Thermoplastic sheet

Reinforced Thermoplastic Sheet. This process uses precombined sheets of thermoplastic resin and glass fiber reinforcement, cut into blanks to fit the weight and size requirements of the part to be molded. The blanks, preheated to a specified temperature, are loaded into the metal mold and the material flows under mol ding pressure to fiU the mold. The mold is kept closed under pressure until the temperature of the part has been reduced, the resin solidified, and demolding is possible. Cycle time, as with thermosetting resins, depends on the thickness of the part and the heat distortion temperature of the resin. Mol ding pressures are similar to SMC, 10—21 MPa (1500—3000 psi), depending on the size and complexity of the part. 

As with SMC, appHcations are limited to high volume because of the capital investment in equipment and tooling. Thermoset compression molders require additional heating and material Handling equipment to adapt their process to thermoplastic sheet fabrication. AppHcations include automotive bumper beams, load floors, radiator supports, battery trays, and package shelves. Chair sheUs, military containers, material Handling pallets, trays, and concrete foaming pans are also produced. 

The rigidi d thermoplastic sheet - Tiocess combines thermoplastic sheet vacuum forming with a spray-up or cold press molding process to add a thermoset composite stmctural backing to a decorative thermoplastic skin. Large parts such as bathtubs, hot tubs, recreation vehicle components, and camper tops have been produced by this process. 

If a thermoplastic sheet is softened by heat and then pressure is applied to one of the sides so as to generate a freely blown surface, it will be found that the shape so formed has a uniform thickness. If this was the case during thermoforming, then a simple volume balance between the original sheet and the final shape could provide the wall thickness of the end product. 

Dry floor finishes (thermoplastic sheeting, carpeting, raised deck flooring, etc.)... 

A large thermoplastic sheet, 10 mm thick, at an initial temperature of 20 C (293 K). is to be heated in art oven in order to enable it to be moulded. The oven temperature is maintained at 100°C (373 K), the maximum temperature to which the plastic may be subjected, and it is necessary to ensure that the temperature throughout the whole of the sheet reaches a minimum of 80 °C (353 K). Calculate the minimum length of time for which the sheet must be heated. 

Anon., Thermoplastic sheets for absorption of carbon dioxide, Jpn. Kokai Tokkyo Koho 80,158,933, 1980. (CA 157990m)... 

Table 2.17 analyses some examples of the relative processing cost versus the annual production in units. The various technologies listed are not suitable for all materials or parts machining is used with numerous materials rotational moulding uses liquid resins vacuum forming uses thermoplastic sheets blow moulding uses special grades of thermoplastics... 

Thermoforming consists of applying a thermoplastic sheet softened by heat onto the walls of a mould to shape it (see Figure 5.29). 

In drape forming, the thermoplastic sheet is clamped and heated and the assembly then sealed over a male mold. The mold may be forced into the sheet or the sheet may be pulled into the mold by introduction of a vacuum between the sealed sheet and mold. By draping the sheet over the mold, the part of the sheet touching the mold remains close to the original thickness. Foamed PS and polyolefins are generally used in this procedure. 

Figure 13.10 The uneven surface of a preimpregnated thermoplastic sheet. The rough surface is oriented relative to the fiber longitudinal axis as shown...

The calendering process is commonly used for shaping high melt viscosity thermoplastic sheets and is particularly suitable for polymers susceptible to thermal degradation or containing substantial amounts of solid additives. This is because the calender can convey large rates of melt with a small mechanical energy input (compared to an extruder). 

Postforming laminates, unlike some thermoplastic sheet materials, cannot be formed into compound curves—but with appropriate techniques complex multiple internal and external bends ( S , U etc.) can be achieved easily. 

Preservation preparation materials such as a variety of conditioned papers desized unbleached muslin, cardboard, tubes, boxes, polyethylene sheeting, and nonstatic thermoplastic sheets must be provided, regardless of cost, to create the basic safe storage environment. Adequate funds must be allocated yearly to freshen and launder preparation materials. 

Thermoplastic sheet can be softened by warming, placed in or on a mold, pressed gently but swiftly to conform against the walls of the mold, cooled to solidify, and trimmed to separate the product from the surrounding unused sheet. 

Polymer Products Specialty Polymer Technology Polyurethane Foam Products Thermoplastic Sheet Non-woven Fabrics... 

Different processes have been developed with a few in use. Their designs usually start with an extruded thermoplastic sheet. Circular blanks cut from the sheet are compression molded into the desired preliminary shape. During the compression action, the blank can be simultaneously stretched, or being thermoplastic can be stretched after compression molding. They generate no trim scrap when formed... 

In use are stamping compression molding presses. Plastic used can be TS sheet molding compounds (SMCs) and stampable reinforced thermoplastic sheet (STX) material (STX is a registered tradename Azdel Inc., Shelby, NC). It is usually composed of a glass fiber-thermoplastic RTP (Chapter 15). 

TS plastics in reinforced sheets and compounds are usually used. Also used are reinforced thermoplastic sheets and compounds. With TSs compression molding (CM) can use preheated material (dielectric heater, etc.) that is placed in a heated mold cavity. The mold is closed under pressure causing the material to flow and completely fill the cavity. Chemical crosslinking occurs solidifying the TS molding material. 

Thermoforming has close similarities with vacuum forming, except that greater use is made of air pressure and plug assisted forming of the softened sheet. The process is invariably automated and faster cycle times are achieved than in the vacuum forming process. Only thermoplastic sheet can be processed by this method. 

Thermoforming a material for a unit change in temperature. Values for plastics range from 0.01 to 0.2 mil/in. Any process of forming thermoplastic sheet which consists of heating the sheet and pulling it down onto a mould surface. 

Use Electrical and electronic component industries, protective equipment, graphic arts and photographic film, cable wrapping and protective overlays for other thermoplastic sheeting, missile applications. 

Declar . [Sheffield Plastics] Thermoplastic sheet for aircraft cabin interiors. 

Thermoforming - The process of heating a thermoplastic sheet to a point at which it softens and flows, then applying differential pressure to make the sheet conform to the shape of a mold or die. 

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