Yongte is professional manufacturer for WPC turn-key production plant. The production process of wood-plastic materials is mainly divided into the following five major steps:
1. Ingredients:
- Raw material selection: The main raw materials of wood-plastic materials include wood powder (which can be sawdust, wood chips, bamboo powder, etc. in the wood processing process), plastics (commonly used are polyethylene, polypropylene, polyvinyl chloride, etc.) and various processing aids (such as coupling agents, lubricants, stabilizers, antioxidants, etc.). When selecting raw materials, it is necessary to ensure that the quality of wood powder is good, the particle size is appropriate and dry, and the performance of plastics meets the requirements.
- Weighing: According to the pre-designed formula ratio, use professional weighing equipment to accurately weigh polymer resin powder, wood powder and other processing aids. For example, if you want to produce wood-plastic materials with higher strength and toughness, you may need to increase the proportion of plastics; if you pursue better wood texture and texture, the proportion of wood powder should be increased accordingly.
2. WPC Mixing:
- Preliminary mixing: Put the weighed materials into a high-speed mixer for stirring. During the stirring process, the high-speed rotating stirring blades fully mix the materials, allowing the wood powder and plastic particles to be evenly distributed together, and the processing aids can also be evenly dispersed in the materials. The stirring speed and time need to be adjusted according to the properties and formula of the materials. Generally, the stirring speed ranges from several hundred revolutions per minute to thousands of revolutions per minute, and the stirring time ranges from several minutes to more than ten minutes.
- Heating treatment: The materials are heated while stirring to gradually soften or even melt the plastic particles so that they can better combine with the wood powder. The heating temperature is usually determined according to the type of plastic used. For example, the heating temperature of polyethylene is generally between 150℃-200℃, the heating temperature of polypropylene is slightly higher, and the heating temperature of polyvinyl chloride is relatively low. When the temperature reaches the set value, it is maintained for a certain period of time to ensure that the material is fully heated.
- Cooling: When the materials are mixed evenly and reach the appropriate temperature, stop heating and put the materials into the cooling mixing drum. The temperature of the material is quickly reduced to the specified temperature by the cooling water that circulates continuously in the cooling mixing drum. The purpose of cooling is to prevent the material from overreacting or sticking due to excessive temperature during subsequent processing, and also to facilitate subsequent operations, such as placing the material in a movable material car for transportation.
3. WPC granulation:
- Plasticization extrusion: The material is subjected to shearing, extrusion and friction in the screw of the extruder, gradually plasticizing and forming a uniform melt. Parameters such as the speed, pressure and temperature of the screw have an important influence on the plasticization effect and need to be adjusted according to actual conditions.
- Pelletization: The melt extruded from the extruder die head is cut into granules by a pelletizing device. Common wood-plastic pelletizing methods are air-cooled pelletizing, etc. Air-cooled pelletizing is to cool and cut the melt with cold air blown out by a fan.
4. WPC Extrusion and molding:
- Mold installation: According to the needs of the production order, select the corresponding product mold and install it on the extrusion equipment. The shape and size of the mold determine the appearance and specifications of the final wood-plastic product. For example, a board mold can be installed to produce wood-plastic boards, and a profile mold can be installed to produce wood-plastic profiles.
- Extrusion: Add the cooled material into the hopper of the extruder, and the material is transported forward under the push of the screw of the extruder. Under the shearing action of the screw, the material is subjected to strong pressure and friction, and the plastic is further plasticized and closely combined with the wood powder to form a uniform melt. The melt is extruded through the die head of the extruder to form a wood-plastic product blank with a specific shape and size. During the extrusion process, it is necessary to set appropriate extruder parameters such as screw speed, extrusion pressure, extrusion temperature, etc. according to the characteristics of the material and the requirements of the product.
- Cooling and shaping: The temperature of the wood-plastic product blank coming out of the extrusion die is high and the shape is not stable. It needs to be cooled through a series of cooling and shaping devices. Common cooling methods include air cooling and water cooling. Air cooling is to cool the product by blowing cold air to the product through a fan, and water cooling is to cool the product through a water tank or cooling water tank filled with cooling water. After cooling and shaping, the shape and size of the wood-plastic product are basically fixed.
- Traction and cutting: Use traction equipment to pull out the cooled and shaped wood-plastic product to keep it moving at a constant speed. At the same time, according to the required product length, the WPC products are cut using cutting equipment to obtain the final WPC products. Cutting can be done by sawing, shearing, etc. to ensure that the size accuracy of the cut product meets the requirements.
5. WPC surface treatment.
- Grinding and polishing
Grinding can remove the rough parts, flaws and unevenness of the WPC surface, making the surface smoother and flatter, laying a good foundation for subsequent processing steps.
- Embossing and carving
Embossed can form various textures and patterns on the WPC surface, increasing the three-dimensional sense and decorativeness of the product.
