

Type Technologies Materials
Extrusion Fused deposition modeling (FDM) Thermoplastics (e.g. PLAABS), HDPEeutectic metals, edible materials
Wire Electron Beam Freeform Fabrication(EBF3) Almost any metal alloy
Granular Direct metal laser sintering (DMLS) Almost any metal alloy
Electron beam melting (EBM) Titanium alloys
Selective laser melting (SLM) Titanium alloysCobalt Chrome alloysStainless Steels,Aluminium
Selective heat sintering(SHS)[citation needed] Thermoplastic powder
Selective laser sintering (SLS) Thermoplasticsmetal powdersceramic powders
Powder bed and inkjet head 3D printing Plaster-based 3D printing (PP) Plaster
Laminated Laminated object manufacturing(LOM) Papermetal foilplastic film
Light polymerised Stereolithography (SLA) photopolymer
Digital Light Processing (DLP) photopolymer

Extrusion deposition

Fused deposition modeling: 1 – nozzle ejecting molten plastic, 2 – deposited material (modeled part), 3 – controlled movable table.

Fused deposition modeling (FDM) was developed by S. Scott Crump in the late 1980s and was commercialized in 1990 by Stratasys.[17]With the expiration of patent on this technology there is now a large open-source development community this type of 3D printer (e.g.RepRaps) and many commercial and DIY variants, which have dropped the cost by two orders of magnitude.

Fused deposition modeling uses a plastic filament or metal wire that is wound on a coil and unreeled to supply material to an extrusionnozzle, which turns the flow on and off. The nozzle heats to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism that is directly controlled by a computer-aided manufacturing (CAM) software package. The model or part is produced by extruding small beads of thermoplastic material to form layers as the material hardens immediately after extrusion from the nozzle. Stepper motors or servo motors are typically employed to move the extrusion head.

Various polymers are used, including acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polylactic acid (PLA), high density polyethylene (HDPE), PC/ABS, and polyphenylsulfone (PPSU). In general the polymer is in the form of a filament, fabricated from virgin resins. Multiple projects in the open-source community exist that are aimed at processing post-consumer plastic waste into filament. These involve machines to shred and extrude the plastic material into filament.

FDM has some restrictions on the shapes that may be fabricated. For example, FDM usually cannot produce stalactite-like structures, since they would be unsupported during the build. These have to be avoided or a thin support may be designed into the structure which can be broken away during finishing processes.

Granular materials binding

The CandyFab granular printing system uses heated air and granulated sugar to produce food-grade art objects.

Another 3D printing approach is the selective fusing of materials in a granular bed. The technique fuses parts of the layer, and then moves the working area downwards, adding another layer of granules and repeating the process until the piece has built up. This process uses the unfused media to support overhangs and thin walls in the part being produced, which reduces the need for temporary auxiliary supports for the piece. A laser is typically used to sinter the media into a solid. Examples include selective laser sintering (SLS), with both metals and polymers (e.g. PA, PA-GF, Rigid GF, PEEK, PS, Alumide, Carbonmide, elastomers), and direct metal laser sintering (DMLS).

Selective Laser Sintering (SLS) was developed and patented by Dr. Carl Deckard and Dr. Joseph Beaman at the University of Texas at Austin in the mid-1980s, under sponsorship of DARPA.[18] A similar process was patented without being commercialized by R. F. Housholder in 1979.[19]

Selective Laser Melting (SLM) does not use sintering for the fusion of powder granules but will completely melt the powder using a high-energy laser to create fully dense materials in a layerwise method with similar mechanical properties to conventional manufactured metals.

Electron beam melting (EBM) is a similar type of additive manufacturing technology for metal parts (e.g. titanium alloys). EBM manufactures parts by melting metal powder layer by layer with an electron beam in a high vacuum. Unlike metal sintering techniques that operate below melting point, EBM parts are fully dense, void-free, and very strong.[20][21]

Another method consists of an inkjet 3D printing system. The printer creates the model one layer at a time by spreading a layer of powder (plaster, or resins) and printing a binder in the cross-section of the part using an inkjet-like process. This is repeated until every layer has been printed. This technology allows the printing of full color prototypes, overhangs, and elastomer parts. The strength of bonded powder prints can be enhanced with wax or thermoset polymer impregnation.

Lamination

In some printers, paper can be used as the build material, resulting in a lower cost to print. During the 1990s some companies marketed printers that cut cross sections out of special adhesive coated paper using a carbon dioxide laser, and then laminated them together.

In 2005, Mcor Technologies Ltd developed a different process using ordinary sheets of office paper, a Tungsten carbide blade to cut the shape, and selective deposition of adhesive and pressure to bond the prototype.[22]

There are also a number of companies selling printers that print laminated objects using thin plastic and metal sheets.

Photopolymerization

Stereolithography apparatus.

Main article: Stereolithography

Stereolithography was patented in 1987 by Chuck Hull. Photopolymerization is primarily used in stereolithography (SLA) to produce a solid part from a liquid.This process dramatically redefined previous efforts, from the Photosculpture method of François Willème (1830-1905) in 1860[23] through the photopolymer process of Mitsubishi`s Matsubara in 1974.[24]

In digital light processing (DLP), a vat of liquid polymer is exposed to light from a DLP projector under safelight conditions. The exposed liquid polymer hardens. The build plate then moves down in small increments and the liquid polymer is again exposed to light. The process repeats until the model has been built. The liquid polymer is then drained from the vat, leaving the solid model. The EnvisionTec Ultra[25] is an example of a DLP rapid prototyping system.

Inkjet printer systems like the Objet PolyJet system spray photopolymer materials onto a build tray in ultra-thin layers (between 16 and 30 µm) until the part is completed. Each photopolymer layer is cured with UV light after it is jetted, producing fully cured models that can be handled and used immediately, without post-curing. The gel-like support material, which is designed to support complicated geometries, is removed by hand and water jetting. It is also suitable for elastomers.

Ultra-small features can be made with the 3D microfabrication technique used in multiphoton photopolymerization. This approach traces the desired 3D object in a block of gel using a focused laser. Due to the nonlinear nature of photoexcitation, the gel is cured to a solid only in the places where the laser was focused and the remaining gel is then washed away. Feature sizes of under 100 nm are easily produced, as well as complex structures with moving and interlocked parts.[26]

Yet another approach uses a synthetic resin that is solidified using LEDs.[27]

Printers

Printers for domestic use

RepRap version 2.0 (Mendel).

MakerBot Cupcake CNC.

Airwolf 3D AW3D v.4 (Prusa).

Several projects and companies are making efforts to develop affordable 3D printers for home desktop use. Much of this work has been driven by and targeted at DIY/enthusiast/early adopter communities, with additional ties to the academic and hacker communities.[28]

RepRap is one of the longest running projects in the desktop category. The RepRap project aims to produce a free and open source software (FOSS) 3D printer, whose full specifications are released under the GNU General Public License, and which is capable of replicating itself by printing many of its own (plastic) parts to create more machines.[29] Research is under way to enable the device to printcircuit boards and metal parts.

Because of the FOSS aims of RepRap, many related projects have used their design for inspiration, creating an ecosystem of related or derivative 3D printers, most of which are also open source designs. The availability of these open source designs means that variants of 3D printers are easy to invent. The quality and complexity of printer designs, however, as well as the quality of kit or finished products, varies greatly from project to project. This rapid development of open source 3D printers is gaining interest in many spheres as it enables hyper-customization and the use of public domain designs to fabricate open source appropriate technology through conduits such as Thingiverse and Cubify. This technology can also assist initiatives in sustainable development since technologies are easily and economically made from resources available to local communities.[30]

The cost of 3D printers has decreased dramatically since about 2010, with machines that used to cost $20,000 costing less than $1,000.[31] For instance, as of 2013, several companies and individuals are selling parts to build various RepRap designs, with prices starting at about €400 /US$500.[32] The price of printer kits vary from US$400 for the Printrbot Jr. (derived from the previous RepRap models), to US$599 for the RoBo 3D Printer to over US$2000 for the Fab@Home 2.0 two-syringe system.[32] The Shark 3D printer comes fully assembled for less than US$2000. The open source Fab@Home project[33] has developed printers for general use with anything that can be squirted through a nozzle, from chocolate to silicone sealant and chemical reactants. Printers following the project’s designs have been available from suppliers in kits or in pre-assembled form since 2012 at prices in the US$2000 range.[32]

Printers for commercial and domestic use

The development and hyper-customization of the RepRap-based 3D printers has produced a new category of printers suitable for both domestic and commercial use. The least expensive assembled machine available is the Solidoodle 2, while the RepRapPro’s Huxley DIY kit is reputedly[weasel words] one of the more reliable of the lower-priced machines, at around US$680. There are other RepRap-based high-end kits and fully assembled machines that have been enhanced to print at high speed and high definition. Depending on the application, the print resolution and speed of manufacturing lies somewhere between a personal printer and an industrial printer. A list of printers with pricing and other information is maintained.[32] Most recently delta robots have been utilized for 3D printing to increase fabrication speed further.[34]

Applications

Three-dimensional printing makes it as cheap to create single items as it is to produce thousands and thus undermines economies of scale. It may have as profound an impact on the world as the coming of the factory did….Just as nobody could have predicted the impact of the steam engine in 1750—or the printing press in 1450, or the transistor in 1950—it is impossible to foresee the long-term impact of 3D printing. But the technology is coming, and it is likely to disrupt every field it touches.

— The Economist, in a February 10, 2011 leader[35]

An example of 3D printed limited editionjewellery. This necklace is made of glassfiber-filled dyed nylon. It has rotating linkages that were produced in the same manufacturing step as the other parts.

Additive manufacturing’s earliest applications have been on the toolroom end of the manufacturing spectrum. For example, rapid prototyping was one of the earliest additive variants, and its mission was to reduce the lead time and cost of developing prototypes of new parts and devices, which was earlier only done with subtractive toolroom methods (typically slowly and expensively).[36] With technological advances in additive manufacturing, however, and the dissemination of those advances into the business world, additive methods are moving ever further into the production end of manufacturing in creative and sometimes unexpected ways.[36] Parts that were formerly the sole province of subtractive methods can now in some cases be made more profitably via additive ones.

Standard applications include design visualization, prototyping/CAD, metal casting, architecture, education, geospatial, healthcare, and entertainment/retail.

Industrial uses

Rapid prototyping

Main article: rapid prototyping

Full color miniature face models produced on a 3D Printer.

Printing going on with a 3D printer at Makers Party Bangalore 2013, Bangalore

Industrial 3D printers have existed since the early 1980s and have been used extensively for rapid prototyping and research purposes. These are generally larger machines that use proprietary powdered metals, casting media (e.g. sand), plastics, paper or cartridges, and are used for rapid prototyping by universities and commercial companies.

Rapid manufacturing

Advances in RP technology have introduced materials that are appropriate for final manufacture, which has in turn introduced the possibility of directly manufacturing finished components. One advantage of 3D printing for rapid manufacturing lies in the relatively inexpensive production of small numbers of parts.

Rapid manufacturing is a new method of manufacturing and many of its processes remain unproven. 3D printing is now entering the field of rapid manufacturing and was identified as a “next level” technology by many experts in a 2009 report.[37] One of the most promising processes looks to be the adaptation of laser sintering (LS), one of the better-established rapid prototyping methods. As of 2006, however, these techniques were still very much in their infancy, with many obstacles to be overcome before RM could be considered a realistic manufacturing method.[38]

Mass customization

Companies have created services where consumers can customize objects using simplified web based customization software, and order the resulting items as 3D printed unique objects.[39][40] This now allows consumers to create custom cases for their mobile phones.[41]Nokia has released the 3D designs for its case so that owners can customize their own case and have it 3D printed.[42]

Mass production[edit]

The current slow print speed of 3D printers limits their use for mass production. To reduce this overhead, several fused filament machines now offer multiple extruder heads. These can be used to print in multiple colors, with different polymers, or to make multiple prints simultaneously. This increases their overall print speed during multiple instance production, while requiring less capital cost than duplicate machines since they can share a single controller. Distinct from the use of multiple machines, multi-material machines are restricted to making identical copies of the same part, but can offer multi-color and multi-material features when needed. The print speed increases proportionately to the number of heads. Furthermore, the energy cost is reduced due to the fact that they share the same heated print volume. Together, these two features reduce overhead costs.

Many printers now offer twin print heads. However, these are used to manufacture single (sets of) parts in multiple colors/materials.

Few studies have yet been done in this field to see if conventional subtractive methods are comparable to additive methods.

Domestic and hobbyist uses

As of 2012, domestic 3D printing has mainly captivated hobbyists and enthusiasts and has not quite gained recognition for practical household applications. A working clock has been made[43] and gears have been printed for home woodworking machines[44] among other purposes.[45] 3D printing is also used for ornamental objects. Web sites associated with home 3D printing tend to include backscratchers, coathooks, etc. among their offered prints.

The open source Fab@Home project[33] has developed printers for general use. They have been used in research environments to produce chemical compounds with 3D printing technology, including new ones, initially without immediate application as proof of principle.[46] The printer can print with anything that can be dispensed from a syringe as liquid or paste. The developers of the chemical application envisage that this technology could be used for both industrial and domestic use. Including, for example, enabling users in remote locations to be able to produce their own medicine or household chemicals.[47][48]

Clothing

3D printing has spread into the world of clothing with fashion designers experimenting with 3D-printed bikinis, shoes, and dresses.[49] In commercial production Nike is using 3D printing to prototype and manufacture the 2012 Vapor Laser Talon football shoe for players of American football, and New Balance is 3D manufacturing custom-fit shoes for athletes.[49][50]

3D printing services

Some companies offer on-line 3D printing services open to both consumers and industries.[51] Such services require people to upload their 3D designs to the company website. Designs are then 3D printed using industrial 3D printers and either shipped to the customer or in some cases, the consumer can pick the object up at the store.[52]

Research into new applications

Future applications for 3D printing might include creating open-source scientific equipment[53][54] or other science-based applications like reconstructing fossils in paleontology, replicating ancient and priceless artifacts in archaeology, reconstructing bones and body parts in forensic pathology, and reconstructing heavily damaged evidence acquired from crime scene investigations. The technology is even being explored for building construction.

In 2005, academic journals had begun to report on the possible artistic applications of 3D printing technology.[55] By 2007 the mass media followed with an article in the Wall Street Journal[56] and Time Magazine, listing a 3D printed design among their 100 most influential designs of the year.[57] During the 2011 London Design Festival, an installation, curated by Murray Moss and focused on 3D Printing, was held in the Victoria and Albert Museum (the V&A). The installation was called Industrial Revolution 2.0: How the Material World will Newly Materialize.[58]

As of 2012, 3D printing technology has been studied by biotechnology firms and academia for possible use in tissue engineering applications in which organs and body parts are built using inkjet techniques. In this process, layers of living cells are deposited onto a gel medium or sugar matrix and slowly built up to form three-dimensional structures including vascular systems.[59] Several terms have been used to refer to this field of research: organ printing, bio-printing, body part printing,[60] and computer-aided tissue engineering, among others.[61]

proof-of-principle project at the University of Glasgow, UK, in 2012 showed that it is possible to use 3D printing techniques to create chemical compounds, including new ones. They first printed chemical reaction vessels, then used the printer to squirt reactants into them as “chemical inks” which would then react.[46] They have produced new compounds to verify the validity of the process, but have not pursued anything with a particular application.[46] Cornell Creative Machines Lab has confirmed that it is possible to produce customized food with 3D Hydrocolloid Printing.[62]

The use of 3D scanning technologies allows the replication of real objects without the use of moulding techniques that in many cases can be more expensive, more difficult, or too invasive to be performed, particularly for precious or delicate cultural heritage artifacts[63] where direct contact with the molding substances could harm the original object’s surface.

An additional use being developed is building printing, or using 3D printing to build buildings. This could allow faster construction for lower costs, and has been investigated for construction of off-Earth habitats.[64][65]

Employing additive layer technology offered by 3D printing, Terahertz devices which act as waveguides, couplers and bends have been created. The complex shape of these devices could not be achieved using conventional fabrication techniques. Commercially available professional grade printer EDEN 260V was used to create structures with minimum feature size of 100 µm. The printed structures were later DC sputter coated with gold (or any other metal) to create a Terahertz Plasmonic Device. [66]

In 2013, Chinese scientists began printing ears, livers and kidneys, with living tissue. Researchers in China have been able to successfully print human organs using specialized 3D bio printers that use living cells instead of plastic. Researchers at Hangzhou Dianzi University actually went as far as inventing their own 3D printer for the complex task, dubbed the “Regenovo” which is a “3D bio printer.” Xu Mingen, Regenovo’s developer, said that it takes the printer under an hour to produce either a mini liver sample or a four to five inch ear cartilage sample. Xu also predicted that fully functional printed organs may be possible within the next ten to twenty years.[67][68] In the same year, researchers at the University of Hasselt, in Belgium had successfully printed a new jawbone for an 83-year-old Belgian woman. The woman is now able to chew, speak and breathe normally again after a machine printed her a new jawbone.[69]

In Bahrain, large-scale 3D printing using a sandstone-like material has been used to create unique coral-shaped structures, which encourage coral polyps to colonize and regenerate damaged reefs. These structures have a much more natural shape than other structures used to create artificial reefs, and have a neutral pH which concrete does not.[70]

Intellectual property

3D printing has existed for decades within certain manufacturing industries and many legal regimes, including patentsindustrial design rightscopyright, and trademark can apply. However, there is not much jurisprudence to say how these laws will apply if 3D printers become mainstream and individuals and hobbyist communities begin manufacturing items for personal use, for non profit distribution, or for sale.

Any of the mentioned legal regimes may prohibit the distribution of the designs used in 3d printing, or the distribution or sale of the printed item. To be allowed to do these things, a person would have to contact the owner and ask for a licence, which may come with conditions and a price.

Patents cover an idea, a technique, and generally last 20 years. So if a special type of wheel is patented, then printing and selling such a wheel would be illegal. Two questions which are less clear are whether printing for personal use would be restricted, and whether distributing designs would constitute infringement or a relate offence such as incitement to infringe.

Copyright covers an expression[71] and often last for the life of the author plus 70 years thereafter.[72] If someone makes a statue, they may have copyright on the look of that statue, so if someone sees that statue, they cannot then distribute designs to print an identical or similar statue.

When a feature has both artistic (copyrightable) and functional (patentable) merits, when the question has appeared in US court, the courts have often held the feature is not copyrightable unless it can be separated from the functional aspects of the item.[72]

Effects of 3D printing

Additive manufacturing, starting with today’s infancy period, requires manufacturing firms to be flexible, ever-improving users of all available technologies in order to remain competitive. Advocates of additive manufacturing also predict that this arc of technological development will counter globalisation, as end users will do much of their own manufacturing rather than engage in trade to buy products from other people and corporations.[13] The real integration of the newer additive technologies into commercial production, however, is more a matter of complementing traditional subtractive methods rather than displacing them entirely.[73]

Space exploration

As early as 2010, work began on applications of 3D printing in zero or low gravity environments.[74] The primary concept involves creating basic items such as hand tools or other more complicated devices “on demand” versus using valuable resources such as fuel or cargo space to carry the items into space.

Additionally, NASA is conducting tests to assess the potential of 3D printing to make space exploration cheaper and more efficient.[75] Rocket parts built using this technology have passed NASA firing tests. In July 2013, two rocket engine injectors performed as well as traditionally constructed parts during hot-fire tests which exposed them to temperatures approaching 6,000 degrees Fahrenheit (3,316 degrees Celsius) and extreme pressures.

Firearms

In 2012, the U.S.-based group Defense Distributed disclosed plans to “[design] a working plastic gun that could be downloaded and reproduced by anybody with a 3D printer.”[76][77]Defense Distributed has also designed a 3D printable AR-15 type rifle lower receiver (capable of lasting more than 650 rounds) and a 30 round M16 magazine.[78] Soon after Defense Distributed succeeded in designing the first working blueprint to produce a plastic gun with a 3D printer in May 2013, the United States Department of State demanded that they remove the instructions from their website.[79]

After Defense Distributed released their plans, questions were raised regarding the effects that 3D printing and widespread consumer-level CNC machining[80][81] may have on gun control effectiveness.[82][83][84][85]

The U.S. Department of Homeland Security and the Joint Regional Intelligence Center released a memo stating that “significant advances in three-dimensional (3D) printing capabilities, availability of free digital 3D printer files for firearms components, and difficulty regulating file sharing may present public safety risks from unqualified gun seekers who obtain or manufacture 3D printed guns,” and that “proposed legislation to ban 3D printing of weapons may deter, but cannot completely prevent their production. Even if the practice is prohibited by new legislation, online distribution of these digital files will be as difficult to control as any other illegally traded music, movie or software files.”[86]

Internationally, where gun controls are generally tighter than in the United States, some commentators have said the impact may be more strongly felt, as alternative firearms are not as easily obtainable.[87] European officials have noted that producing a 3D printed gun would be illegal under their gun control laws,[88] and that criminals have access to other sources of weapons, but noted that as the technology improved the risks of an effect would increase.[89][90] Downloads of the plans from the UK, Germany, Spain, and Brazil were heavy.[91][92]

Attempting to restrict the distribution over the Internet of gun plans has been likened to the futility of preventing the widespread distribution of DeCSS which enabled DVDripping.[93][94][95][96] After the US government had Defense Distributed take down the plans, they were still widely available via The Pirate Bay and other file sharing sites.[97] Some US legislators have proposed regulations on 3D printers, to prevent them being used for printing guns.[98][99] 3D printing advocates have suggested that such regulations would be futile, could cripple the 3D printing industry, and could infringe on free speech rights.

What is RepRap?

RepRap is humanity’s first general-purpose self-replicating manufacturing machine.

RepRap takes the form of a free desktop 3D printer capable of printing plastic objects. Since many parts of RepRap are made from plastic and RepRap prints those parts, RepRap self-replicates by making a kit of itself – a kit that anyone can assemble given time and materials. It also means that – if you’ve got a RepRap – you can print lots of useful stuff, and you can print another RepRap for a friend

RepRap is about making self-replicating machines, and making them freely available for the benefit of everyone. We are using 3D printing to do this, but if you have other technologies that can copy themselves and that can be made freely available to all, then this is the place for you too.

Reprap.org is a community project, which means you are welcome to edit most pages on this site, or better yet, create new pages of your own. Our community portal and New Development pages have more information on how to get involved. Use the links below and on the left to explore the site contents. You’ll find some content translated into other languages.

RepRap was the first of the low-cost 3D printers, and the RepRap Project started the open-source 3D printer revolution. It has become the most widely-used 3D printer among the global members of the Maker Community.

3D-printing-user-chart

A family using one RepRap to print only 20 domestic products per year (about 0.02% of the products available) can expect to save between $300 and $2000: “…the unavoidable conclusion from this study is that the RepRap is an economically attractive investment for the average US household already.” Source: B.T. Wittbrodt et al., Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers, Mechatronics