Mold pressure pad

Compressed air thermoforming is a technique borrowed from sheet steel processing its main use in plastics processing is in plastic cup production. Machines are also coming into use for the production of engineering components, such as computer covers. A flexible-pressure pad is used to press the hot sheet into the mold cavity, with the aid of an air cushion maintained under pressure. Compared with vacuum forming, this... 

Parallels n. (1) Spacers placed between the steam plate and press platen to prevent the middle section of a compression mold from bending under pressure. (2) Pressure pads or spacers between the steam plates of a mold when the land area is too small. The pads control the height when the mold is closed and thus prevent crushing parts of the mold. 

Pressure pad n. A reinforcement of hardened steel, several of which may be distributed around the dead area in the faces of a mold to help the land absorb the final pressure of closing without collapsing. 

Similar to matched metal stamping except that a metal mold half is replaced by a block of solid rubber. Processing material cannot flow to the extent that it can with matched-metal forming. However, more uniform pressure is exerted on the material charge due to the rubber pad. 

Voids in Part Injection Pressure too Low Excessive Injection Rate Short Injection Time Low Melt Temperature Low Mold Temperature Cooling Rate too Low Gate Size too Small Incorrect Pad Size... 

Closed-cell foams result when the decomposition and gelation are carried out in a closed mold almost filled with plastisol. After the heating cycle, the material is cooled in the mold under pressure until it is dimensionally stable. The mold is then opened, and the free article is again subjected to heat (below the previous molding temperature) for final expansion. Protective padding, life jackets, buoys, and floats are some items made by this process. 

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