Bottles, Preforms and Closures: A Design Guide for PET Packaging
180
Bottles, Preforms and Closures: A Design Guide for PET Packaging
180eBook
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Overview
As a consultant to the plastics industry, Ottmar Brandau’s focus is on using his engineering knowhow and production management experience to improve quality and productivity, cut down cycle time and introduce secondary processes such as inline printing. This book is a thoroughly practical handbook that provides engineers and managers with the toolkit to improve production and engineering aspects in their own businesses – saving money, increasing output and improving competitiveness by adopting new technologies.
In this book, Brandau covers the engineering aspects of bottle production and the relevant production processes (focusing on blow molding), along with plant layout and organization and production management, to produce the definitive handbook for engineers and managers alike.
- Learn the tricks of the trade from an experienced engineer and manager
- Save money: Practical strategies to improve cycle times
- Increase productivity: Improve plant layout and organization and implement secondary processes such as inline printing
Product Details
| ISBN-13: | 9781437735284 |
|---|---|
| Publisher: | Elsevier Science |
| Publication date: | 06/29/2012 |
| Series: | Plastics Design Library |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 180 |
| Sales rank: | 383,987 |
| File size: | 5 MB |
About the Author
Read an Excerpt
Bottles, Preforms and Closures
By Ottmar Brandau
Elsevier
Copyright © 2012 Elsevier Inc.All rights reserved.
ISBN: 978-1-4377-3528-4
CHAPTER 1
PET Beverage Bottles
Dr. Christian Detrois, and Thomas Steinbauer, formerly with Krones AG
Chapter Outline
1.1 From the First Idea to the Finished Bottle 2
1.1.1 Development Over the Past 25–30 Years 2
1.1.2 Starting Point of a Product Development 4
1.1.2.1 Product Life Cycle 4
1.1.2.2 Competitors 6
1.1.2.3 Product 7
1.1.2.4 Filling Process 7
1.1.2.5 Bottle Transport 8
1.1.2.6 Preform 9
1.1.2.7 Shape of the Base 9
1.1.2.8 Mouth/Neck/Cap 9
1.1.2.9 Volume 10
1.1.2.10 Markets 11
1.1.2.11 Labeling 11
1.1.2.12 Transport Packaging Specifications 11
1.1.2.13 Approval Procedure 11
1.1.2.14 Time Frame 12
1.1.3 Design Engineering 12
1.2 Determination of Bottle Properties 13
1.2.1 Top Load 13
1.2.2 Internal Pressure 14
1.2.3 Handling Stability 14
1.2.4 Stress Cracking 14
1.2.5 Barrier 15
1.3 Generating the First Design in CAD 17
1.3.1 The Bottle Design Already Exists 17
1.3.2 Creation of a New Design 18
1.4 From Shape to Full-Fledged Design for a Dependable Process 22
1.4.1 From the Ideal to the Real Preform 22
1.4.1.1 Standard Preform 22
1.4.1.2 Purpose-made Preform 22
1.4.2 Bottle Design for a Dependable Process 24
1.5 Verification of the 3D Design Through Finite-element Simulation 26
1.5.1 What is FEM? 26
1.5.2 What FEM Can Do 27
1.5.3 What FEM Cannot Do 28
1.6 Selection of the Mold Concept to Meet Customer-specific Criteria 28
1.6.1 Shell Molds 29
1.6.2 Hot-fill Molds 29
1.7 Mold Design and Mold Manufacture 30
1.7.1 Mold Design 30
1.7.2 Mold Making 34
1.8 Mold Trials and Examination of Sample Bottles 35
1.8.1 Mold Trials on Laboratory Machines 35
1.8.2 Process Finding During Mold Trials 37
1.8.3 Laboratory Tests on Sample Bottles 38
1.8.3.1 Verifying the Main Dimensions 38
1.8.3.2 Capacity 39
1.8.3.3 Top Load 40
1.8.3.4 Burst Pressure (or Internal Pressure) Tests 41
1.8.3.5 Stress Cracking Resistance 42
1.8.3.6 Fillability 42
1.8.3.7 Crystallinity 42
1.8.3.8 Drop Test 43
1.8.3.9 Barrier 44
1.8.3.9.1 Barrier Against Oxygen 44
1.8.3.9.2 Barrier Against Loss of CO2 44
1.8.3.10 Segment Weight Distribution 45
1.1 From the First Idea to the Finished Bottle
"Think Process – Not Product"
1.1.1 Development Over the Past 25–30 Years
The market for PET bottles has seen a dramatic growth over the past 25 years. According to figures of DeWitt & Company Incorporated, worldwide PET consumption for bottle production was only 970,000 tons in 1988 and has increased to a staggering 13,954,000 tons that was estimated for 2011. With this growth, the market and economic conditions affecting bottle production have also changed dramatically.
Although driving down costs was a central theme in product development in the 1980s, that focus has shifted to innovation. It is no longer enough to keep costs down and shorten time to market. Today, the ability to innovate has become vital.
Furthermore, the processes within product development have changed significantly, in particular, in countries with higher price levels. What started as a serial development, i.e., the sequential processing of tasks, became parallel or concurrent processing of individual steps in the 1990s, and is now characterized by the utilization of a company's total resources for a single project, sometimes even on a global scale.
With regard to organization, the 1980s were dominated by departmental thinking. The 1990s saw the introduction of project groups that have since become highly flexible teams as a result of the ever-increasing requirements of product development. For each project, the right people are brought together from the available resources to achieve the best results and keep the time to market as short as possible. Ideally (and in some large companies this has already become a reality) the employees no longer have their own desks but rolling workstations, which can be moved together for flexible project work.
The big challenge today lies in making the technological knowledge – which in most cases is still locked up in the brains of the more experienced staff – available to the entire company and securing its availability to the company for the future. State-of-the-art CAD systems in conjunction with databases now permit such an advanced knowledge management.
The figure above illustrates how documentation and use of the accumulated knowledge developed over time. About 30 years ago, the first digital 2D drawings still left a great deal of scope for interpretation, especially with respect to design elements that were complex and difficult, or even impossible, to describe in geometrical terms. The 1990s saw the introduction of 3D systems that were able to display free-form surfaces and design elements of sophisticated containers. This kind of visualization was still somewhat feature oriented, but around the turn of the millennium, larger companies started using digital processes. Unlike mere mold makers, such companies – in a manner similar to machinery and systems suppliers that offer a comprehensive mold service – have adopted a process approach, which also means that questions of transport or filling are already addressed during the development phase. This comprehensive approach can best be described by the maxim "Think process – not product." Today, rule-based computer systems and software packages are used, which make it possible to examine, verify, and benchmark the required container at a very early stage. For example, modification of the shoulder part of a bottle can be analyzed and evaluated in different variants to establish the best solution as a benchmark.
Such knowledge-based systems enable organizations to maintain the accumulated expertise and make it accessible to all employees, irrespective of their geographical location. This is the only way short development times can be achieved in a cost-efficient manner. It should be noted, however, that only high-end systems such as Unigraphics NX permit such a style of working and offer an efficient support in the day-to-day work.
1.1.2 Starting Point of a Product Development
Experience has shown that 80% of the costs for developing a product are determined at a very early stage in the design phase. Even before the first stroke of the pen or the first click of the mouse in the CAD system, a number of issues must have been settled to permit an efficient and speedy development of a product design in cooperation with the customer. In this respect, the sequence in which the questions are addressed is not critical and may differ with each specific project.
1.1.2.1 Product Life Cycle
One of the first things to determine is the intended product life cycle. Will it be a premium product with a very long useful life? A mineral water bottle for the catering trade, for example, which is placed on the table by the waiter, must have a high-quality design that stands the test of time as well as being physically robust. Premium products also serve to enhance the identification with the brand. Global carbonated soft drink (CSD) suppliers sell their products in bottles with a characteristic design, which are good examples of long-life products.
At the other end of the range, there are low-cost bottles for six packs, discount chains, or seasonal products that may only be offered for a single summer. Such seasonal products can be found in Asia, for example, where certain types of tea are sold in bottles that are specifically designed for each harvesting season. This of course results in very short life cycles for the container designed.
In this context the question of whether the bottle is intended to be returnable or nonreturnable will be answered.
1.1.2.2 Competitors
Identification of competitors and the specific products with which the new container will compete will affect the bottle design. It is hardly useful to develop a product only to discover that it is too similar to something already offered by a competitor. Here, a close cooperation with the customer's marketing department is required.
1.1.2.3 Product
Another key issue is the product for which the bottle will be used. Still or carbonated mineral water, CSDs, beer, fruit juice, tea, or dairy products each require different design features.
1.1.2.4 Filling Process
Directly related to the contents is the question of the filling method, which also should be discussed in the very early design phases. Will the contents be aseptically filled or hot filled? Will the bottle be pressurized? Will a nozzle be used to spray nitrogen over the contents to eliminate oxygen from the headspace? It is also important to know if and how much the contents tend to foam. Will a long-tube filler or spreader be used? In the latter case, it is important that the contents can flow down the inner wall of the bottle without protrusions that may disrupt the flow.
1.1.2.5 Bottle Transport
How will the bottles be transported during production? Will the bottles coming from the stretch blow molding machine be transported through the subsequent process stages by an air conveyor or a conveyor belt? Which type of conveyor belts will be used? In addition to rubber mat-top conveyors, gravity roller tables, and articulated conveyor belts, there are also combinations of the above and special designs, which in turn raise the issue of speed differentials within the same conveying system. Apart from the conveying medium, e.g., air conveyor or conveyor belt, the speed of transport has an impact that should not be underestimated.
1.1.2.6 Preform
Another key question relates to the preform: Will a standard preform be used? Has this already been selected or determined, or will a special-purpose preform be developed? (read more in Chapter 2).
1.1.2.7 Shape of the Base
In some cases the base of the bottle must have a specific shape. In general, the following base shapes are possible, but these are merely given as examples because there are numerous variants:
• Multiple-foot base: The most well-known multifoot base is the petaloid base. Footed bases that are resistant to internal pressure are used for carbonated contents, such as mineral waters, beer, and CSDs, when the internal pressure exceeds 1 bar. Apart from the petaloid base, there are many special variants.
• Still water base: For still products with no internal pressure, a still water base can be used. Bases of this type use an outer, circular rim on which the bottle rests. The center of the base is more or less dished internally and ribs may be used to mold a thin but strong base.
• So-called champagne bases offer a good resistance to internal pressures up to 4 bar. This type of base design is characterized by a higher wall thickness in the base area. As a result of the required special preforms with a step core design (and a lower output during blow molding), this variant is more expensive and is therefore preferably used in the premium sector and beer.
• For hot-filled products, special hot-fill bases are used, which are resistant to the vacuum load created when the contents cool down.
1.1.2.8 Mouth/Neck/Cap
The selection of the bottle neck finish (28 mm, 38 mm, PCO, etc.) also raises the question of which type of closure or cap is to be used (see Chapter 3).
Again, the contents will have a major influence on the final definition of the neck finish.
• The PCO neck (PCO for plastic closure only), in what has become a standard diameter of 28 mm, is used for carbonated products. One of the characteristic features of this design are the vertical grooves in a multiple-turn thread, which allow excess pressure to escape in a controlled way when the bottle is opened. With this neck design, the cap must be rotated by at least 1.5 turns before it is lifted off.
• Still water necks.
• Wide-neck designs with diameters from 38 mm to 55 mm are used, for instance, for mixed milk drinks, although they are frequently selected purely for marketing reasons.
(Continues...)
Excerpted from Bottles, Preforms and Closures by Ottmar Brandau. Copyright © 2012 Elsevier Inc.. Excerpted by permission of Elsevier.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Table of Contents
Part One: PET Preforms (Ottmar Brandau, Dr. Laura Martin)1. Introduction2. Manufacture and States of PET3. Behaviour in the Blow Mould4. Manufacture of PET Preforms5. Preform Design Methodology6. Preform Design Examples
Part 2: PET Beverage Bottles (Dr. Christian DeTrois, Thomas Steinbauer)1. From the First Idea to the Finished Bottle2. Determination of Bottle Properties3. Generating the First Design in CAD4. From Shape to Fully-Fledged Design for a Safe Process5. Verification of the 3D Design through FE Simulation6. Selection of the Mould Concept to Meet Customer-Specific Criteria7. Mould Design and Mould Manufacture8. Mould Trials and Examination of Sample Bottles
Part 3 Closures for PET Bottles (Ottmar Brandau, Romeo Corvaglia)1. Introduction2. Neck Finishes for Various Bottle Types3. Closure Types4. Tamper Evident Bands5. Resins6. Manufacturing Methods7. Economic Guidelines8. Test Procedures9. Process Control during Injection Moulding; Light-weigh caps, new standards
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A practical handbook for a major area of plastics processing, the author's focus on fault analysis and troubleshooting is targeted at practicing engineers and directly impacts the bottom line by improving production efficiency and product quality.
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