Twisting: (16.04.2011 ; 00:20)
Twisting subjects the sheet metal to torsion loading rather than a bending load, thus causing a twist in the sheet over its length. This type of operation has limited applications. It is used to make such products as fan and propeller blades. It can be performed in a conventional punch and die which has been designed to deform the part in the required twist shape.
(Groover M.P., “Fundamentals of Modern Manufacturing: Materials, Processes, and Systems 3rd Edition”, page 460)
Block Tool System: (16.04.2011 ; 11:50)
Known as the Block Tool System it is an attempt to provide a system of small interchangeable cutting tool units consisting of cutting edge and locating device that can be clamped manually or automatically to a specially designed multi-station tool post.
By having magazines of these cutting units attached to the machine tool, cutting units can easily be interchanged and replaced on the tool post as required. The Block Tool System also features measuring probe units located in a similar fashion to the cutting units, for automatic tool tip position gauging.
(“Sandvik Launches New Interchangeable ‘Cutting Unit’ System”, “Production Engineer”, December 1980, Vol. 59, Iss 12, page 20)
Compatibilizers (16.04.2011 ; 17:10)
The properties of polymers can be tailored to some extent by the copolymerization of two or more monomers simultaneously. In this way the monomers are mixed and fixed together on a molecular level. However, for small batches, it may be more convenient to mix homo polymers by melt blend blending. However, a serious drawback is the lack of miscibility. This issue can be circumvented to some extent by the use of proper compatibilizers. Compatibilizers are a special type of additive. Whereas certain additives do their duty simply by physical action during the whole service time, e.g., antiblocking agents, other types of additives start with a chemical reaction in the case of emergency, e.g., light stabilizers. In contrast, compatibilizers are effective by a chemical reaction already in the stage of processing.
Some of the fundamental requirements for a compatibilizer as additive for reactive processing include:
- Optimal interfacial tension
- Sufficient and easy mixing
- Functional groups in the parent polymers
- Fast reactivity of the additive, at processing
- Enhanced adhesion between the phases in the solid state.
(J. K. Fink, A Concise Introduction to Additives for Thermoplastic Polymers, page 209, 215, 217)
Nanocomposites: (16.04.2011 ; 19:05)
A composite is a combination of two or more different materials that are mixed in an effort to blend the best properties of both. A nanocomposite is a composite material, in which one of the components has at least one dimension that is nanoscopic in size, that is around 10-9m; a carbon fiber, commonly used as a reinforcement in sporting goods, is approximately 7 μm in diameter, or 10-6m; a carbon-carbon chemical bond, the basic unit of life, is about 1.5 Å, or 10-10m.
A nanocomposite can be made from any combination of materials, as long as one of those is nanoscopic in at least one dimension. The nanocomposite is composed of a continuous matrix and a discontinuous reinforcing phase. There are three different types of basic building block materials: polymers, ceramics, and metals. Each of these three classes has specific properties that may be of value in a nanocomposite. Metals are conductive, strong, and ductile. Ceramics are very strong, brittle, chemically resistant, and insulating. Polymers are usually impact resistant, ductile, and insulating. Composite mixtures of these three types of material can result in properties that are a combination of the behaviors of the individual components.
(T.E. Twardowski, “Introduction to Nanocomposite Materials: Properties, Processing, Characterization” page 2,11)
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