Injection Molding Equipment  Screw Design  Sprues and Runners 

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

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

Maxxam™ FR FLAME RETARDANT POLYOLEFIN FORMULATIONS PROCESSING GUIDE Injection Molding Parameters Maxxam™ FR flame retardant polyolefin formulations are engineered to meet stringent flammability performance requirements. Runners • Full-round or modified trapezoid runners are the best design and provide the least surface to cross section ratio. 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 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 injection speed • Use appropriately sized barrel Brittleness Degraded/overheated material • Decrease melt temperature • 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 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 injection speed Insufficient packing • Increase hold pressure and time Flash Injection pressure too high • Decrease injection pressure • Increase clamp pressure • Increase transfer position Excess material volume • Decrease pack pressure • Decrease shot size Melt and/or mold too hot • Decrease screw speed Loose clamp • Reset mold height • Increase clamp tonnage Troubleshooting Recommendations Incomplete Fill Melt and/or mold too cold • Increase nozzle and barrel temperatures 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 Nozzle Drool Nozzle temperature too hot • Decrease nozzle temperature • Increase screw decompression Shrink Too much shrink • Increase cooling time Too little shrink • Decrease cooling time Sink Marks Part geometry too thick • Reduce wall thickness • Reduce rib thickness Melt too hot • Decrease nozzle and barrel temperatures Insufficient material volume • Increase packing pressure Troubleshooting Recommendations (continued) Sticking in Mold Overfilled cavity • Decrease injection rate and pressure • Decrease hold pressure • Decrease cooling time Mold design • Increase draft angle • Polish cores in direction of ejection Part is too hot • Increase cooling time Warp Process related • Increase cooling time • Increase pack pressure • Increase pack time 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 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 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.

Runners • Full-round runners or a modified trapezoid runner are the best designs. Step each 90° bend in the system down in size (from sprue to gate) approximately 1/16" (1.5mm) to reduce pressure drop Cold Slug Wells • Place these wells at the base of the sprue to capture the cold material first emerging from the nozzle

Runners • Full-round runners or a modified trapezoid runner are the best designs. Step each 90° bend in the system down in size (from sprue to gate) approximately 1/16" (1.5mm) to reduce pressure drop Cold Slug Wells • Place these wells at the base of the sprue to capture the cold material first emerging from the nozzle

Runners • Full-round runners or a modified trapezoid runner are the best designs. Step each 90° bend in the system down in size (from sprue to gate) approximately 1/16" (1.5mm) to reduce pressure drop Cold Slug Wells • Place these wells at the base of the sprue to capture the cold material first emerging from the nozzle

Mold Design Recommendations Gates 1. Decrease injection pressure and injection rate Mold Design 1. Increase cooling time Mold Design 1.

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