1. Plastic characteristics and shutdown precautions
Various plastic raw materials have different characteristics. When the machine is shut down, the characteristics of the rubber compound must be considered to save time and avoid plastic deterioration.
Methods of plastic varieties for plastic characteristics:
PS is a hard rubber, with good thermal stability, and will not decompose when heated for a long time at the molding temperature, so the shutdown only needs to turn off the electric heating
ABS is a hard glue with good thermal stability. It will not decompose when heated for a long time at the molding temperature, so it is only necessary to turn off the electric heating when the machine is shut down.
PE and PP are soft glues, and have good thermal stability. They will not decompose when heated for a long time at the molding temperature, so the shutdown only needs to turn off the electric heating.
Due to the temporary suspension of PC production (such as the night shift is not started), the barrel must be kept at about 160 ° C to prevent the rubber from getting wet. If you want to change the material, you need to clean the barrel with PE, remove the screw and clean the screw with a copper brush.
For PVC heat-sensitive materials, turn off the electric heating before shutting down, and then push out the PVC until the barrel temperature drops to 150 ° C. Finally, use PP, PE and other thermally stable plastics to push out the plastic in the barrel.
PMMA is easy to decompose at higher temperature, but the thermal stability is good at normal molding temperature, so it is only necessary to turn off the electric heating during shutdown.
Nylon PA plastic has good thermal stability. It is not allowed to clean the barrel before shutdown, but the power must be turned off immediately, otherwise the plastic will deteriorate after 15 minutes.
POM is a heat-sensitive plastic. When the machine is stopped, the pressure is reduced 10 minutes before the electric heating is turned off, and then the plastic in the barrel is continuously pushed out. When the material is changed, it is first cleaned with soft glue.
2. The color change of the same material
When changing the color of the same material, try to change from a light color to a thick color material, and change from a transparent material to an opaque material.
When changing from dark color to light color, and from opaque to transparent material, if the color is still not clean after ten times of air shooting, remove the nozzle and cylinder head for cleaning.
3. The replacement of different materials
Thermoplastics will adhere to the metal surface at high temperatures, but will not adhere at low temperatures. This feature is used in the refueling action to make the material to be replaced adhere to the inner wall of the barrel for the replacement of dissimilar materials cut by the high viscosity material of the cold screw .
4. Change the plastic and color at the same time
In this case, a plastic with similar characteristics should be selected and used together with a cleaning agent. Common cleaning agents are: screw cleaning agents, kerosene, etc.
If the barrel is not cleaned in this case, remove the nozzle, clean the cylinder head, and remove the screw if necessary.