Injection Molding Sprue and Sprue Puller Design  Sprue puller designs vary with the hardness of the material.

Injection Molding Sprue and Sprue Puller Design  Sprue puller designs vary with the hardness of the material.

Injection Molding Home // Products // Thermoplastic Elastomers // TPE Knowledge Center // Injection Molding Guide // Injection Molding: Part Design // Injection Molding: Part Design The shear thinning behavior of SBCs should be considered when designing injection molds and also when setting mold conditions during processing.

Injection Molding Home // Products // Thermoplastic Elastomers // TPE Knowledge Center // Injection Molding Guide // Injection Molding: Part Design // Injection Molding: Part Design The shear thinning behavior of SBCs should be considered when designing injection molds and also when setting mold conditions during processing.

Injection Molding The GLS™ Injection Molding Guide provides in-depth information on part design, mold design and processing for styrenic block copolymer (SBC) thermoplastic elastomers (TPEs). Sprue and Sprue Puller Design

Injection Molding The GLS™ Injection Molding Guide provides in-depth information on part design, mold design and processing for styrenic block copolymer (SBC) thermoplastic elastomers (TPEs). Sprue and Sprue Puller Design

After the gate freezes, any additional material volume or pressure will only pack the sprue and runner system, which can cause difficulties with sprue removal during part ejection. It should be noted that the gate size/location, runner dimensions and other aspects of the mold design may also affect the properties of a part. Due to their higher modulus, hard formulations require less aggressive sprue-pullers.

After the gate freezes, any additional material volume or pressure will only pack the sprue and runner system, which can cause difficulties with sprue removal during part ejection. It should be noted that the gate size/location, runner dimensions and other aspects of the mold design may also affect the properties of a part. Due to their higher modulus, hard formulations require less aggressive sprue-pullers.

In the case of softer GLS materials, it may be necessary to use a more aggressive sprue puller such as a pine tree design (Figure 10). If the product design requires a sprue gate, a hot sprue is preferred over cold because it reduces scrap, decreases cycle time, and allows for easier processing. If the product design requires a sprue gate, a hot sprue is preferred over cold because it reduces scrap, decreases cycle time, and allows for easier processing.

Sprue puller designs vary with the hardness of the material. The different sprue designs possible and their relative dimensions are shown in Figures 4 through 7. See Regrind Hard formulations, 28 Hold time, 26 Hot runner systems, 17–20 Hot sprue bushings, 8 Hot tip gates, 19–20 Injection pressure, 26 Injection speed, 25 Injection time, 26 Machine selection, 21 Manifold design, 18 Mold cooling, 17 Mold finish, 7 Mold surface, 7 Mold temperatures, 24 Mold texture, 7 Mold types, 6 Nozzle selection, 22 Overmolding,20 Overpacking, 27 Part ejection, 17 Purging, 23 Radii/fillets, 4 Regrind, 23 Runner balance, 10–11 Runner keepers, 13 Screw position, 26 Screw rpm, 25 Screw selection, 22 Shear dependence, 3 Shear rate, effect on viscosity, 3 Shot size, 25 Shrinkage, 5 Soft formulations, 27 Spiral flow, 4 Sprue design, 8 Sprue gates, 15 Sprue puller design, 8–10 Steel selection, 6–7 Submarine gates, 14 Sucker pins.