Mold parts Sprue bushing

That part of the injection molding tool, against which the nozzle pushes during the injection process to inject the melt. The bore of the sprue bush is cone-shaped and with many single impression molds connects directly into the cavity... 

As an alternative, the screw and barrel (plunger, barrel, and stuffing mechanism) are horizontal, feeding into the horizontally positioned closed mold through a sprue bushing at the parting line of the closed mold (Fig. 6.21). 

The support plate backs up the B plate in the mold, and melt is delivered from the nozzle to the sprue bushing. The locating ring aligns the mold with the nozzle, whereas the leader pins and bushing align the two sides of the mold. In the ejection system, the sprue puller and ejector pins, are attached to the ejector plate, which is, in turn, connected to the machine s ejection plates by the ejector rod. When the mold is opened, the sprue puller draws the part to the B side of the mold, whereas the... 

The seating ring centers the sprue bushing on the injection platen of the machine directly in line with the nozzle of the injection cylinder. The sprue bushing should be as short as possible from the nozzle to the parting line of the mold and have a taper of at least 3 deg in order to maintain the heat of the melt. Cold slug wells should be used wherever possible to permit the leading cold resin to be trapped and to permit the hot resin to... 

Figure 7.10 Schematic of a two-plate mold. A Knockout plate, B ejector retainer plate, C ejector travel, D support plate, E sleeve-type ejector, F rear cavity plate, G cavity, H front cavity plate, I locating ring, J sprue bushing, K damping piate, L parting iine, M core or force, N ejector pin, O sprue puiier, P damping piate, Q retainer piate, R knockout pins, S core or force pin.

Fig. 19.35. Schematic of injection molding operation. A. When the mold starts to close, the screw has just finished charging the front end of the cylinder. B. With the mold closed, the heating cylinder then moves toward the sprue bushing and is ready to commence the injection cycle. C. The hydraulic cylinder then forces the screw forward under the injection head and fills the cavity. D. Cooling and charging cycle the mold is filled and, after the holding time, the screw starts to rotate and charge the front end of the cylinder. E. The screw is still charging the front end of the cylinder, and the cylinder starts to move away from the sprue bushing. F. The finished cycle the mold opens and the molded part is ejected with the sprue bushing. Du Bois, J. H., and John, F. W., Plastics, Reinhold, 1967 by permission of Van Nostrand Reinhoid Co.)...

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