https://www.avient.com/sites/default/files/2020-12/therma-tech-processing-guide.pdf
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.
https://www.avient.com/sites/default/files/2022-06/Maxxam FR Injection Molding Processing Guide.pdf
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.
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.
https://www.avient.com/sites/default/files/2020-09/stat-tech-tri-fold-processing-guide.pdf
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
https://www.avient.com/sites/default/files/2020-09/lubrione-processing-guide.pdf
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
https://www.avient.com/sites/default/files/2020-09/edgetek-processing-guide.pdf
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
https://www.avient.com/products/thermoplastic-elastomers/tpe-knowledge-center/overmolding-guide/overmolding-mold-design
Injection Molding Guide
Injection Molding: Part Design
Injection Molding: Mold Design
https://www.avient.com/products/thermoplastic-elastomers/tpe-knowledge-center/overmolding-guide/overmolding-part-design
Injection Molding Guide
Injection Molding: Part Design
Injection Molding: Mold Design
https://www.avient.com/sites/default/files/2020-10/2020-gravi-tech-processing-guide.pdf
Mold Design Recommendations
Gates
1.
Decrease injection rate
Mold Design
1.
Decrease injection pressure and
injection rate
Mold Design 1.
https://www.avient.com/sites/default/files/2022-06/Nymax BIO Bio-based Polyamide Solutions Processing Guide.pdf
Place cold slug wells at the base of the sprue to capture the cold material first
emerging from the nozzle.
2.
Reduce decompression
Mold design
1.
Increase cool time
Mold design 1.
https://www.avient.com/idea/optimizing-automotive-structural-component-designs-advanced-modeling
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