Plastic mold injection molding process

Injection Robots&Automation

Filling stage

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Filling is the first step in the whole injection molding cycle, and the time is counted from the time the mold is closed to start injection until the mold cavity is filled to about 95%. Theoretically, the shorter the filling time, the higher the molding efficiency, but in practice, the molding time or injection speed is subject to many conditions.

Pressure-holding stage

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The role of the holding pressure stage is to continuously apply pressure to compact the melt and increase the plastic density (densification) to compensate for the shrinkage behavior of the plastic. During the holding pressure process, the back pressure is high because the mold cavity is already filled with plastic. In the process of holding pressure compaction, the injection molding machine screw can only slowly move forward for a small movement, and the flow rate of plastic is also slower, which is called holding pressure flow. As the plastic is cooled and cured by the mold wall, the viscosity of the melt increases quickly, so the resistance in the mold cavity is great. In the later stage of holding pressure, the material density continues to increase, and the molded part is gradually formed. The holding pressure phase should continue until the gate is cured and sealed, at which time the cavity pressure in the holding pressure phase reaches the highest value.

In the holding phase, the plastic is partially compressible because the pressure is quite high. In the higher pressure area, the plastic is denser and the density is higher; in the lower pressure area, the plastic is looser and the density is lower, thus causing the density distribution to change with position and time. The flow rate of plastic is very low in the holding process, and the flow no longer plays a dominant role; pressure is the main factor affecting the holding process.

the cooling stage

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In injection molding molds, the design of cooling system is very important. This is because the molded plastic products can only be cooled and cured to a certain rigidity, and the deformation of plastic products due to external forces can be avoided after demolding. Since cooling time accounts for about 70% to 80% of the whole molding cycle, a well-designed cooling system can significantly shorten the molding time, improve injection molding productivity and reduce costs. Improperly designed cooling system will make the molding time longer and increase the cost; uneven cooling will further cause warping and deformation of plastic products.

the demolding stage

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Demolding is the last part of the injection molding cycle. Although the products have been cold-set, demolding still has an important impact on the quality of the products. Improper demolding may lead to uneven force during demolding and deformation when ejecting the products. There are two main ways of demoulding: top bar demoulding and stripping plate demoulding. When designing the mold, we should choose the suitable demoulding method according to the structural characteristics of the product to ensure the product quality.

Injection molding robot take out

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Injection molding robot take out
Since injection molding robots can significantly increase productivity and reduce production costs, they can stabilize and improve the quality of injection molded products. Therefore, the role of Yubao injection molding manipulators in injection molding production is becoming more and more important. The quality of injection molding is related to the molding efficiency, mold accuracy, molding process, production quantity; with the injection molding machine operator tension, artificial production costs increase, the injection molding machine to take out the robot is also more and more widely used. yubao robot in the application process mainly shows the following uses:

1, robot to remove the mold products, replacing the original semi-automatic production to fully automated production;

2, robot outside the mold to take products, buried in the mold products (labeling, buried metal, secondary molding, etc.);

3、Automatic packaging and storage of the products after taking out by robot;

4、Forming material automatic feeding system, waste recycling system;

5、The whole factory production control system, etc;