Troubleshooting

Your ability to manufacture high-quality parts varies depending on the complexity of your application and the varying sizes of your dies, molds, and other equipment.

The physical properties of your products, their visual aesthetics, dimensional requirements, and material integrity can be compromised when your processing conditions change.

Fortunately, Vydyne resins and Ascend engineers can help you maintain product quality and processing efficiency.

Vydyne nylon 66 (polyamide 66) has proven its versatility and reliability in myriad different manufacturing processes, within a broad range of manufacturing parameters. Based on Vydyne's 30+ year performance history, Vydyne nylon technical specialists have built the Troubleshooting Guide that you see below. It will help you identify any processing problems and suggest possible corrective actions for you to take.

If you don't see the answer to your question in this Troubleshooting Guide, please contact us. We are eager to help.

To display troubleshooting help, first select a problem category and then the type of problem. The system displays possible corrective actions to resolve your problem.

Suggested Corrective Action

Machine

  • Check for cracked machine cylinder.
  • Clean overhead area around hopper.
  • Move mold to machine with smaller cylinder.
  • Properly seat nozzle against bushing.
  • Purge or clean dirty cylinder or nozzle.
  • Reduce screw RPMs to reduce frictional heat
  • Turn on feed throat water.

Material 

  • Correct over drying to improve flow and fill.
  • Dry material if moisture or volatiles are entrapped at weld lines.
  • Material may be setting up too fast.

Mold

  • Change mold slide grease to higher temperature grade.
  • Check for grease or oil in mold.
  • Reduce lube level of knockout pins.
  • Reduce temperature of hot runner block.

Suggested Corrective Action

Machine

  • Decrease booster time.
  • Lower melt temperature settings.
  • Reduce booster pressure.
  • Reduce injection speed.

Material

  • Change grade or material flow.

Mold

  • Center mold core if shifted.
  • Change gate location.
  • Check mold venting - enlarger and or clean.

Suggested Corrective Action

Machine

  • Move mold to machine with smaller cylinder.
  • Reduce material melt temperature.
  • Speed up molding cycle.

Material

  • Reduce level of fines in regrind.
  • Use higher temperature color pigments.

Suggested Corrective Action

Machine

  • Check for proper feed throat cooling.
  • Lower back pressure.
  • Lower material melt temperature.
  • Lower nozzle temperature.
  • Lower rear zone heat.
  • Move mold to machine with smaller cylinder.
  • Purge cylinder.
  • Reduce screw RPMs.
  • Shorten cycle time.
  • Use smaller machine so shot size = 40% to 80% of barrel's polystyrene capacity rating.

Material 

  • Examine material in hopper and freshly opened containers for off-color contamination source.

Mold

  • Check venting.
  • Reduce temperature of hot runner block.

Suggested Corrective Action

Machine

  • Change to shorter nozzle.
  • Check for water source near hopper.
  • Check nozzle for burr or partial blockage.
  • Correct excessive melt decompress.
  • Increase back pressure.
  • Insure that nozzle is properly seated against sprue bushing.
  • Lower nozzle temperature.
  • Lower screw RPMs.
  • Move mold to machine with smaller cylinder.
  • Open gates or increase number or gates.
  • Reduce injection speed.
  • Reduce material melt temperature.

Material 

  • Dry material before use.
  • Install fresh desiccant in material drier.
  • Reduce regrind level.

Mold

  • Check for water leak in mold.
  • Open sprue, runners, gates, or vents.

Suggested Corrective Action

Machine

  • If worse, decrease injection speed or increase gate size or number.
  • Move mold to machine with smaller cylinder.
  • Reduce material melt temperature by lowering barrel settings, reducing screw back pressure, or reducing screw speed.

Material 

  • Check for material contamination, non-uniform regrind, excessive fines.
  • Check part relative viscosity.
  • Check resin moisture content.
  • Decrease amount of regrind.
  • If resin is too dry, reduce drying time or temperature, lower stock temperature or pressures.
  • If resin is too wet, dry material before use.
  • Moisturize parts before shipping or use.
  • Use higher impact grade of material.

Mold

  • Increase radii of fillets and corners.
  • Lower mold temperature.

Suggested Corrective Action

Machine

  • Increase back pressure, increase screw speed.
  • Increase injection speed (rate).
  • Increase material melt temperature.
  • Purge machine cylinder.

Material 

  • Check material for contamination.
  • Dry material before use.

Mold

  • Increase mold temperature

Suggested Corrective Action

Machine

  • Increase back pressure, increase screw speed.
  • Increase injection speed (rate).
  • Increase material melt temperature.
  • Purge machine cylinder.

Material 

  • Check material for contamination.
  • Dry material before use.

Mold

  • Increase mold temperature

Suggested Corrective Action

Machine

  • Increase material melt temperature.
  • Increase booster time.
  • Reduce set point.
  • Check all heater bands and pyrometers.
  • Move mold to machine with larger cylinder.
  • Turn on hopper throat cooling water.
  • Increase injection speed.
  • Repair broken or worn check valve.

Material 

  • Change to material with better or easier flow.

Mold

  • Increase mold temperature.
  • Part design too thin.
  • Improve or change gate location.
  • Increase nozzle or sprue diameter.

Suggested Corrective Action

Machine

  • Change pressure set point.
  • Increase cure time.
  • Increase cushion.
  • Increase injection hold pressure.
  • Increase injection hold time.
  • Increase injection pressure.
  • Reduce material melt temperature.
  • Replace or repair worn or broken check ring.

Material 

  • Change to material with better or easier flow.

Mold

  • Increase gate size.
  • Increase runner or sprue or nozzle diameter.
  • Reduce mold temperature.
  • Relocate gates to thicker sections of part.

Suggested Corrective Action

Machine

  • Decrease injection hold time.
  • Increase cure time.
  • Increase material melt temperature for better packing.
  • Reduce material melt temperature.

Material 

  • Switch to mineral reinforced material.
  • Switch to nucleated material to reduce shrinkage.

Mold

  • Balance temperature on both
  • Check for uniformity of ejection.
  • Increase runner, sprue, or nozzle diameter.
  • Relocate gating.

Suggested Corrective Action

Machine

  • Increase injection pressure.
  • Increase injection speed.
  • Increase material melt temperature.

Material 

  • Check moisture content of material.
  • Material may be recrystallizing too fast.

Mold

  • Change gate location to change material flow pattern.
  • Check for core shifting causing unbalanced wall thickness.
  • Improve venting in weld area.
  • Increase mold temperature.
  • Increase part wall thickness.
  • Provide an overflow well next to weld area.

Suggested Corrective Action

Machine

  • Change cut-over point.
  • Decrease cycle time.
  • Increase clamp tonnage.
  • Lower material melt temperature.
  • Move mold to larger machine.
  • Reduce feed setting or cushion.
  • Reduce injection boost pressure.
  • Reduce injection hold pressure.
  • Reduce injection hold time.
  • Reduce material feed setting.

Material 

  • Check for high moisture content.
  • Switch to material with stiffer flow.

Mold

  • Align or adjust mold.
  • Check mold closure.
  • Examine mold for contamination on mating surfaces.
  • Improve mold venting.
  • Reduce mold temperature.

Suggested Corrective Action

Machine

  • Increase screw decompression.
  • Reduce back pressure.
  • Reduce material melt temperature.
  • Reduce nozzle temperature.
  • Reduce screw RPMs.
  • Switch to smaller orifice diameter nozzle.
  • Use reverse taper nozzle.

Material 

  • Check level of regrind. Dry material.

Suggested Corrective Action

Machine

  • Check for burned out heater band.
  • Check heater band wattage density.
  • Decrease cycle time.
  • Increase mold temperature.
  • Increase nozzle temperature.
  • Move heater bands forward on nozzle.
  • Use nozzle with larger orifice.
  • Use reverse taper nozzle.

Suggested Corrective Action

Machine

  • Check for bridging at feed throat in hopper.
  • Check for broken or worn check valve.
  • Check for worn screw or barrel.
  • Reduce rear zone temperature on barrel.

Material 

  • Check for excessive fines or lubricants.
  • Check moisture content of material.
  • Check pellet cut and bulk density of material.

Suggested Corrective Action

Machine

  • Decrease injection boost time.
  • Decrease injection hold time.
  • Decrease injection pressure.
  • Decrease material melt temperature.
  • Increase cure time.

Material 

  • Increase lubricant level.
  • Reduce regrind level.

Mold

  • Check for adequate draft angles.
  • Check for undercuts.
  • Increase mold temperature.

Suggested Corrective Action

Machine

  • Decrease injection booster time.
  • Decrease injection hold time.
  • Decrease injection pressure.
  • Increase cure time.
  • Increase nozzle heat.

Material 

  • Increase lubricant level.
  • Reduce regrind level.

Mold

  • Align seating of nozzle to sprue bushing.
  • Ensure that orifice of nozzle is smaller that orifice of sprue bushing.
  • Increase taper of sprue bushing.
  • Inspect sprue for burrs, undercuts, or nicks.
  • Provide more adequate sprue puller.
  • Reduce stationary mold temperature.