Cooling Channel Schemes of Plastic Injection Molding

A number of various cooling channel schemes or layouts are commonly used in injection molding. For cooling a core-shaped part, a V channel (Fig 1), basic fountain (Fig 2), and fountain baffle channel (Fig 3) are used to provide optimum cooling. For irregular-shaped parts, the baffle design concept is used, which circulates flow up close to the mold surface and provides turbulent flow inside the mold (Fig 4).

    

                                                     Fig 1 V-channel cooling lines     

                

                                               Fig 2 Fountain channel cooling lines

                                                Fig 3 Fountaion baffle cooling lines       

                                        

                                            Fig 4 Modified baffle design with flow director

Another method used, which does not utilize a liquid medium such as water, is the conductive insert. This method provides spot cooling to a specific area, such as a thick section, where placing a cooling line can be difficult. These inserts are made from materials such as aluminum or beryllium copper. (Fig 5) illustrates this conductive insert method.

Fig 5 Conductive insert

Here are some cooling system setting principles. On the premise of mold structure allows, cooling circuit should be kept to a more, the cooling hole channel diameter should be as large as possible to achieve the cavity surface temperature is more uniform, and little internal stress of plastic parts, low distortion, high accuracy. When the plastic parts wall thickness uniform, cooling waterway to the cavity surface  distances are equal, when the plastic parts wall thickness uneven, thick local of cooling channel should be close to the distance to the cavity surface, the distance can also be appropriate, general channel to hole distance on the surface of the cavity is 10 ~ 15 mm.

Gate should strengthen the cooling, the cooling water temperature difference between the various export should be small as far as possible. When plastic melt filling the mold, near the gate ,the highest temperature, the farther away from the gate, the lower the temperature. In order to narrow the export of cooling water temperature difference, should arrange waterways according to the different cavity shape.

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