Impression roller

Within the gravure process, ink is applied directly to the cylinder which is then transferred to the substrate. Cylinders rotate within an ink trough where each designed cell of the cylinder is filled with ink. A doctor blade is positioned against the cylinder to wipe away excess ink, leaving ink only in the cells (see Figure 8.3). In order to prevent the ink in the cells from drying before it is released to the substrate from the impression roll, the doctor blade is positioned very close to the point where the substrate meets the cylinder. Ink is subsequently drawn from out of the cylinder cell by the combination of a capillary effect from the substrate and directly applied pressure from the impression rollers. 

It should be noted that the seal pattern is only on the heated platen or sealing roller, with the cooling platen or cylinder being smooth or flat (i.e. there is no impression or pattern on the plastic side of the web). 

The printing plate is laid on a flat bed or forme which passes backwards then forwards (reciprocating bed principle) (see Figure 16.3). At one end of its travel it is inked by rollers and then as it returns the printed item is passed between an upper impression cylinder and the plate. The impression cylinder then rises to allow the forme to return for inking. Due to the reciprocating action, speeds are relatively low, say 3,000 sheets per hour. 

Embossing can also be performed without rollers, e.g., using textured aluminum foil in one-time use, or stainless steel plates with engraved textures can be used in the press cycle time and again, offering multiple impression economies. 

Hot air. a focused stream of heated compressed air is directed towards the join line of the interface between the fabric plies. A roller is placed directly behind this area to apply pressure once the material begins to flow and before or as it cools. The profile of this roller can define the weld impression. 

Photograph IV shows that the plastic matrix before U.V. irradiation is lifted from the master plate. The matrix is impressed by a roller or hydraulic press onto these plates after the preheated 1, 2-PBD plate is placed on the master plate. Photograph V shows that the surface of 1, 2-PBD matrix is photo-cured by U.V. irradiation. Photograph VI shows that the relief... 

TLC and GC/MS can be used to determine the age of writing inks on questioned documents. Dating techniques that use TLC are based on analysis of ink dye components, while GC/MS can date inks based on detection, identification, and quantification of the residues of the vehicle solvents in ink hnes. Capabihty to date most ballpoint, porous tip, roller pen, stamp pad, and jet printer inks by analyzing the single ink entry, stamp impression, or printed test in question was shown by testing in the Division of Identification and Forensic Science, Israel Police Headquarters. 

Fig. 2.9. Cooling and polishing roll stack and flat die of a production unit for 9 m wide geomembranes. The size of the railing and the 1201 waste container give an impression of the giant dimensions of the equipment. Two rolls are horizontally arranged and the third roll is offset downwards in the roll stack. The carpet of molten material is being drawn diagonally at 45° from the die into the roller nip...

Pig. 2.20 Structural sketch of a rubbing machine. A rubbing machine consists of a roller covered by rubbing cloth, and a platform to hold the substrate. The roller or the substrate stage moves at a constant speed while the roller is rotating at several hundreds of rpm. The gap between the roller and the stage is adjusted to change the pile impression. 

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