Machining chambers

The setup details of the two-sided EMM technique are schematically represented in Fig. 4.6. The job sample is held vertically in the machining chamber. The job is made the anode of the electrolytic cell. The tool consists of two cathode assemblies mounted over the vertically held job. Highly localized dissolution of metal from the unmasked region of the two sides of the work sample is achieved by scanning the tool assembly over the work sample. The electrolyte flows through the tool assembly and passes across the surface between the cathode tool and masked workpiece anode. An extremely small lEG is maintained between the work sample and cathode, which provides uniform localized metal removal due to stable current flow distribution with negligible stray current effect. The cathode tool... 

Figure 5.1 shows a schematic view of a basic unit of an EMM system setup, which consists of various subsystems, namely, a mechanical machining unit, controller unit, direct current (DC) pulsed power supply, electrolyte flow system, and machining chamber with a work holding arrangement. 

There are also large-scale production machines in which the heated air is provided from a single source into a series of chambers with different flow rates controlled by damper-and-valve systems. Each manufacturer has its own techniques for providing the temperature and airflow control in the machine chamber. Many of the smaller laboratory and production machines control the heated airflow inside the entire drying chamber by providing for a balance between an inlet air blower and the exhaust air fan. On at least one laboratory machine that uses compressed house air, an in-line heater is provided as an option to produce an elevated temperature inside the casting chamber. 

Following each use the impingement mixing chamber is cleared by advancing a piston that eliminates the need for solvent flushing as is required for low pressure machines. 

A method for the fractionation of plasma, allowing albumin, y-globulin, and fibrinogen to become available for clinical use, was developed during World War II (see also Fractionation, blood-plasma fractionation). A stainless steel blood cell separation bowl, developed in the early 1950s, was the earhest blood cell separator. A disposable polycarbonate version of the separation device, now known as the Haemonetics Latham bowl for its inventor, was first used to collect platelets from a blood donor in 1971. Another cell separation rotor was developed to faciUtate white cell collections. This donut-shaped rotor has evolved to the advanced separation chamber of the COBE Spectra apheresis machine. 

Rockwell hardness testing has been extended to both low and high temperature regimes usually by enclosing the sample and part of the machine in an environmental chamber and using extensions for the anvil and indenter. 

Fig. 10. Schematic of casting machine used to make microporous membranes by watervapor imbibition. A casting solution is deposited as a thin film on a moving stainless steel belt. The film passes through a series of humid and dry chambers, where the solvent evaporates from the solution, and water vapor is absorbed from the air. This precipitates the polymer, forming a microporous membrane that is taken up on a collection roU (25).

Development of the Mooney viscometer gave compounders an indication of the processibiUty of different lots of the uncompounded polymer. This machine measures the torque resistance encountered by a rotor revolving in a chamber surrounded by polymer at a constant temperature. The resulting Mooney number describes the toughness of the polymer and is an indirect measure of molecular weight. 

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