LAUNCH MACHINERY WORKS CO.,LTD


	PRODUCTS ON SOLUTIONS TO MOULDING TROUBLE

The molding plastic product in principle is produced in accordance with standard specification. Some time, the operation conditions may be varied or minor adjustment can be made to operation condition, mold design or molding machine and filtration of the raw material in use, such problem can be solved by molding adjustment condition.

Attention to molding adjustment condition:

Each adjustment must be wait until the result before next alteration.
After adjustment must be pay attention some time until operation stability. Usually pressure alteration condition can be know in one or two shot molding operation but temperature alteration must pay attention about ten minutes for stable result.
This chapter will list the possible problems to final product item by item and applied with solution methods.

1. Shrinkage/Sink Mark	5. Air Bubble Inside Product	9. Black Streak	coming soon
2. Product Warpage	6. Flashing	10. Silver Streak or Air Bubble	coming soon
3. Coarse or Hazy Surface	7. Sprue Stick to Mold	11. Flow Mark	coming soon
4. Black Mark	8. Product Stick to Mold	coming soon	coming soon

Phenomenon	Cause	Solution
Shrinkage/Sink Mark	Product shot weight not enough Sprue no balance Screw metering not enough Injection pressure too low Injection speed too low Nozzle Head Stuck Injection Time too short Holding Pressure not enough Cooling time not enough Mold temperature unable Barrel temperature too high Machine or Barrel size too big Holding position adjust unable Product thickness is uneven Screw prevention ring damaged	- Adjustment sprue dimension or position Increase screw metering Increase injection pressure Increase injection speed Take out to clean Increase injection time Increase holding pressure Increase cooling time Adjust mold temperature Decrease Barrel temperature Change machine or Barrel size Injection end position must be in the front Checking product or modify Take out to repair
Product Warpage	Cooling time not enough when ejector Material temperature too low Product size or thickness unable Material feeding too much Sprue design not balance Ejector rods eject not balance Mold temperature unable Near sprue area material density not steady	Decrease mold temperature, increase cooling time and decrease material temperature Increase material and mold temperature Modify product design or use jam and fixture for final product Decrease injection pressure, speed, time, and shot weigh Modify sprue design Modify ejector system Adjust mold temperature Increase or decrease injection time
Coarse or Hazy Surface	Mold inside have water Mold release oil too much Mold temperature too low Mold surface no smooth Material shot weight not enough	Clean up and checking Clean up mold surface Increase mold temperature Refine mold surface Increase injection pressure, speed or time
Black Mark	Material overheat, temperature too high Machine or barrel size too big Nozzle head hole too small or temperature too high Barrel & screw cause friction Screw rotation speed too fast Barrel inside design have undercut	Decrease barrel temperature Change machine or barrel size Adjust temperature or nozzle head hole Repair barrel & screw Decrease screw rotation speed Checking barrel & screw surface if cracking or erosion
Air Bubble Inside Product	Injection shot short that causes over shrinkage Injection pressure too low Injection shot weight not enough Sprue and runner gate too small Product thickness in uneven Material no drying or moist Mold temperature unable Back pressure too low Cooling time too long Barrel temperature not enough Mold water cooling too fast Injection speed too high Material temperature too high	- Increase injection pressure Increase injection weight Modify sprue or runner gate to big Modify sprue or runner gate design Fully drying material Increase mold temperature Increase back pressure Decrease cooling time to make the water cold down Decrease Barrel nozzle first, second zone temperature and increase third zone temperature Decrease mold water cooling time or increase mold water temperature Slow down injection speed Decrease material temperature
Flashing	Material over pack Material temperature too high Mold close no tight Injection pressure too high	Decrease injection time, speed and shot weight Decrease material or mold temperature Repair mold Decrease injection pressure
Sprue Stick to Mold	Sprue cooling not enough Sprue too big Sprue ejector angle not enough Sprue outside hold is damaged Sprue surface coarse or under-cut Sprue and nozzle no centralize Sprue no hold pin Material over pack Material temperature too high Injection pressure too high	Delay cooling time or decrease cooling temperature Modify mold design Modify mold angle design Modify mold design Modify mold design Re-adjust to fix Install hold pin Decrease injection time, speed, and shot weight Decrease material temperature Decrease injection pressure
Product Stick to Mold	Material over pack Injection time too long Injection speed too fast Injection Pressure too high Material temperature too high Material shot weight too much Material feeding no balance Mold temperature too high or too low Mold surface is hazy Mold ejector design has under-cut Ejecting cause vacuum condition	- Decrease injection time Decrease injection speed Reduce barrel pressure Reduce barrel temperature Decrease injection shot weight Modify sprue design Adjust mold temperature to suitable condition Refine mold surface Modify mold design Slow down mold open or ejector speed or modify mold
Black Streak	Material is dirty Material overhead and stick to barrel surface Barrel have undercut to make material overheat Injection to mold and burn mark	Check or change material and purge out Take output barrel to clean, reduce material temperature and decrease heating time and fully purge out material Check nozzle and barrel surface if cracking or erosion Reduce injection pressure and time, reduce material temperature and modify sprue position and enlarge mold air vent hold
Silver Streak or Air Bubble	Material mixed with lubrication oil or pigment and difficult to dissolved Material addendum mixed unsuitable Injection speed too fast Material not dry or moist Material temperature too high	Reduce volume or replacement to high temperature grade Material addendum completely mixed Decrease injection speed Full dry the material or increase high pressure Reduce material temperature or change to small size barrel and machine
Flow Mark	Mold temperature too low Sprue too small Injection speed too high or low Injection speed too fast or slow Product thin wall not balanced Material melting incomplete Material dirty or mixed with something evidence	Increase mold temperature Enlarge sprue design Adjustment suitable injection pressure Adjustment suitable injection speed Modify product design or sprue position Increase material temperature and back pressure Check or change the material

More Information Coming Soon