Mold/platen insulations

Molds should be well-insulated to reduce energy costs. Insulating hardboard should be put between the mold and the clamp platens and the sides of the mold and the circulating oil hoses should be insulated as well. A typical 15-ton steel automotive fender tool, properly insulated, required 20 kw to maintain its temperature during production. 

One problem that most controls do not consider involves the effect of heat on tie-bars, which can directly influence mold performance, particularly at start-up. If the heat differs from top and bottom bars, it is necessary to insulate the mold from the platens. The insulator pad used also confines heat more to the mold, producing savings in heat and/or better heat control. The following paragraphs describe calculation of the elongation of these usually evenly heated bars, and of thermal mold growth (1). 

Many molds, particularly those used for engineering thermoplastics, run at relatively high temperatures, for example, 80 C (176° F). If the mold is not insulated then, heat losses to the atmosphere, and to the machine, can easily equal those lost by the injection cylinder. So, insulate the mold from the platens and, if possible, insulate the outside surfaces of the mold. If a hot runner mold is being considered then, try and reduce heat exchanges between the hot runner parts and the cold, component-forming parts. 

Thermalate, Mold and platen thermal insulation, Haysite Reinforced Plastics... 

Figure 6-17. Coaxial electrical cable s PS insulation buttons are here being injection molded, using a cold runner system, but it could also use a hot runner one. In this continuous production process, the injection-molding machine (IMM) is on a platform that moves in a rectangular pattern to permit the platens to open and move away from the buttons, as well as to move at the speed of the six-cable copper wire line when the mold is closed and the IMM is injecting the PS. Copper wires are started out with large diameters and are pulled through reduction squeeze rolls to their final thin diameter prior to entering the IMM. The wire-reduction line is to the left of the IMM, with the wire pullers to its left. Automatic devices remove the runners on-line just after they leave the IMM and the additional cooling station fiiat is shown in this view.

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