Plastic tray production process and procurement attention points

Plastic pallets are available in the following four ways:
The first type: injection molding.

The plastic tray products produced by the injection molding method are flat, smooth, crisp, compact, and have a large degree of product design freedom. They are divided into double-sided integral plastic trays and double-sided assembled plastic trays.

The double-sided integral tray generally has a weight of more than 15 kg/block, and the shape is relatively complicated, requiring an injection molding machine with a clamping force of more than 2,500 tons. The trays are complex in shape, large in investment, and relatively high in cost, but due to fewer production processes, relatively high production efficiency and good product quality. At present, there are not many methods used in general plastic processing plants.

The double-sided assembled tray is divided into upper and lower two-piece trays, which are respectively assembled by injection molding. Although this product requires 2 pairs of molds, the mold structure is greatly reduced, the total investment of the mold is still cheaper than the whole type, and the requirements for the clamping force of the equipment are also reduced. The clamping force is ≥1500 tons, and the general plastic processing plants are all It’s easier to do. This type of production may become the mainstream of plastic pallet production.

Second: extrusion blow molding.

The extrusion-hollow blow molding of the plastic tray is similar to the general hollow product blow molding method, and because of its large size and double-sided type, a large extruder, a mold clamping machine, and a mold are required. At present, domestic blow molding machine manufacturers have developed a large-scale hollow molding machine that specializes in high-speed production of high-strength blow molding trays. It is produced by HMWHDPE high-strength plastics. It has fast forming speed, good product quality, high strength, high rigidity and very long length. The service life of the general blow molding tray can reach 510 years, and it can work stably in the environment of -4040 °C.

The dynamic load of its products can reach more than 3t, and the flexural strength reaches a high level. It is the preferred tray for long-life, high-intensity environments. It is currently more expensive than other plastic trays because of its exceptionally long service life, so its price/performance ratio is the highest among all pallets. This method will achieve rapid development in recent years as the price of molding equipment is greatly reduced. It will have a great advantage for saving limited oil resources and saving logistics costs.

The third type: vacuum forming method.

The plastic trays produced by the vacuum forming method are also available in single-sided and double-sided types. Single-sided blister trays are mostly used for packaging and transportation of small motors (such as vacuum cleaner motors, power tool motors, etc.) and wire trays. Recently, they have developed rapidly and are mainly used exclusively. The double-sided blister trays are assembled in two forms: the upper half is an extruded fixed length, fixed width plastic sheet, the lower half is a large vacuum blister; the upper and lower half are large vacuum blister Products. The method requires large-scale vacuum blistering equipment for production molding, the equipment cost is low, the mold cost is also low, but the product wall thickness is uneven.

The fourth type: The fourth is the extrusion molding method. The plastic trays produced by this method are all assembled. That is, an extruder, a machine head, and the like are used to extrude the slats for the upper and lower panels and the I-shaped connecting plates with the compound wings for the connection support, and then assemble them. The advent of wood-plastic composites has driven the development of plastic pallets for extrusion molding. It is based on natural plant fiber (including wood flour husk, straw powder, rice bran, etc.) and waste plastics, so that the plastic tray has the advantages of woody, water and insect resistance, and can be planed, sawed and nailed. . Among the four molding methods, the production equipment and molds have the least investment, the lowest cost, and the best performance-price ratio.

Five points for producing high-quality blow-molded pallets

1. Size the die head to the mold. Design the die to the width of the mold and use the timing functions for mold closing and blowing to inflate the parison to the right size. Less flash means less energy spent crushing it. Keep the process stable by setting molding time, hydraulic pressure and flow, blowing and cooling water pressure and flow, the wall thickness controller profile and the shot length to suit the product’s shape. 2. Choose the right resin formula. Pallets are usually blown from HDPE. Select the grade for impact, compression and crack resistance while keeping material cost down.

2. Choose the right screw. Screws can be designed for high plasticizing capacity, for even color mixing, or as high-output double alloy screws for both. Pick one to suit the material and product. 4. Design the mold carefully. For double-sided and nine-leg pallets, allow proper draft angles so the part is not overstretched. Reinforcing ribs set the pallet’s strength, so use as many and as strong ribs as the design allows. 5. Keep the regrind ratio reasonable. Mix regrind and virgin material at a ratio confirmed by testing, and blend it evenly. Too much or too little affects product quality.