Professional manufacturer of thermoforming machines.
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Professional manufacturer of thermoforming machines.
Basic Steps of Thermoforming
1. Material Preparation
The first step in the thermoforming process is selecting and preparing the appropriate plastic sheet material. Commonly used sheets include Polystyrene (PS), Polyethylene Terephthalate (PET), High Impact Polystyrene (HIPS), Polypropylene (PP), and Polylactic Acid (PLA). Different materials have different properties and are suitable for various applications. The choice of material is the foundation of the entire process's success, so special attention is needed.
Table: Common Thermoforming Materials and Their Properties
| Material | Abbreviation | Properties | Common Applications |
| Polystyrene | PS | Rigid, easy to process | Disposable utensils, packaging boxes |
| Polyethylene Terephthalate | PET | High transparency, impact resistance | Beverage bottles, food packaging |
| High Impact Polystyrene | HIPS | Strong impact resistance, good rigidity | Electronic housings, frozen food packaging |
| Polypropylene | PP | Good heat resistance, chemical stability | Food packaging, pharmaceutical packaging |
| Polylactic Acid | PLA | Biodegradable, eco-friendly | Compostable utensils, bio-packaging |
During the material preparation stage, the sheet surface also needs to be cleaned to remove any dust or impurities that could affect the forming quality. For certain high-demand applications, the sheets may also require pre-treatment, such as applying anti-static agents or surface modification.
2. Heating
Heating is one of the most critical steps in the thermoforming process, where the plastic sheet is heated to its softening temperature, making it sufficiently malleable. Heating equipment typically uses infrared heating or resistance heating to ensure the sheet is heated evenly.
Different materials require different heating temperatures and times. For example, PET sheets usually need to be heated within a temperature range of 120-160°C, while HIPS sheets typically require heating between 80-120°C. The heating process not only needs to consider the material's softening point but also must ensure that the sheet does not decompose or degrade during heating. Therefore, precise temperature control of the heating equipment is necessary, and cooling or adjustments may be needed when required.
In industrial production, the uniformity of heating is crucial for the forming quality. If the sheet is not heated evenly, it may result in surface waviness, depressions, or thickness variations in the finished product. These issues not only affect the appearance of the product but may also impact its mechanical properties and durability. Therefore, special attention must be paid to the uniformity of the sheet during the heating phase.
3. Forming
Forming is the process of transferring the heated plastic sheet into a mold and using vacuum suction, pressure, or mechanical force to shape it. The forming process can be divided into vacuum forming, pressure forming, and mechanical forming, each with its own unique advantages and applications.
In vacuum forming, the sheet is closely adhered to the mold surface to form the desired shape. This method is typically used to produce thin-walled products such as disposable utensils and food packaging boxes. Pressure forming presses the sheet into the mold, suitable for making high-strength and complex-shaped products. Mechanical forming uses mechanical devices to apply pressure directly, mainly used for manufacturing thick-walled products.
During the forming process, parameters such as pressure, time, and temperature need to be controlled. Excessive pressure may cause the sheet to rupture, while insufficient pressure may result in incomplete product shapes. Prolonged forming time may cause material aging, while too short a time may prevent the complete reproduction of the product's details.
4. Cooling
Cooling is the process of rapidly cooling the formed plastic product to a solid state. The cooling speed directly affects the product's dimensional stability and surface quality. Cooling is usually done using air or water, depending on the shape of the product, material, and production efficiency requirements.
5. Cutting
After cooling is completed, the formed products need to be cutted to remove excess parts, ensuring clean and precise edges. The cutted products need further inspection to ensure that they meet the required dimensions and shapes.
6. Waste Collection
Waste generated during the thermoforming process, such as edge cuts and defective products, is usually collected for recycling. This not only helps reduce raw material waste but also meets environmental requirements. After waste collection, these materials can be reprocessed into new sheets for continued production.
Professional manufacturer of thermoforming machines.
