Gökhan UÇAN-030070028-7th week

Three-Dimensional Printing: 24.03.2011 00.40

This RP technology was developed at Massachusetts In­stitute of Technology. Three-dimensional printing (3DP) builds the part in the usual layer-by-layer fashion using an ink-jet printer to eject an adhesive bonding material onto successive layers of powders. The binder is deposited in areas corresponding to the cross sections of the solid part, as determined by slicing the CAD geometric model into lay­ers. The binder holds the powders together to form the solid part, while the unbonded powders remain loose to be removed later. While the loose powders are in place during the build process, they provide support for overhanging and fragile features of the part. When the build process is completed, the part is heat treated to strengthen the bonding, followed by removal of the loose powders, To further strengthen the part, a sintering step can be applied to bond the individual powders.

The part is built on a platform whose level is controlled by a piston. A layer of powder is spread on the existing part-in-process. An ink-jet printing head moves across the surface, ejecting droplets of binder on those regions that are to become the solid part. When the printing of the current layer is completed, the piston lowers the platform for the next layer.

(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.793)

Separable Connection: 24.03.2011 01.07

Separable connections are designed to permit disassembly and reassembly; they are meant to be connected and disconnected multiple times. When connected they must provide metal-to-metal contact between mating components with high reliability and low electrical resistance. Separable connection devices are called connectors and they come in a variety of styles to serve many different applications. Connectors typically consist of multiple contacts, contained in a plastic molded housing, designed to mate with a compatible connector or with individual wires or terminals. They are used for making electrical connections between various combinations of cables, printed circuit boards, components, and individual wires.

A wide selection of connectors is available. The design issues in choosing among them include power level (e.g., whether the connector is used for power or signal transmission), cost, number of individual conductors involved, types of de­vices and circuits to be connected, space limitations, ease of joining the connector to its leads, ease of connection with the mating terminal or connector, and fre­quency of connection and disconnection. Some of the principal connector types are cable connectors, terminal blocks, sockets, and connectors with low or zero insertion force.

(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.851-852)

Droplet Deposition Manufacturing: 24.03.2011 01.23

These systems operate by melting the starting material and shooting small droplets onto a previously formed layer. The liquid droplets cold weld to the surface to form a new layer. The deposition of droplets for each new layer is controlled by a moving x-y spray nozzle workhead whose path is based on a cross section of a CAD geometric model that has been sliced into layers. After each layer has been applied, the platform supporting the part is lowered a certain distance corresponding to the layer thickness, in preparation for the next layer. The term droplet deposition manufacturing (DDM) refers to the fact that small particles of work material are deposited as projectile droplets from the workhead nozzle.

Several commercial RP systems are based on this general operating principle, the differences being in the type of material that is deposited and the corresponding technique by which the workhead operates to melt and apply the material. An important criterion that must be satisfied by the starting material is that it be readily melted and solidified. Work materials used in DDM include wax, thermoplastics, and metals with low melting point, such as tin, zinc, lead, and aluminum, have also been tested. For example, the droplet deposition technique can be used to apply solder droplets for integrated circuit packaging and fine-line printed circuit boards.

(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.789-790)

Terminal Blocks: 24.03.2011 01.32

Terminal blocks consist of a series of evenly spaced receptacles that allow connections between individual terminals or wires. The terminals or wires are often attached to the block by means of screws or other mechanical fastening mechanisms to permit disassembly.

(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.852)