In recent years, with the growing intensification of plastic pollution, global plastic bans and eco-friendly packaging have become major trends. Paper egg trays, due to their affordability, environmental friendliness, simple production process, and 100% recyclability, have gradually become dominant in the egg packaging industry. Egg trays made from paper pulp and plant fibers through molding are continuously recyclable. They contain no toxic components, and the natural materials make them biodegradable and compostable. In addition, it has good stability, lightweight, high strength, excellent cushioning performance, and appealing visual effects. As a result, its market share in egg packaging continues to expand, and more and more investors are choosing to enter paper egg tray production.
The paper egg tray manufacturing process is not complex, but for some beginners, there are still many issues that can be difficult to resolve. Next, we will provide solutions to some common problems that often arise during the production process.
Paper Egg Tray Manufacturing Process
The paper egg tray production line involves several stages to transform paper into molded egg trays.
1. Raw Material Preparation
The primary raw materials, such as waste newspaper, cardboard, or office paper, are collected, soaked in water, and then mechanically shredded and mixed with water to create pulp slurry in a paper pulping machine. During this process, any ink, glue, and contaminants are removed from the paper fibers, leaving behind a fibrous slurry.
2. Molding Process
The pulp slurry is then transferred to a large tank, where it is pumped to an egg tray molding machine. The molding machine consists of a series of molds in the shape of egg trays. These molds can be designed to produce various sizes and types of trays depending on the product requirements. After the slurry is ready, the machine uses a vacuum system to pull the pulp into the molds, ensuring that the fiber evenly fills the mold and creates the shape of the egg tray.
3. Drying
Once the egg tray is molded, it must be dried to remove excess moisture. This can be done in several ways:
- Natural drying: For smaller-scale or environmentally conscious operations, egg trays can be dried outdoors in the sun.
- Equipment drying: In larger scale operations, the egg trays are transferred to an industrial egg tray dryer, where hot air or steam is used to speed up the drying process, such as a brick kiln dryer, box-type dryer, or automatic metal dryer.
4. Packaging
After drying, the paper egg trays may need to be trimmed to remove any excess pulp around the edges to give the trays a neat, uniform appearance. In some cases, egg trays may undergo additional treatments like pressing or coating to improve strength and moisture resistance. The final egg trays are stacked and packaged with the help of an egg tray packing machine, and then ready for shipment. Depending on the size and customer requirements, egg trays can be bundled together using plastic wrap or packed into larger boxes.
Solutions For Common Issues In The Egg Tray Manufacturing Process
Excessive Pulping Time
If the raw materials are difficult to break down, on one hand, you should consider the density of the raw materials; on the other hand, you should adjust the blades and speed of the pulping machine. Generally, high-end pulping machines are equipped with spiral blades and flat blades, and feature side blades inside. If the pulping speed is too slow, you should consider the sharpness of the blades and the motor speed. For different pulping machines, you can adjust the motor speed accordingly to optimize the pulping efficiency.
Excessive Moisture Content
The moisture content of freshly molded egg trays is generally around 70%. If the moisture content is too high, it can result in excessive molding time, high energy consumption, and even cause edge cracking issues. Therefore, if the moisture content is too high, it is necessary to consider factors such as whether the egg tray is too thick, whether the vacuum level is too low, whether the suction time is too short, and whether the molding mold has been sealed with a rubber pad, among others.
Uneven Thickness Of Egg Trays
If the egg trays produced in the same batch exhibit uneven thickness, the following factors should be considered:
(1) Are the suction holes of the mold uniform? If not, adjust by adding or blocking holes as necessary based on the actual situation. (2) Is the metal mesh clogged? If so, clean it promptly. (3) If it is pulp injection, check whether the injection pipe directly impacts the egg tray. Adjust the position of the pipe nozzle promptly. (4) Check the sealing condition of the vacuum system. (5) Check if the pulp release valves are stuck. If so, repair them promptly. All four valves must operate simultaneously to ensure uniform thickness.
The Egg Tray Surface Has Mesh Marks
(1) The gap between the molds is too small, or the egg tray weight is too large. (2) The metal mesh is too thick. (3) The mold or equipment lacks sufficient flatness, which may lead to a concave shape in the middle of the mold or equipment, causing mesh marks on the edges of the egg tray. (4) Foam in the pulp tank can also result in mesh marks. (5) Excessive pressure in the pressure cylinder. The pressure can be reduced, typically around 3-4 kg is sufficient.
Excessive Molding Time
(1) The moisture content of the wet egg trays is too high. (2) The molds or equipment are uneven, causing uneven heating. (3) The temperature of the thermal oil is too low. (4) The heating plates are clogged, reducing thermal conductivity. (5) The cylinder pressure is too low. (6) The egg tray thickness is too large. Generally, when the thickness reaches 1mm, the molding time is about 60-90 seconds.
Egg Tray Edge Cannot Be Cut
(1) The cutting blade is not sharp enough. (2) The equipment or mold is uneven, causing some areas to remain uncut. (3) The cylinder’s descent or booster distance is insufficient. (4) The cylinder pressure is too low.
Egg Tray Has Burrs
(1) The cutting blade is dull. (2) The mold gap is too large. Generally, the mold gap should be 0-2 mm. (3) The egg tray is too thick, and the surface dryness is too high, which may lead to surface cracking issues. (4) The equipment is uneven, and the strength points are uneven, making burrs more likely to occur.
Failure Of Waterproof, Oil-Repellent, And Other Additives
(1) Is there any omission in adding the additives, or has the amount been reduced? (2) Has the water quality been contaminated, with excessive microorganisms? (3) Are there any conflicts with other additives, such as defoamers? (4) If the moisture content of the egg tray after molding exceeds 10%, failure of the additives is more likely to occur.