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How to Solve Common Problems in PET Stretch Blowing Machine

  PET stretch blowing machine common problems solutions see as below:

 

No. Forming situation Reason Solution
1 Roll up or buildup at the bottom or neck of bottle Delay minor blowing time too long Shorten the delay minor blowing time
Temperature too low at the place where buildup Raise the heating temperature at corresponding place in tube blank
2 Deformation at bottleneck Blank head overheat Check cooling water circulating
Temperature of 1st segment heating lamp too high Reduce the voltage of 1st segment heating lamp
Air circulation not equal in heating case Check the ventilator fan in heating case.
3 Bottom of the bottle too thick Preheat of bottle bottom not finished Raise temperature of heating case
Blowing too late Blowing in advance
Advance blowing pressure too low Increase advance blowing pressure
4 bottle bottom broken Humidity not enough, permeation not enough Increase humidity
Delay stretching time too long Shorten delay stretching time
Extension ratio too large Reduce extension ratio
Bottom of tube blank too thin Improve bottom design of tube blank
5 Buckling in bottle bottom Temperature of bottom too high (poor cooling in sprue) Reduce the temperature of bottle bottom properly
Advance blowing too late Advance blowing 0.1~0.2s ahead
Blowing time too short Longer blowing time 0.1~0.2s for 1 to 3 times
Advance blowing pressure too low Increase advance blowing pressure
6 Bottle bottom not full Temperature of bottle bottom too low Increase the temperature of bottom of heating area
No enough air release hole or not equal at the bottle bottom of mold Add air release hole and make them distribute equally.
Design of stretching rod head not corresponding with the shape of bottom of tube blank Replace stretching rod head
Blowing pressure not enough Increase blowing pressure
rate of flow not enough at blowing valve Wash blowing valve by gasoline
Blowing time too short Increase blowing time
7 Decentration on bottle bottom Related to bottle blank temperature, advance blowing, high pressure blowing etc. Reduce temperature of bottle blank; faster stretching speed; check the gap between stretching head and bottom mold; delay advance blowing, and reduce advance blowing pressure; delay high pressure blowing; check whether bottle blank decentration
Stretching too short Make sure the stretching rod leave bottle bottom for 0.1mm
Delay minor blowing time too short Increase delay minor blowing time
8 Bottom become white Temperature too high Reduce temperature
Bottle blank too cold Raise the temperature of bottle blank
The weight of bottle blank is too light Add weight of tube blank
Stretching rod shifted from the centre line of bottle Adjusting the position of stretching rod
Advance blowing too late, advance blowing pressure too low Increase advance blowing pressure
Stretching rod didn’t reach the bottom Adjusting the position of magnet ring switch
Temperature too high Reduce temperature
Thickness of tube blank is not equal Improve the quality of tube blank
Injection density is not equal Improve the heating
Heating not equal Check whether the rotation of tube blank has problem
9 Bottle bottom too thin Blowing too earlier Delay blowing time
Temperature of bottom is too high Reduce temperature of bottom
Bottom of tube blank is too thin Increase the thickness of bottom of tube blank
10 Bottle sticked on the base mold The time of mold closing and base mold raising is not synchro Faster the raising time for base mold
Plastic blowing time is too short Longer the plastic blowing time
11 Buckling at the middle of bottle Blowing time is too short Longer blowing time 0.1~0.2s for 1 to 3 times
Temperature of middle of bottle is too low Increase the temperature of middle of bottle properly
12 Crack at the middle of bottle just after blowing Whole temperature of tube blank is too low Increase the temperature of whole oven tunnel, increase properly the voltage of infrared lamp from 1st segment to 7th segment
Delay minor blowing time is too long Shorten delay minor blowing time
Temperature difference of every part of bottle blank is too large Heating equably
13 Bottle blank sticked on the stretching rod No minor blowing or high pressure air source Adjust minor blowing and high pressure air source
Blowing valve not working Check whether blowing valve connected power, whether industry blowing valve opened
14 Bottle blank stretched longer, but not expanded No high pressure air source Open high pressure air source
Blowing time is too short Longer blowing time
15 Upper part of bottle is too thick Temperature of upper part is too low Increase temperature at upper part
the position of air release hole of mold is far from upper part Adjusting the position of air release hole
Extension ratio is too low Increase extension ratio
Blowing ratio of upper part of bottle is too low Change the shape of bottle
The speed of stretching rod is too slow Adjusting the speed of stretching rod
16 Obvious mold closing line The pressure for mold closing is not enough Increase the mold closing pressure, adjust the angle of support rod for mold closing (<5̊)
Sealing is too earlier Move backward the position of position switch of mold closing
17 Mold closing line with different size Mold closing is too loosing Lock tightly the mold base
18 Whole bottle turbid and not transparent Whole temperature of bottle blank is not enough Increase whole temperature
19 The transparent of bottle is not good Heating temperature is too high Reduce the temperature
Heating time is too long Shorten the heating time
moisture in the compressed air Removing moisture by dryer
The tube blank is not transparent itself Improve the quality of tube blank, select to use material and improve the dryness of material
Tube blank design not proper Improve the size design of tube blank
The blowing ratio is too small Reduce the diameter of tube blank
20 pearly luster and whiten on the bottle Heating temperature is too low Raise temperature or slower the rotation speed
The thickness of tube blank is unequal Improve the quality of tube blank
The thickness of tube blank is too thick, heating permeation not enough Reduce the thickness of tube blank, or try to raise the cover of heating equipment, so as to increase the temperature distribution on the surface of tube blank
21 There is prints on the bottle The quality of tube blank is not good Check the quality of tube blank
Mold not clean Cleaning the mold
22 Deformation just after leaving mold Blowing time too short Increase the blowing time
The temperature of cooling water is too high Reduce the temperature of cooling water
23 Thickness distribution unequal at axial direction Temperature of tube blank is unequal Adjusting heating temperature
Advance blowing pressure too low or too high Increase or reduce advance blowing pressure
Advance blowing too late or too earlier Earlier or later advance blowing
24 Deformation after a longtime Bottle blowing pressure too low Increase bottle blowing pressure
Bottle blowing too short Longer the bottle blowing time
25 Bending when heating bottle blank Rotation wrongly when heating bottle blank Make sure whether touch or hit aluminium baffle-board, etc.
Overheat at partial of bottle blank Adjusting the output of heater
Pimple on the bottle blank Check whether the bottle blank is qualified
26 Volume of produced bottle not enough didn’t blowing to form shape Check whether there is jam at the outlet
Air pressure not enough for plastic blowing Check the air circuit and supply source for plastic blowing

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