Fabrication processes thermoforming

Thermoforming—A fabrication process in which sheets of thermoplastic material are softened by heating and then shaped by pressing into a mold. 

Thermoforming refers to a fabrication process which essentially involves the following three steps ... 

Franklin Associates. Life Cycle Inventory of Plastic Fabrication Processes Injection Molding and Thermoforming. Kansas Prairie Village 2011. 

Fabrication processes for rigid plastics include compression molding, thermoforming, sheet extrusion, steam-chest expansion, and so on. 

Related to ABS, styrene-acrylonitrile (SAN) is hard, rigid, and transparent. It has no butadiene. It is characterized by excellent chemical resistance, good dimensional stability, and ease of processing. All fabricating processes can be used with SAN, but because it is not toughened, thermoformed shapes may crack during conventional trimming. 

Processing. SAN copolymers may be processed using the conventional fabrication methods of extmsion, blow mol ding, injection molding, thermoforming, and casting. Small amounts of additives, such as antioxidants, lubricants, and colorants, may also be used. Typical temperature profiles for injection mol ding and extmsion of predried SAN resins are as follows (101). 

Polysulfones are easily processible by other thermoplastic fabrication techniques, including extmsion, thermoforming, and blow mol ding. Extmsion... 

Processing and Application. Polystyrene and the other thermoplastics would not have been able to enter on their triumphal march if the manufacturers of processing equipment had not been able to provide efficient fabrication methods. A decisive factor was that between 1950 and 1960 the injection molding machine with a screw preplasticizer was developed and extrusion through slit dies to give sheeting or film followed by thermoforming was evolved. 

Very few studies have been performed investigating the effect of branching on the extensional rheological properties of polystyrenes. Such investigations can be valuable because many of the fabrication operations associated with commercial applications of polystyrene include operations in which the polystyrene melt undergoes an extensional deformation. Some examples are extruded foam sheet, blown film, oriented (tentered) sheet, and thermoforming. The types of deformations associated with these processing operations are best described as... 

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