Processing/fabrication techniques injection molding

The injection-molding process provides low cost fabrication of large and small parts to precision tolerances. Many of these parts are nearly impossible to make in production voliunes by other techniques. Injection molding can form parts as small as a cubic milUmeter (micromolding), and parts as large as garbage dumpsters and 1.2 x 2.4 m (4 x 8 ft) filter panels are in production. A wide range of... 

Injection molding, an economical mass production technique, has also been used to fabricate microcantilevers out of thermoplastic polymers (McFarland et al. 2004 McFarland and Colton 2005a, b). In this process, a molten polymer such as polypropylene is forced under pressure into a steel cavity (mold) the shape of the cavity defines the dimensions of both the base and the cantilever(s). Injection-molded microcantilevers have been shown to be of equal caUber to commercial silicon miCTOcantile-vers. McFarland et al. (2004) and McFarland and Colton (2005a, b) specified in detail the fabrication of injection-molded microcantilevers. Despite their advantages over silicon-based cantilever arrays, polymeric cantilever arrays are not commercially available. 

A new process was described that produces a fabric-covered injection molded part using an in-mold-fabric decoration technique. Since the process was designed for injection molding, it is suited for the mass production of high-quality, low-cost parts. 

Chemical activities in the field of mass screening are often related to combinatorial chemistry [51,52]. One major goal, especially in the field of solid phase chemistry involving polymers like DNA or peptides, aims at the increase in the number of compounds per reactor volume and time. Commercially available microtiter plates are established as reactors in this case whereby robotic feed systems fit perfectly to their dimensions. A drastic reduction of reaction volume and increase in number of reaction vessels ( wells ) leads to the so-called nanotiter plates (e.g. with 3456 wells). Microfabrication methods such as the LIGA process are ideal means for the cost effective fabrication of nano-titer plates in polymeric materials by embossing or injection molding techniques so that inexpensive one-way tools are realized. 

ETFE copolymers can be readily fabricated by a variety of melt-processing techniques.19 They have a wide processing window, in the range 280 to 340°C (536 to 644°F) and can be extruded into films, tubing, and rods or as thin coating on wire and cables. Injection molding of ETFE into thin sections is considerably easier than injection molding of melt-processible perfluoropolymers because the former has... 

Whereas all conventional thermoplastic fabrication techniques have been successfully employed to convert pellets of HIPS into useful articles, extrusion (film, sheet, profile and multi-layer) and injection molding (solid, structural foam and gas-assist) are the predominant processing technologies. Innovative hardware technologies, in both extrusion and injection molding, have provided means to combine less expensive materials, such as polystyrene, with polymers or structures offering key performance characteristics. 

Aside from PTFE and PCTFE, copolymers of TFE and a few other fluorocarbon polyuners are processed by melt-processing methods. Commercial fluoropolymers that have found application in chemical processing industries include PFA, FEP, ETFE, ECTFE, and PVDF. These plastics are fabricated into parts by common techniques such as injection molding, transfer molding, blow molding, compression molding, rotational molding, and extrusion (Table... 

The application of widespread standard polymer processing techniques to the formation of colloidal crystals was introduced by Ruhl et al. [60]. They demonstrated the fabrication of a large colloidal crystal film, which comprises core-shell latex particles. Upon coagulation the soft shell of the particles causes the formation of a rubbery mass, which can be uniaxially compressed. The radial horizontal flow during the compression induces crystallization of the particles from the surface of the plates inward. The soft shell constitutes the matrix in which the hard spheres are embedded. This technique is promising for efficient application to other polymer processing methods like extrusion or injection molding. 

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