Design Guide for Plastics

April 2009

Design Guides for Plastics Clive Maier, Econology Ltd

TANGRAM TECHNOLOGY

This publication is made up of a series of articles published in Plastics and Rubber Weekly as a piece work. The kind assistance of the author and PRW is acknowledged in the publication of the work. The publication will be updated in a regular basis as new sections of the guide are published by PRW.

The design hints in this booklet are given in good faith and represent current good practice. The short nature of the hints means that not all information can be included. No responsibility can be taken for any errors or consequential damages resulting from using these hints. This publication may be freely reproduced except for sale or advertising purposes. It may be hosted on web sites for free downloading providing that it is used in it’s entirety and that reference is made to the original publication. © Clive Maier 2004
Typeset by Tangram Technology Ltd.

Contents
Preface ........................................................................................... 1 Introduction ................................................................................... 2 Injection moulding......................................................................... 4
Basics
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. Wall thickness .......................................................................................... 5 Corners...................................................................................................... 6 Ribs ........................................................................................................... 7 Bosses .................................................................................................... 10 Design for recycling .............................................................................. 13 Living hinge

Links: on most pages take you to a literature library where scores of design articles, guides and manuals are available for downloading. Dow too has a massive library onsite, and it is particularly easy to locate what you want. You can navigate by product, market or process. A product finder help designers to select appropriate materials by defining market, application and manufacturing process. Designers are always inspired and emboldened by what other people have done, so they will particularly appreciate Ticona’s picture library which is searchable by market, process, material or keyword. The ‘TechInfoCenter’ contains a library of downloadable design guides and manuals, while its materials database makes it easy to compare different options. GE Plastics was renowned for its design initiatives and the tradition lives on under its new identity as Sabic Innovative Plastics. The website includes online calculators for stiffness, flow, snap-fits, fatigue, part cost and thermal analysis. On top of that, there are quick calculators for shear rate, thread failure, weight, modulus across the flow direction, tooling volume, boss design, thermal stress, thermal expansion and beams. BASF is another to provide design software tools. Its calculators for beams, screws and snap-fits come as downloadable ZIP files that you extract and install as executables on your own PC. Bayer MaterialScience maintains separate ‘TechCenters’ for plastics, polyurethanes, thermoplastic polyurethanes, and coatings, adhesives and sealants. its Plastics TechCenter is the gateway to a literature library and a number of design aids, including a test version of Bayer’s software tool ‘Design + Processing Properties’ that provides calculations to support the design of parts and moulds. D+PP works via a downloaded and locally-installed web client which accesses a central Bayer DPP server via the internet. While onsite, be sure to check out Fantasia, a link to dedicated BASF site that helps designers visualise the use of colours and special effects on plastics parts. This brief survey gives only a glimpse of what is available to the designer from just of few of the many manufacturers of thermoplastics. So the message is build up your bookmarks to make the most of these free resources. BASF PlasticsPortal – Europe Bayer MaterialScience Dow Engineering Thermoplastics DuPont SABIC Innovative Plastics Ticona http://www.plasticsportal.net/wa/ plasticsEU~en_GB/ http:// www.bayermaterialscience.com/ http://plastics.dow.com/plastics/ eur/ http://plastics.dupont.com/ http://www.geplastics.com/ http://www.ticona.co.uk/ 62 About Econology: Econology is a plastics industry information service company, with particular expertise in communications and software. The bedrock of the business is a long record of industrial experience and achievement but what makes the company effective is a mastery of information sources and technology. Our strength is knowing where to find and how to use facts and figures, buyers and sellers, media and markets, technology and training, processes and people. Econology is directed by Clive Maier, a plastics industry professional and a Fellow of the Institute of Materials Minerals & Mining. He writes regularly for leading plastics industry journals circulating in the UK, Europe, and South East Asia. Other publications include a major volume on polypropylene and a number of other books and industry reports. For further details about Econology, contact: Clive Maier Econology Ltd. 4 Norsted Lane, Pratts Bottom ORPINGTON, BR6 7PG Tel: [phone], Fax: [phone], email: [e-mail]