The Classification of Plastic Industry
Last updated: 27 Aug 2020 | 12931 Views |
Plastic products mainly compose of various kinds of plastic beads depending on customers’ demands. Some factories modify their material by adding color or other chemicals, combining them together before the fusion as a part of preparation before the forming processes such as injection, extrusion, blow, and etc.
After having gone through forming process, the plastic products will constantly set when the temperature cools down. Freeze casting and the decoration follow for finish work.
Thai plastic industry classifies plastic forming industry by considering the processes and types of plastic products as the following table.
| No. | Production Type | Product Type | Material |
| 1 | Blow Molding | Lubricant container/ Shampoo container | PP, PE, PET, HDPE |
| 2 | Stretch Blow Molding | PET bottle | PET, PP, HDPE |
| 3 | Injection Molding | Automobile parts, Electronic components, Household appliances, Electrical appliances, Shelves | Thermoplastics (PP, PE, HDPE, ABS, PS, PC) |
| 4 | Blown Film Extrusion | Plastic bag | HDPE, LDPE, LLDPE |
| 5 | Film Extrusion | Thin film (Packing film, Sticky tape, and etc.) | PP, PE, LDPE, HDPE |
| 6 | Sheet Extrusion | Plastic sheet, Plastic folder, and etc. | PP, PE, PS, PMMA |
| 7 | Pipe/Tube Extrusion | Aqua duct, Drain, PVC/ PE pipe, and etc. | PVC, PE, PP |
| 8 | Profile Extrusion | Down spout, Window sill, Raceway, Jamb, and etc. | PVC Rigid, HDPE |
| 9 | Rotational Molding | Large water tank, Bin, Box, and etc. | PVC, PP, HDPE |
| 10 | Thermoforming | Food tray, Water cup, and etc. | PS, PE, PP ,PET |
| 11 | Laminating | Food bag, Multilayer packaging bag, and etc. | PE, PP |
| 12 | Tape Yarn/ Filament | Plastic sack, Fertilizer sack, Jumbo bag, and etc. | PP, HDPE, PA6, PA66, PET |
| 13 | Compressed Molding | Mug, Plate, Bowl, Spoon, Melanin houseware | Melamine |
| 14 | Others (Calendering, etc.) | Other plastic products | Etc. |
Blow molding is used to blow plastic bottle. Starting form choosing main material which is plastic beads such as HDPE, PP, PE, then fuse them in extruder heated by electrical heater. Next, screw will compress the liquid plastic according to the principle of movement along with molding machine run on hydraulics system. The plastic beads will go through die head to form parison. Then, molding machine will blow, compressing air to fit the plastic in mold. When it fits the mold, the chiller will release cool water to freeze the plastic so that it remains in controlled shape. The products from blow molding are lubricant container, oil gallon, shampoo container, and etc.
Stretch Blow Molding is used to produce containers as well. This method aims to stabilize the plastic containers by ensuring density standard. It is cheaper and results in seamless containers. The products’ quality is higher than that of blow molding. Stretch bold molding can be divided into two steps which are creating the pre-form by injection and taking it into stretch blow process to form the shape.
Injection Molding. Starting from putting the plastic material either in bead form or powder in the same cylindrical tube, then the socket screw will transfer them to the front of cylindrical which contains electrical heater inside to fuse the plastic. The socket screw will push the plastic into old in which the chiller will release cool water to freeze the product in shape. After that, the product can be easily detached from the old for further step of decoration. Products from injection molding are various such as electrical components, automobile parts, electrical appliance, houseware, toys, and etc.
Rotational Molding. This method is suitable for producing large hollow products. It will result in products with neat surface, time-saving, and even density. The principle of its function are;
- 1. Loading: Most of the material is Thermoplastic in liquid or powder form. The plastic will be put into hollow old before the mold is closed.
- 2. Molding or curing: The old will be moved to hearted room before being rotated in 2 axis rotation along with being heated so that it will melt and fir evenly in the mold by gravity force, not centrifugal force.
- 3. Cooling: Next, the mold will be moved to cool room. This can be done by splashing cool air or water to the mold which, all along, still continue rotating. This process can reduce the shrink of product during the cooling process.
- 4. Unloading when the product is frozen and stable, it can be removed from the mold.
note: Tape Yarn is integrating production which means that the tape is extrusion, and there are further steps before it becomes plastic sack.
Thermoforming and Luminating is the process that follows sheet/film extrusion which means the material that will be produced into finish product needs secondary processs.
- Thermoforming functions by heating film or plastic sheets until they reach certain point where they are soft, then pressing them into mold. Vacuum forming and blow forming are commonly used. The cooling process needs to follow so that the film or plastic stays in old shape. The products from Thermoforming: food containers, food tray, pickup truck top, water cup, and etc.
- Laminating is the process in which the material will be coated with plastic. It can be done using different kinds of material, whether with
powder, electrostatic, heat, and etc. The principle is coating the material with liquid plastic. The principle is coating the material with liquid plastic. The thickness depends on preferences. The material that can be coated, for example, paper, cloth, or even the same plastic. This process makes the product more durable, resistant to water and humidity, and less sensitive to scratch.
