Technical development and market prospects of molded wood shaving trays

2019-08-17 12:04:04

Abstract: Pallets are tools for stacking and transporting goods. The use of small-diameter timber and twigs to produce shaving-molded pallets can replace solid wood pallets and improve wood utilization. This paper introduces the production overview, production process, product characteristics and the latest technology of molded wooden shaving trays, and expounds the broad market prospects of shaving molded trays in China.

Keywords: molding, shavings, pallets, paving process

The Technology Development and Market Prospect of Presswood
Molded Particle Pallet

Abstract: Pallet is a kind of tool for storing and transporting goods. Molded particle pallet is produced with branch and small diameter wood , so that utilization ration of wood is raised. This article introduced the production situation, producting
Technology, properties of pallets and new technology of presswood molded particle pallet. And find conclusion drawn is that presswood molded particle pallet will have a wide market and developing prospect in china.

Keywords: Presswood molded, Particle, Pallet, Forming technology

The pallet is a carrier for stacking goods and is a tool for mechanized loading and unloading and handling. The pallets distribute the scattered small goods and containers in a certain amount, and transport the transportation system together with the forklifts to form the assembly unit in units of units. Therefore, the pallets have become an indispensable important tool for the modern logistics system and are widely used in countries all over the world. With the development of the national economy, especially China's accession to the WTO, the transportation of goods continues to increase, and the demand for pallets is also growing. In the past, most of the pallets used solid wood as a raw material to meet the needs of the pallet market. However, with the decreasing of forest resources, the full use of small-diameter wood, wood processing residues and lignocellulosic materials has been paid more and more attention. Germany and the United States have successively researched and developed wooden molded wood shaving trays to improve wood and lignocellulosic materials. Utilization.

The social ownership of pallets is very large. According to the data, there are 10 pallets for Americans and 6 for Japan. In North America, 400 million industrial pallets are produced annually, with an output value of 9 billion US dollars ^[1] . However, 95% of the pallets in North America are solid wood products, accounting for 40% of the total hardwood production. China's foreign wood packaging and bedding materials are also considerable. If we do not use renewable environmentally friendly products, it will seriously affect China's ecological resources. Sustainable development.

In 1971, Werzalit Company invented a patented technology for adding wood fiber materials mixed with thermosetting resins and wood shavings to form particleboard in metal molds. In 1979, Litco used the technology to build the first Presswood Pallet Plant, which is currently marketed in Germany, Australia, New Southwest, China, Brazil, and Japan.

Molded industrial pallets are an important type of shaving molded products. They are mainly used for handling and storing goods in docks, freight yards, warehouses, workshops, shopping malls, etc. They form a mobile unit or handling unit with goods, with forklifts, trucks, cranes. And so on. Industrial pallets are generally available in sizes from 400 mm to 600 mm, from 600 mm to 800 mm, from 800 mm to 1000 mm, and from 1000 mm to 1200 mm. The dynamic load capacity is from 250kg to 1250kg, the pallet weight is 10kg~15kg, the curved edge of the tray, the trough beam and the ingenious perfect rib design make the load factor as high as 80 (dynamic load). The shaving-molded industrial pallet is a special-shaped, thin-shell member with equal strength (see Figure 1). It has light weight and high strength. Its load capacity and self-weight ratio (load capacity) are as high as 60~80 (dynamic load) and 200~300 (static load). .

1 Process principle of pallet production

The finely divided wood chips are steam dried from 148 Â° C to 138 Â° C from high temperature to low temperature for 30 minutes, then mixed with a thermosetting resin, and subjected to compression molding at 220 Â° C, and the pressure is 1400 psi or 98 kg/cm 3 . In this process, the internal temperature of the tray reaches 105 Â° C, and the time when the internal temperature of the tray exceeds 56 Â° C for more than 30 min, the final moisture content of the product does not exceed 9%.

The entire production process is carried out under high temperature and high pressure, killing any insects and fungi remaining in the wood, and at the same time preventing the re-propagation and re-invasion of any other insects due to the high density of the wood products produced. This molded product is the latest "artificial wood packaging material" instead of the traditional "solid wood packaging material". Its products no longer need insect-repellent treatment, and there are no living insects in the product. It complies with ISPM15 (Insternational Standard for Phytosanitary Measures 15). The demand for exporting wood packaging products, and through various life cycle cyclic fatigue tests ^[2] , can be shipped to other countries together with the goods without any special treatment.

2 Production process of molded tray ^[3~5]

2.1 Preparation of raw materials and shavings: Lightweight wood (increasing density of pallets), shavings, generally 50mm long, 10-20mm wide and 0.5mm thick. The small diameter wood, branch coffin or wood processing residue should be cleaned of dust, and the bark content should be strictly controlled, not exceeding 5% to ensure good shaving pattern, and the thickness of shavings is 0.3~0.5mm. After the wood chips are magnetically selected, they are sent to a double drum planer to be processed into shavings, and then sent to a dryer. The moisture content of the shavings after drying is controlled within a range of 2 to 3%. Small shavings and unqualified oversized shavings need to be sorted and removed.

2.2 Mixing glue: In order to prevent the broken shavings, it is not advisable to use high-speed mixing machine. Generally, the drum mixing machine can be used to set two spraying systems to apply two kinds of glues that should not be mixed together. Generally, the isocyanate and urea-formaldehyde resin are mixed, or the phenolic resin and the melamine resin have a sizing amount of 2% to 15%, generally 4% to 10%. After the metered shavings and the quantitative urea-formaldehyde resin are simultaneously fed into the mixing machine, the moisture content of the shavings after mixing should be controlled within the range of 8-10%.

2.3 Paving and hot pressing: special equipment is used. The paving is carried out twice. The tray feet are pre-pressed and pre-pressed, and then the flat part of the tray is laid. Some shallow-foot trays can also be paved at once. The punch is fixed on the upper movable beam of the hot press, and the die is transferred between the hot press and the paving machine, and placed on the lower work table of the hot press, and has a special demoulding device. The mixed rubber shavings are placed in the mold, pre-pressed, and hot pressed to complete the mold after the resin is completely cured. The sizing shavings are firstly placed in a metal mold for cold pressing preforming. It is then pressure molded in a hot press.

2.4 Flange: mainly for trimming, that is, removing excess flash from the edge of the product.

3 Technical characteristics of the product

Millwood's Pallet Design System (PDS) can be used to design a wide variety of pallets and simulate the deformation, damage and fatigue of the pallet. The main technical features of the product are:

(1) The water content is low, generally controlled between 6% and 8%. The tray does not absorb moisture or deform during use.

(2) Stable size, light weight, no distortion and warpage.

(3) The molded product has high dimensional accuracy, and the specially designed ribs ensure the strength and precision of the product.

(4) It can maintain the strength and rigidity constant, eliminate the natural defects of the wood itself during the molding process, and the strength is higher than that of the traditional wood board assembly.

(5) The weight is 60% lighter than the hardwood products of solid hardwood wood.

(6) The rounded corners are designed to prevent damage to the product during packaging and shipping. Automated bundling can be achieved, saving operating time.

(7) Multiple pallets can be stacked together, with 50 pallets approximately 7 feet in height. The static load is 10 times the dynamic load, and the pallet can be used to shovel the pallet from four sides.

(8) It can be transported to meet the import and export business without the need for smoke treatment.

(9) It can be made from wood processing residues and waste materials and low grade wood.

(10) The product is environmentally friendly and can be recycled, recycled, reused, and low in pollution, with a recovery rate of 100%.

(11) The price is cheaper than traditional conifer or broadleaf trees. The average price per pallet is around $6 (see Table 1).

(12) Wood shavings or wood fibers are directly molded by using an environmentally friendly urea-formaldehyde resin adhesive as an adhesive.

(13) Each standard container loan container can hold 1000 pallets, minimizing the user's transportation costs.

(14) The maximum load capacity is up to 25,000 lbs.

(15) The same number of pallets saves 3/4 of the space compared to regular wooden pallets. Forklifts can carry 60 pallets at a time, while ordinary wooden pallets can only carry 18-20 at a time.

4 Market prospects

Recently, the Secretariat of the International Plant Protection Convention of the Food and Agriculture Organization of the United Nations published in Rome the International Standard for Phytosanitary Measures, Guidelines for the Management of Wood Packaging Materials in International Trade, which specifically specifies the removal or killing of harmful organisms in packaging containers for solid wood products. The treatment method, and the wood packaging materials such as plywood, particleboard, oriented strand board and the like which are produced by the high temperature and high pressure treatment of the adhesive are regarded as the disease substances of the logs, and the disease substances have been killed, and no fumigation treatment is required ^{[ 6]} .

Recently, Inka has developed a molded tray with a size of 1140 Ì1140mm, which can be used with ISO containers. Replace the F8M and F8S with a pallet codenamed F8LF-2 (loading capacity 900kg) and codenamed F8LF-2S (bearing capacity 2500kg). This 800 Ì1200mm pallet surface rib design not only meets the strength requirements, but also Has a certain curve beauty. Products have been exported to Australia, New Zealand, Japan, Taiwan, China, Mexico, Brazil, Angola, Chile, India, South Africa, Canada and the United States. All pallets can be reused and recycled, and new composites can be remanufactured with other materials.

At present, 90% of the pallets used in China are urgently needed to be upgraded. For example, there are 500 disposable trays in a port in Tianjin, with an annual consumption of 1.5 million. For example, a port in Shenzhen requires 200,000 trays per year, and only Shenzhen There are six ports of various sizes. In addition, dozens of three-dimensional warehouses with a scale of 2,000-5,000 cargo spaces are built each year in China, and each warehouse requires more than 100,000 pallets. It is estimated that the annual consumption of the country can reach more than 200 million pieces ^[7] .

China not only has a large number of fast-growing plantation timber resources, abundant small-diameter timber, branches and wood and wood processing residues, but also a large number of crops such as straws, cotton poles and other resources that can be used for sustainable use. The use of adhesives that meet the requirements of green environmental protection will not affect the natural environment and human health during use and reuse, and is an environmentally friendly product. This product not only has high strength, but also has good durability. The unit price of each product does not exceed RMB 50. If you seize the opportunity and develop such products in time, you will be able to quickly seize this huge market with unlimited demand.

references

[1] Liu Lei. Green and environmental logistics equipment - plastic composite tray, logistics technology, 1999, 4 (3): 37 ~ 40
[2 Walker. Pallet life cycle test report.United States.Postal Service,Oct.1994
[3] Wang Wei et al. â€œPractical Encyclopedia of Timber Industryâ€. Particleboard Roll. Beijing. China Forestry Publishing House, 1998
[4] Ouyang Lin. Shaving Molding Technology. Wood Processing Machinery, 1994, (2): 12~15
[5] Chen Shiying. Shaving Molding Pallet Process. Timber Industry, 1999, 13(2): 3~6
[6] International Standards for Phytosanitary Measures. Guidelines for the Management of Wood Packaging Materials in International Trade. Rome, March 2002
[7] Bao Yipei. Production technology and equipment of China's shaving molded products. Wood Processing Machinery, 1998, (1): 4~5

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