Substrate machining

The example shown in Fig. 8.4 incorporates an additional vision system from below, which is helpful for alignment purposes. With the aid of this type of configuration, SACE machining can be used to modify glass substrates machined by other technologies such as wet etching [22]. 

T.F. Didar, A. Dolatabadi, R. Wiithrich Local hardness and density variation in glass substrates machined with Spark Assisted Chemical Engraving (SACE). Materials Letters 63 (2009), pp. 51-53. 

Diamond point turning (substrate) Machining a metal using a light cut with a very sharp, wear-resistant point on a diamond tool, thus obtaining a very smooth, mirror-like, as-machined surface. 

Improved surface finishes can be achieved by machining the substrate. Machining usually covers the terms grinding, lapping and polishing. 

Stitchbonded fabrics ate used in home furnishings, footwear, filtration, packaging, and coating. Machine widths ate in the 2-m range fabric weights range from about 75—250 g/m. A variation of stitchbonding is used to make multiaxial-layeted yam and yam-and-sheet stmctures for composite material reinforcement substrates. 

Electrical Properties. Polysulfones offer excellent electrical insulative capabiUties and other electrical properties as can be seen from the data in Table 7. The resins exhibit low dielectric constants and dissipation factors even in the GH2 (microwave) frequency range. This performance is retained over a wide temperature range and has permitted appHcations such as printed wiring board substrates, electronic connectors, lighting sockets, business machine components, and automotive fuse housings, to name a few. The desirable electrical properties along with the inherent flame retardancy of polysulfones make these polymers prime candidates in many high temperature electrical and electronic appHcations. 

The stabihty of the emulsions further permits them to be compounded in simple Hquid-blending vessels by means of agitators, eg, marine-type propellers, paddles, or turbines. The adhesives can be adapted to any type of machine appHcation, ie, from spray guns to rollers to extmder-type devices. Different appHcators are fairly specific in their viscosity requirements, as are the various substrates receiving the adhesive. 

The viscosity of an adhesive directly influences its penetration into a substrate as the viscosity increases, the penetrating power decreases. It also determines the amount of mileage or spread that can be obtained. An optimum viscosity exists for each substrate and each set of machine conditions and must be achieved in order to manufacture an efficient adhesive. Poly(vinyl acetate) emulsions are frequently too low in viscosity to be metered efficiently or to perform well as adhesives by themselves. They must be bodied to working viscosities, eg, by adding thickeners. 

Cladding may be less expensive than selective electro deposition when coatings greater than 1 p.m of a noble metal are required, but may be more expensive than electro deposition for thinner coatings. Selective techniques are most easily used for sheet metal substrates that are to be machine stamped and formed into contacts. Clad noble metals are considerably more ductile (and less hard) than comparable electro deposits and, therefore, are better suited to forming operations. Contacts that are made into separate parts from rod by screw machining are usually coated on all exposed surfaces by barrel electroplating. 

The main application today for poly(vinyl carbazole) arises out of its photoconductivity and is in electrostatic dry copying machines. The polymer is applied from solution in thin film (10-15 p.m) layers onto a conductive substrate. 

While detail may be found in the ASTM D-3330 or PSTC-1 and PSTC-2 standards, the peel test is typically carried out as follows The tape is conditioned at 23°C and 50% relative humidity for 1 day. Next, the tape is rolled down with a weighted standard roller onto a clean test substrate (usually polished 302 stainless steel), allowed to dwell for a specified time (usually 1 min), and then clamped with the testing fixture in the test machine and peeled at a specified rate. 

The balance of this chapter will be devoted to several classic and representative enzyme mechanisms. These particular cases are well understood, because the three-dimensional structures of the enzymes and the bound substrates are known at atomic resolution, and because great efforts have been devoted to kinetic and mechanistic studies. They are important because they represent reaction types that appear again and again in living systems, and because they demonstrate many of the catalytic principles cited above. Enzymes are the catalytic machines that sustain life, and what follows is an intimate look at the inner workings of the machinery. 

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