Sheets thermoforming

Plastics Compounding Redbook, 19 543 Plastics fabrication 20 222-223 microwave technology in, 16 530 Plastic sheet specifications, 16 291 Plastic sheet thermoforming, 23 399 Plastics industry, titanium dioxide in, 25 25-26... 

Blow moulded and sheet thermoformed products for food, personal care, health, medical and lab ware applications, household chemicals and beauty aid products. .. 

Wilkinson Industries manufactures foodservice packaging products including aluminum foil, OPS clear containers, roll foil and foil pop-ups, and the new natural plastic packaging, NaturesPLAstic, made from NatureWorks PLA. Wilkinson extrudes OPS sheet, thermoform containers and domes, aluminum foil containers and converts roll stock into foodservice foil products. 

Hollow objects can be produced using twin-sheet thermoforming, in which two sheets of plastic are thermoformed and sealed together. This can be done sequentially, with one sheet formed first and then the other added and formed, or simultaneously, with both sheets formed and sealed together in a single step (Fig. 10.11). 

Figure 10.11 Twin-sheet thermoforming, simultaneous forming (reprinted with permission...

There is a largely untapped opportunity for wood-plastic composites [10] in packaging and material handling. This is evident from the fact there are nearly 600 million pallets made each year in North America and only about 50 million are plastic. One Canadian manufacturer, Dura-Skid, produces pallets by assembling lineals made from wood-filled HDPE. The main advantage of wood-plastic composites to the pallet manufacturer is the excellent stiffness to weight ratio afforded by wood filler. The greatest opportunity may be in structural foam and twin-sheet thermoformed pallets. 

Air-assist vacuum forming n. A modification of the process of sheet thermoforming in which partial performing of the sheet is effected by air flow or air pressure before vacuum pull-down. 

Bubble forming n. A variant of sheet thermoforming, in which the plastic sheet is clamped in a frame suspended above a mold, heated, expanded into a blister shape with air pressure, then molded to its final shape by means of a descending plug applied to the blister and forcing it downward into the mold. Weismantal GF (1981) Paint handbook. McGraw-Hill Corporation Inc., New York. 

Drape drap [prob. back-form. fr. drapery] (1847) V. (1) With reference to plastics films and coated fabrics, their abfiity to hang without creases and to form graceful folds when used as draperies, shower curtains, and the like. (2) In sheet thermoforming, the ability of the preheated sheet to conform to the mold under the influence of gravity. 

Free forming n. A variant of sheet thermoforming in which a bubble is blown into the clamped, heat-softened sheet, either by applying a vacuum to the side that will be convex or pressure to the underside. The method has been used most with cast-acrylic sheet for applications where the best possible optical properties are foremost, such as airplane canopies. 

Infrared heating n. A heating process used mostly in sheet thermoforming and for... 

Mechanical grease forming n. A method of sheet thermoforming used with acrylic sheet when excellent opticals are imperative and the shape desired cannot be produced by free forming. The mold surface is covered with a 1- to 2-mm-thick layer of felt soaked with melted grease that must be cleaned off the sheet after forming. 

Plastify adj. To soften a thermoplastic resin or compound by means of heat alone, as in sheet thermoforming. Should not be confused with plasticize or plasticate. 

Steady state n. A condition of processes or parts of processes in which the state variables describing the process, e.g., temperature, pressure, compositions and velocities of streams, and amounts of materials residing in various process equipment, do not change with time. Most extrusion operations closely approximate the steady state except during startup and shutdown, whereas injection molding and sheet thermoforming are unsteady, intermittent processes. 

Thermoform (1956) n. To change the shape of a plastic rod, profile, tube, or sheet by first heating it to make it pliant, next, forming the desired shape, and finally, cooling the formed shape. Sheet thermoforming is by far the most important class of these operations. 

Thermoformability n. The ease with which a heat-softened plastic sheet (or rod, etc.) can be given a new permanent shape, particularly by the techniques of sheet thermoforming. Some attempts have been made to devise tests of sheet thermoformability, but none have been widely used or adopted by ASTM as of 1992. 

Thermoforming (1) n. See sheet thermoforming. (2) Any process in which heat softening is used to assist in the forming or reshaping of a plastic rod, tube, bar, sheet, or profile. When performed directly following extrusion of the profile, the term post-forming is often used. 

Vacuum forming (straight vacuum forming) n. Process in which heated thermoplastic sheets are converted to other configurations by causing them to flow into molds with apphcation of a vacuum. The simplest, original technique of sheet thermoforming. 

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