Details on demoulding of wet paper molds in pulp molding technology
The demoulding process of pulp molded products involves two different molding methods: vacuum molding and hydraulic molding. Demolding is an important link in the pulp molding production process, which directly affects the quality, production efficiency and cost of the product.
Vacuum molding: In vacuum molding, the wet paper mold is adsorbed onto the mold under the action of vacuum to form the desired shape. The vacuum degree is generally 520Pa, and the air pressure during demoulding is generally 0.2MPa. In this process, the control of vacuum degree and air pressure is crucial for both molding and demoulding.
Hydraulic molding: The vacuum degree of hydraulic molding is about 780Pa, and the compressed air pressure for blowing out the wet paper mold is about 0.1~0.2MPa. This method controls the pressure through the hydraulic system to achieve better molding effect.
What are the advantages of hydraulic molding over vacuum molding?
- Higher molding pressure: Hydraulic molding can provide higher molding pressure, which helps the wet paper mold fit the mold more closely, thereby improving molding quality.
- Better control accuracy: The hydraulic system can control pressure and speed more accurately, which is particularly important for complex molding processes.
- Stronger adaptability: The hydraulic molding method can adapt to a wider range of materials and more complex product shapes, providing greater design flexibility.
- Higher production efficiency: Due to the fast response speed of the hydraulic system, the molding cycle can be shortened and production efficiency can be improved.
- Better product consistency: The hydraulic molding method can provide more consistent molding pressure, thereby improving product consistency.
3. Demolding angle: The demolding angle is an important factor affecting the demolding effect. The traditional demolding angle is 3°~6°, but now the demolding angle of high-end pulp molding can be less than 2°, and technically it can even reach 0°. The design of the demolding angle needs to balance the difficulty of demolding and the dimensional accuracy of the product.
What is the impact of a demolding angle below 2° on production efficiency?
- Reduce demolding time: A smaller demolding angle can reduce the time required for demolding because the product is easier to remove from the mold.
- Improve the degree of automation: A smaller demoulding angle helps to achieve a more efficient automated demoulding process and reduce manual intervention.
- Reduce product damage: A smaller demoulding angle can reduce product damage during the demoulding process and reduce the scrap rate.
- Improve product surface quality: A smaller demoulding angle helps to maintain the smoothness of the product surface and reduce the risk of scratches or cracks.
- May increase mold cost: Achieving a demoulding angle below 2° may require a more complex mold design, which may increase the manufacturing cost of the mold.
- Improve production continuity: Due to the fast demoulding speed, machine downtime can be reduced and the continuity of the production line can be improved.
Multiple molding process: In the demoulding process, multiple molding process is often used. This method can improve the molding quality of the product. Some manufacturers have developed corresponding molds that can achieve a one-time molding process, which can reduce costs and improve production efficiency.
In the production of pulp molded products, by controlling parameters such as vacuum, air pressure, demoulding angle, and adopting advanced molding processes, product quality and production efficiency can be improved.