Pneumatic Forming

a means of forming items from sheet thermoplastic polymers.

In pneumatic forming, the blank, which is 1.5–10 mm thick, is fastened to the edges of the mold, heated to a temperature at which the polymer is in the high-elastic state, and formed into the item by the action of compressed air at an excess pressure of 50 -2,500 kilonewtons per sq m, or 0.5–25 kilograms-force per sq cm. The main methods of pneumatic forming are negative, positive, and free forming, which are analogous to the methods used in vacuum forming. The advantage of pneumatic forming over vacuum forming lies in the possibility of varying the excess pressure on the blank over a wide range, which makes possible the forming of items from thicker sheets.

An advanced method for the production of items with thick walls is the combination of pneumatic forming with mechanical forming—for example, in a press (mechanopneumatic forming). Pneumatic forming is used for the manufacture of parts for aircraft windows, various sanitary and household items (for example, baths, sinks, and parts for refrigerators), and containers.