Problems and reasons of blow molding machine products

Problems and reasons of MEPER blow molding machine products

As a plastic product producer, the blow molding machine sprays out liquid plastic, and uses the wind generated by the machine to blow the sprayed plastic onto a mold cavity with a specific shape, and cools it to form the product to be produced. This method Greatly improved production efficiency. In the daily production process, there will be some problems with blow molding machine products. Let's understand these problems and their reasons below.

1. The transparency of the product is not good. The reasons may be: the preform is opaque, the secondary heating temperature is too high, the secondary heating time is too long, the blowing air contains moisture, and the surface of the blowing mold is rough.

Solutions: 

(1) dry raw materials, use high-transparency parison;

(2) reduce oven temperature; 

(3) shorten heating time; 

(4) use freeze dryer to remove water; 

(5) polish mold surface.

2. The position of the gate at the bottom of the product is pearly and white, and the reasons are: the blowing temperature of the preform is too low, the blowing time is advanced, the temperature of the preform is uneven, and the drawing line speed is too low, etc.

Solutions: 

(1) increase the secondary heating temperature and prolong the secondary heating time; 

(2) slow down the blowing time; 

(3) change the temperature distribution of the oven; 

(4) increase the drawing line speed.

3. The product cannot be molded. The reasons are: insufficient blowing air pressure, insufficient blowing air flow, too slow rising speed of blowing air pressure, excessive stretching force, and unequal secondary heating speed.

Solutions: 

(1) Increase the air pressure; 

(2) Increase the air flow; 

(3) Improve the pressure regulating structure and increase the air pressure rising speed; 

(4) Choose a reasonable tensile force during design; 

(5) Adjust the temperature of the baking box .

4. The wall thickness of the product is uneven, and the reasons are: uneven wall thickness of the parison, uneven temperature of the parison, low stretching ratio, and offset of the stretching rod.

Solutions: 

(1) Adjust the preform; 

(2) Adjust the temperature distribution of the oven; 

(3) Increase the stretching ratio; 

(4) Adjust the stretching rod.

5. The middle of the product is thin, the reason: the stretch blowing temperature is too high, the middle temperature of the parison is too high, etc.

Solution: reduce the blowing temperature, lower the heating temperature in the middle of the oven.

6. The upper part of the product is thinner and the bottom is thicker. Reasons: the speed of the stretching and blowing line is too high, the choice of blowing time is improper, and the temperature of stretching and blowing is not appropriate.

Solutions: 

(1) reduce the blowing temperature; 

(2) slightly advance the blowing time; 

(3) adjust the heating temperature of the oven, reduce the temperature of the bottleneck part, and increase the temperature of the bottom part.

7. The bottom of the product is thin and the upper part is thick. Reasons: the speed of the stretching and blowing line is too low, the selection of the blowing time is improper, and the temperature of the stretching and blowing is not appropriate.

Solutions: 

(1) increase the blowing speed; 

(2) delay the blowing time; 

(3) increase the temperature of the upper part of the oven and lower the temperature of the bottom. Blowing personnel should always pay attention to checking the quality of the bottle.