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.

Sprue Gate The sprue is gated directly into the part. Injection Mold Design Engineering. Successful Injection Molding: Process, Design, and Simulation.

The diameter of the feed is the runner closer to the sprue, and the branch is the diameter further from the sprue. Sprue Gate The sprue is gated directly into the part. Injection Mold Design Engineering.

Spiral flow testing results for GLS products are presented below using injection speeds of 3 in/sec and 5 in/sec. Special TPEs can achieve up to 40 inches at an injection speed of 5 in/sec. Shut-Off Design

Spiral flow testing results for GLS products are presented below using injection speeds of 3 in/sec and 5 in/sec. Special TPEs can achieve up to 40 inches at an injection speed of 5 in/sec. Shut-Off Design

Mold Design Recommendations Gates 1. Step each 90° bend in the system down in size (from sprue to gate) approximately 1.5mm (1/16") to reduce pressure drop. 5. Place these wells at the base of the sprue to capture the cold material first emerging from the nozzle. 2.

Follow up by purging machine with general purpose PP • Residence time should not exceed 5 minutes for Maxxam FR products • General ventilation is suggested Shut Down • Purge the equipment with a general purpose PP • All tooling and equipment must be free of any residual Maxxam FR upon shut down • Continue generating parts made from the natural PP until clear • Wipe down tool steel with mold cleaner • When using a hot runner system, care must be taken to remove residual product from the manifold MOLD DESIGN RECOMMENDATIONS Cold Slug Wells • Place cold slug wells at the base of the sprue to capture the cold material first emerging from the nozzle • Place cold slug wells at every 90° bend in the runner system • Well depths approximately 2–3 times the diameter of the runner provide best results Draft Angle • Draft angle should be 1/2°–1° per side. Runners • Full-round or modified trapezoid runners are the best design and provide the least surface to cross section ratio. Increase the vent depth to 0.010" at 0.100" away from the cavity and vent to atmosphere. • Vents should be placed at the intersection of each 90° bend in the runner system off of the cold slug well and vented to atmosphere PROBLEM CAUSE SOLUTION Black Specks Contamination • Purge barrel with general purpose PP • Verify correct nozzle is being used • Pull screw for cleaning Degraded/overheated material • Decrease melt temperature • Decrease back pressure • Decrease injection speed • Use appropriately sized barrel Brittleness Degraded/overheated material • Decrease melt temperature • Decrease back pressure • Decrease injection speed • Use appropriately sized barrel Gate location and/or size • Relocate gate to nonstress area • Increase gate size to allow higher flow rate and lower molded-in stress Burning Process related • Decrease nozzle and barrel temperatures • Decrease mold temperature • Decrease injection rate Mold design • Clean, widen and increase number of vents • Increase gate size to reduce shear Fibers/Minerals on Surface or Uneven Surface Appearance Melt temperature too low • Increase melt temperature • Increase mold temperature • Increase injection speed Insufficient packing • Increase hold pressure and time • Increase shot size Flash Injection pressure too high • Decrease injection pressure • Increase clamp pressure • Decrease injection rate • Increase transfer position Excess material volume • Adjust transfer position • Decrease pack pressure • Decrease shot size • Decrease injection rate Melt and/or mold too hot • Decrease nozzle and barrel temperatures • Decrease mold temperature • Decrease screw speed Loose clamp • Reset mold height • Increase clamp tonnage Troubleshooting Recommendations PROBLEM CAUSE SOLUTION Incomplete Fill Melt and/or mold too cold • Increase nozzle and barrel temperatures • Increase mold temperature • Increase injection rate Mold design • Enlarge or widen vents and increase number of vents • Check that vents are unplugged • Check that gates are unplugged • Enlarge gates and/or runners • Perform short shots to determine fill pattern and verify proper vent location • Increase wall thickness to move gas trap to parting line Shot size • Adjust transfer position to 98% full • Increase shot size Nozzle Drool Nozzle temperature too hot • Decrease nozzle temperature • Decrease back pressure • Increase screw decompression Shrink Too much shrink • Increase cooling time • Decrease mold temperature Too little shrink • Decrease cooling time • Increase mold temperature Sink Marks Part geometry too thick • Reduce wall thickness • Reduce rib thickness Melt too hot • Decrease nozzle and barrel temperatures • Decrease mold temperature Insufficient material volume • Adjust transfer position • Increase shot size • Increase injection rate • Increase packing pressure Troubleshooting Recommendations (continued) PROBLEM CAUSE SOLUTION Sticking in Mold Overfilled cavity • Decrease injection rate and pressure • Decrease hold pressure • Adjust transfer position • Decrease nozzle and barrel temperatures • Decrease mold temperature • Decrease cooling time Mold design • Increase draft angle • Polish cores in direction of ejection Part is too hot • Decrease nozzle and barrel temperatures • Decrease mold temperature • Increase cooling time Warp Process related • Increase cooling time • Increase melt temperature • Increase pack pressure • Increase pack time • Decrease mold temperature Mold design • Inspect for non-uniform mold cooling Part design • Inspect for non-uniform wall thickness Temperature control unit incorrect temperature • Check settings • Inspect thermocouple Weld Lines Melt front temperatures are too low • Increase pack and hold pressure • Increase melt temperature • Increase injection rate • Increase mold temperature Mold design • Increase gate size • Perform short shots to determine fill pattern and verify proper vent location • Add vents and/or false ejector pin • Move gate location 1.844.4AVIENT www.avient.com Copyright © 2022, Avient Corporation.

MOLD DESIGN RECOMMENDATIONS Gates • Many different types of gates can be used such as pin, fan, tunnel, tab and edge gates. Runners • Full-round runners or a modified trapezoid runner are the best designs. Cold Slug Wells • Place these wells at the base of the sprue to capture the cold material first emerging from the nozzle. • Place wells at every 90° bend in the runner system. • Well depths approximately 1.5 times the diameter of the runner provide the best results.

MOLD DESIGN RECOMMENDATIONS Gates • Many different types of gates can be used such as pin, fan, tunnel, tab and edge gates. Runners • Full-round runners or a modified trapezoid runner are the best designs. Cold Slug Wells • Place these wells at the base of the sprue to capture the cold material first emerging from the nozzle. • Place wells at every 90° bend in the runner system. • Well depths approximately 1.5 times the diameter of the runner provide the best results.

MOLD DESIGN RECOMMENDATIONS Gates • Many different types of gates can be used such as pin, fan, tunnel, tab and edge gates. Runners • Full-round runners or a modified trapezoid runner are the best designs. Cold Slug Wells • Place these wells at the base of the sprue to capture the cold material first emerging from the nozzle. • Place wells at every 90° bend in the runner system. • Well depths approximately 1.5 times the diameter of the runner provide the best results.