Silver pattern of injection moulded products, including […]
Silver pattern of injection moulded products, including surface bubbles and internal pores. The main cause of defects is the interference of gases (mainly water vapor, decomposition gas, solvent gas, air). The specific reasons are as follows:
(1) The barrel, the screw wears or the rubber head and the apron have a dead angle of the material, which is decomposed by heat for a long time.
(2) If the heating system is out of control, causing the temperature to be too high and decomposed, check whether there are any problems with the heating elements such as thermocouples and heating coils. The screw is not designed properly, causing a solution or easy to bring in air.
2. Mould aspect:
(1) Poor exhaust.
(2) The frictional resistance of the runners, gates and cavities in the mould is large, causing local overheating and decomposition.
(3) Unbalanced distribution of gates and cavities, and unreasonable cooling system will cause heat imbalance and local overheating or obstruction of air passages.
(4) The cooling passage leaks into the cavity.
(1) The plastic has a large humidity, and the proportion of the added recycled materials is too large or contains harmful scraps (the scraps are easily decomposed), and the plastic should be sufficiently dried and the scraps should be eliminated.
(2) Moisture absorption from the atmosphere or moisture absorption from the colorant, and the coloring agent should also be dried. It is preferable to install a dryer on the machine.
(3) The amount of lubricant, stabilizer, etc. added to the plastic is excessive or unevenly mixed, or the plastic itself has a volatile solvent. Decomposition occurs when the mixed plastic is difficult to maintain heat.
(4) The plastic is contaminated and mixed with other plastics.