Plastic mold opening and injection molding-Shanghai Mulan Precision Mold Co., Ltd.


Author: MULAN –Plastic Molding Manufacturer

​1.1 Magnetic plastic Magnetic plastic is a kind of polymer material. It is mainly composed of synthetic resin and magnetic powder. Magnetic plastics can be divided into ferrite system and rare earth based on magnetic powder classification. The performance of magnetic plastics is affected by factors such as magnetic powder material, magnetic powder filling rate, resin and molding process. Magnetic plastics have the characteristics of high strength, low density, strong magnetic retention ability, and high processing and forming precision.

The finished product of magnetic plastic is less brittle and easier to assemble. 1.2 Unsaturated polyester film plastic This plastic is a resin paste composed of resin, filler, initiator and thickener, etc. It also belongs to thermosetting molding compound. Unsaturated polyester film plastics are mostly white. Appears translucent. Colors can also be added upon request. This plastic contains 10-30% glass fiber and 50-70% filler. The resin content is 20-80%.

The mechanical strength of unsaturated polyester film plastic is relatively high. Dimensional stability is also relatively good, and the surface is relatively smooth, and complex molded products can be produced. 1.3 Thermosetting injection plastic The base material of this kind of plastic product is composed of specific thermoplastic and thermosetting phenolic resin, and then adding glass fiber and other fillers, and at the same time adding some other additives. Then it is made by special processing, it is a powdery phenolic plastic, it has good mildew resistance and temperature resistance, and its insulation and physical properties are good. The molding cycle is also relatively short. In addition, there are plastic products based on epoxy resin. This kind of plastic uses epoxy resin as the base material and triethylenetetramine as the curing agent. Then add filler etc.

​Contact Mr. Tang 138257691502 Plastic extrusion molding process principle and process parameter analysis Plastic processing technologies mainly include the following types: compression molding, extrusion molding, injection molding, blow molding and calendering and other processing technologies. This paper focuses on the analysis and research of extrusion molding. 2.1 The principle of extrusion molding process The extrusion molding process is formed in three stages: plastic polymers are molded through a die, and then solidified and shaped. First, it must enter the extruder barrel, and then under the action of the rotating screw, it will be melted, homogenized, and pressurized.

Finally, the melt is extruded from the die of the extruder to form a parison. After cooling and shaping, the final plastic product is formed. 2.2 Extrusion molding process parameters ①Cylinder temperature: The temperature of the barrel is usually set to be high at both ends and low in the middle, and the temperature in the feeding section is occasionally higher than that in the homogenization section; within the range. Excessively high temperature will cause poor stability of the extrudate and unstable production. Too low temperature will cause processing difficulties and seriously damage the equipment; Size and other factors; ④ screw speed and extrusion rate; the screw speed and extrusion rate need to be controlled within a reasonable range, this process parameter is very important for the physical properties of plastic products; ⑤ Traction speed; The speed is slightly faster, about 1-10. This can ensure the stability of the plastic product. 3 Plastic molding process 3.1 Extrusion of pipes There are two kinds of pipes: hard pipe and soft pipe. The processing technology of the two pipes is basically the same.

During processing, the material is homogenized through the barrel, and then extruded through the barrel to form a plastic tube, which is cooled by the shaping device to solidify the surface. Then it is cooled and shaped through the cooling water tank, and then pulled out at a constant speed by the traction device. Final cut. The processing of the hose does not require a shaping device, after natural cooling or spray cooling, the use of conveyor belts or self-weight traction. The following two points need to be paid attention to when winding to a certain length and cutting the pipe for extrusion molding: (for the extrusion and cooling of pipes with large diameters, spray nozzles should be evenly arranged around the pipes.

Avoid uneven shrinkage of the pipe caused by different water temperatures in the upper and lower layers of the tank; ② The traction speed should be carried out at a uniform speed to avoid the phenomenon of uneven pipe wall thickness. 3.2 Extrusion of sheet metal The process flow of sheet metal processing is as follows: the material is firstly plasticized by the extruder evenly. It is then extruded through a slot die to form a slab. Then immediately pass through the three-roll calender for cooling and shaping, and use the guide roller to cool and shape the plate processed by the calender, and then trim the edge. Finally, the final cutting is carried out by the two-roll tractor.

Introduction to the key process of plate processing: ①Slit head: The melt must be distributed at a uniform speed in the slit head so that the material can flow out of the outlet at the same speed. Ensure that the thickness of the board is uniform and the surface is smooth. The currently widely used head is the hanger type head. ②Calender: After the slab is extruded, it should immediately enter the three-roll calender for cooling and shaping. When entering the calender, the head must be as close to the calender as possible. To ensure the smooth progress of the calendering process.

At the same time, control the temperature of the rollers of the calender. Ensure that the cooling rates of the upper and lower surfaces of the slab are consistent, so that the shrinkage rate of the slab is as close as possible to reduce the internal stress of the slab. ③Guide roller; the most important function of the guide roller in sheet metal processing is cooling. The cooling delivery length of the guide roller is determined by the thickness of the processed slab and the specific heat capacity of the plastic. The thinner the slab and the smaller the specific heat capacity, the shorter the cooling delivery length of the guide roller. Conversely, the longer the cooling delivery length of the guide roller. ④ Trimming; Trimming is a unique process of sheet metal extrusion molding. Generally, disc cutting 97 is used for trimming. The cutter is generally installed in front of the pulling roller.

⑤ Traction; the traction device can help the board enter the cutting device, avoid the backlog of materials coming out of the calender, and can flatten the board. The speed of the plate basin during traction is slightly lower than the speed of the plate conveyed by the calender. This is of great help to the cooling shrinkage of the plate writing material. ​Contact: Mr. Tang 13825769150​​.

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