Platens insulating

Table 18. Microporous powder pressed to platens as a thermal insulating material...

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. 

The fluid film system completely eliminates the heat sink/ radiation loss since the platens remain stationary. The heat in the platen is radiated into the product. The reservoir behind the platen is easy to insulate and this insulation remains in place with no hinderance to inspection or maintenance. Further, since the heat is controlled in zones corresponding to the need profile of the formulation, there is no wasteful input of energy into the product. 

Support and insulation of the platen was also a problem, and the use of marbles seems to be an inexpensive choice because about 700 worth of marbles would provide support and thermal isolation, and has the added advantages of easy transport and modification of the chamber. Marbles also reduce the volume of the vacuum chamber and thereby reduce pump-down time and energy. 

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.

The homogeneous southern pine particleboards with a density of 50 pounds per cubic foot were pressed to 5/8 inch stops using a closing pressure of 500 psi with a platen temperature of 360 F for the prescribed press time of 5, 6, or 7 minutes. A resin solids of 6%, based on oven dry weight chips, was used for all boards. No wax or other material was added. Immediately upon removal from the hot press, boards were stored in an insulated, but unheated, oven for an overnight period of simulated hot stacking. Two duplicate boards were made for each hot press time and resin combination. 

Compression moulding is carried out on moulding powders or sheet moulding compounds (SMC). The presses are vertical, with the hydraulic cylinder above or below the horizontal platens. The mould is heated to between 160 to 200 C, being thermally insulated from the platens (Figure 1.9). The required amount of prepolymer (mixed with catalyst or curing agent) is placed into the open mould it is then closed and pressure is applied to cause the material to flow around the cavity. The mould remains closed until the... 

Electrically, hf welding presses need to have one electrode assembly, and this normally includes one of the press platens, isolated from the press frame. Post insulators cast... 

Insulate the hot runner manifold and nozzles from the machine platen or mould cavities by air or compressed temperature resistant sheeting... 

The mould is heated electrically. It is recommended that control of both mould halves is separate. The heating power for small moulds should be between 1,600 and 2,200 Watt per mould half, varying according to the mould size (e g., 215 x 300 mm). The mould temperatures vary according to the thermoset material. Standard values range from 150 to 240 °C. The mould should have exchangeable inserts and insulating platens of 10 mm thickness. 

Making LSR moulds requires expert know-how. It is recommended that only mould designers and makers who already have experience in this technique are used. In view of the high mould temperatures you need insulating platens with a thickness of 10 mm for the mould. 

---