Product Categories

Contact Us

Guangzhou Jeepine Intelligent Compression Molding Machine Co.,Ltd
Add:C4 Building of Scientific & Technological Enterprise Accelerator, 11# Kaiyuan Avenue, Science Town of Luogang Development Zone, Guangzhou, China
Tel:+86-20-32394013
Fax:+86-20-32988886
Mobile&Whatsapp:+8613450479355
E-mail:sales@jeepine.com.cn

Jeepine News

Home > News > Content
The Most Complete History Of The PET Bottle Embryo Quality Defect Solution
Feb 11, 2018

The most complete history of the PET bottle embryo quality defect solution

A.what is a PET?

PET is a kind of polyester

Is the abbreviation of English PolyethyleneTerephthalate

English full name: polyethylene terephthalate

The characteristics of PET raw material

Transparency is remarkable as high as 90% above, excellent surface gloss, glass shaped appearance.

Bao sweet sex is superior, the good air tightness.

Excellent chemical resistance, headed by acid is almost all organic drug resistance.

Good health, between PDA - the largest chemical laboratory department approval.

Poison gas burning will not occur.

Strength characteristics of excellence, by biaxial stretching, various features can be further improved.


B.why to dry before production bottle embryo PET raw materials?

1. Remove the moisture in the PET

 

Because the PET has certain water imbibition, in the process of transportation, storage, use can absorb a large number of moisture.High levels of water will increase in the production:

The increase of Acetaldehyde - AA (organic).The impact on the bottles have a smell, leads to sour beverage (but the impact is not big to the human body)

- IV (IntrinsicViscosity) reduced viscosity.Have influence on the pressure of beverage bottle, easy to break.(nature by PET hydrolytic degradation caused by)


2. As the preparation for a PET into the injection molding machine for high temperature shear plasticizing 


3.water absorption properties of PET

 

Water content of raw material particles are usually range in 0.1 0.3% (1000 to 3000 parts per million (PPM)

 

4.the main points of the PET drying

Dry set temperature DHS 165 DHS - 165 C

Residence time 4 to 6 hours

The feed opening temperature more than 160 DHS C

Dew point below 30 DHS C

Dry wind flow after 3.7 m/h per kg/h

5.the dry degree

Ideal water content after drying of about: 10 to40 PPM (+ / - 10 PPM), that is 0.001-0.004%

 

Excessive drying also exacerbate:

The increase of Acetaldehyde - AA (organic)

- IV (IntrinsicViscosity) reduced viscosity

(nature is caused by PET oxidation degradation)


6.how to optimize the production cycle

Open and close mold speed

Ejection speed

Remove the plate and ejector plate spacing adjustment

Sprue shutoff valve open time

Injection speed and maximum pressure limit

The holding pressure/time and cooling time

Manipulator are allowed to enter the mold position setting

(cycle optimization in order to keep the mold under the premise of the average temperature is just right)


7.the reasons of common quality defects and solutions

1)AA value too high

1. material performance has quality problem - raw materials into the warehouse before testing the quality of the raw material

2. drying effect is bad - > check the dryer operation (such as dew point, drying temperature/time)

3. gun barrel heating temperature is too high - temperature as far as possible under the premise that the quality will be reduced

4. and screw back pressure is too high, under the premise that the quality of the back pressure is set to (400 ~ 600 psi)

5. cycle time is too long to optimize the cycle time (avoid raw materials in screw for too long)


2)The bottle embryo yellow

1. the drying time is too long/temperature is too high to have excessive and dry raw material release, to take materials dry

2. gun barrel temperature too high - temperature decrease (generally in the embryo bottle does not produce white mist temperature increasing of 2 ~ 5 ℃) to normal temperature

3. mold temperature is too high - temperature will drop to the appropriate temperature (275 ~ 280 ℃)

4. raw material in screw for a long time, the raw material for the gun barrel hot air injection


3)The wall thickness change rate is too large

1. the screw temperature is too high to turn the screw right temperature

2. and screw back pressure is too large will screw back pressure to fit to the pressure

3. injection speed is too fast and appropriate lower injection speed (generally 3.5 ~ 4 S)

4. mold cooling circulating water temperature of cooling water temperature is too high - inspection (9 ~ 11 ℃ + 2 ℃)

5. cooling time is too short to longer cooling time (generally set up for 3 ~ 4 S)


4)The surface scratch (embryonic body/thread)

1. Clear sticky material - > 1, die mold

2. mold damage to replace the damaged parts or repair

3. remove the plate cylinder damage to replace the damaged the syringes or repair

4. die lip ejection position/stress - ejection position/pressure will be dispatched to the appropriate state

5. remove the plate - > check out inappropriate position of suction tube and the die lip distance location (typically set to: 22 mm)


5) IV drop too much

1. raw material storage time is too long to do first in first out method to use

2. drying effect is bad to check whether the drying machine is normal, maintain dryer, check dry beads use time (usually 2 ~ 3 years to replace)

3. gun barrel heating temperature is too high - temperature as far as possible under the premise that the quality will be reduced

4. and screw back pressure is too large under the premise that the quality of the back pressure, generally set to: 400 ~ 600 Psi

5. mould heating temperature is too high to reduce the temperature of heating temperature, generally set to: 280 ~ 285 ℃

6. bottle embryo storage time is too long or warehouse environment temperature, humidity is too high - inspection of wet/temperature (below is commonly: 70% / 28), completes the first-in, first-out method of inventory

7. raw material itself has the quality problem to inform supplier performance


6)Contraction deformation

1. the cooling time is too short to longer cooling time (set as: 3 ~ 4 s)

2. the holding time is too short/pressure is insufficient to lengthen the holding time (set as: tertiary combined 6 ~ 8 s);Increase the holding pressure (1:800 psi, 2:700 psi, 3:600 psi)

3. mold cooling water temperature on the high side and lower water temperature (set as: 9 ~ 11 ℃ plus or minus 2 ℃)

4. mold elevated circulating water pressure is low - pressure (set to: 6 ~ 7 Kg)


7) No molten material

1. screw, the heating temperature is too low - temperature increasing

2. screw slippage caused to raw materials and shear (general oil production color is this phenomenon) check whether the color oil oil is too high, change the color of oil

3. screw back pressure, pressure is too small to improve screw back pressure

4. the drying temperature is low, check whether the screw feed temperature is achieved (normal requirement for 160 ℃)


8) Bottle is short of material

1. the injection quantity is not enough to increase injection (injection to complete the rest of the position for 5 ~ 8 mm)

2. the injection pressure is too low to improve the injection pressure

3. the injection speed too slow to speed up the injection (optimum injection time is: 3.5 ~ 4 s)

4. the holding position is too large to reduce the holding position (900 ~ 1200 psi) injection pressure is:

5. the holding pressure is too small to increase the holding pressure

6. mold cooling circulating water temperature low to increase the cooling water temperature (set as: 8 ~ 10 ℃)

 

9)Long sprue spin sprue

1. raw material drying effect is poor - > down to dry

2. hot runner valve needle cylinder block to maintain hot runner

3. hot runner/nozzle temperature is too high to turn down the temperature properly

4. the holding time is too short to lengthen the holding time

5. the holding pressure is too small to increase the holding pressure

6. cooling time is too short to longer cooling time


10)The sprue was drawing

1. the hot runner nozzle cannot be closed or nozzle mouth has wear to maintain hot runner or replace a new cylinder nozzle

2. hot runner nozzle temperature is too high to reduce nozzle heating temperature

3. the gate valve closing time delay too long delay to reduce the gate valve closing time

4. control valve failure to maintain valve, valve, needle valve

 

11) Trace moisture

1. die mold cooling water temperature is too low - rise circulating water temperature

2. the workshop temperature or humidity causes sweat to lower air conditioning temperature

3. die mold leaking - inspection leakage causes and ruled out


12) At the bottom of the crystal

1. hot runner and nozzle temperature is low and nozzle and hot runner temperature rising

2. the holding pressure and low pressure reduction the third grade

3. mold cooling water is low or high adjusted again to check whether the cooling water temperature is reasonable

4. cold water passage clogged - die maintenance mould water circulation channel

 

13) The bottle white mist

1.the lack of raw material drying and dry down to the raw material

2. screw heating temperature is too low to improve screw heating temperature

3. screw and skid (general oil production color embryo to appear) will gun barrel temperature increased

4. low back pressure to increase the back pressure stress


14) Bottle embryo black spots/pollution

1. raw materials from the contaminated or itself exists impurities to the impurity of raw material put out smoke, pay more attention to raw material part whether contaminated)

2. the dry raw material is polluted and put the raw materials with quality problems

3. gun barrel temperature/hot runner nozzle temperature is too high - temperature will drop to the appropriate temperature

4. production environment, or poor equipment cleaning and hygiene to keep the workshop and equipment cleaning and hygiene

5. bottle embryo in warehouses to keep the warehouse environment health and packaging are in good condition

  

15) Flash

1. the die lip, mold core, cavity damage to replace or repair damaged parts

2. the injection pressure is too large to reduce the injection pressure

3. too much pressure to reduce pressure or the holding position

4. the heating temperature is too high to reduce the heating temperature

5. clamping pressure is too low to increase the clamping pressure (200 ~ 230 psi is commonly:)

6. raw materials in the heating period of residence time is too long to shorten the production cycle  

16) Bottle skinning

1. the nozzle temperature too high or too low - > section of the nozzle to moderate temperature

2. nozzle mouth wear new nozzle to replace the new nozzle and heat insulation

3. hot runner wear deformation or to replace a new valve valve needle

4. the holding pressure on the third class is too large to low pressure reduction

 

17) The bottom of the bottle inside shrink

1. the mold core cooling pipe scale or rust too much to clean up the mold core cooling channel

2. mold core pipe loose - > new to dismantle pipe

3. water pressure to increase water too (generally as follows: 6 ~ 7 bar)

4. water temperature is too high to adjust the cold water machine the water temperature


18) The doors

1. nozzle temperature is too high to reduce nozzle heating percentage ratio

2. nozzle insulation set to replace the new nozzle insulation aging set

3. the bottom of the cavity cooling water passage clogged - > open mold cleaning the bottom of the cavity

4. water pressure to increase the water pressure

5. the water temperature is too high to reduce the water temperature

 

19) Shark fin stripes

1. mold hot runner temperature is too high to reduce the temperature of hot flow path

2. mold injection nozzle heating temperature is too high to lower the temperature in the nozzle

3. mold injection nozzle heat insulation set of aging to replace the nozzle

4. nozzle needle valve activities were to maintain hot runner or replace the needle valve


20)The sprue pinhole

1. mold nozzle temperature is too high to reduce the nozzle temperature

2. take glue position is too small to the appropriate glue location

3. mold hot runner temperature to lower temperature of the hot runner

4. drying effect is poor to stop new dry (about 2 ~ 3 hours)

5. the injection speed too fast, slow down the injection speed

6. the holding pressure, and time is too small to lengthen the holding pressure and time

 

21) The embryo bottom shrink

1. the injection quantity is not enough to increase injection quantity (rest position is: 5 ~ 8 mm)

2. the holding position is too big and the holding pressure

3. cooling water temperature is too high to reduce the cooling water temperature

4. cooling time is too short to longer cooling time

5. the holding pressure is too small to increase the holding pressure