Sprue gate

A circular plate of diameter 0.5 m is to be moulded using a sprue gate in its centre. If the melt pressure is 50 MN/m and the pressure loss coefficient is 0.6 estimate the clamping force required. 

Polythene at 170°C is used to injection mould a disc with a diameter of 120 mm and thickness 3 mm. A sprue gate is used to feed the material into the centre of the disc. If the... 

Mold design is a decisive factor for the molding success such as dimensioning and location of the sprue gates, dimensioning of shear edges, flow aids, cooling and ejector techniques, etc. 

The melt cake is distributed in the mold cavity by closure of vertical flash face only half of the mold (compression phase), whereupon the closed cavity is filled with the sprue gate closed as well. 

The mixture is transferred from an upper chamber of the compression mold, by a ram, through a sprue gate system into the lower section of the mold (cavity). 

Whereas in CM the mass filled into the mold is plasticized from the walls, plastification of the plastic in TM takes place in an additional cavity (Fig. 50). Similarly to injection molding, the plasticized mass is injected through a sprue gate into the mold cavity. Another method is to heat mass tablets before placing them in the cylinder, for instance using high-frequency waves [6]. 

Sprue gate system, sprue gate position. 

A stretched outer skin (often with biaxial stretching near the sprue gate due to dwell pressure)... 

For example, in direct injection molding of lid-like, thin-walled structural components (e.g., headlight reflectors), pronounced circular orientations of the short glass fibers are observed in the BMC (bulk molding compound) UP resins around the sprue gate. The solution is usually ICM or push-pull injection molding. 

Fig. 26 Cone or sprue gate for a plastic toothed wheel [3] (correct optimized properties)...

A cone or sprue gate, Fig. 26, on the other hand, results in a radially balanced, inside-to-outside filling process with point-symmetric orientations. 

When the molding is ejected, the sprue is pulled off at the (warmer) nozzle end. Therefore, the stem remains on the molding and must be removed by an additional operation. The sprue-gate is employed on high quality technical articles and on thickwaUed moldings. 

After solidification, the container is tipped over and the unbonded sand flows out together with the castings. Because there are no binders or other additives the sand is reclaim-able. The castings are then subjected to further operations, e.g. removal of sprue, gate, risers, any machining required, heat treatment, etc. similar to other casting processes. 

Sprue gating (direct gating) n. In injection molding with single-cavity molds, particularly those with circular symmetry, filling from the center with the sprue connected directly to the gate and mold cavity. 

A gate connects the runner to each mold cavity. With a sprue gate, the gate connects directly to the cavity. This type is commonly used on larger parts in single... 

A tool was selected for use in completing preliminary molding tests. The tool produces a center, sprue gated disk approximately 4 inches in diameter and 5/16 inches thick. The thickness of the disk can be increased as desired to evaluate large cross section parts. It is fitted with a transducer for the measurement of cavity pressure. 

Single impression tool, centrally filled from a sprue gate (i.e. no runner needed, the cavity filling from the sprue directly). The central boss part is of greater thickness than the rest of the moulding it is cooled with a large volume of ambient temperature water to balance its cooling rate with that of the other parts. 

Sample 1. The melt flows radially from the sprue gate. Already the influence of asymmetrically placed cores is seen. 

Fig. 7.6. Tensile deformation in constrained flow (a) tapering section of extrusion die (b) calendering and (c) injection moulding fed from a sprue gate as the liquid expands radially into the mould, elongational stresses are set up in the direction of the tangent (after Cogswell).

Fig. 7.31. For a cup-shaped moulding the correct gate is (b), the sprue gate an edge gate (a) produces a weld line (after Pye).

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