Plastics Product Design Part 12 doc

Engineering data information source ___ -- In addition to what has been presented throughout this book such as the sobare on designing products in Chapter 5, this section provides sour

metalworking permits tolerances as low as one tenth of those on the drawing, assuming the latter being reasonable for plastics

Under difficult circumstances, it has been proved to be a good practice

if critical dimensions are kept smaller in the mold first, and then being revised after a test run under production conditions thus permitting machining the cavity if required In any case, close tolerances should be applied on such dimensions only as directly related to invariable mold dimensions Any otlier dimension, which is related to a mold dimension

in two different mold parts, should allow a generous tolerance

Economical production requires that tolerances not be specified tighter than necessary However, after a production target is met, one should mold “tighter” if possible, for greater profit by using less material Many plastics change dimensions after molding, principally because their molecular orientations or molecules are not relaxed To ease or eliminate the problem, one can change the processing cycle so that the plastic is “stress relieved,” even though that may extend the cycle time Also used is heat-treat, the molded part based on experience or according to the resin supplier’s suggestions

Theoretical efforts to forecast linear shrinkage have been limited because of the number of existing variables One way to solve this problem is to simplifjr the mathematical relationship, leading to an estimated but still acceptable assessment This means, however, that the number of necessary processing changes will also be reduced

The parameters of the injection process must be provided They can either be estimated or, to be more exact, taken fi-om the thermal and rheological layout The position of a length with respect to flow direction is in practice an important influence This is so primarily for glass-filled material but also for unfilled thermoplastics The difference between a length parallel to (0”) and perpendicular to (90”) the flow direction depends on the processing parameters Measurements with unfilled PP and ABS have shown that a linear relationship exists between these points

Regarding this relationship, when designing the mold it is necessary to know the flow direction To obtain this information, a simple flow

pattern construction can be used However, the flow direction is not constant In some cases the flow direction in the filling phase differs from that in the holding phase Here the question arises of whether this must be considered using superposition

In order to get the flow direction at the end of the filling phase and the beginning of the holding phase (representing the onset of shrinkage),

an analogous model was developed that provides the flow direction at

A differential (two dimensional/quasi) equation has the same form as is used for a stationary electrical potential field,

as it can be realized with an unmantled molding out of resistance paper and a suitable voltage

To control the theoretically determined flow with respect to the orientation direction, a color study was made The comparison between flow pattern, color study, and analogous model is shown in Figs 6.8 and

6.9 For a simple geometry the flow pattern method describes the flow direction in the filling phase as well as the holding phase (Fig 6.8)

This description changes when a core is added and the flow is disturbed

(Fig 6.9) In this case the flow at the beginning of the holding phase differs from the flow pattern as it is shown in the color study as well as

in the analogous model Even the welding lines are broken in the holding phase so that at this place another flow direction than that in

the filling phase is found With further measurements this influence has

to be tested by using more-complcx moldings Available are computer

s o h a r e programs that provide guide lines to melt flow behavior in the mold cavities (Chapter 5)

Recvcled Plastic

When plastics are granulated the probability is its processability and performance when reprocessed into any product may be slightly reduced; could be significantly rcduced Fig 6.10 shows how

properties per ASTM tests for different plastics can effect properties of

Figure 6.8 Comparison between an analogous model, flow pattern studies

Figure 6.9 Comparison between an analogous model, a flow pattern studies with a core added

fig re 6.1 0 Example of the effect o f recycling plastics once through a granulator

or without virgin plastics is subject to operating in a larger fabricating process window (Chapter 1 )

Different approaches are used to improve performances or properties of

mixed plastics such as: (1) additives, fillers, and/or reinforcements (use specific types such as processing agent, talc, short glass fibers), (2) active interlayers (crosslinking, molecular wetting), and (3) dispersing and diffusing (fine grinding, enlarging molecular penetration via melt shearing)

Most processing plants have been reclaiming/recycling reprocessable

TP materials such as molding flash, rejected product, film trim, scrap, and so on during the past century TS plastics (not remeltable) have been granulated and used as filler materials

If possible the goal is to significantly reduce or eliminate any trim, scrap, rejected products, etc in an industrial plant because it has already cost money and time to go through a fabricating process; granulating

just adds more money and time Also it usually requires resetting the process to handle it alone (or even when blending with virgin plastics and/or additives) because of its usual nonuniform particle sizes, shapes, and melt flow characteristics Perhaps it was overheated during the cutting action of a granulator, etc Keeping the scrap before/afier granulating clean is an important requirement

When fiber RPs are granulated, the lengths of the fibers are reduced

On reprocessing with virgin materials or alone, their processability and performance definitely change So it is important to determine if the change will affect final product performances If it will, a limit for the amount of regrind mix should be determined or no recycled RP is to be used Consider redesigning the product to meet the recycled performance or use it in some other product

Engineering data information source _

In addition to what has been presented throughout this book such as the sobare on designing products in Chapter 5, this section provides source information concerning plastic material data basis The available information worldwide has reached a volume that makes it impossible for one to review all the sources In order to retrieve the desired or needed information, indexes and abstracts are continuously prepared by individual libraries, technical organizations, and professional societies

By the 1960s computers became available for storing and manipulating information This lead to the creation and marketing of automated data banks

Available for manual searching are abstracts that typically provide the name of the author, a brief abstract of the article, the title of the article, and identifl where the article was published Alphabetical author and subject indexes are usually provided, and an identifling number is assigned to refer to the abstract Many abstracts are published monthly

or more frequently Annual cumulations are available in many cases A comprehensive listing of abstracts and indexes can be found in Ulrich’s International Periodical Directory (annual from R R Bowker, New York) Most of the major indexes and abstracts are now available in machine- readable form For a comprehensive list of databases and online vendors

see Information Industry Market Place (International Directory of

Information Products & Services from R R Bowker, New York) The names of online databases frequently differ from their paper counterparts Engineering Index (monthly from Engineering Information Inc.) for

6 - Plastic performance 425

example, offers COMPENDEX and Engineering Meetings online

Many of the professional societies producing online databases will

undertake a literature search A society member is frequently entitled to

reduced charges for this service In addition to indexes and abstracts, periodicals, encyclopedias, and handbooks are available online There seems to be virtually no limit to the information that can be made available online or on CD-ROMs, which can be networked in large institutions with many potential users Thc high demand for quick information retrieval ensures the expansion of this service In addition

to the online indexes, several library networks and consortia, such as OCLC, the Online Computer Library Center, located in Columbus, Ohio, produce online databases These are essentially equivalent to the catalogs of member libraries and can be used to determine which library owns a particular book or subscribes to a particular periodical

Publication

The major emphasis on information is placed on publications and services designed to identifjr and obtain information Because of space limitations references to individual works, which contain the required information, are limited to a few The most important source of information is the primary literature It consists mainly of the articles published in periodicals and of papers presented at conferences New discoveries are first reported in the primary literature It is, therefore, a major source of current information Most engineers are familiar with a few publications, but are not aware of the extent of the total production

of primary literature

As an example there is the publication Machine Design that issues 22

per year It covers design engineering of manufactured products across the entire industry spectrum It offers solutions to design problems, new technology developments, CAD/CAM updates, etc It is published by Penton Media, Inc., 1100 Superior Ave., Cleveland, OH 44114; Tel 216-696-7000; Fax 216-696-8765; website

wvw machinedesign com

Engineering Index (Engineering Information Inc published monthly) abstracts material fiom thousands of periodicals and conferences It is known as Compendex in its electronic version

Handbooks and encyclopedias are part of the secondary literature (included in the Bibliography section) They are derived from primary sources and make fiequent references to periodicals Handbooks and encyclopedias are arranged to prescnt related materials in an organized fashion and provide quick access to information in a condensed form

While monographs include books written for professionals, they are either primary or secondary sources of knowledge and information Textbooks are also part of the tertiary literature They are derived from primary and secondary sources Textbooks provide extensive explanations and proofs for the material covered to provide the reader with an opportunity to understand a specific subject thoroughly

Thomas Register

Use has always been made by many of the Thomas Register of

American Manufacturers These books may occupy considerable real estate either in your office, your company’s library, or somewhere in purchasing The people at Thomas Register have developed (since 2000) two things that are of considerable help to those who have come

to rely on this reference The first are Thomas Register CD-ROMs, and the second is the Thomas Register web site One can get at the Thomas Register web site at www.thomasregister.com

The first time user must register to use it, but registration is free The Thomas Register web site offers several distinct advantages over the traditional printed version The first few advantages are obvious and not really exciting One is simply real estate Finding a place to store (much less use) the bound versions of the register is difficult If you have access

to the Internet, you have access to the register The second big advantage is, in theory, how current the information is One would assume that an electronic version would be updated morc often than volumes you have sitting on your bookshelf The improvement in storage space is met with the CD-ROM version as well

Once registered, you can move directly to the search portion of the site, where you are allowed to search on a company name, product or service, or brand name Selecting one of these three categories and entering the appropriate key word or words, the register quickly returns

a set of broad categories For example, searching under the word

“extrusion” under products/services yielded 157 product headings Obviously this contains a significant number of categories that are not appropriate for plastics extrusion, but serves as an example Each product heading is reported along with a set of columns recording the number of companies found, (and now the bigger and vcry exciting advantages of the web site) the number of companies with on-line catalogues, the number of companies with literature requests via fax, and the number of companies with on-line ordering and links to web sites

Selecting one of the broad product headings gets one into the listings

of the individual companies themselves, where, if available, one can

6 - Plastic performance 427

jump to an on-line catalogue, on-line ordering, or move to the company’s web site If none of these features are available, there is a short blurb about the company, location, phone numbers, and what type of products they offer, very similar to the “bare-bones” listing in the bound versions of the register The designers of the Thomas web site have done an excellent job in that they split the screen when you jump to a company web site The left-hand side of the screen gives you the Thomas Register choices of contacting the company, etc while the right hand side is the site of the individual company

As with any conventional desk reference, the primary means of contact

with the bound versions of the Thomas Register is the telephone With the web site, to be able to go from a search for a list of suppliers of a

given item or service (either nationally or by state) to order from an on- line catalogue is a huge advantage and one would suspect, an advantage for a company that offers that option A cursory stroll through a few randomly chosen categories shows that not everyone is offering on-line catalogues and on-line ordering Look for these services to grow considerably as more and more people begin to rely on the Internet for goods and services

Thomas Regional Directory Company has been in business since 1977, and publishes 19 Regional Industrial Buying Guides, in print and on CD- ROM, and now on a web site (www.thomasregional.com) The Thomas Regional Dircctory is listed as a “partner” to the Thomas Register

Thomas Regional provides access to a searchable database of more than 480,000 manufacturers, distributors, and service companies organized under 4,500 product/service categories in 19 key U.S industrial markets As with the Thomas register, one can search by product/ service or company name in the region of interest to you As Thomas Regional points out in their own introduction

You can also refine your search based on company type (manufacturer, distributor, manufacturer’s rep, and service company), geographic location (state, city/county, area code), trade name, key words, and other specifications such as I S 0 9000 certified, and minority and woman-owned businesses View also supplier brochures, catalogs, line cards, and fax forms and contact suppliers directly via our Contact Company feature

Thomas Regional also offers listings (by region) of trade shows and special events, including locations, dates, contacts, listings of industry and professional organizations, and government and business resources Where available, each reference has a link to the web site of the organization in question They will begin offering some new features

that capitalize on their database of companies As Thomas Regional points out in a press release published on their web site, industrial buyers today face the same recurring problems with the large search engines that researchers, consumers, and virtually everyone else encounters

Thcse searches generally produce hits in the range of thousands to

millions, with far too little of it on target For that reason, Thomas Regional will be creating a series of web sites that provide buyers with

“vertical portals” to specific industries Thcsc portals provide access to

Thomas Regional’s extensive databases of industrial suppliers, organized according to industry or trade Thomas Regional is leveraging the usefulness of its content through comprehensive databases that fulfill the specific need of each industry

Thomas Regional claims that ultimately over 90 industrial

“communities” will have their own Thomas-powered web sites tailored

to their interests, which will go a long way to improve the efficiency and speed of their searches The first of these vertical web sites has been launched for the facilities management and engineering profession and may be found at www.facifitiesengineering.com

Industry Societies

When discussing the subject of periodicals published by societies and commercial publishers, articles are identified usually by issue, and/or volume, date, and page number Bibliographic control is excellent, and

it is usually a routing matter to obtain a copy of a desired article However, some problems exist such as periodicals that are known by more than one name, and the use of nonstandard abbreviations Using the International Standard Serial Number (ISSN) that accurately identifies each publication solves both of these problems With the increasing size and use of automated databases one should consider using ISSN or some other standard

An important source of the latest information is &om papers presented

at conferences where the sponsoring agency is frequently a professional society (such as Society of Plastics Engineers) or a department of a

university (such as the Plastics Dept., University of Massachusetts Lowell) These conferences are usually annual affairs

Encyclopedia and Industrial Books

There are many hundreds of encyclopedias and handbooks covering science and technology Internet sites with comprehensive catalogs of books include amazon.com and barnesandnoble.com The date of

publication should be checked before using any of these works if the required information is likely to have been affected by recent progress The following list represents only a sampling of available works of outstanding value

The concern with industrial health and safety has placed an additional

responsibility on the designer to see that materials and products are

handled in a safe manner Sax's Dangerous Properties of Industrial Materials (Kluwer, 1996) provides an authoritative treatment of this subject This book also covers handling and shipping regulations for a large variety of materials and products

Designers are concerned with the interaction between humans and machines This area has become increasingly sophisticated and specialized Books on Human Factors have been written for the design engineer rather than the human factor specialist The books provide the engineer with guidelines for designing products for convenient use by people

Standards

Government agencies, professional societies, businesses, and organiz- ations devoted almost exclusively to the production of standards produce codes, specifications, and standards In USA the American National Standards Institute (ANSI located in New York City) acts as a clearing house for industrial standards ANSI frequently represents the interests of USA industries at international meetings Copies of standards from most industrial countries can be purchased tkom ANSI

as well as from the originators

Copies of standards issued by government agencies are available from several centers maintained by the government for thc distribution of publications Most libraries do not collect government specifications Many of the major engineering societies issue specifications in areas related to their functions These specifications are usually developed, and revised, by membership committees

The American Society of Mechanical Engineers (ASME) has been a pioneer in publishing codes concerned with areas in which mechanical engineers are active As an example in 1885 ASME formed a Standardization Committee on Pipe and Pipe Threads to provide for greater interchangeability

A frequently used collection of specifications is the Annual Book of Standards (53-55) issued by the American Society for Testing and Materials (ASTM) Committees drawn primarily from the industry

most immediately concerned with the topic prepare these standards A member of the standards department usually prepares the standards written by individual companies They are frequently almost identical to standards issued by societies and government agencies and make fkequent references to these standards The main reason for these in- house standards is to enable the company to revise a standard quickly in order to impose special requirements on a vendor

The USA government is the largest publisher in the world Most of the publications are available from the Superintendent of Documents (USA Government Printing Office, Washington, DC 20402) Publication catalogs are available on the Government Printing Office web site, GPO.gov Increasingly, the GPO is relying on electronic dissemination rather than print These publications are provided, fiee of charge, to

depository libraries throughout the country Depository libraries are obligated to keep these publications for a minimum of five years and to make them readily available to the public The government agencies most likely to publish information of interest to engineers are probably the National Institute of Science and Technology, the Geological Survey, the National Oceanic and Atmospheric Administration, and the National Technical Information Service

The large number of standards issued by a variety of organizations has resulted in a number of identical or equivalent standards IHS (Information Handling Services, 15 Inverness Way East, Englewood,

Co 80150) makes available virtually all standards on CD-ROM

Engineering Information

The most comprehensive collections of engineering information can be found at large research libraries In USA they include those in New York City, Boston, Chicago, and Los Angeles These libraries are

accessible to the public They provide duplicating services and will answer telephoned or written reference questions Substantial collections also exist at universities and engineering schools These libraries are intended for use by faculty and students, but outsiders can frequently obtain permission to use these libraries by appointment, upon payment of a

library fee, or through a cooperative arrangement with a public library Special libraries in business and industry frequently have excellent collections on the subjects most directly related to their activity They are usually only available for use by employees and the company

Public libraries vary considerably in size, and the collection will usually reflect the special interests of the community Central libraries, particularly in large cities, may have a considerable collection of

6 - Plastic performance 431

engineering books and periodicals Online searching is becoming an increasingly fiequent service that is provided by public libraries Regardless of the size of, a library, the reference librarian should prove helpful in obtaining materials not locally available These services include inter-library loans from networks, issuing of courtesy cards to provide access to nonpublic libraries, and providing the location of the nearest library that owns needed materials

Information Broker

In the past couple of decades a large number of information brokers

have come into existence For an international listing see Burwell World

Directory of Information Brokers (Burwell Enterprises, Houston, TX

1996, etc.) Information brokers can be of considerable use in researching the literature and retrieving information, particularly in situations where the designer or engineer does not have the time and resources to do the searching The larger brokers have a staff of trained information specialists skilled in online and manual searching Retrieval

of needed items is usually accomplished by sending a messenger to make copies at a library

Most information brokers are located near research libraries or are part

of an information center The larger information brokers usually cover

all subjects and offer additional services, such as translating foreign

language materials Smaller brokers, and those associated with a

specialized agency, fkequently offer searching in a limited number of subjects The selection of the most appropriate information broker should receive considerable attention if a large amount of work is required or a continuing relationship is expected

Engineering Societies and Associations

Societies and associations have exerted a strong influence on the development of the designer, engineer, and other professionals As an

example the ASME (American Society of 'Mechanical Engineers) publishes the periodicals in order to keep individuals informed of new developments and forward other important information Examples of

the periodicals include: ( 1 ) Applied Mechanics Reviews (monthly), ( 2 )

CIME (Computers in Mechanical Engineering, published by Springer-

Veriag, New York), ( 3 ) Mechanical Engineerin8 (monthly), and ( 4 ) Transactions (quarterly) The Transactions include the following areas: heat transfer, applied mechanics, bioengineering, energy resources technology, solar energy engineering, dynamic systcrns, mcasurcmcnt &

control, and engineering materials and technology

Many engineering societies have prepared a code of ethics in order to

guide and protect engineers Societies frequently represent the interests

of the profession at government hearings and keep the public informed

on important issues They also provide an opportunity for continuing education, particularly for preparing for professional engineer’s examinations Examples of societies and trade associations in USA are: Adhesives Manufacturers Assoc

American Chemical Society

American Electronics Assoc

American Institute of Chemical

American Institute of Steel

American Mold Builders Assoc

American

American Society of Civil

Engineers

American Society of Heating,

Refiigerating, & Air-

Conditioning Engineers

Engineers

Engineers

Construction

American Society of Mechanical

Association of Rotational Molders Composites Fabricators Assoc Institute of Electrical & Electronics

Instrument Society of America National Association of Corrosion

National Electrical Manufacturers

National Fire Protection

Plastics Institute of America Society of Automotive Engineers Society of Plastics Engineers Society of Plastics Industry Underwriters Laboratories

Databases

Examples of hard copy databases for plastic material selections are listed

in Chapter 5 and the Bibliography sections

IBM patents website http://www.patents.IBM.com The IBM Intellectual

6 - Plastic performance 433

Property Network (IPN) has evolved into a premier Website for searching, viewing, and analyzing patent documents The IPN provides you with free access to a wide variety of data collections and patent information

Federal web locator http://www.infoctr.edu/fkd/ The Federal Web Locator is a service provided by the Center for Information Law and Policy and is intended to be the one stop shopping point for federal government information on the World Wide Web This site

is hosted by the Information Center at Chicago-Kent College of Law, Illinois Institute of Technology

M A A C K Bztsiness Services A Maack & Scheidl Partnership CH-8804 Au/near Ziirich, Switzerland tel:+41-1-781 3040, Fax:+41-1-781

1569, http://www.MBSpolymer.com Plastics technology and marketing business service, which organizes global conferences, and edits a range of reports and studies, which focus on important worldwide aspects of polymer research, development, production, and end uses Provides updates on plastic costs, pricing, forecast, supply/demand, and analysis Identified early in the cycle are trends

in production, products and market segments

Material Safety Data Sheets (MSDS) http://www.msdssearch.com/

msdsscarch.com, Inc., is a National MSDS Repository, providing FREE access to over 1,000,000 Material Safety Data Sheets; the largest centralized reference source available on the Internet msdssearch.com is dedicated to providing the most comprehensive single source of information related to the document known as a

Material Safety Data Sheet (MSDS) MSDS SEARCH serves as the conduit between users of MSDSs and any reliable supplier msdssearch.com provides access to 350K MSDSs from over 1600

manufacturers, 700K MSDSs from public access databases, links to MSDS software, services, training and product providers, links to Government MSDS information, an MSDS discussion forum where you can ask questions, and supplies MSDSs directly from manufacturers via search engine

The Canadian Center for Occupational Health and Safety CCOHS,

250 Main Street East, Hamilton ON L8N 1H6 Canada, tel: 1-800- 263-8466 (toll free in Canada only)/l-905-572-4400, Fax: 1-905- 572-4500, http://www.ccohs.ca/products/databases/msds.html

Promotes a safe and healthy working environment by providing information and advice about occupational health and safety

Training programs

An example of a training program offered to the plastic industry is presented The Plastics Institute of America (PIA), in collaboration with the Division of Continuing Studies and Corporate Education at the University of Massachusetts Lowell, offers a series of modules providing employee training designed to enhance the knowledge, understanding and skills of mechanics and other technical staff working primarily with plastics

Examples of their training programs follow:

Control Systems (40 hour Module)

Safety (Ohm’s Law) lockout tagout importance, machine guarding schemes

IO devices (operations, identification, advantages and disadvantages, purposes of encoders and resolvers)

PLCs (basic components, analog and digital domains, basic laddcr logic instruction)

HMI (password protection, HMI functions and purpose)

Electronic Cam Switch Bank (function review)

Control Systems Evolution (definition, examples)

Troubleshooting and Diagnostics (mechanical and non-mechanical problems, determination of probable problem cause, mechanic’s responsibilities )

Servo Systems (concepts and purpose, type motors and variations, explanations and applications of direct, gearbox and screw motor- to-load coupling, motor and encoder shaft alignments, servo system concepts, servo tuning, servo profiles)

Metric Measurement (12 h o w Module)

Linear Measurement (micrometers, dial calipers, surface plates, optical comparators, scientific rotation)

Temperature (thermometers, thermocouples, RTDs)

Hardness/Friction/Gloss/Color

Cali bration

Measurement and inspection re: quality control

Overview of sizes (pins, holes, identification of sizes)

Pressure (strain gauges, piezoelectric transducers, Bourbon gauges) Test methods of Plastics ASTM/ISO

6 - Plastic performance 435

Engineerin Drawin, (20 hour Module)

Sketching

Print reading and interpretation

Standard notation and symbols

Assembly and part drawings

Surface finishes

Screw threads and fasteners

Basic shop terminology

Computer Fundamentals (12 hour Module)

Overview of computer systems

Windows 98: help screens, mouse, pull down menus, icons, passwords, menu bars, etc

Introduction to database management and databases

Navigating through databases

Interpreting screens produced by databases

- Interpreting database results

- Databases

Communicating with remote sites

Statistical Process Control (20 hour Module)

Fundamental mathematical skills

Target values and variances

Process variability

Polymers (20 hour Module)

Markets for plastics

Commercial production of plastics

Physical properties of plastics

Fabrication of plastics

Applications

lntvoduction to Injection Moldin8 (1 6 hour Module)

What is injection molding?

Plasticating systems

Clamping systems

The electrical system

Basic machining processes and expected outcomes

Processes that are out of control

Use of SPC to improve the processes

The injection mold

The molding process

Industvial and Molding Hydraulics (20 hour Module)

Standards, basic fluid power law and terminology

ANSI/ISO Circuit symbols, print interpretation

Circuit elements and their hnctions

Mechanical descriptions

Control concepts

Mold Design and Maintenance for Diagnostics (20 hour Module)

Design considerations

Mold design basics

Cavity and core construction

Heat transfer considerations

Cold runner molds

Hot runner systems

Freeing mechanism/part ejection

Mold maintenance

Elastomem (1 6 hour Module)

General classes of elastomers

Compounding and the rubber recipe

Vulcanization and vulcanizing agents

Fillers

Processing and processability testing

Physical testing

Thermoplastic elastomers (TPE)

Rotational Molding (1 6 hour Module)

Preventive /Predictive Maintenance (20 hour Module)

Injection molding plasticating unit

Heating units

Injection molding hydraulic maintenance

Safety inspection and procedures

Storage maintenance of molds

Blow MoldinH (1 6 hour Module)

Blow molding processes

Plastics Process Conwol (20 hour Module)

Principles of process control

DESIGN

RELIABILITY

Product design starts when one visualizes a certain material, makes

approximate calculations to see if the contemplated idea is practical to

meet requirements that includes cost, and, if the answer is favorable, proceeds to collect detailed data on a range of materials that may be considered for the new product The application of appropriate data to

product design can mean the difference between the success and failure

of manufactured products made from any material The available plastic test data requires an understanding and proper interpretation before an attempt can be made to apply them to the product design

There are two important sources of information on plastics There is

the data sheet compiled by a manufacturer of the material and derived from tests conducted in accordance with standardized specifications

‘The other source is the description of outstanding characteristics of each plastic, along with the listing of typical applications If suppliers’ data were to be applied without a complete analysis of the test data for each property, the result could prove costly and embarrassing

The nature of plastic materials is such that an oversight of even a small detail in its properties or the method by which they were derived could result in problems and product failure Once it is recognized that there are certain reservations with some of the properties given on the data sheet, it becomes obvious that it is very important for the designer to

have a good understanding of these properties Thus the designer can interpret the test results in order to make the proper evaluation in selecting a material for a specific product