Egg tray making machine, egg tray production line, common fourteen FAQs about paper pulp tray
1. What are the different types of raw materials for paper pulp trays?
Answer: The materials for paper pulp trays are commonly divided into two categories. One category is virgin pulp, such as wood pulp, bamboo pulp, sugarcane pulp, straw pulp, etc. The second category is recycled materials, including corrugated paper, newspaper, and white paper. Additionally, colored paper pulp tray products can be produced using different colored raw materials as per customer requirements.
2. Why do paper pulp tray products have varying weights
Answer: There are two main reasons for the variation in weight. Firstly, the pulp concentration changes during production. The consistency of the prepared pulp changes as it leaves the molding machine’s pulp vat, typically controlled between 2.56% and 3.6%. Secondly, vacuum conditions fluctuate continuously during the molding process. The negative pressure in the vacuum tank of the air compressor changes with production, and the combination of these two variables results in weight variations within ±10% for products molded with the same drainage time.
3. Why can’t you achieve the color I need for the paper pulp trays, or why is the color inconsistent?
Answer: Coloring of paper pulp tray products is typically done by adding water-based dyes to the base pulp during the forming process. Color consistency may be affected by changes in pulp concentration during production and the sensitivity of most dyes to temperature variations. Colors may change with fluctuations in drying line temperatures (ranging from 150°C to 250°C) during the hot-press shaping process. Therefore, products with high color requirements may not be suitable for coloring.
4. Why do some of your products not have a smooth surface like others?
Answer: After forming, paper pulp tray products are fully wet and undergo deformation during the drying process. They are then reshaped using high temperature (150°C to 250°C) and high pressure (3T to 50T) molds to regain their original design geometry. The smoothness of paper pulp trays is influenced by the vertical force applied during the shaping process, resulting in smooth surfaces but slightly rougher sloped areas. The degree of smoothness after shaping also depends on the product’s design, with smaller slopes and more reinforcing ribs leading to greater decreases in smoothness.
5. Why do some of these products have minor surface cracks?
Answer: When paper pulp tray products are formed, pulp fibers naturally accumulate in layers. Liquid pulp does not flow out evenly in some slots, resulting in thickness variations compared to the design standard after drying. During high-pressure shaping, the outermost layer of fibers with uneven thickness due to different liquid absorption will break and result in fine cracks on the surface. This phenomenon does not affect the product’s strength and is generally acceptable in the industry.
6. Why can’t I add a button to secure my product?
Answer: During the molding and shaping of paper pulp trays, the upper and lower molds are closed and require a certain demolding angle. Wet products cannot be removed from the mold during forming, making it impossible to design paper supports with inverted clasps.
7. Why do folded products have uneven burrs around the edges?
Answer: Folded structure products are formed with flat edges. When vacuum and natural pulp absorption occur, the mold’s edges consist of stainless steel filter screens. The accumulated pulp fibers at the absorbed edges will be irregular cotton fluff. This is a result of an uncontrollable process. After forming and folding, the burrs will be redirected to the sides and do not affect packaging or serve as production control elements. If customers have high demands, burrs can be removed by trimming with a knife.
8. Why do you set a minimum order quantity?
Answer: The production of paper pulp trays involves pulping, molding, mold assembly, mold adjustment, drying, and mold shaping, taking approximately half an hour. A low quantity would significantly increase production costs. Furthermore, paper pulp tray products are low-value-added items, and shipping costs rise considerably with low quantities. Therefore, a minimum order quantity is established.
9. Why can’t you design based on my specific dimensions?
Answer: Firstly, industrial machines typically have size limitations, with standard machines having maximum dimensions of 800mm x 600mm and special models at 1500mm x 1500mm or 1200mm. Beyond these dimensions, production becomes impractical. Secondly, specifying smaller design dimensions is important for cushioning the structural impact, requiring a certain amount of space for structural design.
10. Why do some products feel different from others?
Answer: The fundamental principle of shock absorption and cushioning in paper pulp trays is achieved through the circular structure and reinforcement positions. Therefore, different design structures using the same pulp will have different shock resistance and tactile characteristics. Similar mold types may use different pulps due to variations in fiber length and shrinkage characteristics, leading to differences in feel. It’s essential to communicate the desired shock resistance standards to engineers before selecting materials and design options to create different circular structures and reinforcement positions accordingly.
11. Why can’t this mold be modified further?
Answer: For paper products, customers need to provide accurate packaging requirements and precise dimensions for each product before the mold is created. Initial design work should be sufficient. Once the mold is completed, the cavity of the forming mold is hollow, with a standard thickness of 10mm. Therefore, modified dimensions should be smaller than 10mm, as modifying the shaping mold is not possible if the cavity dimensions are too large and cannot be changed due to a lack of material in the upper or lower mold.
12. Why is the abbreviation for paper pulp tray “MPP”?
Answer: Paper pulp molding, the English name is “paper pulp molding packaging,” abbreviated as MPP, commonly known as paper pulp tray.
13. Why doesn’t this modified mold produce products as smooth as the original?
Answer: After the 2008 financial crisis, most paper pulp tray factories’ mold cavities are created using CNC machining, with the entire process being automated. Modified positions are adjusted manually and have lower precision than CNC machining. Consequently, modified positions won’t be as smooth as the original ones.
14. Why has the delivered product’s length (width) increased?
Answer: During the production and packaging of paper pulp tray products, they tend to stack due to their inclination. After placement, the products in the transport department become wider due to stacking. However, the deformation and rebound of paper support components also ensure that larger-sized products are not affected during actual use.