Common problems and solutions.
Problems Reasons Solutions
Not feeding Screw crack Change the screw
Plastic block in the feeding hole Get rid of the block
Temperature too high in feeding part Reset the feeding part temperature to assure
the waterway to go fluently
The material pieces too big
Change the feeding hole design, make the feeding part groove deeper.
Products have black dots or turn yellow Screw and barrel wear out
As to wear situation, change the screw or
Screw set have dead angles Change the screw or tip set
Material carbonized
Use the screw material which has better anti corrosion
Nozzle orifice too small Drill to be bigger
Screw compression ratio too big Change the right screw
Screw temperature too high Change the design to decrease the shear heat
Bad plasticizing Plastic not melt enough Increase the barrel temperature
Bad color mixing
Bad screw color mixing effect
Use mixing design screw or mixing tip set or mixing nozzle.
Injection end not steady Check ring move gap too big Change small move gap check ring
Check ring and seat ring not match well Change new rings.
Gap between check ring ang barrel too bigh Change the relative wear parts.
Leak between barrel and barrel head Barrel and barrel head not bond well Check the match between them
Barrel head surface not flat enough Check the surface.
Tensile Strength of screw and barrel is not enough Chang material 
Products have bubbles Back pressure too low, compression ratio too small Change the size or design.
Injection speed too slow, screw not good in venting  
Screws has abnormal noise Barrel has not installed well Check every size ; reset; take out the
impurities; bad liquidity raw 

Material should use good ejiction effect tip set
Screw barrel assemble size problem
Screw not straight enough
Screw ejection design not fluent
Barrel has impurities inside