Common problems in injection molding

 

1. What are the reasons for warpage and shrinkage of injection molded products?

 

Answer: 1. The temperature of the barrel is too low;

2. The molding cycle is too short;

3. The injection pressure is too high;

4. The injection speed is too fast;

5. The pressure holding time is too long;

6. The mold temperature is not uniform, the cooling system of the mold should be adjusted, and the cooling circuit should beset reasonably;

7. The gate section is too small;

8. The design of the ejection mechanism is unreasonable, and the ejection area and ejection point should be increased as much as possible;

9. The mold strength is insufficient, so try to increase its rigidity.

 

 

2. When ABS uses a black masterbatch, the product is easy to break and peel. How to solve it?

 

Answer: Too much toner is used in the pigment of the masterbatch, causing the product to peel off. The masterbatch pigment can be replaced.

 

3. How to control the white product with many black spots and color mixing?

 

Answer: 1. Raw materials. In the process of mixing and batching, pay attention to clean, prevent impurities and dust from mixing;

2. Machine.

(1) The inside of the barrel should be cleaned, whether there is a carbonized layer and glue on the screw;

(2) Whether the screw head, nozzle flange and nozzle parts are tight, the inner wall is smooth and there is no dead angle phenomenon;

(3) Whether the screw head is worn, whether the screw installation center meets the requirements, and whether there is a swing phenomenon.

 3. Mould. The mold runner has no sharp angle, and the pour point should not be too small.

 

4. What are the reasons and troubleshooting methods for injection molding products' lack of injection?

 

Answer: The main reasons and troubleshooting methods of injection molding products are:

1. If the melt temperature is too low, increase the temperature of the barrel and nozzle appropriately;

2. The molding cycle is too short and should be extended appropriately;

3. The injection pressure is low and should be increased appropriately;

4. The injection speed is too slow and should be increased appropriately;

5. The holding time is too short and should be extended appropriately;

6. Insufficient material supply, increase the material supply;

7. The screw back pressure is low and should be increased appropriately;

8. The structure size of the gating system is too small, so the gate and runner section should be enlarged appropriately;

9. Poor venting of the mold, vent holes should be added to improve the venting performance of the mold;

10. The mold strength is insufficient, so the mold rigidity should be improved as much as possible.

 

5. What effect does the temperature of the feed inlet of the injection machine have on the product?

 

Answer: The too high or too low temperature at the feed inlet will cause the unstable material return of the machine, make the feed volume unstable, and affect the size and appearance of the product.

 

6. What are the steps to set the injection molding process?

 

Answer: The steps to set the injection molding process:

1. Set the melt temperature;

2. Set mold temperature;

3. Set the screw conversion position and speed;

4. Set back pressure;

5. Set the injection pressure to the maximum value of the machine;

6. Set the holding pressure;

7. Set injection speed;

8. Set the pressure holding time;

9. Set the sample cooling time;

10. Set the mold opening time;

11. Set the ejection board stroke;

12. Minimize the holding time.

 

7. What are the main reasons for flash in injection molded products?

 

Answer: The main reasons for the flashing of injection-molded products are:

 1. The template is not flat or deformed due to insufficient rigidity of the template;

2. The clamping force is not enough, and the mold is not locked;

3. The injection pressure is too high;

4. The raw material MFR value is too high and the melt viscosity is low;

5. The material temperature and mold temperature are too high.