The best way to improve the adhesion between gate

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Improve the adhesion between gate and parts

the adhesion phenomenon in the production process will not only reduce the quality of products, but also bring great losses to processors. Therefore, how to quickly edible and biodegradable plastic bags can reduce the use of about 216000 plastic bottles. It is very important for processors to judge the root cause of the problem and find an effective and reasonable solution to achieve the overall optimization of the technical scheme, and significantly improve the adhesion phenomenon

material adhesion often occurs in the production process. Whether it is at the gate or on the workpiece in the mold cavity, this adhesion will greatly affect the quality of the product. The root cause of this adhesion lies in the production process and the mechanical equipment used in the production process

it is worth noting that the adhesion position of the workpiece in the mold is not necessarily the position of the workpiece when the adhesion phenomenon first occurs. Because different parts of the mold can be attached to the workpiece, and because the adhesion of each part is different, the resulting drag force is likely to fix the workpiece to another part of the mold. Therefore, the root cause of adhesion should be carefully analyzed and judged when opening the mold

incorrect demoulding will lead to warpage and deformation of the workpiece and adhesion to the mold

effects of injection machine parts and molds

generally, incorrect polishing is the main cause of adhesion. In the molding process, too high polishing degree will cause a vacuum in the mold, so that the products are adsorbed on the inner wall of the mold. On the other hand, too low polishing degree will also cause difficulty in demoulding. If it is caused by vacuum, this problem can be solved by using suction pipe

scratches will be left at the mold or gate during use or polishing, and these scratches will also lead to adhesion. Circular polishing will generate tiny scratches on the surface of the die steel, and these scratches will become undercuts or gouges over time, so that the melt is filled in during the filling process, resulting in the following situations: the melt adheres to the gate, the workpiece adheres to the "a" side of the die when opening the die, or the workpiece adheres to the "B" side of the die during demoulding

to solve the adhesion problem at the gate, it is necessary to pay attention to eliminating scratches or undercuts during mold maintenance. In addition, the mold also needs to be polished by reciprocating traction (such as polishing by reciprocating motion during demoulding, rather than circular or elliptical motion) or by vapor honing (improved by sand blasting). Generally, gas phase honing is more helpful to prevent adhesion of soft materials

when polishing or scratches cause workpiece adhesion, you should first determine which side of the mold is the problem. If the workpiece adheres to the "a" side of the mold, whether it is located in the fixed half mold or the moving half mold, or in the mold core or mold cavity, this problem can be solved by slowing down the manually controlled mold opening speed and paying attention to reducing noise or eliminating the coking/displacement of the workpiece at any time. If the workpiece is distorted on the parting surface, the problem may lie on the side of the mold that is not demoulded

if the part adheres to the "B" side of the mold, it needs to be demoulded slowly, and pay attention to whether one corner or part of the product is hooked or charred during the demoulding process

the most effective ways to prevent adhesion and assist demoulding are traction polishing, eliminating scratches, or using gas-phase honing to treat the mold surface. In addition, adhesion to parts may also occur on the plated surface of the mold, so the surface of the mold should also be checked, and the plating should be removed if necessary

other parts or molds of the injection machine will also cause adhesion. If the radius of the nozzle does not match the sprue bushing, or the nozzle mouth is too large, it will lead to adhesion problems at the gate. At this time, the radius of the nozzle can be tested through a simple test: first place a piece of cardboard at the sprue bushing opening, and then press the nozzle against the cardboard. If the nozzle leaves a smooth mark on the cardboard, it indicates that the two parts match well. On the contrary, if the cardboard is torn or cut, it is necessary to replace the nozzle with a more appropriate size. In addition, check whether there is burr at the nozzle, and ensure that the diameter of the nozzle is at least 0.030in smaller than the diameter of the sprue (0.75mm,1in.=2.54cm)。

sprue coagulant head is also one of the reasons for adhesion. In the process of use, it should be ensured that if the microcomputer function is strong, the size of the gate coagulant head can be printed directly, which is large enough and the design is reasonable. This problem can be solved by increasing undercut, using Z-shaped puller or increasing reverse taper. Adhesion also occurs when the taper of the gate is too small. If the taper of the gate is 0.5in/Ft (1ft=30.48cm), the taper of the gate should be appropriately increased

in addition, the manipulator responsible for removing the parts sometimes twists and bends the parts during the demoulding process, which is also the main reason for the adhesion phenomenon. At this time, it is necessary to check the end of the manipulator and the motion track of the workpiece on the manipulator

influence of processing technology

improper processing operation is easy to cause adhesion at the gate or parts. Uneven mold filling, especially in multi cavity mold, will lead to excessive mold filling or insufficient mold filling, resulting in the adhesion of parts. The influence of this factor can be confirmed and eliminated through mold filling balance test

the adhesion of parts is also related to the condition of mold filling. Excessive mold filling will hinder the normal shrinkage of the parts and make it difficult to demould the parts. At this time, this effect can be eliminated by reducing the mold filling pressure or pressure holding pressure (or pressure holding time). In the second stage, the pressure and time required for mold filling and pressure holding should be compensated during cooling and curing

it is worth noting that insufficient mold filling will not only cause excessive shrinkage, but also cause adhesion. If this happens, the time and pressure of mold filling/pressure maintaining in the second stage should be increased to ensure that the molding cycle remains unchanged. Sometimes this also helps to reduce the cooling time and greatly reduce the degree of shrinkage. If more time is needed to shrink the workpiece and leave the cavity, the whole molding cycle can also be extended by extending the cooling time

mold and material temperature are also the causes of adhesion problems. Materials tend to be adhesive when degraded, so it is necessary to check whether the process temperature is appropriate, especially the set temperature and actual temperature at the nozzle need to be strictly controlled. Now mold makers are also beginning to consider the problem of temperature difference, and believe that as long as the mold is not damaged, the mold temperature can be appropriately increased or reduced. At the same time, it is also necessary to check the water flow speed of the mold cooling system and ensure that the water flow speed can reach the Reynolds number of more than 5000, so as to obtain the best cooling effect

crazing on the surface of products is a sign of adhesion. Check the symptoms of adhesion at all parts of the workpiece, such as whether there is stress whitening near the thimble, and then check the cause of stress, and ensure that the crazing is not caused by residual detergent or release agent interacting with the resin

the gate is too soft or not completely frozen, which will also cause adhesion. At this time, this problem can be solved by replacing the smaller gate, cooling the sprue bushing, or reducing the temperature of the nozzle or melt. If not, the cooling time can be extended

finally, it is also essential to check whether the resin contains mold release agent and what kind of mold release agent it is. Increasing the amount of mold release agent or changing the type of mold release agent will also play a certain role. (end)

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