Injection/transfer molding machine

Figure 25 Schematic diagram of an injection/transfer molding machine [9]. (a) Hydraulic separation unit for upper mold plate, (b) Hydraulic separation unit for middle mold plate, (c) Shuttle system with automatic sprue nipple removal, (d) Brushing unit for cleaning middle mold plate, (e) Hydraulic ejector for automatic ejection.

Phenol-formaldehyde molding compositions are traditionally processed on compression- and transfer-molding machines with a very small amount being extruded. However, the injection-molding process as modified for thermosetting plastics is being increasingly used and it is today the most common method used to process phenolic compounds. The shorter cycle times and low waste factor available with... 

Figure 1.4 Three Station Injection Blow Molding Machine [Miller, 1983]. The parison is injection molded on a core pin (instead of as a tube in free air, as with extrusion blow molding) at the preform mold station (1). The parison and neck finish of the container are formed there. The parison is then transferred on the core pin to the blow mold station (2) where air is introduced through the core pin to blow the parison into the shape of the blow mold. The blow container is then transferred to the stripper station (3) for removal.

Normally, the injection blow molding machines use the horizontal rotary transfer table (Gussoni Method) as Wheaton, Jomar, Bekum, Fischer, and Johnson Controls. Battenfeld Fischer also produced a vertical rotary... 

Injection Molding Machines Glow Molding Con-presion Presses Transfer presses Thermotorming Machines Molds i Die Auxiliary Equipment Liquid Depensing Systems Irrpregnators Plotters... 

Injection mold machines are rated by their ability to mold polystyrene in a single shot [3], Mold pressures can range from 55 to 275 MPa and cycles as low as 15 s. It is possible to injection mold a thermoset resin, although it is very difficult. Compression molding or transfer molding is used in these cases ... 

There are essentially two methods of using the plasticating screw. The first is the screw-plunger system also called the two-stage or screw-pot system. The screw rotates in the heated barrel and consequently plasticizes the polymer material. The plasticized material is then transferred into a second heated cylinder from which it is injected into the mold by a plunger. Figure 11.6 shows the basic features of a screw-pot injection molding machine. 

A typical arrangement for a direct screw-transfer injection-molding machine for thermosets is shown in Figure 2.16. The machine has two sections mounted on a common base. One section constitutes the plasticizing and injection unit, which includes the feed hopper, the heated barrel that en closes the screw, the hydraulic cylinder which pushes the screw forward to inject the plasticized material into the mold, and a motor to rotate the screw. The other section clamps and holds the mold halves together under pressure during the injection of the hot plastic melt into the mold. 

In this process the parison is injection molded rather than extruded. In one system, for example, the parison is formed as a thick-walled tube around a blowing stick in a conventional injection-molding machine. The parison is then transferred to a second, or blowing, mold in which the parison is inflated to the shape of the mold by passing compressed air down the blowing stick. The seqnence is shown in... 

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