Evaluation of Plastic Waste Management in Thailand Using Material ...

2. Injection molding: First, the plastic resin is through the electrical heater by the
screw in the injection unit. The electrical heater makes the resin be melted, and then
the liquid/melted plastic is pressed through the nozzle into mold which is closed.
The mold is cold by cooling water from the chiller. Finally, products will be
adjusted at the end of process before sale. Figure 2.3 shows the injection molding
process.
Figure 2.3 Injection molding (PIT, 2013)
3. Extrusion: The extrusion process consists of six different process for different
products e.g., blow film extrusion, film extrusion, sheet extrusion, pipe/tube
extrusion, profile extrusion, and tape yarn/filament extrusion. The different point of
six extrusion process is the die head depending upon forms of products. For
example, the die head for pipe/tube extrusion is thick and a pipe shape, while the
die head of sheet extrusion is wide, thick and like plate. The extrusion process flow
is shown in Figure 2.4, and Figure 2.5 shows the extrusion process for pipe/tube
production.
Extruder
Die
Head
Adjust Cooling Pull out
Figure 2.4 Extrusion process flow (PIT, 2013)
8
Rolling
Cutting
Storing