Spiral mold test

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.

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

Fig. 10-9. Spiral flow test mold and plastic molded spiral test specimen, using an injection molding machine.

Spiral-flow test n. A method of evaluating the molding flow of a resin to injection or transfer molding in which the melt is injected into a spiral runner of constant trapezoidal cross-section with numbered and subdivided centimeter (or inches) marked along the runner. The mold is filled from a sprue at the center of the spiral and pressure is maintained until flow stops, the number just aft of the molded-spiral tip giving the flow distance. The spiral-flow test has been widely used since it was introduced in the early 1950s but has been standardized in USA only for thermosetting resins, in ASTM D 3123. 

Spiral flow (test and mold). There are two types of spiral flow molds— one for the very soft flow encapsulation compound generally associated with the encapsulation grades of the epoxy family of compounds and a spiral flow mold, which is used when testing the high-pressure phenolic, DAP, melamine, urea, epoxy, and thermoset polyester com-poimds. 

Figure 2.27 Spiral flow test and mold (Emmi).

Receiving Inspection. Many types of tests have been devised for testing raw materials. Depending upon the severity of the need for inspection, the types of tests selected may vary from being basic and simple to sophisticated and complex. Some of the most common basic tests are the melt index test, specific gravity, bulk density, spiral flow test, and viscosity tests. Gel permeation chromatography, infrared analysis, thermal analysis, and rheometry are some of the more elaborate raw material quality control tests. These tests are discussed in detail in Chapter 7. Some processors also choose to mold test bars from a small sample of raw material and conduct physical tests such as tensile, impact, and flexural tests and then evaluate the results to see if they meet the preestablished specifications. 

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. 

Some of the test methods being used to measure the processing stability of polypropylene include melt flow drift measurements at elevated temperatures using an extrusion plastometer (melt indexer), melt viscosity retention measurements using a torque rheometer, retention of melt flow after repeated extrusions, and injection molded spiral test measured by the flow in inches at various temperatures and the retention of melt flow of the injected spirals. The nine commercial resins were evaluated by these methods. 

Rheology is a complex subject, and in the formulated colorant industry two simplified approaches have served well in the majority of cases. These are the single-point method, melt flow, and the molding simulation test, spiral flow. 

Flow properties of thermosets can also be measured using transfer molding into a spiral flow tool as described in ASTM D3I23 [66]. Material injected under specified transfer conditions flows spirally outwards along a groove with numbered distance marks until cured to an extent that flow ceases. Molding is carried out at 150 C. Length of spiral is measured to the nearest 25.4 mm (1 inch). The standard states that the test is suitable for... 

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