All Right Machinery
PET bottle making technology
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Preform Design for PET Bottles
How to optimize preform design and minimize PET resin consumption is always challenging to every bottle maker to obtain quality PET bottles.
Biaxial Stretch Ratio
The Desirable Biaxial Stretch Ratio is around 8
Each direction of X and Y stretch ratio is about 2.83 (R = X x Y)
Length of Preform
Preform length can be decided based on bottle height (minus neck where no stretch is made) divided by 2.83 (l = L / Y)
Diameter of preform
The preform diameter is the bottle diameter divided by 2.83 (d = D / X)
The Thickness of Preform Wall
The preform wall thickness is bottle wall thickness times biaxial stretch ratio
(
w = W x R).
For example, if the desired bottle wall thickness is 0.5mm, height is 300mm excluding neck, diameter is 95mm
Wall thickness of the preform will be around 0.5x8=4mm, (w = W x R);
Length of the preform will be around 300/2.83=106mm, (l = L / Y);
Diameter of the preform will be around 95/2.83=33.5mm, (d = D / X).
R is biaxial stretch ratio, X and Y stands for stretch ratio of each direction.
L is bottle height excluding neck, l is preform length excluding neck.
D is bottle diameter, d is preform diameter.
W is the wall thickness of bottle, w is the wall thickness of preform.
* Above data is obtained from our experiences and observations and it is for reference only for designing most drink bottles with narrow neck finishes. For the preforms of wide neck jars, however, the possibility of processing seems more important than the stretch ratio when we design preforms. Welcome viewers to send us comments for improving preform design.
Neck Designs
Neck design is also important to reduce cost as well as to save non-renewable resources. Remember savings on both preforms and caps (or closures) by selecting right necks! Compare neck designs below may assist your choices.
Threads |
Weight |
Applications |
|
 |
28 PCO 1810 Single Start Thread turn 720° |
5.1g |
Carbonated Beverages
• Cola type drinks • Lemonades • Other soft drinks |
 |
28 PCO 1881 Thread turn 650° |
3.8g |
Carbonated Beverages
Short Bottles • Cola type drinks • Lemonades • Other soft drinks |
 |
28 BPF-C Single start Thread turn 720° |
6.1g |
Carbonated Beverages
• Cola type drinks • Lemonades • Other soft drinks |
 |
28 Alcoa 1716 Single Start |
5.9g |
Carbonated Beverages
• Cola type drinks • Lemonades • Other soft drinks |
 |
28 PCO Corvaglia Single start Thread turn 744° |
3.6g |
Carbonated Beverages
• Cola type drinks • Lemonades • Other soft drinks |
 |
26.75 Alaska 3 start Thread turn 120° |
3.6g |
• Juice • RTD tea • Energy drinks • Spring water • Mineral water |
 |
30/25 low 3 start turn 120° |
3.7g |
• Juice • RTD tea • Energy drinks • Still water |
 |
30/25 high 3 start Thread turn 120° |
3.9g |
• Juice • RTD tea • Energy drinks • Spring water • Mineral water |
 |
38 HF Bericap 2 start Thread turn 180° |
7.0g |
• Juice • Still water • RTD tea • Energy drinks |
 |
38 CF Bericap 3 start Thread turn 120° |
4.3g |
• Juice • Still water • RTD tea • Energy drinks |
 |
25 ROPP Single Thread turn 720° |
2.8g |
• Pharmaceutical bottles |
 |
28 ROPP Single |
3.7g |
• Pharmaceutical bottles |
More preform neck designs for different applications are available in the market.
| For Edible Oil Bottles | 29-21 dropless neck | Applicable closure: Press-on |
| 29-21 snap on neck | Applicable closure: Press-on | |
| 32-25 snap on neck | Applicable closure: Press-on | |
| 32-27.5 snap on neck | Applicable closure: Press-on | |
| 37-29 snap on neck | Applicable closure: Press-on | |
| 39-29 dropless neck | Applicable closure: Press-on | |
| 39-29 snap on neck | Applicable closure: Press-on | |
| For Ketchup Bottles | Special Orientated neck | Applicable closure: Snap top dispensing caps |
| For Crown Neck Bottle | 29 crown cork neck | |
For Shampoo Bottles For Detergent Bottles |
18-410 neck 20-410 neck 22-415 neck 24-410 neck 28-400 neck 28-410 neck 28-414 neck M28 SP400 Ratchet neck 29-32 neck finish |
Applicable closures: Pull-push caps Child resistant caps |
| For Food For Seasoning For Personal Care For Cleaner |
33-400 neck 43-400 neck |
Applicable closures: Child resistant caps Hinged dispensing caps Twist caps Tamper evident caps |
Joint us to discuss and select neck finish for your bottle.
Being cost effective not only reduces cost but also saves world limited resources!
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