Blow Molding-Compression-Stretched

Processes basically go through the following stages (1) starts with an extruded sheet, 

Thermoformed (3-D shape) plastics provide a great variety and quantities of marketable products, in a wide size range from millions of drinking cups or containers (each 

At least 30wt% percent of all extruded products are thermoformed. They have many advantages over other manufacturing methods. For the mass production of products (packaging, picnic dishes, cups, etc.) sheets and films can be produced in-line with 

The process basically forms the sheet after it has been heated to the point at which it is soft and flowable, and then applying differential pressure (atmospheric pressure, air pressure, vacuum, or their combinations) to make the sheet or film conform to the shape of the male or female mold producing many different products (Table 8-23). The more precise and controlled pressure applied, the more efficient in reproducing products at the lowest cost occurs (Fig. 8-50), 

Cellulose acetate Cellulose propionate Cellulose acetate butyrate High-density polyethylene Nylon 

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Stretch blow molding Compression molding Sintering... 

The injection blow molding process involves two stages. In the first stage, a plastic part called a preform is made, using a traditional injection molding process. The preform is a precise shape, with precise wall thicknesses. This preform is then transferred to a blow molding station, where it is placed in another mold and held in place by specific features of the preform that mate with the blow mold cavity. Compressed air is then injected into the center of the part, forcing the unsupported walls of the preform tube to stretch and expand outward, until they hit the walls of the second mold. Once the material cools and solidifies, the mold is opened and the part is removed. 

Here compressed air is used to form the sheet. In one variation, a plastic sheet is heated and sealed across the female cavity (Figure 11.14). Air at controlled pressure is introduced into the mold cavity. This blows the sheet upward into an evenly stretched bubble. A plug which fits roughly into the mold cavity descends on the sheet. When the plug reaches its lowest possible position, a vaeuum or, in some cases, air under pressure is used to complete part formation. 

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