Spiral mold

SF Spiral Flow index, the length of specimen molded into spiral mold Injection molding machine. Allrounder 221-75-350 Arburg... 

Since the materials have a very soft plasticity rating, or inches of flow on spiral mold, the materials are all molded in special transfer molding presses and specially designed transfer molds. Because an acid catalyst and glass or mineral fillers are used to make the compound, these materials may have an adverse effect on the hardened steel mold with the result that there may be excessive runner and gate wear. 

Another practical approach to the question of moldability, especially in comparing one polymer with another, is the use of a standard spiral mold cavity and the measurement, under prescribed molding conditions, of the spiral length filled (7). 

Spiral Mold Test. Processing stabilities were also determined by the spiral mold test (5). The resins were injection molded in a 3-ounce reciprocating screw injection molder at 25°F. (14°C.) intervals from 425° (219°C.) to 600°F. (316°C.) using a 55-inch spiral mold under the following conditions mold temperature, 80°F. injection pressure, 16,000... 

Figure 8. Spiral mold test. Spiral lengths at designated molding temperatures...

Figure 9. Spiral mold test. Melt flows of the injection molded spirals at 230°C.

Spiral mold cooling n. A method of cooling injection molds (or heating transfer molds) wherein the heat-transfer medium flows through a spiral passage in the body of the mold. In injection molds, the cooling medium is introduced at the center of the spiral, near the sprue section, because more heat is concentrated in this area. 

Figure 4. Spiral flow of high impact alloys. Injection machine Toshiba IS-90B mold 10 mm x 3 mm (spiral) molding conditions injection pressure 78 MPa injection speed 20 mm/s mold temperature D°C.

The tangential flow of a power-law fluid through an annulus under only an imposed pressure gradient with both cylinders stationary is useful in the analysis of spiral molds [14]. In this case, F = 0 so, Eq. (20) with A-+ x yields... 

Kubat, J. and Szalanczi, A. (1974) Polymer-glass separation in the spiral mold test, Polym. Engg Sci., 14, 873-7. 

Viscosity is affected by the discussed additives in different ways. Figure 10.36 shows a marginal decrease in viscosity with concentration. Addition of ultrahigh molecular weight silicone additive, which is used as a mold release, decreases viscosity of polyethylene melt and thus lowers energy input in extrusion (Figure 10.37). Addition of 0.2 wt% of silicone additive reduced Brabender torque by 40%, elongational viscosity by a factor of four, and increased spiral mold flow by 30%. ... 

ASTM D3123 Spiral Flow - This test measures how a filled molding compound will behave when injection or transfer molded. It enables the molder to set the optimum mold temperature. The compound is forced into a heated spiral mold under controlled conditions. Once cure is complete the part is removed and the flow length is measured directly from the specimen. 

Spiral flow was measured in an injection molding machine with a spiral mold. The flow length (in cm) in the mold was measured under the given test conditions. Melt temperatures, mold temperature, gauges of spiral flow, and boost pressure were 250 °C, 270 °C, 80 °C, 0.75 mm. 

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