Covered roll

This is an instrument for hardness testing and not a plastometer. The Pusey and Jones tester is used for determining hardness particularly on curved surfaces, such as rubber-covered rolls. It operates on a dead-weight principle. 

Different roll coating methods and roll arrangements S = steel roll, R = rubber-covered roll, E = engraved roll. (Courtesy of Faustel Corporation.)... 

Two methods of glue application are currently being used in production of glue-lams. The older method is to pass the boards through rubber-covered roll spreaders so that both sides are coated simultaneously. The boards are then stacked horizontally until all are spread and clamps are in proper position for pressure application. During this assembly time the wet glue film is exposed to the atmosphere for only a short time. This minimizes loss of solvents and water to the atmosphere. 

Rubber-covered rolls (100% fluorocarbon elastomer or laminated to other elastomers)... 

Exxon Butyl. [Exxon] Isobutylene-iso-prene elastomer for flat belts, coated materials, rubbor-covered rolls, hose, mats, molded/extruded prods., o-rings, shock and vibration pro., inner tubes, water barrier applies., elec, goods. 

In the traditional production of marzipan raw filler, sweet almonds are scalded, peeled on rubber-covered rolls, coarsely chopped, and then ground with the addition of not more than 35% of sucrose. The mixture is then roasted, e. g., in open roasting pans (95 °C 45 min) or continually. After cooling, an equal amount of powdered... 

Dandy rolls, which are highly op>en, wire covered rolls used on fourdrinier machines ahead of the water line, for improvement of formation quality and for watermark application (Fig. 6.41). 

Modern multinip-calenders are similar in function to supercalenders. The main difference is that the filled rolls are replaced by polymer covered rolls. As a result, modern multinip-calenders can be installed on-line and can be run more than... 

Covered rolls, especially those in the lower hardness range, often are designed with specialty types of nitrile. These would include ... 

When selecting the grade of polysulfide to use for a given application the service conditions are the key criteria to consider. Thiokol FA, as previously indicated, is used mainly in covered rolls and specialty hose where its excellent solvent resistance may be needed. It is often blended with other elastomers such as polychloroprene if some sacrifice in solvent resistance can be tolerated, or with a high acrylonitrile NBR if a minimal loss in solvent resistance is dictated. 

It was also recognized that none of the metal electrode/covered-roll configurations would work when treating conductive substrates such as foils or metallized film, and that a very complex form of electrode would be required. The early bare-roll type systems consisted of a metal ground roll and a series of dielectric covered electrode rolls that were motor-driven. This was a very expensive, cumbersome method of treating conductive substrates, but it was the only method available. 

Bare roll treater rolls are typically specified to have smaller diameters than those of covered roll systems, because of the area of dielectric required to dissipate the heat generated in the corona. With bare roll systems, the diameter is dictated by the length of the roll (driven by the maximum material width to treat) and the number of electrodes required (specified by the Watt density requirement). This dielectric-less ground roll design is always paired with dielectric-surfaced (typically ceramic) electrodes to promote uniform corona discharging to both conductive and non-conductive material surfaces. 

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