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A rapid prototyping process developed at the Massachusetts Institute of Technology (MIT). Layers of powder are bonded by inkjet to form a part. The term is also used generically as synonym for rapid prototyping.
Refers generally to the low-cost segment of the rapid prototyping machine market. The output of these systems is typically considered adequate for concept and appearance modeling, but may lack the accuracy or other attributes of more costly systems. This terminology is used extensively in the Wohlers Report, but others may not draw as fine a distinction.
Defined as the difference between an intended final dimension and the actual dimension as determined by a physical measurement of the part. In addition to those for linear dimensions, there are accuracy specifications for such features as hole sizes and flatness.
adaptive slicing
The use of variable layer thickness in an additive fabrication process, generally thinner layers being used where part detail is greatest.
additive fabrication / additive manufacturing
Fabrication of a part by adding materials to a substrate or previously formed portions of a part. The most common additive fabrication methods utilize a layered approach, but other geometries are possible. The term is also used generically as a synonym for rapid prototyping.
Refers to the fact that parts may have different physical properties depending on which direction measurements are made, and such differences can also arise if the exact same part is made in a different way. This can happen if the building orientation of the part in the machine is changed, and also from the sequence in which the part's elements are fabricated.
Tooling which is typically capable of producing quantities of several tens to several hundreds of parts. That is to say, it "bridges" the quantity between very low volume prototype tooling and full production tooling. In some cases bridge tooling may offer sufficient volume to meet production requirements. Most rapid tooling technologies can be considered bridge tooling because they're not yet capable of truly high quantity production.
A part which has been sintered or had other secondary operations performed on it to bring it from the loosely-bonded, as-formed "green" state. Parts in the brown state are generally dimensionally stable, but are often porous and usually must be infiltrated with another material before use.
A part intended primarily for form or appearance study, but which typically cannot be used to either check fit to other parts, or provide functionality of the final part in an application.
3D Systems' trade name for a process of producing injection-mold tooling directly by stereolithography. AIM stands for ACES Injection Molding, where ACES stands for Accurate Clear Epoxy Solid, another 3D trade name.
Soligen is the exclusive supplier for this specialized version of MIT's three dimensional printing process (3DP). It is used exclusively for investment casting applications.
The Electron Beam Melting (EBM) process from Arcam is a powder-based process having a lot in common with selective laser sintering, but replaces the laser with a scanned electron beam to produce fully-dense metal parts.
A virtual market for buyers and sellers implemented through the Internet or World Wide Web. Also known as a web exchange.
final machining
A secondary operation in which parts formed by a rapid prototyping method are brought to acceptable final finishes and tolerances typically by subtractive CNC technology.
A qualitative term for the appearance of a part. For example, technologies based on powders have a sandy or diffuse finish; some inkjet technologies produce a smooth finish due to use of extremely thin layers; sheet-based methods might be considered poorer in finish because stairstepping is more pronounced.
A part that has been formed by a rapid prototyping process, but is in a loosely-bonded state. For example, metal or ceramic parts formed by some selective laser sintering systems are in a "green" state when removed from the machine. They are then sintered by a secondary operation to a "brown" state.
Generally refers to tooling which is made by using an RP-generated part as a pattern for a secondary process as opposed to directly fabricating a tool using the RP process itself.
Helisys, now defunct and succeeded by Cubic Technologies, was the first producer but also several other manufacturers provide this technology. Layers of paper or other materials are cut and bonded to form a part.
A laser powder forming rapid prototyping process developed by AeroMet Corporation. It was mainly aimed at producing large parts from reactive materials such as titanium for aerospace applications, but the company became inactive in Oct., 2005.
A rapid prototyping process which deposits metal powder into a pool of molten metal or other build material formed by a focused laser beam. There are several variants either commercially available or under development. LENS ® was developed by Sandia National Laboratories and commercialized by Optomec. It can also be used for repairing and modifying existing parts and tools. (LENS ® and Laser Engineered Net-Shaping (TM) are registered trademarks of Sandia National Labs. and Sandia Corp.)
Similar to inkjet printing where individual molten droplets are controlled and printed to specific locations.
mass customization
A process whereby small lots of individualized parts or products are produced. The opposite of mass production whereby large numbers of identical parts or products are produced.
This DARPA program is aimed at simplifying the manufacture of electronic devices and systems, and providing greater flexibility than is possible using existing technologies. In size, mesoscale devices fall between integrated circuits and surface-mount components.
Refers to the smallest detail of a part that can faithfully be reproduced. Mathematical definitions are usually based on a minimum curvature as a limit, but anecdotal values based on experience are more commonly utilized.
This is an inkjet RP method produced by Solidscape (formerly Sanders Prototypes), and the related company, Sanders International. It produces the highest accuracy and resolution of all RP methods, but is slow and has limited material choices.
This is an inkjet RP method produced by 3D Systems, Inc. It uses a wide area head and is most often used for generating quick concept models. The materials available are wax-like plastics and accuracy is lower than that available from stereolithography.
An object or part which possesses the mechanical geometry of a final object or part, but which may not possess the desired mechanical, thermal or other attributes of the final parts. Patterns are used in secondary processes to form tools to make parts for end-uses.
photocuring
See photopolymerization below.
photopolymer / photopolymerization
Material systems which change from a liquid to a solid state upon application of light (actinic) radiation. Light sources can be a laser or lamp, but related radiation-curable materials may be made solid by application of microwave or heat-based radiation sources. Photopolymers are typically complex mixtures of compounds rather than consisting of a single component.
post-processing
Secondary operations necessary to turn an additively fabricated-part into a useable one. Such operations may include cleaning, removal of supports or unused powder, post-curing and surface finishing operations such as sanding. Also see secondary operations.
An application of MIT's Three Dimensional Printing Process to the fabrication of injection molds. Steel powder layers are bonded by photopolymer selectively applied by a wide area inkjet head.
Most often refers to the process of fabricating tools from a rapid prototyping process. Rapid tooling may utilize direct or indirect methods: In direct methods, the part fabricated by the RP machine itself is used as the tool. In indirect methods, the part fabricated by the RP machine is used as a pattern in a secondary process. The resulting part from the secondary process is then used as the tool. In recent years, the term rapid tooling has been borrowed by practitioners of industry-standard methods such as subtractive CNC to refer to the ability to streamline these processes to compete with additive technologies.
resolution
Refers to the minimum increment in dimensions that a system achieve. It's one of the main determining factors for finish, appearance and accuracy, but certainly not the only one.
The process of measuring an existing part to create a geometric CAD data definition of the part. In common non-technical usage, reverse engineering may also refer to measuring or analyzing a part or a product for the purpose of copying it.
Manual or machine-based operations which must be carried out on a part fabricated by a rapid prototyping system before use. Secondary operations may include, post curing, support-removal, sanding, machining, etc.
Any one of a large number of processes such as rubber molding. Sprayform, EcoTool, etc., that utilize a rapid prototyping-fabricated part as pattern to create a final tool or part.
selective laser melting
A process similar to selective laser sintering, but which fully melts metal or ceramic powders to directly form fully-dense parts.
A rapid prototyping technology in which powders are fused layerwise by a laser. The technology produces accurate parts and models in engineering polymers, metals and polymer-coated sand for casting applications. Speed is similar to stereolithography, but material selection is wider.
This photopolymer-based technology was provided by Cubital. The company has been dissolved, but the process may still be available from a very few service bureaus. A xerographically-generated mask is used to cure an entire layer of photopolymer at one time. It offers good accuracy coupled with high throughput, but is considered quite expensive.
A type of inaccuracy, as well as a visual appearance artifact It refers to the stepped appearance of the edges of a part, a consequence of additive fabricating a part in layers of necessarily finite thickness.
A rapid prototyping process that fabricates a part layerwise by hardening a photopolymer with a guided laser beam. Stereolithography is frequently used as a general term for "rapid prototyping," but this is neither precise nor correct.
A file format used in RP to define the geometry of the part to be made. STL files are created by CAD programs by translating their native or neutral files into the STL format. The STL file defines the coordinates of numerous triangular facets that approximate the shape of an object or part.
subtractive machining
The fabrication of a part by removing material from a stock shape of material. The stock shape may be a prismatic solid, cylinder, plate, etc. The removal of material may by cutting, turning, electro-discharge or other means. Common machinery such as millers, lathes and drills are subtractive tools.
Many rapid prototyping machines need a means to hold in place unsupported geometries during fabrication, such as the top of a part in the shape of the letter "T." These supports are usually calculated and added to the part by the system's software and may be formed of the same material as the part, or from a different material entirely. Support structures are either mechanically removed or dissolved away in secondary operations before the part can be used.
virtual prototyping
Computer-based prototyping without recourse to a physical part or object.
voxel
The three dimensional equivalent of a pixel. A pixel is a "picture element," and a voxel is a "volume element." A voxel may also be defined as the minimum volume that a rapid prototyping system can fabricate.
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