| Trouble Shooting for Product Defects |
| Reason | solution |
| yellow dot | Barrel temperature is too high | reduce temperature |
| The plastic stay time is too long in barrel | Shorten the injection cycle time. |
| Some zone of barrel temperature is too high | reduce temperature |
| There have die corner in barrel | Repair or change |
| black line | check ring is worn | change |
| Decompresstion distance is too long, there have air in material | Reduce distance |
| venting is not smooth in mould | add venting groove |
| The screw or check ring is dirty | Clean barrel, screw and check ring |
| small black dot | Plastic is burned in barrel | （A）clean the barrel |
| （B）feed harder plastic to clean the barrel inner surface. |
| （C）avoid the plastic stay over time under high temperature heating. |
| brown stripe | Barrel temperature is overheating. | （A）reduce barrel temperature. |
| （B）reduce the screw speed |
| （C）reduce the plasticized back pressure |
| （D）clean nozzle or barrel |
| big black dot | There have dirty dust in material | （A）close the hooper. |
| There have Air in the mould cause plastic burn | （A）improve mould exhausting |
| （B）redesign mould and plastic part |
| （C）redesign the gate location. |
| （D）decrease the injection pressure or speed. |
| （E）change barrel or mould temperature to change the plastic flow in the mould. |
| black stripe | There have too much friction between material and barrel | （A）add plastic with lubricant |
| （B）increase barrel rear part temperature. |
| There is decentraction between barrel and screw | （A）adjust the screw position again, make sure there is enough distance between the screw and barrel, and the air can exhaust from the barrel successfully. |
| nozzle overheating, plastic burn | Decrease injection nozzle temperature. |
