Printing precision

Figure 11.9 is an optical micrograph of the pixels within the printed 128 x 128 pixel array. The pixel size is 340 pm, corresponding to a resolution of 75 dots per inch (dpi). The metal line-width is about 50 pm, and is determined by the size of the wax drop from the jet-printer. However, the printing precision and good line... 

Insert injection mol ding is used to manufacture snap closures for yogurt and ice cream cups and tubs and for breakfast cereal cans. In insert injection mol ding, a die-cut printed paperboard or other flat material is placed in the mold. The plastic is extmded around the insert to form a precision skeletal stmcture. 

Electronic Film Output. Imagesetters are precision electromechanical devices that image monochromatic color separations onto photographic film or paper. Each separation is used to expose a printing plate for a single ink color (4). 

Ma.ke-Rea.dy, Because pressure is needed for ink wetting and transfer and because the image elements in letterpress vary in size, the same amount of printing pressure or squeeze exerts more pressure on highlight dots than on shadow dots. This necessitates considerable make-ready to even the impression so that the highlights print correctly and do not puncture the paper. Precision plates and premake-ready systems have helped reduce make-ready time, but it is still appreciable for quaUty printing and is a reason letterpress has been largely replaced by other processes. 

Proofing materials have many of the same sources of variability as film, plus the added problem of registering, ie, accurately overlaying, the different colored layers. The printing plate must be exposed precisely to hold all that is discernible in the films. The accuracy of the exposure is critical because the plate must retain all the information contained in the films for faithful reproduction on the press. 

Cleaning Supercritical fluids such as CO9 are being used to clean and degrease quartz rods used to produce optical fibers, produc ts used in the fabrication of printed circuit boards, oily chips from machining operations, and precision bearings in militaiy applications, and so on. Here, CO9 replaces convention chlorocarbon or chlorofluorocarbon solvents. 

Remember from Chapter 2, the NPSHa formula is NPSHa = Ha + Hs - Hvp - Hf - Hi. If you want to raise the NPSHa, it will be necessary to increase the elements (Ha, Hs) that add energy to the fluid, or decrease the elements (Hvp, Hf, Hi) that rob e- rgy from the fluid. Also remember that the NPSHr reading, printed on a pumn c -ve, currently represents a point where the pump is already suffering a 2. ss in function due to cavitation. Some people in the industry are calling for a more precise definition of NPSHr, and higher safety margins on NPSHa. 

Pressure sensitive adhesives can be coated on a substrate such as a polyester or paper backing to make a tape or label, or on a release liner to make a transfer adhesive, or a special substrate to make a graphic film or retro-reflective sheeting product. In some cases, where precision placement of the PSA is required, one may also coat directly on the substrate using techniques such as screen-printing. 

This process uses a moving laser beam, directed by a computer, to prepare the model. The model is made up of layers having thicknesses about 0.005-0.020 in. (0.012-0.50 mm) that are polymerized into a solid product. Advanced techniques also provides fast manufacturing of precision molds (152). An example is the MIT three-dimensional printing (3DP) in which a 3-D metal mold (die, etc.) is created layer by layer using powdered metal (300- or 400-series stainless steel, tool steel, bronze, nickel alloys, titanium, etc.). Each layer is inkjet-printed with a plastic binder. The print head generates and deposits micron-sized droplets of a proprietary water-based plastic that binds the powder together. 

Interlacing then takes place, a precise digital merging by computer of the angles into a master image. When printed on a lenticular sheet such as Eastman Chemical s Spec-tar PETG, the grooves of the sheet force the... 

The rotors can be preloaded with lyophilized reagents, which can be dynamically dissolved by the addition of buffer to the spinning rotor. Multiple samples can then be introduced into each of the radial cuvettes, or a single sample can be dynamically apportioned between the multiple cuvettes, each of which contain reagents for a different enzyme reaction. Consequently, multiple samples can be monitored for the same enzyme activity, or several different enzyme activities can be measured for the same sample. The very fast data reduction offered by the online computer provides the operator with printed results as soon as the analysis is complete. This approach provides highly precise data (Table II). 

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