Mold Cooling System

The mold may consist of regions where circuits are not feasible. Additional cooling channels such as baffles, bubblers, or thermal pins may be used to divert the coolant flow into these regions. Shoemaker (2006) has shown some examples. 

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Injection-molding cooling systems can be analyzed quite readily today. Generally, two analyses are done. The first concerns the flow of the coolant in the cooling system the second concerns the heat transfer from the part, through the mold, and into the coolant. 

In certain processes (such as rubber tire manufacture and plastic injection molding operations), it is common for a valve sequencing system to first provide hot steam followed by cold cooling water and thus for cross-contamination to occur. The result may be the stripping of passivated cooling system surfaces by steam and for the condensate to be infiltrated by cooling water. 

Hot Runners. When the molten plastic is pumped into the water-cooled mold, the cooling system solidifies both the plastic product in the mold cavities and also the plastic material in the runners. Later the solid runners must be separated, reground, and reused. This is an extra burden on the process. An alternative is to avoid cooling the runners, and actually keep them hot, so that the molten polymer in them remains ready for the next shot into the mold. 

Mold cooling is typically provided by water channels in the mold, when metal molds are used. A system of fans blowing air over the top of the mold can aid in cooling, and this can be used alone for wood or plastic molds, which do not generally contain internal cooling. 

Generally, the blow mold is a cavity representing the outside of a blow-molded part The basic structure of a blow mold consists of a cast or machined block with a cavity, cooling system, venting system, pinchoffs, flash pockets, and mounting plate. The selection of material for the construction of a blow mold is based on the consideration of such factors as thermal conductivity, durabrhty, cost of the material, the resin being processed, and the desired quality of the finished parts. Commonly used mold materials are berylHum, copper, aluminum, ampcoloy, A-2 steel, and 17-4 and 420 stainless steels. 

Basically the BM lines have an extruder with a die to form the parison or with an injection mold to form the preform. The hot parison or preform is located in a mold. Air pressure through a pin-type device expands the parison or preform to fit snugly inside the mold cavity. Blow-molded products are cooled via the water-cooling systems within mold channels. After cooling, the parts are removed from their respective molds. See blow molding mold Coca-Cola bottle bottle, beer foundry shell molding. 

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