Frequent Questions

DEFECTS THAT ARE PRESENTED IN THE PROCESS OF TRANSFORMATION

(Click on each option to see more information)

Extracting the mold piece difficulty

POSSIBLE CAUSE SUGGESTED SOLUTION
– Pieces too cold. Verify mold temperature.
– Excessive packing of the material. Reduce packing pressure.
– Defects in the mold (finish, design).
 Possible surface coating to the mold.
Rectify the surface of the mold.
Change mold ultimately.
– Inappropriate material. Switch to one with less fluency.

Poor surface finish in the piece

POSSIBLE CAUSE SUGGESTED SOLUTION
– Resin enters the mold cold.
 Verify temperature profile for the material.
Check nozzle temperature.
Check mold temperature.
– Filling the mold very slowly. Increase temperature profile for the material.
Increase nozzle temperature.
Increase mold temperature.
Increase injection pressure.
– Defects in the mold (finish, design).
 Possible surface coating to the mold.
Rectify the surface of the mold.
Verify that the configuration of the corridors and entrances is ideal for the piece.

Poor color in the piece

POSSIBLE CUASE SUGGESTED SOLUTION
– Inappropriate coloring. Change the type of dye or concentration.
– Bad distribution in the premix. Increase back pressure in material recharge.
– Improper screw.
 See the possibility of changing the screw configuration.
Screw replacement.

Internal bubbles in the piece

POSSIBLE CUASE
 SGGESTED SOLUTION
-Insufficient plastic in the mold to prevent a contraction produced by edges, nerves. Increase food.
Increase the size of the entry.
Increase injection pressure.
-Moisture in the material. Proper drying of the material before processing.
Check the peripheral drying and transport equipment to the feed hopper.
-Uneven temperature in the mold. Check the feed channels for cooling the mold, which are not obstructed.

Rupture or piece with cracks

POSSIBLE CAUSE SUGGESTED SOLUTION
-Cold mold Raise the mold temperature.
– Improper design or mold prints.
 Possible surface coating to the mold.
Rectify the surface of the mold.
Change mold ultimately.
– Excessive packing of the material. Check packing pressure.

Burr or flash

POSSIBLE CAUSE SUGGESTED SOLUTION
-Excessive feeding. Reduce feeding.
– Injection pressure too high compared to clamping force. Decrease pressure.
– Overheated material.
 Check the temperature profile of the material.
Decrease mold temperature.
– Mold out of adjustment. Verify mold calibration for closing.
– Low closing force.
 Increase closing pressure.
Check if the machine is adequate for the pressure required by the part to be injected.
– Very large vents and clearings in the mold. Review designs.

Flow lines

POSSIBLE CAUSE
 SUGGESTED SOLUTION
– Very cold mold. Raise the mold temperature.
Check the feed channels for cooling the mold, which are not obstrected.
– Low injection pressure. Increase injection pressure.
– Clogged channels. Channel Cleaning
Check if the design is appropriate.
– Inappropriate entrance or nozzle very narrow.
 Rectify the nozzle.
Change the nozzle.
Decrease injection speed.
– Bad dispersion of the color concentrate or pigment. Load the material more slowly.
– Insufficient dosage. Increase the dosage.
– Temperature too low. Increase the temperature of the barrel.
Modify the temperature profile.

Incomplete parts

POSSIBLE CAUSE
 SUGGESTED SOLUTION
– Insufficient material load in the cavity. Inject more material.
Increase injection pressure.
– Lack of material in the hopper. Inject more material.
– Non-uniform temperatures in the mold. Check and clean mold cooling system.
– Temperature too low. Increase the barrel temperature.
– Poor mold design. Correction of tickets and corridors.
Change of mold.
– Vent system in the clogged mold. Cleaning of the venting systems.
– Cannon too small. Change the mold to a machine of greater capacity.
– Obstruction of the hopper or nozzle. Clean and release of glued material.
– Valve plugged.
– Holding time too short. Increase injection speed.
– Injection speed too low.
– Channels too small. Modify the size of the mold channels.
– Insufficient breathing.

Welding lines

POSSIBLE CAUSE
 SUGGESTED SOLUTION
– Plastic too cold.
 Increase mold and barrel temperature.
Increase injection pressure.
– Variation in the thickness of the pieces.
 Redesign of the piece.
Redesign of the material input to the piece.
– Mold too cold. Increase mold temperature.
– Insufficient pressure Increase injection pressure.
– Low injection speed. Increase injection speed.
– Inadequate venting systems. Cleaning of the venting systems.
Redesign of the venting systems.

Warping, buckling, crooked

POSSIBLE CAUSE SUGGESTED SOLUTION
– Inappropriate material. Change to a more fluid material.
– Poor mold design.
 Change the place of entry.
Improve the polishing of the mold.
– Inadequate processing temperatures. Increase resin temperature.
Increase the cooling time.

There is no load of material

POSSIBLE CAUSE SUGGESTED SOLUTION
– Clogged hopper throat. Clean the hopper throat.
– Inadequate temperature profile. Verify that the temperature profile is adequate.
– Worn screw. Screw change.

Plug and vacuum

POSIBLE CAUSA SOLUCIÓN SUGERIDA
Contractions and slits by rapid injection. Attention in mold design.
Reduce melting temperature.
Reduce cavity wall temperature.
Increase screw forward speed.
Increase containment pressure.
Increase containment pressure time.
Increase injection volume.
Avoid the use of mold release agents whenever possible.
Injection pressure too low. Increase the pressure.
Pressure holding time too short. Increase pressure holding time.
Low injection speed. Increase injection speed.
Overheated material. Decrease the barrel temperature.
Humidity Open the vent or pre-pack the material.
Non-uniform mold cooling. Modify mold cooling channels or water flow.
Channels or gate very small. Modify the mold.
Bad design of the piece.

Sunken and hollow marks

POSSIBLE CAUSE SUGGESTED SOLUTION
Thick sections of peace. Make the design with thinner sections.
But the contraction of the internal material causes the scab to depress below the nominal surface. Decrease the compaction pressure.

Matt zone near the casting point

POSSIBLE CAUSE SUGGESTED SOLUTION
High efforts Increase static friction, greater by force. Shear.

Stretch marks (burned stretch marks, oxidation stretch marks, streaks in the material)

POSSIBLE CAUSE SUGGESTED SOLUTION
Burns, moisture and air. Lower temperature too high and / or residence times too long.
Moisture Tarnished mold, rolled, lower long areas.
Air, bubbles Increase injection speed, dry material before process, raise temp. Mold.

Bursts

POSSIBLE CAUSE SUGGESTED SOLUTION
Appears behind narrow sections. Lower the dough temperature (it is near the upper limit of the process).
(shear points) or living edges of the mold. Decrease the spindle feed rate a reduction is obtained.
Cycle interruption or low volume Design supply.
Recicle Download content.
Hot wash mode
Valve nozzle
High shear Lower spindle speed, short stay in equipment.

Bow-legged

POSSIBLE CAUSE
SUGGESTED SOLUTION
Cooling too intensive. Increase the cooling time inside the mold.
Improper design of the piece.
Cooling time too short.
Inappropriate Extraction System
Efforts in the material. Use a reinforced polymer.

Black spots

POSSIBLE CAUSE SUGGESTED SOLUTION
There are carbonizations. Bleed the spindle.
Reduce the process temperature.
Clean the spindle manually.

Orange peel

POSSIBLE CAUSE SUGESTED SOLUTION
Incompatibility of the material. Decrease the process temperature.
Increase mold temperature.
Change the color concentrate.

Incomplete part

POSSIBLE CAUSE
SUGGESTED SOLUTION
Insufficient material in the cavity. Inject more material.
Lack of material in the hopper.
Cannon too small. Change the mold to a machine of greater capacity.
Temperature too low. Increase the barrel temperature
Obstruction of the hopper or nozzle. Clean and release of glued material.
Valve plugged.
Holding time too short. Increase injection speed.
Injection speed too low.
Channels too small. Modify the size of the mold channels.
Insufficient breathing.

Burr part

POSSIBLE CAUSE SUGGESTED SOLUTION
Excessive dosage. Dose less material.
Injection temperature too high. Decrease the injection temperature.
Injection pressure too high. Decrease injection pressure.
Very long injection time. Decrease injection time.
Very high mold temperature. Decrease mold temperature.

Joining lines

POSSIBLE CAUSE SUGGESTED SOLUTION
General temperature very low in the mold. Increase the temperature.
Fade temperature not uniform. Unify temperature in dice.
Injection pressure too low. Increase the pressure.
Injection speed too low. Increase injection speed.
Insufficient breathing in the junction zone of the found flows. Modify the respiration of the material in the mold.
Not uniform filling speed. Increase injection speed.
Unsuitable flow of material through channels or cavity. Modify the gate to standardize the flow.

Degradation by trapped air

POSSIBLE CAUSE SUGGESTED SOLUTION
Humidity/ moisture Dry the material.
Degradation of additives. Decrease the temperature.
Temperature too high
Insufficient mold respiration. Modify mold breathing.

Delamination of layers

POSSIBLE CAUSE SUGGESTED SOLUTION
Temperature too low. Increase the temperature.
Injection speed too low. Increase injection speed.
Low back pressure of the machine. Increase machine back pressure.
Mold temperature too low. Increase mold temperature.

Fractures or cracks on the surface

POSSIBLE CAUSE SUGGESTED SOLUTION
Mold temperature too low. Increase the temperature
Ejection system too aggressive or inappropriate. Modify ejector bars.
Use a robot to remove the piece
Excessive packing. Decrease the holding pressure.

Ejector bar marks

POSSIBLE CAUSE SUGGESTED
Cooling time too short. Increase the cooling time.
High mold temperature. Decrease the melt temperature.
Polymer temperature too high.
Inadequate location of ejector bars. Modify the location of ejector bars.
Ejection speed too high. Decrease ejection speed.

Burned the piece

POSSIBLE CAUSE SUGGESTED SOLUTION
Burned by jet effect. Decrease injection speed.

The color concentrate does not mix

POSSIBLE CAUSE
 SUGGESTED SOLUTION
Incorrect temperature profile. Test an inverse temperature profile.
Lower the temperature of the first two areas of the injection unit.
Use a more aggressive temperature profile.

The color is darker

POSIBLE CAUSE SUGGESTED SOLUTION
The temperature is too high. Decrease the temperature.
The gate is too small and the polymer burns under pressure. Modify the mold gate.

Bad wall thickness distribution (top down)

POSSIBLE CAUSE SUGGESTED SOLUTION
Comparison narrowing down. Use of comparison programmin.
Increase extrusion speed comparison.
Lower temp. Stock
Use material with less MI

Asymmetric Part

POSSIBLE CAUSE SUGGESTED SOLUTION
Comparison twisted falls. Stretch the comparison drop Pre pinch and comparison punch pre.
The symmetric is not part. Use the die setting to increase the thickness of the thin surface.

Poor welding

POSSIBLE CAUSE SUGGESTED SOLUTION
moisture mushrooms Reduce mold as much as possible
Incorrect closing speed Increase or decrease the speed of closing of the final mold (deceleration).
Increase cushion gap for the start of the deceleration.
Blown air body Determine the pizaca depth of the bag suitable for the weight of the part.

Poor in line of separation

POSSIBLE CAUSE
 SUGGESTED SOLUTION
Low blowing pressure Increase air pressure
Remove excess restrictions on air lines, disconnect dividing lines of vents.
Disconnect dividing line of vents.
Low rate air stroke Increase air pressure.
Remove excess restrictions on air lines.
Disconnect dividing line of vents.
Cause more ventilation.
Trapped air Cause more ventilation.

Hitch

POSSIBLE CAUSE SUGGESTED SOLUTION
Thickness imbalance Adjust bushings
Uneven temperature check heaters in head area
Dirty head clean head

Explosions / holes

POSSIBLE CAUSE SUGGESTED SOLUTION
Nozzle Pollution Purge