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Common problems and solutions of injection mold

2022-08-10 Hits: 10 views

Plastic products are very common in life, and plastic products are produced and processed by injection molds. The structure and size of injection molds directly affect the quality of plastic products. During production, some problems of injection mold will also affect the production efficiency.
1.The reset plate of injection mold is not reset.
After the injection mold is opened, the mold reset plate does not reset. The reason for this is that the reset cylinder leaks oil, resulting in uneven stress during reset and unbalanced stress on the reset plate. The reset rod of the die is pulled, the fit between the reset rod and the guide sleeve becomes tight, and the reset plate cannot be pushed out. Check whether the oil seal of the mold reset cylinder is worn or not, if so, replace the oil seal in time, check whether the mold reset rod is pulled, polish and lubricate the mold reset rod.
2.Stuffing of feed nozzle
When the injection mold is opened, the material head of the product is broken and blocked in the feed mouth of the mold, resulting in dissatisfaction when the next product is injected. This is because the hot runner temperature of the mold can’t reach the melting point of raw materials, the sprue of the mold has burrs, or it is caused by improper injection process. Adjust according to the requirements of injection molding process, and check whether the sprue bushing of the mold has burrs.
3.The core-pulling slider does not reset.
If the die core-pulling slider is not reset, it is easy to cause the product to crack. The reason is that the mold slider is tight and the slider return spring fails. Repair the mold slide block and replace the return spring.
4.The product sticks to the cavity.
This is because the injection molded product is not satisfied, and the thimble position of the mold is empty, resulting in the product not being ejected. Also, the cooling time of injection molding products is not enough, and the products are deformed, resulting in the products not being ejected. The solution is to adjust the injection molding process and the cooling time of the mold.
5.The injection products are white.
The causes of whitening phenomenon are insufficient cooling time, blocked cooling water channel of the mold, insufficient demoulding angle of the reinforcing rib of the mold, unsmooth surface of the reinforcing rib and poor roughness. The solution is to check the cooling water channel of the mold, polish the reinforcing ribs of the mold and increase the demoulding angle of the reinforcing ribs of the mold.
6.Poor liquidity
When the fluidity of raw materials is poor, the structural parameters of injection mold are the main reasons that affect the under-injection. Therefore, it is necessary to improve the stagnation defect of the mold gating system, such as setting the runner position reasonably, enlarging the size of the gate, runner and sprue, and adopting a larger nozzle. At the same time, an appropriate amount of additives can be added to the raw material formula to improve the flowability of the resin. In addition, we should also check whether the recycled materials in the raw materials are excessive, and appropriately reduce their dosage.
7.Insufficient feeding
At present, the commonly used feeding control method is the constant volume feeding method. Whether the roller amount is uniform with the fruit grain diameter of the raw material and whether there is “bridging” phenomenon at the bottom of the feeding port. If the temperature at the feeding port is too high, it will also cause poor blanking. To this end, the charging port should be dredged and cooled.
8.The material channel is blocked.
When impurities in the molten material block the nozzle or cold material blocks the gate and runner, the nozzle should be folded down to clean or enlarge the cross section of the cold material cavity and runner of the mold.
9.Poor exhaust of the mold
When a large amount of gas left in the mold due to poor exhaust is squeezed by the flow material, resulting in a high pressure greater than the injection pressure, it will hinder the melt from filling the cavity. In the process operation of the mold system, some auxiliary measures such as increasing the mold temperature, decreasing the injection speed, reducing the flow assistance of the gating system, reducing the clamping force and increasing the gap between the molds can be taken to improve the poor exhaust.
10.The mold temperature is too low.
After the melt enters the low-temperature mold cavity, it will cool too fast to fill all corners of the mold cavity. Therefore, the mold must be preheated to the temperature required by the process before startup. When startup, the throughput of cooling water in the mold should be properly controlled. If the mold temperature can’t rise, check whether the design of the mold cooling system is reasonable.
11.cavity filling dissatisfaction
The reason why the cavity is not fully filled is that the injection pressure is insufficient. The relationship between injection pressure and mold filling length is close to the direct ratio. The injPlastic products are very common in life, and plastic products are produced and processed by injection molds. The structure and size of injection molds directly affect the quality of plastic products. During production, some problems of injection mold will also affect the production efficiency.
1.The reset plate of injection mold is not reset.
After the injection mold is opened, the mold reset plate does not reset. The reason for this is that the reset cylinder leaks oil, resulting in uneven stress during reset and unbalanced stress on the reset plate. The reset rod of the die is pulled, the fit between the reset rod and the guide sleeve becomes tight, and the reset plate cannot be pushed out. Check whether the oil seal of the mold reset cylinder is worn or not, if so, replace the oil seal in time, check whether the mold reset rod is pulled, polish and lubricate the mold reset rod.
2.Stuffing of feed nozzle
When the injection mold is opened, the material head of the product is broken and blocked in the feed mouth of the mold, resulting in dissatisfaction when the next product is injected. This is because the hot runner temperature of the mold can’t reach the melting point of raw materials, the sprue of the mold has burrs, or it is caused by improper injection process. Adjust according to the requirements of injection molding process, and check whether the sprue bushing of the mold has burrs.
3.The core-pulling slider does not reset.
If the die core-pulling slider is not reset, it is easy to cause the product to crack. The reason is that the mold slider is tight and the slider return spring fails. Repair the mold slide block and replace the return spring.
4.The product sticks to the cavity.
This is because the injection molded product is not satisfied, and the thimble position of the mold is empty, resulting in the product not being ejected. Also, the cooling time of injection molding products is not enough, and the products are deformed, resulting in the products not being ejected. The solution is to adjust the injection molding process and the cooling time of the mold.
5.The injection products are white.
The causes of whitening phenomenon are insufficient cooling time, blocked cooling water channel of the mold, insufficient demoulding angle of the reinforcing rib of the mold, unsmooth surface of the reinforcing rib and poor roughness. The solution is to check the cooling water channel of the mold, polish the reinforcing ribs of the mold and increase the demoulding angle of the reinforcing ribs of the mold.
6.Poor liquidity
When the fluidity of raw materials is poor, the structural parameters of injection mold are the main reasons that affect the under-injection. Therefore, it is necessary to improve the stagnation defect of the mold gating system, such as setting the runner position reasonably, enlarging the size of the gate, runner and sprue, and adopting a larger nozzle. At the same time, an appropriate amount of additives can be added to the raw material formula to improve the flowability of the resin. In addition, we should also check whether the recycled materials in the raw materials are excessive, and appropriately reduce their dosage.
7.Insufficient feeding
At present, the commonly used feeding control method is the constant volume feeding method. Whether the roller amount is uniform with the fruit grain diameter of the raw material and whether there is “bridging” phenomenon at the bottom of the feeding port. If the temperature at the feeding port is too high, it will also cause poor blanking. To this end, the charging port should be dredged and cooled.
8.The material channel is blocked.
When impurities in the molten material block the nozzle or cold material blocks the gate and runner, the nozzle should be folded down to clean or enlarge the cross section of the cold material cavity and runner of the mold.
9.Poor exhaust of the mold
When a large amount of gas left in the mold due to poor exhaust is squeezed by the flow material, resulting in a high pressure greater than the injection pressure, it will hinder the melt from filling the cavity. In the process operation of the mold system, some auxiliary measures such as increasing the mold temperature, decreasing the injection speed, reducing the flow assistance of the gating system, reducing the clamping force and increasing the gap between the molds can be taken to improve the poor exhaust.
10.The mold temperature is too low.
After the melt enters the low-temperature mold cavity, it will cool too fast to fill all corners of the mold cavity. Therefore, the mold must be preheated to the temperature required by the process before startup. When startup, the throughput of cooling water in the mold should be properly controlled. If the mold temperature can’t rise, check whether the design of the mold cooling system is reasonable.
11.cavity filling dissatisfaction
The reason why the cavity is not fully filled is that the injection pressure is insufficient. The relationship between injection pressure and mold filling length is close to the direct ratio. The injection pressure is too small, the mold filling length is short, and the cavity filling is not satisfied. Therefore, the injection pressure can be increased by slowing down the injection speed and appropriately prolonging the injection time.
The above contents are the common problems and solutions of injection molds. According to the causes of the problems, we can analyze and judge them, and then solve the problems, effectively control the production of defective products, and speed up the production efficiency.
MINGYU MOLD- A professional plastic injection mold manufacturer. Contact Us Now!ection pressure is too small, the mold filling length is short, and the cavity filling is not satisfied. Therefore, the injection pressure can be increased by slowing down the injection speed and appropriately prolonging the injection time.
The above contents are the common problems and solutions of injection molds. According to the causes of the problems, we can analyze and judge them, and then solve the problems, effectively control the production of defective products, and speed up the production efficiency.
MINGYU MOLD- A professional plastic injection mold manufacturer. Contact Us Now!

 

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