04.03.13 Preform Design for PET Bottles

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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

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28 PCO 1881

Single Start

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

Thread turn

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

• Milk

• Still beverage drinks

• Still water

• Dairy products

• RTD tea

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• Energy drinks

38 CF Bericap

3 start

Thread turn 120°

4.3g

• Juice

• Milk

• Still beverage drinks

• Still water

• Dairy products

• RTD tea

• Energy drinks

25 ROPP

Single

Thread turn 720°

2.8g • Pharmaceutical bottles

28 ROPP

Single

Thread turn 720°

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 neckApplicable closure: Snap top

dispensing caps

For Crown Neck Bottle 29 crown cork neck

For Shampoo Bottles

For Lotion Bottles

For Sprayer 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

28 canyon neck

29-32 neck finish

29-23 special neck

Applicable closures:

Mist spray caps

Trigger spray caps

Pump dispensing caps

Dispenser caps

Flip-top caps

Yorker spout caps

Tilt-top-disc caps

Pull-push caps

Child resistant caps

For Food

For Seasoning

For Personal Care

For Cleaner

33-400 neck

43-400 neck

43-485 neck

45-400 neck

53-485 neck

63-485 neck

Applicable closures:

Pull-push caps

Child resistant caps

Dual door caps

Hinged dispensing caps

Plain caps

Twist caps

toggle swing 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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