Defect 1. Lack of materials
A. Defect reason:
The small parts and corners of the finished product cannot be completely formed, due to the improper processing of the mold or the poor exhaust, and the design defect (insufficient wall thickness) due to insufficient injection dose or pressure in the molding.
B. Mold improvement measures:
Correct the mold where the material is missing, take or improve the exhaust measures, increase the material thickness, and improve the gate (enlarge the gate, increase the gate).
C. Molding improvement:
Increase the injection dose, increase the injection pressure, etc.
Defect 2. Shrinkage
A. Defect reason:
It often occurs in the uneven wall thickness or material thickness of the molded product, which is caused by different cooling or solidification shrinkage of the hot melt plastic, such as the back of ribs, edges with side walls, and the back of BOSS columns.
B. Mold improvement measures:
Reduce the material thickness, but keep at least 2/3 of the material thickness; thicken the runner and increase the gate; add exhaust.
C. Molding improvement:
Increase the material temperature, increase the injection pressure, prolong the pressure holding time, etc.
Defect 3: Air pattern
A. Defect reason:
Occurs at the gate, mostly because the mold temperature is not high, the injection speed and pressure are too high, the gate is not set properly, and the plastic encounters the turbulent structure when pouring
B. Mold improvement measures:
Change the sprue, polish the runner, enlarge the cold material area of the runner, enlarge the sprue, and add texture to the surface (you can also adjust the machine or repair the mold to catch the joint line).
C. Molding improvement:
Increase mold temperature, decrease injection speed, decrease injection pressure, etc.
Defect 4. Deformation
A. Defect reason:
The slender parts, thin-walled parts with large area, or large finished products with asymmetric structure are caused by uneven cooling stress or different ejection force during molding.
B. Mold improvement measures:
Correct the thimble; set the tensioning pin, etc.; if necessary, add the male mold to adjust the deformation.
C. Molding improvement:
Adjust the mold temperature of the male and female molds to reduce the pressure holding, etc. (The adjustment of the deformation of small parts mainly depends on the pressure and time, and the adjustment of the deformation of large parts generally depends on the mold temperature)
Defect 5. The surface is unclean
A. Defect reason:
The surface of the mold is rough. For PC material, sometimes due to the high mold temperature, there are glue residues and oil stains on the mold surface.
B. Mold improvement measures:
Clean the die surface and polish it.
C. Molding improvement:
Lower the mold temperature, etc.
Defect 6. Stomata
A. Defect reason:
Transparent finished PC material is easy to appear when molding, because the gas is not exhausted during the injection molding process, improper mold design or improper molding conditions will have an impact.
B. Mold improvement measures:
Increase the exhaust, change the gate (increase the gate), and the PC material runner must be polished.
C. Molding improvement:
Strict drying conditions, increase injection pressure, reduce injection speed, etc.
Defect 7. Out of dimensions tolerences
A. Defect reason:
Problems with the mold itself, or improper molding conditions cause the molding shrinkage to be inappropriate.
B. Mold improvement measures:
Correct the mold, such as adding glue, reducing glue, or even reopening the mold in extreme cases (inappropriate shrinkage rate causes excessive dimensional deviation).
C. Molding improvement:
Usually, changing the holding time and injection pressure (second stage) has the greatest impact on the size. For example, increasing the injection pressure and increasing the pressure holding and feeding effect can significantly increase the size, or reduce the mold temperature, increase the gate or increase The gate can improve the regulation effect.
Post time: Oct-20-2022
