Serkan Orhan, 030070165, 10th week part2

3)Calibration [Group: Quality Control]


There is no old definition.


[New][Better]

There are as many definitions of calibration as there are methods. According to ISA's The Automation, Systems, and Instrumentation Dictionary, the word calibration is defined as "a test during which known values of measurand are applied to the transducer and corresponding output readings are recorded under specified conditions." The definition includes the capability to adjust the instrument to zero and to set the desired span. An interpretation of the definition would say that a calibration is a comparison of measuring equipment against a standard instrument of higher accuracy to detect, correlate, adjust, rectify and document the accuracy of the instrument being compared. 

Typically, calibration of an instrument is checked at several points throughout the calibration range of the instrument. The calibration range is defined as "the region between the limits within which a quantity is measured, received or transmitted, expressed by stating the lower and upper range values." The limits are defined by the zero and span values. The zero value is the lower end of the range. Span is defined as the algebraic difference between the upper and lower range values. The calibration range may differ from the instrument range, which refers to the capability of the instrument. For example, an electronic pressure transmitter may have a nameplate instrument range of 0-750 pounds per square inch, gauge (psig) and output of 4-to-20 milliamps (mA). However, the engineer has determined the instrument will be calibrated for 0-to-300 psig = 4-to-20 mA. Therefore, the calibration range would be specified as 0-to-300 psig = 4-to-20 mA. In this example, the zero input value is 0 psig and zero output value is 4 mA. The input span is 300 psig and the output span is 16 mA.

(Calibration: A Technician's Guide, Mike Cable,2005, pp. 1-2)

4)Powder Injection Molding  [Group: Manufacturing method]

There is no old definition.

[New]

The potential of powder injection moulding (PIM) for cost effectively forming small, complex, precision parts is finding application in the markets of fire arms, business machines and printers, hand tools, aircraft, automotive, ordnance, medical and dental, cameras and controls. The process is finding acceptance on a part by part basis, and is expected to penetrate almost all market segments in competition with investment castings. Powder injection moulding process is similar to plastic injection moulding, with the difference that the polymer is filled with dispersed metallic or ceramic powders. This technology permits production of stronger, more tar urns and more complex P/M parts. The process has virtually unlimited possibilities of low cost, three-dimensional design features and the ability to handle very fine metal powders than enable sintering to high densities, conferring high ductility and strength to the finished parts. PIM becomes more attractive when compared with other manufacturing techniques for medium to high volume production of small parts. The process is economical when intricate three-dimensional details in the part need lobe introduced. Pressure die casting can produce the same shapes and details as PIM, but not in comparable materials — low alloy steels, stainless steel. magnetic alloys. nickel alloys, tool steels, etc. Investment casting no doubt covers a wide range of alloys than are currently available for PIM, the latter is particularly awful for fine details such as blind holes, recesses, sharp edges and internal or external threads. 
A general flow chart illustrating the steps of the PIM process is shown in Fig.9.1.

(Powder Metallurgy Technology,G. S. Upadhyaya, 2002, p. 131)