Cooling Demolding

Polymer Molding Temp rc) Time of molding (mins) Time of cooling/ demolding... 

After cooling, the final part is removed and the mold is recharged with resin. Since the mold surfaces are often complex, processors commonly apply mold release agents to allow the part to demold. Mold release agents are lubricants that coat the metal surface with a waxy material preventing the polymer from adhering to the mold s surface. Examples of mold release agents include silicone sprays or olefin based waxes. 

Multiple arm machines rotate molds into the different stations of the process. A three-arm machine would, for example, have one mold filling while another is heating in the oven and the third cooling in preparation of demolding. This is very efficient but requires that each stage takes the same time to accomplish. When there are three different parts, the largest part or the one with the thickest walls defines the speed for the entire process. 

The heat cycle is followed by the cooling cycle. Because EPS is an excellent thermal insulator, it takes a relatively long time to remove the heat before demolding. If the heat was to remain, the product would distort. Cooling is usually by water spray over the mold. To facilitate removal, particularly for complex shapes mold release agents are used. The final density is about 0.7 to 10 lb/ft3 (II to 160 kg/m3) or in normal molding the density of the product will closely approximate the bulk density of the unheated beads. 

A rule of thumb formula for calculating cooling is given in greater detail in Lesson 7.5. The formula employs variables of the melt temperature, wall temperature, demolding temperature, as well as the plastic material s thermal... 

Period an article spends in the cooled mold after injection, imtil it is sufficiently stable for demolding... 

A compressed air thermoforming machine is essentially a deep drawing machine with a controlled heat shield, except that, in place of an upper ram, a pressure bell is used. The heated rubbery material is pressed into the molding tool using a differential pressure of up to 100 psi. After cooling and demolding, the formed part is precisely shaped. 

Once the curing procedure was complete, the setup was cooled down and demolded to obtain the copolyester modified polystyrene shape memory polymer (CP-PSMP) composite. 

Thermoforming results in characteristic thickness distributions of the part s walls. Once the sheet contacts the mold surface, it sticks and locally cools. The wall thickness distributions are due to hindering and stretching of the hot sheet material. Thermoformed sheet once formed as product is cooled below its softening to freeze is normally performed by conduction via the mold surface. The mold is kept at a constant temperature by cooling or heating. Finally, the thermoformed product is demolded and cut out or trimmed by various means around the formed regions. 

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