Thin-walled technology

Soluble core molding The soluble core technology (SCT) is called by different names such as soluble fusible metal core technology (FMCT), fusible core, lost-core, and lost-wax techniques (3). In this process, a core [usually molded of a low melting alloy (eutectic mixture) but can also use water soluble TPs, wax formulations, etc.] is inserted into a mold such as an injection molding mold. This core can be of thin wall or solid construction. 

Representing a recent development in advanced weapons technology, FAE weapons employ foliage discriminating fuzes that actuate on target contact and rupture thin-walled warheads to disperse highly volatile liq chemicals in aerosol... 

An alternative process for the production of PVC foam using microcellular foam technology, not requiring impact modifier, for thin wall profile (280) has been reported. Proof of concept experiments confirm the satisfactory solid state extrusion of PVC pellets, prefoamed in a batch solid state microcellular process (109). 

The technology to produce thin walled extruded ceramic substrates was first developed by a European eompany. 

The production of thin-walled parts is one of the major challenges of the plasticprocessing industry today. Thin-wall applications are found mainly in packaging, casings and housings, but also in technical devices and articles (medical, optical, electronic, and telecommunications technologies). 

A major influence on the choice of material is now being played by downsizing and, more importantly, thin-wall moulding technology, bringing more demanding requirements for properties. 

Technologies that will influence the use of materials in the future are (as well as thin-walling) EMI shielding and the changes in flame retardant additives, under pressure from the need to comply with environmental regulations in various countries. 

All technology discussed here is based on the assumption that the plastic part is thin walled and makes use of the Hele-Shaw approximation. Three-dimensional finite element analysis (3D/FEA) eliminates this requirement. In so doing, it introduces a new class of components to simulation. With 3D/FEA it is possible to. simulate the molding of parts for which a midplane is not available. Typically, such parts are chunky— some examples are given in Fig. 7.64. Many parts... 

The main applications are concerned with the production of ultra-pure hydrogen for laboratory and small scale electrolysers and the processing of tritiated water. Recent studies into alkahne electrolysis cells using thin-wall Pd-Ag tubes have demonstrated the applicabihty of these technologies for commercial hydrogen electrolysers. Other tests have verified the use of these hollow cathode cells for recovering tritium from tritiated water in the fuel cycle of the next fusion reactors. 

So far, we have considered catalytic materials that conform to the side walls of a microreactor. A downside to a functionalized coating at a channel wall is the limited catalytic surface area that can be provided. As an alternative, thin-film technology can be used for depositing catalytic materials on more complex three-dimensional surfaces inside microchannels [49]. Impregnation methods can also be used on porous silicon surfaces [50]. The mass transfer rates described for such structures are sufficient for all but the fastest heterogeneous reactions. 

In modern technology, thin films play an important role in many applications. Thin films provide an example in which one of the dimensions is very small compared to the other two consequently, the stress acting in the microscopic direction will also be much smaller than in the other two and, as such, may be disregarded. Sheets, thin films or thin-walled bodies are other examples in which one of the stresses may be ignored. Thus, a state of plane stress exists when one of the principal stresses is assumed to be zero and the flat body or the thin film may be... 

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