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I.WHAT DOES THE DRYRING THE PLASTIC MEAN ,WHY DO WE NEED TO DRYING THE PLASTIC?
I.1 what does the plastic drying mean?
🔹 Plastic drying is the process of drying (removing water) from plastic.
🔹 Plastic drying is a mandatory step before putting plastic into the plastic injection machine to create products.
I.2 why we need to dry the plastic?
To understand why we need to dry plastic, we need to understand the operating principles of plastic injection machines. Plastic is put into the plastic injection machine to be produced in granular form, after being heated by heat cycles, it changes to a liquid state and is then injected into the mold to shape the product. Refer to the operating process through the following video:
https://asg.vn/wp-content/uploads/2023/11/Injection-Molding-Animation-2.mp4
🔹 Question: If plastic with high moisture content (not yet dried) is put into production, what will happen?
AnswersIn a high temperature environment (200-400 degrees Celsius), the water in the plastic will evaporate, taking up the volume of the plastic, thereby causing product errors.
🔹 Air bubble
🔹 Silver streak
Water reacts with molten polymers at high temperatures, called a hydrolysis reaction, causing a change in the polymer molecular structure, causing the product to have poorer physical properties, reducing impact resistance and elasticity. Anise.
II. Plastic drying method
II.1 Plastic drying mode
🔹 Each type of plastic has different hygroscopicity and heat resistance properties, so there will be different plastic drying modes.
🔹 Each region with a different climate will have a different drying mode (Vietnam has high environmental humidity, a lot of water in plastic, different from environments with low humidity)
➜ Below is the recommended drying mode for plastics suitable for the climate in Vietnam
No. Plastic type Drying temperature Drying time (hours)
| 1 | LCP | 110 ∼ 150 | 4 ∼ 8 |
| 2 | PEEK | 150 | 6 ∼ 8 |
| 3 | PPS | 140 ∼ 250 | 3 ∼ 6 |
| 4 | PSU | 120 ∼ 150 | 3 ∼ 4 |
| 5 | ABS | 80 ∼ 90 | 2 ∼ 3 |
| 6 | PMMA | 70 ∼ 100 | 2 ∼ 6 |
| 7 | PC | 120 | 4 ∼ 6 |
| 8 | PA6 | 80 | 8 ∼ 15 |
| 9 | PA66 | 80 | 8 ∼ 15 |
| 10 | PA11 | 70 ∼ 80 | 8 ∼ 15 |
| 11 | PA46 | 80 | 8 ∼ 10 |
| 12 | POM | 110 | 2 ∼ 3 |
| 13 | PBT | 120 | 4 ∼ 5 |
| 14 | PET | 130 ∼ 140 | 4 ∼ 8 |
| 15 | GPPS | 80 ∼ 90 | 4 ∼ 8 |
II.2 Plastic drying process
- Step 1: Clean the drying equipment – make sure the tank and pipes are clean to avoid discharging plastic.
- Step 2 Put the plastic to be dried into the tank - pour by hand or use the automatic plastic supply system.
- Step 3: Set the appropriate drying mode.
- Step 4: Xả hết nhựa trong tank, vệ sinh các đường dẫn khi không còn sử dụng.
II.3 Notes when drying plastic
🔹 Make sure the plastic is dried for enough time before being put into production (usually the plastic drying time must be managed manually, so it may happen that the plastic has not been dried for enough time before being put into production). Can be improved by installing a drying time controller.
🔹 If the product has bubbles or silver stains, you need to check the drying mode again.
III. Plastic drying equipment
🔹 There are 2 main types of plastic dryers on the market, the main difference is that 1 type has a dehumidifier and the other type does not have a dehumidifier.
III.Plastic dryer
The basic principle is that the air flow will be pushed by the fan through the heating element to heat up, where the air is heated according to the set temperature - there is a temperature sensor system to control.
Hot air is pushed into the bottom of the hopper and gradually dispersed upward
The plastic in the drying process rises from the bottom. Once dried, the plastic at the bottom will move out through the outlet at the bottom.
III.2 3-in-1 dehumidifying dryer
This is a machine that combines a drying hopper + moisture separator + plastic vacuum cleaner
This machine line has outstanding advantages in drying quality, but in exchange for its large machine size and high cost.
ASG Vietnam Engineering Company Limited is a unit specializing in handling plastic injection problems with more than 10 years of experience. We are always ready to listen to your questions 24/7 via hotline 0917.54.88.11
