Deran Turan - 514111013 - 2.nd Week Unanswered Words

Prototyping (Modelling) (New): Prototyping or model making in the traditional sense is an age-old practice. The intention of having a physical prototype is to realize the conceptualization of a design.

Prototyping processes have gone through three phases of development; three phases are described as follows.

First Phase: Manual Prototyping

Second Phase: Soft or Virtual Prototyping

Third Phase: Rapid Prototyping

(CHAU C. K., LEONG K. F. and LIM C.S., Rapid Prototyping Principles and Applications, p. 8-10)

Prototyping (Previous) (Better): Prototyping is a method used by designers to acquire feedback from users about future designs. The process of prototyping, on the other hand, can be characterized as explorative, experimental, or evolutionary.

An explorative prototype is used to explore system requirements in cooperation with users and can, as such, be seen as a communication medium and facilitator between user and designer in the same way as a mock-up.

An experimental prototype is the type of prototype that is closest to the classical concept of prototype. It is experimental in the sense that it is built to try to determine whether the planned system will be adequate and acceptable when finished. Experimental prototypes can be used as requirements specification. Lastly, prototypes can be evolutionary, meaning that a system evolves through multiple generations/prototypes succeeding each other. Thus, each prototype is an early version of the system that is further worked upon until the prototype has evolved into a finished system.

Floyd, Christiane (1984): A Systematic Look at Prototyping. In: Budde, R.,Kuhlenkamp, K., Mathiassen "Approaches to Prototyping". Springer Verlag pp. 1-17 

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Stereolithography (Modelling) (New) (Better): Stereolithography process creates three-dimensional plastic objects directly from CAD data. The process begins with the vat filled with the photo-curable liquid resin and the elevator table set just below the surface of the liquid resin. The operator loads a three-dimensional CAD solid model file into the system. Supports are designed to stabilize the part during building. The translator converts the CAD data into a STL file. The control unit slices the model and support into a series of cross sections from 0.025 to 0.5 mm (0.001 to 0.020 in) thick. The computer-controlled optical scanning system then directs and focuses the laser beam so that it solidifies a two-dimensional cross-section corresponding to the slice on the surface of the photo-curable liquid resin to a depth greater than one layer thickness. The elevator table then drops enough to cover the solid polymer with another layer of the liquid resin. A leveling wiper or vacuum blade (for Zephyr^TM recoating system) moves across the surfaces to recoat the next layer of resin on the surface. The laser then draws the next layer. This process continues building the part from bottom up, until the system completes the part. The part is then raised out of the vat and cleaned of excess polymer. The main components of the SLA system are a control computer, a control panel, a laser, an optical system and a process chamber.

(CHAU C. K., LEONG K. F. and LIM C.S., Rapid Prototyping Principles and Applications, p. 42-43)

Stereolithography (Previous): The most widespread rapid prototyping technology is called stereolithography. Stereolithography creates plastic prototypes of arbitrary geometric complexity directly from computer models of designed parts. The planning for prototyping is vastly simplified and so is the requirement for fixturing. The parts are synthesized via photopolymerization: cured by a laser beam directed across an X-Z surface, a liquid monomer mix is converted to solid plastic objects, point by point, layer by layer, as true as allowed by the photopolymer in all three dimensions. Stereolithography does not require experienced model makers to operate, and the machine runs unattended once the building process starts. It is relatively straightforward for the designer to program and run the Stereolithography by himself. Thus, the overall cycle time for product development is considerably reduced, especially when objects are complicated or delicate.

(Po-Ting Lan, Shuo-Yan Chou, Lin-Lin Chen, Douglas Gemmill, Computer-Aided Design,Volume 29, Issue 1, January 1997, pg 53-62)

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Laminated Object Manufacturing (Modelling) (New): Laminated Object Manufacturing® (LOM^TM)process is an automated fabrication method in which a 3D object is constructed from a solid CAD representation by sequentially laminating the part cross-sections. The process consists of three phases: pre-processing; building; post-processing.

(CHAU C. K., LEONG K. F. and LIM C.S., Rapid Prototyping Principles and Applications, p. 112)

Laminated Object Manufacturing (Previous) (Better): Laminated object manufacturing produces a solid physical model by stacking layers of sheet stock that are each cut to an outline corresponding to cross sectional shape of a CAD model that has been sliced into layers. The layers bonded on the top of the previous one before cutting. After cutting the excess material in the layer, remains in the place to support the part during building. Starting material in LOM can be virtually any material in sheet stock form, such as paper, plastic, cellulose, metals or fiber-reinforced materials. Stock thickness is 0.05 to 0.50 mm. In LOM, the sheet material is usually supplied with adhesive backing as rolls that are spooled between two reels. Otherwise, the LOM process must include an adhesive coating step for each layer.

(Groover M.P., Fundamentals of Modern Manufacturing, 4th Ed., Pg 793, Kayra Ermutlu)

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Ink-Jet printing (Modelling) (New) (Better): Ink jet printing comes from the printer and plotter industry where the technique involves shooting tiny droplets of ink on paper to produce graphic images.  RP ink jet techniques utilize ink jet technology to  shoot droplets of liquid-to-solid compound and form  a layer of an RP mod Three-Dimensional Printing is  based on the inkjet printing process, where binder is  printed on a powder layer to selectively bind powder together for each layer.

(M. ILIESCU, E. NUŢU, L. GEORGESCU, Finite Element Method Simulation and Rapid Prototyping, Proceedings of the 8th WSEAS International Conference on ELECTRIC POWER SYSTEMS, HIGH VOLTAGES, ELECTRIC MACHINES, Verice, Italy, November 21-23 2008, p. 257)

Ink-jet printing (Previous): Ink-jet printing process has been recently explored as a solid freeforming fabrication (SFF) technique to produce 3D ceramic parts. Numerous solid freeform fabrication techniques to form ceramic parts have been developed during the last decade. They consist in building ceramic parts by depositing the material, layer by layer, on the basis of computer-aided design (CAD) files of the structures. By a simple modification of the file, it becomes possible to change the configuration of the component; therefore, these methods are specifically appropriate to generate 3D complex ceramic structures without expensive tooling for prototypes or even for small productions. Ink-jet printing prototyping process consists in the deposition of ceramic system micro-droplets (a few pl) ejected via nozzles to build the successive layers of the 3D structures. Consequently, by adjustment of the aperture of the printing head and the control of the spreading phenomenon of the droplet, one can expect to reach a standard definition around 50nanometer which could finally decrease to 10nanometer, in taking into account the tremendous evolution in the printing field. Moreover, this technique exhibits the additional capability to deposit different materials on the same layer via a multi-nozzle system.

(Rémi Noguera, Martine Lejeune, Thierry Chartier,Journal of the European Ceramic Society, Volume 25, Issue 12, 2005, Pages 2055-2059)

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CMM Coordinate measuring machine (Modelling) (New) (Better): These are mechanical systems designed to move a measuring probe to determinate coordinates of points on a workpiece surface. CMMs comprised of four main components: The machine itself, the measuring probe, the control or computing system, and measuring software. Machines are available in a wide range of sizes and designs with a variety of different probe technologies.

Important specifications for coordinate measuring machines are the measuring lengths along the x, y and z axes as well as resolution and workpiece weight.

Figure: Coordinate Measuring Machine

Coordinate measuring machines may have manual control, CNC control or PC control. Manual control implies that machine positioning is operator controlled. The operator physically moves the probe along the axis to make a contact with the part surface and record the measurement (digital readout). A Computer Numerical Control (CNC) may also control machine positioning. PCs, or personal computers, also control machine positioning in some coordinate measuring machines. The PC record the measurements made during the inspection and performs various required calculations. Automatic measuring machines may involve one or more types of gauging devices.

(Metrology & Measurement, A. K. BEWOOR, V. A. KULKARNI, p. 367-368)

Coordinate Measuring Machine (Previous): Coordinate measuring machines are important developments in measurement technology. Basically, each consists of a platform on which the work piece being measured is placed and then moved linearly or rotated. A probe, attached to a head capable of lateral and vertical movements, records all measurements. Coordinate measuring machines also called measuring machines, are very versatile; they are capable of recording measurements of complex profiles with high sensitivity (0.25 m) and with high speed.

(Kalpakjian, Smith; Manufacturing Engineering and Technology 4^th Edition; pg. 957)

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Solid Ground Curing (Modelling) (New) (Better): Solid Ground Curing process includes three main steps: data preparation, mask generation and model making.

Figure: Solid Ground Curing Process

Data Preparation: In this first step, the CAD model of the job to be prototyped is prepared and the cross-sections are generated digitally and transferred to the mask generator.

Mask Generation: After data are received, the mask plate is charged through an “image-wise” ionographic process. The charged image is then developed with electrostatic toner.  

Model Making: In this step, a thin layer of photopolymer resin is spread on the work surface. The photo mask from the mask generator is placed in close proximity above the workpiece, and aligned under a collimated UV lamp. The UV light is turned on for a few seconds. The part of the resin layer which is exposed to the UV light through the photo mask is hardened. The un-solidified resin is then collected from the workpiece. This is done by vacuum suction. Following that, melted wax is spread into the cavities created after collecting the liquid resin. Consequently, the wax in the cavities is cooled to produce a wholly solid layer. Finally, the layer is milled to its exact thickness, producing a flat solid surface ready to receive the next layer.

(CHAU C. K., LEONG K. F. and LIM C.S., Rapid Prototyping Principles and Applications, p. 57-60)

Solid Ground Curing (Previous): Solid ground curing was developed by Cubital. SGC is  a RP system that utilizies an ultraviolet light to cure each layer of liquid resin. In contrast of laser based system SGC process cures whole layer in one exposure, rather than tracing part with a beam. 

Ali K. Kamrani, Emad Abouel Nasr, Engineering Desing and Rapid Prototyping, P.345