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Common problems and solutions in the production of PET bottles by injection molding machines

writer:LI SONG Share

The injection molding process is a complex process that involves mold design, mold manufacturing, raw material characteristics and raw material pretreatment methods, molding process, injection molding machine operation and other factors, and is closely related to processing environmental conditions, product cooling time, and post-processing technology. Process. Therefore, the quality of plastic products not only depends on the injection precision and measurement accuracy of the injection molding machine, but also is affected and restricted by other factors.

Common problems and solutions in the production of PET bottles by injection molding machines:
1. PET bottleneck is skewed
The oil passage is blocked, dredge the mold body oil passage
Exhaust hole of the stretch rod is blocked. Clear the blowing hole of the stretch rod
The nozzle seal is damaged. Replace the nozzle seal.

2. The center point of the PET bottle is off
Pre-blowing pressure is too high, reduce pre-blowing pressure
The pre-blowing flow is too large, reduce the pre-blowing flow
Pre-blowing position is too early, postpone pre-blowing position
Stretch rod bent Replace stretch rod
The gap between the stretch rod and the bottom mold is too large Adjust the gap between the stretch rod
The preform temperature is too high, reduce the preform setting temperature

PET bottle
3. The bottom of the PET bottle is deformed
The bottom mold oil temperature is too high, reduce the hot oil engine oil temperature
The bottom mold blow valve is damaged. Replace the bottom mold blow valve
The temperature of the bottom of the preform is too high, reduce the temperature of the bottom of the preform

4. The bottom of the PET bottle is wrinkled
Pre-blowing pressure is too small Increase pre-blowing pressure
The pre-blowing flow is too small, increase the pre-blowing flow
Pre-blowing too late, pre-blowing early

5. PET bottle-hard neck
Insufficient neck heating Increase the amount of neck heating
Pre-blowing pressure is too large, reduce pre-blowing pressure
The pre-blowing flow is too large, reduce the pre-blowing flow
Pre-blowing too early, delay pre-blowing
The position of the heating furnace is too high. Adjust the position of the heating furnace.
The drawing rod is slow. Overhaul the drawing cylinder

6. Poor molding of the clamping line
Die compensation seal is damaged Replace the compensation seal
Improper adjustment of mold gap Adjust the mold gap

7. The side wall of the PET bottle is deformed before filling
The cooling blow time is too short. Extend the cooling blow time
The mold body temperature is too high, reduce the mold body temperature
There is no cooling air blowing out of the stretch rod. Overhaul the stretch rod blowing system

8. The side wall of the PET bottle is deformed after filling
Mold body temperature is too low Increase the temperature of the mold body hot oil
Preform set temperature is too low Increase preform set temperature
The cooling blow time is too long, reduce the cooling blow time
Uneven plastic distribution Adjust the blowing process to make the material evenly distributed
The flow of hot oil is too small, dredge the oil circuit and clean the oil filter

9. Large shrinkage
Low mold temperature Increase mold temperature
The preform temperature is low Increase the preform setting temperature
The cooling blow time is too long, shorten the cooling blow time
The oil passage is blocked, dredge the oil passage

10. The diameter of the PET bottle is too large or too small
Improper setting of cooling air blowing time Adjust cooling air blowing time
Uneven distribution of plastics Adjust the process to make the distribution of materials even

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