Rapid Manufacturing
Both a concept and a book with the same title.
= Rapid Manufacturing is a broad term including the use of Rapid Prototyping, Rapid Tooling, and the direct use of Layer Manufacturing technologies to produce final products quickly.
Concept
Definition 1
"Rapid Manufacturing is a new area of manufacturing developed from a family of technologies known as Rapid Prototyping. These processes have already had the effect of both improving products and reducing their development time; this in turn resulted in the development of the technology of Rapid Tooling, which implemented Rapid Prototyping techniques to improve its own processes. Rapid Manufacturing has developed as the next stage, in which the need for tooling is eliminated. It has been shown that it is economically feasible to use existing commercial Rapid Prototyping systems to manufacture series parts in quantities of up to 20,000 and customised parts in quantities of hundreds of thousands. This form of manufacturing can be incredibly cost-effective and the process is far more flexible than conventional manufacturing."
Definition 2
From the Wikipedia at http://en.wikipedia.org/wiki/Rapid_manufacturing
"Rapid manufacturing is a technique for manufacturing solid objects by the sequential delivery of energy and/or material to specified points in space to produce that part. Current practice is to control the manufacturing process by computer using a mathematical model created with the aid of a computer. Rapid manufacturing done in parallel batch production provides a large advantage in speed and cost overhead compared to alternative manufacturing techniques such as laser ablation or die casting. The true definition of rapid manufacturing involves the production of series products or the use of the created part in production (see Hopkins, Hague and Dickens, 2005). Where the part is used in the development process only then the appropriate term is rapid prototyping." (http://en.wikipedia.org/wiki/Rapid_manufacturing)
How Does It Work?
Basic Functioning
From http://www.csa.com/discoveryguides/rapidman/overview.php
“Basically, all layer manufacturing systems consist of a combination of a computer CAD system with an operation machine to perform the fabrication of a layer under computer control. First, a 3D CAD representation of the part is created by a computer software package such as ProEngineer, SolidWorks, or Autocad. The computer representation of the part is then sliced into layers of a certain thickness, typically 0.1 to 0.25 mm, and their two-dimensional (2D) profiles stored in a triangulated (tessellated) format as a .STL file. Second, the software converts the .STL data to machine data, which are sent to the operation machine to generate each layer of the part by the specific fabrication process. The process is repeated many times, building the part layer by layer. The final step is finishing, removing the part from the machine, detaching support materials, and performing any necessary cleaning or surface finishing. Polishing, sealing, or painting the parts can improve their appearance.”
(http://www.csa.com/discoveryguides/rapidman/overview.php )
The Four Processes of Manufacturing
By Lawrence J. Rhoades on what it the processes that need to be automated at http://www.nae.edu/NAE/bridgecom.nsf/BridgePrintView/MKEZ-6AHJL5?OpenDocument
"Nearly all discrete parts are made using a series of steps or processes that, with few exceptions, fall into one of four groups:
- Casting or molding produces an object by transforming a material from a liquid to a solid. A material in liquid form is poured or injected into a preformed mold (or die), allowed to solidify (normally by cooling, but sometimes by heating or chemical curing), and, once solidified, removed from the mold as a solid object. The mold is typically made from a metal with a higher melting temperature than the formed material. Sometimes the mold is disposable (e.g., sand or ceramic) and is destroyed during the removal of the formed part. In these cases, the mold itself is “molded” from a durable, preformed pattern.
- Forming is a process of applying force, and sometimes heat, to reshape, and sometimes cut, a ductile material by stamping, forging, extruding, or rolling. Like the tools used in casting or molding, the tools used in forming are preformed and durable.
- Machining is used to “cut” specific features into preformed blanks (e.g., slabs, bars, tubes, sheets, extrusions, castings, forgings, etc.) by manipulating a fast-moving cutting tool relative to the work piece on a special (usually computer-controlled) machine tool, such as a lathe, mill, or grinder. In the machining process, even though the cutting-tool material is considerably more durable than the work piece material, the tool is subject to wear and tear. Typically, many different tools are used, and a specific “cutter path” is programmed for each feature and each tool. Compensation is made for tool wear.
- Joining includes welding, brazing, and mechanical assembly of parts (made by molding, forming, or machining) to make more complex parts than would otherwise be possible with those methods. Typically, special fixtures or special tooling and programming of assembly machines or robots are used for each assembled part."
(http://www.nae.edu/NAE/bridgecom.nsf/BridgePrintView/MKEZ-6AHJL5?OpenDocument)
Typology
The technologies now available include a variety of different processes, such as Stereolithography, Selective Laser Sintering, Shape Deposition Manufacturing, and Laminated Object Manufacturing.
Glossary at http://www.csa.com/discoveryguides/rapidman/gloss.php
Stereolithography (SL) was the first commercialized fabrication process, producing parts from photo-sensitive polymer resin. It operates by scanning the liquid surface of a bath of the resin with an ultraviolet (UV) laser beam that causes the resin to cure in the shape of a layer of the part. The lowest layer is carried on an elevator platform that is lowered by the slice thickness after each new layer is formed at the surface. The layers combine to form the desired 3D shape of the part. The SL process can fabricate plastic molds for pattern making or blocks for metal sheet forming, as well as produce a wide range of polymer prototypes.
Selective Laser Sintering (SLS) is another process, with a wider range of material than SL. SLS can produce highly complex parts from materials such as metal, plastic, ceramic, and sand. The material in powdered form is deposited on a platform, and a carbon dioxide (CO2) laser is used to selectively melt or sinter powder into the desired shape for each layer. The layers are lowered on a platform, with loose powder around the growing structure acting as a support for the top powder layer. The strength and porosity of the material can be controlled by adjusting various process parameters, such as laser scanning speed and power. Products have ranged from turbine rotors to medical inserts.
Shape Deposition Manufacturing (SDM) is another layer manufacturing process that combines the techniques of deposition and CNC machining. Each layer is machined after it is deposited, and support material is added and machined to receive subsequent layers. The incremental machining allows a smooth surface to be achieved, even with thick layers, and the use of support material allows layers with overhanging, undercut, and separated features to be supported during the fabrication. The support material is removed at the end by melting or dissolving, and final machining is not usually required. SDM is a good choice for custom tooling, precision assemblies, structural ceramics, and wax molds for casting. It allows a high quality surface finish, intricate undercut features, and multi-material structures with inserts.
The Laminated Object Manufacturing (LOM) process was developed by Helisys of Torrance, CA . It produces parts from a sheet material bonded together in layers to form a laminated structure. The original material used for the layers was paper, but several other sheet materials are now available, including plastic, water-repellent paper, and ceramic and metal powder tapes. The process has been used to make casting dies for automotive parts. The 3D Printing process is based on ink-jet printing technology. A group of print heads moves across a powdered material in a scanning pattern, distributing a liquid binder to bond the material in the shape of each layer. The part is lowered, additional powder is added, and the process is repeated. At the end, the part is removed from the powder bed and cleaned. The field of potential application ranges from functional metal parts to small-series parts and mold inserts. Such mold inserts are suitable for plastic injection, metal die casting, extrusion tooling, etc . (http://www.csa.com/discoveryguides/rapidman/overview.php )
Status Report: Benchmarks
How can you know if the field becomes mature? Two criteria: the ability to make fully functional objects, and to mold metals, not just plastic.
"Digital production (or rapid manufacturing) transforms engineering design files directly into functional objects—ideally, fully functional objects. This technology emerged from rapid prototyping systems that first produced nonfunctional, “appearance models” (limited-use, engineering-design and marketing aids made from nondurable plastic materials). Over time, the plastic materials were strengthened until the models became fairly functional. However, the real-world benchmark materials for full functionality in manufacturing are metals." (http://www.nae.edu/NAE/bridgecom.nsf/BridgePrintView/MKEZ-6AHJL5?OpenDocument)
Book
Book: Rapid Manufacturing: An Industrial Revolution for the Digital Age. Ed. by Philip Dickens et al. Wiley, 2006
The book "addresses the academic fundamentals of Rapid Manufacturing as well as focussing on case studies and applications across a wide range of industry sectors." (from the publisher)
More Information
See our related entries on Desktop Manufacturing and Personal Fabricators
Glossary at http://www.csa.com/discoveryguides/rapidman/gloss.php
Rapid Prototyping at http://www.cc.utah.edu/~asn8200/rapid.html
European collaboration on the topic at http://rm-platform.com/