Flashing

Problems of technology: plasticizing temperature is too high; injection molding time is too long; feeding
       volume is too large; injection molding pressure is too high; mold temperature is too high or there are adulterants
       between two plates.

Problems of mold: distortion of mold; there is error between the size of mold core and that of mold cavity;
       plate asse mbly is not parallel or the air vent is too deep.

Problems of equipment: unparallel plates or the plates can not close tightly.

Problems of raw material: too high flowability.

Distortion

Problems of technology: material temperature is too high; mold temperature is too high; pressure holding
       time is too short; force the mold to release when the cooling time is not enough.
       Problems of mold: gate position is not right; gate number is not enough; the wrong ejection position results in
       unequal stress.

Flow line

Problems of technology conditions: material temperature is too low and hasn’ t fully plasticized;  injection
       molding speed is too slow;  injection pressure is too small;  pressure of pressure holding is not enough;  mold
       temperature is too low; injection molding quantity is insufficient.

Problems of mold: gate is too small; gate number is inadequate;  runner gate is rough or poor glossiness of
       molding surface.

Problems of equipment: system fails after temperature control; pressure of oil pump decreases.

Problems of raw material: too many volatile matters; poor flowability or with adulterants.

Bubbles

Problems of technology conditions:  injection molding pressure is too low; pressure of pressure holding is not                   enough; pressure holding time is inadequate or material temperature is too high.

Problems of mold: poor ventilation; unreasonable gate position or too small gate size.

Problems of raw material:with moisture content and not dry enough; insufficient drying time or shrinking
       percentage is too high.

Sink mark

Problems of technology conditions: fed material is insufficient, injection molding time is too short;  pressure
       holding time is too short; material temperature is too high; mold temperature is too high; cooling time is too short.

Problems of mold: too thin runner, too small gate and poor ventilation.

Problems of equipment: inadequate injection molding pressure or there are adulterants blocking up the nozzle.

Problems of raw material: shrinking percentage is too high.

Unsteady size

Problems of technology conditions:  injection molding pressure is too low;  feed cylinder temperature is too
       high; pressure holding time changes; injection molding period is unsteady or mold temperature is too high.

Problems of mold:Gate size is unequal, mold cavity size is inaccurate; mold core becomes loose; mold
        temperature is too high or there is no waterway.

Problems of raw material:  the trademark and brand changes;  the size of grains differs in size or there are
       volatile matters.

Ejection difficulties

Problems of technology conditions:injection molding pressure is too high;pressure holding time is too long;
       injection molding capacity is too large or mold temperature is too high.

Problems of equipment: ejection power is not enough or ejection stroke is inadequate.

Problems of mold: no draft angel; poor glossiness; wrong way of ejection; quality of fit is not right,  poor
       ventilation; plate distortion.

Splay

Problems of technology conditions:  material temperature is too high; injection molding speed is too fast;
       injection molding pressure is too high; uneven plasticization; too much ejection agent.

Problems of mold: gate is too thin; poor glossiness of mold; poor ventilation.

Problems of equipment: back pressure is too low or there is tape casting matters in the nozzle.

Problems of raw material: with moisture content and is not dry enough; too much lubricant.

Gas mark

Problems of technology conditions: material temperature is too high; injection molding pressure is too high;
       injection molding speed is too fast; dead time is too long; ejection agent is not pure.

Problems of mold: gate is too thin; poor ventilation; complex mold cavity; poor glossiness of mold cavity.

Problems of raw material: There are adulterants in the material or there is powder in the granules.

Discoloration

Problems of technology conditions:material temperature is too high; injection molding pressure is too high;
       molding cycle is too long; the mold has not cooled down; the temperature of nozzle is high.

Problems of mold: gate is too thin.

Problems of equipment:  there is obstruction in the material cylinder or nozzle;  screw rev is too fast;  mold core
       and the center of nozzle is non-concentric.

Problems of raw material: material contamination; dissolution of colouring agent, or high percentage of volatile                 matters.

Welding mark

Problems of technology conditions:injection molding pressure is too high;injection molding time is too short;
       material temperature is too low; mold clamping force is too strong; ejection agent is not suitable.

Problems of mold: mold temperature is too low; runner is too thin; gate position is not right; poor ventilation.

Problems of equipment: poor plasticization.

Problems of raw material: poor flowability; too much lubricant or there are adulterants in the materials.

Gloss defect

Problems of technology conditions: material temperature or mold temperature is relatively low; injection pressure
       is too low; injection molding speed is fast or too slow; cooling time is too short.

Problems of equipment: insufficient material supply;

Problems of raw material: raw material hasn’t been dried or there are volatile matters among them;  raw material
       is easy to degrade ; too much auxiliary agent or ejection agent or because of their poor quality ; there are foreign             materials among them.