1. Rapid Prototyping
rapid prototyping technology, also known as rapid prototyping (Rapid Prototyping Manufacturing, referred to as RPM) technology, born in the 20th century, the late 80’s, High-tech manufacturing technology is based on a material deposition method, it is considered the last 20 years, a major achievement in the field of manufacturing. It combines mechanical engineering, CAD, reverse engineering, layered manufacturing technology, digital technology, materials science, laser technology in one, automatically, direct, fast and accurate design idea into a prototype with a certain function or direct manufacturing of parts so that aspect of the new design validation and so provide a means of achieving an efficient low-cost parts for prototyping. That is, rapid prototyping technology is the use of three-dimensional CAD data by rapid prototyping machine, the deposited material into layers of physical prototypes.
Characteristics of rapid prototyping technology
(1) Production of the prototype material used is not limited, a variety of metallic and non-metallic materials can be used;
(2) Prototype replicating, high interchangeability;
(3) regardless of process and manufacturing prototype geometries, even more advantageous when machining complex surfaces; short
(4) processing cycle, costs low, regardless of cost and complexity of the product, typically 50 percentage decrease manufacturing costs, saving processing cycle 70% or more;
(5) highly integrated technology, for producing integrated design can be achieved;
RP technology background
(1) with a global market integration, competition is fierce in manufacturing, product development speed is increasingly becoming the main contradiction. In this case, the capacity (time and cost) self-Rapid Product Development (rapid design and rapid tooling) became the basis of the strength of the manufacturing sector of global competition.
(2) manufacturing in order to meet the changing needs of users, requires a strong manufacturing technology flexibility, even in small quantities can single-piece production without increasing the cost of the product. Therefore, the development speed and flexible manufacturing technology products will be very crucial.
(3) From the technology point of view, computer science, CAD technology, materials science, technology development and popularization of laser material foundation for the technology to generate new manufacturing technology.
The basic principles of the RP technique
Rapid prototyping technology is under computer control, based on discrete, packed bulk materials using different methods principle, and finally finished part forming techniques.
1, from the forming perspective, can be regarded as part ldquo; point rdquo; or ldquo; surface rdquo; superimposed. From CAD electronic model discretization ldquo; point rdquo; or ldquo; surface rdquo; geometric information, combined with the forming process parameter information, control material regularly and accurately from point to plane, from the surface to the body packed parts.
2, from a manufacturing point of view, it is the CAD three-dimensional geometric modeling information generating part, multi-dimensional control system, by a laser beam or other method of bulk material layer by layer to form a prototype or part.
type of RP technology
Over the last decade, with a global market integration, manufacturing competition is fierce. Especially the extensive application of computer technology and the rapid widespread CAD / CAM technology, making the rapid development of RP technology has been extraordinary, showing strong vitality and broad prospects. Rapid prototyping technology development so far, its high integration, high flexibility, high speed technology and has been developing rapidly. Currently, the existing rapid prototyping process for dozens of different kinds, of which there are four basic types of the main process: photocurable molding, laminated object manufacturing, selective laser sintering and fused deposition process.
1. The photocurable molding
SLA (Stereo lithography Apparatus) process, also known as stereolithography, three-dimensional stereolithography, and printing, which is a process for the liquid photosensitive resin material fills the tank, controlled by the computerA laser beam tracking system tracks the layered cross-sectional, and irradiated to the liquid resin in the tank, which the cured resin layer, a layer height after lifting platform lowered, the level of the formed and covered with a resin, and then scanning a new layer, the new layer is firmly adhered cured previous layer, thus producing repeated until the entire part is completed, to obtain a three-dimensional solid model. Characteristics of this process are: high precision prototypes, good strength and hardness components can be prepared by a particularly complex shape of the hollow parts, the model produced good flexibility, free entry, is an indirect molding method is ideal. Disadvantage is the need to support the resin shrinkage reduces the accuracy, additional photo-curable resin are poisonous not meet the development trend of green manufacturing.
LOM (Laminated Object Manufacturing) process or a laminated object manufacturing is called, the process principle is cut foil and paper The hierarchical geometry parts, the adhesive layer obtained sheet into a three-dimensional solid. Which process is: firstly covered with a layer of foil, and then with CO.’S, laser cut out of this layer profile, all of the non-chopped part portion under computer control to facilitate removal. After the completion of this layer, and then covered with a layer of foil, and rolling with a roller heated to cure the binder, so that the new layer covered on become firmly bonded to the body, then the cutting of the contour of layer , and so forth until the process is complete, remove the last shred part to obtain complete part. Features of this process is reliable, supportive model, low cost and high efficiency. The disadvantage is that before and after treatment time consuming, and can not manufacture a hollow structural member.
3. Selective Laser Sintering
SLS (Selective Laser Sintering) processes, a material often used in the metal powder material, ceramic, ABS plastic or the like as a molding material. The process is to: first covered with a layer of powder on the table, sintering (not part of the hollow portion sintered powder material remains) under computer control selectively the laser beam is then partially sintered together to form a cured the solid part of the part. Then be completed at one level, the new layer with the layer to be firmly sintered together. After completion of all of the sintering, removing excess powder so as to obtain a sintered part. Features of this process is to adapt to a wide range of material, not only to the manufacture of plastic parts, but also the manufacture of ceramics, goldPart metal material, such as wax. Modeling high precision, high strength prototype, so it can be a function of test sample or assembly simulation.
4. fused deposition modeling
FDM (Fused Deposition Manufacturing) also called Fused Deposition manufacturing process, which processes the thermoplastic molding material is silk material, the material of the heater wire through melted liquid extrusion head, the extrusion head controlled by a computer in the cross-sectional profile of each of the parts and accurate movement, so that the melted thermoplastic material filaments extruded through the nozzle, with parts overlying constructed, and in a very short rapid solidification time, forming a layer of material. Thereafter, the extrusion head move axially upwardly a slight distance under the layer of material for construction. Such layer by layer from the bottom to the top piled into a solid model or part. Characteristics of this process is to use, simple to maintain, low cost, fast, the general complexity of the prototype requires only a few hours can be molded, and non-polluting.
In addition to the above four most familiar in the art, there are many technologies have also practical, three-dimensional printing technique, a light-shielding process, direct shell, direct sintering, manufacturing holographic interferometry.
applications RP technology
and constantly improve the level of application of RP technology is an important aspect to promote the development of RP technology. Currently, rapid prototyping technology has been in the modeling industry, machinery manufacturing, aerospace, military, architecture, film and television, home appliances, light industry, medicine, archeology, culture and art, sculpture, jewelry and other fields have been widely used. And with the development of the technology itself, and its applications will continue to expand. The practical application of RP technology is focused on the following aspects:
(1) apply in the new product design process of rapid prototyping technology to build a new product development model for the design and development of industrial products . The use of RP technology to quickly, directly and accurately design ideas into physical model (sample) has a certain function, which not only shortens the development cycle and reduce development costs, but also enable enterprises occupy the first in the fierce competition in the market machine.
(2) Application in the field of mechanical engineering because of RP own characteristics, so that it is in the field of machinery for a wide range of applications, used for manufacturing a single-piece manufacture, small quantities of metal parts. HaveThese special complex parts, since only a single-piece production, or small quantities of less than 50, generally can be molded directly by RP techniques, low cost, short cycle.
(3) rapid tooling conventional mold for a long time and high cost. The rapid prototyping technology with traditional mold manufacturing technology, can greatly reduce the mold of the development cycle, improve productivity, it is an effective way to mold design and manufacturing weaknesses solution. Application of rapid prototyping technology in the manufacturing mold of the mold may be divided into two direct and indirect molding system, direct molding refers to the use of RP deposited directly out of the mold for manufacturing, molding is indirectly made a rapid first molded part, and then copied from the parts to give the desired mold.
(4) applications in the medical field in recent years, people applied research on RP technology in the medical field more. To medical imaging data were prepared based on human organ models using RP technology, has great value for the surgery.
(5) Application in the field of arts and culture in the field of arts and culture, rapid prototyping and manufacturing techniques used for art, cultural reproduction, digital sculpture.
(6) in the aerospace art in the aerospace sector, the aerodynamic simulation ground (i.e., wind tunnel experiments) is advanced design of the space shuttle system performance (i.e., Space Shuttle) are indispensable less important part. The shape of the model used in the experiment is complicated, high precision, but also has a streamlined characteristics, use of RP, according to the CAD model, complete solid model automatically by RP device, can be a good model quality assurance.
(7) in the appliance industry applications Currently, rapid prototyping systems in the domestic appliance industry has been popular with a large degree of application, many household electrical appliance enterprises to go in the forefront. Such as: the United States, Warburg, Guangdong Kelon; Jiangsu Chunlan, Little Swan; Qingdao Haier and so on, all have adopted rapid prototyping system to develop new products, we have received very good results. Application of rapid prototyping technology is extensive, it is believed that with rapid prototyping and improve manufacturing technology continues to mature, it will be promoted and applied in more and more areas.
direction of development of rapid prototyping technology
From the current research and application of RP technology point of view, further research and development of rapid prototyping technologyWork mainly in the following aspects:
(1) the development of good performance rapid prototyping materials, such as low cost, easy to shape, deformation, high strength, durability and non-polluting molding material.
(2) increase the processing speed of the system and develop RP process for manufacturing parallel.
(3) improve the rapid prototyping system reliability, increase their productivity and large production capacity, to optimize the device structure, in particular to improve accuracy, surface quality, mechanical and physical properties of molded parts, the mold is further performed processing and functional assays provide a basis.
(4) the development of high-performance rapid prototyping software RPM. Increase the data processing speed and accuracy, the research and development using the method of direct sliced CAD raw data, to reduce the loss of precision generated by the STL format and sliced conversion process.
(5) the development of new energy shaping.
(6) The method of rapid prototyping and process improvement and innovation. Direct metal forming art and will be the future research and application mdash; hotspots.
(7) Rapid Prototyping and CAD, CAE, RT, CAPP, CAM and high-precision automatic measurement, integration of reverse engineering.
(8) improving research networking services, remote control.