Global standards could resolve inconsistencies.

No more comparing apples and oranges! Processors and end users push for uniform testing procedures, seek to harmonize their standards.

Everyone knows it's a problem: Inconsistent materials test data hurt the credibility of the plastics industry with its customers.

An industry-wide effort is under way to find a solution. The goal is to end the confusion in material testing and provide truly reliable, comparable information for processors, designers and end users--all of whom now find themselves competing in international markets and in need of recognized global standards.

Despite an accelerated rate of progress during the last two years, there is still a considerable distance to go before this goal is realized. Traditionally, the source of this confusion involves the use of multiple testing procedures and inconsistent methods for test-sample preparation, making it virtually impossible to compare accurately the resulting properties on any two data sheets. These inconsistencies are quietly acknowledged by processors, resin producers and end users.

Various forces, led by major plastics-consuming end users, are coming together to push the movement to harmonize and standardize the material test data of U.S. and international resin producers in order to facilitate design and manufacturing for global markets. Getting more reliable, consistent material test data into the hands of designers and engineers is seen as an especially critical factor for the continued penetration of plastics into industrial applications.

Significant progress already has been made to harmonize the testing protocols of the American Society for Testing and Materials (ASTM) in Philadelphia with those of the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC)--both based in Geneva, Switzerland--for providing a more rational forum for screening competing materials types for various applications.

But unanswered questions remain as to the specific execution of this harmonization and how much variability actually will be removed from the resulting materials data. Much of the current debate focuses on unifying the ASTM/ISO methodologies.

A major area of concentration in this harmonization movement is to establish strict, uniform standards for preparing and molding "dog-bone" test samples. This includes guidelines for specimen geometry, mold design, and molding conditions. It will make obsolete the traditional multiple-cavity "family molds," which include test specimens of numerous sizes and shapes, in favor of a two-cavity tensile-bar mold. The logic here is that a more balanced mold with fewer but identical cavities will produce more uniform samples. The same tensile-bar mold would be used for testing all types of rigid engineering thermoplastics, while other polymer types, such as elastomers and thermosets, would ultimately receive their own mold standards.

A far more challenging area of harmonization involves unification of testing procedures and methodology. According to the wide range of sources interviewed for this article, this area presents numerous obstacles to harmonization. These include such questions as sample conditioning (e.g., annealing and moisture levels) and tensile strain rates; differences between closely related test methods (e.g., Charpy vs. Izod impact, or HDT vs. Vicat heat resistance); and conflicts between English and metric units.

THE PACE OF HARMONIZATION

Given the current situation, it's doubtful there will be a system for material test data free of loopholes or noncomparable information in the near future. But while resin-company executives admit a perfect world isn't possible, they point to end users as being the dominant factor imposing discipline in this field.

Major end-user OEMs, especially in the automotive industry, are now demanding greater comparability and consistency in material testing data in order to do business in international markets. Resin suppliers, in turn, are recognizing the definite marketing advantages of supplying more reliable material properties to engineers and designers faced with the daunting challenges of global competition. The same advantages hold true for processors, who are now being called upon to contribute more to the design process.

To some extent, resin suppliers are likely to continue to provide specialized test data to suit the whims of particular markets or major customers. However, they'll also be compelled to offer test data that meets the emerging consensus of industry standards. Eventually, there will be a point of diminishing returns on supplying this customized, non-standard test data, as changing marketing requirements will no longer justify the cost for doing these additional tests.

Greater discipline also will come from the efforts of resin producers and industry groups involved in the ongoing harmonization process. Harmonization between ASTM and ISO test standards involves a "turf battle," to some degree, with debates over which system is more stringent or provides more "real-world" test data. Most U.S. resin-company executives on ASTM committees admit ISO formerly had held an advantage over ASTM in requiring more exact specifications for the preparation of test specimens and the execution of tests. ASTM was known to allow more options in its testing methods--in effect, permitting loopholes--while ISO was seen as being far more stringent and authoritarian.

However, these executives quickly point out the gap has closed in recent years, with ASTM correcting its loopholes and tightening its specifications. They also say the degree of supposed debate over English measurements versus metric units is greatly exaggerated: U.S. engineers and designers either have no problem working with each system or require only minor training to convert-the measurements. Resin producers do say the "new" metric readings on data sheets present a marketing challenge that will require customer education.

Historically, the absence of standards for information provided by data sheets and product manuals is readily apparent when comparing competing resin types from different suppliers. There is little assurance of even a basic consistency in test bar samples. What kind of test mold was used? Was the sample compression molded or injection molded? If injection molded, was it end-gated or center-gated? Was the sample thickness 1/8 in. or 1/4 in. or something else entirely? Was the sample annealed or unannealed prior to testing? Was the sample conditioned to equilibrium moisture percentage or was it tested "dry as molded"? Was the test conducted at 66 or 264 psi, notched or unnotched, to yield or to break?

|WE MUST TAKE OUT THE HAZE'

Edward Munoz, president of the Advanced Materials Group of Hoechst Celanese Corp. in Chatham, N.J., says standardized test data will benefit everyone. His firm recently announced plans to complete conversion from ASTM materials testing standards to ISO for virtually its entire line of engineering and high-performance resins by January 1995.

"During the 1980s we grew up touting one high-performance material over another," he says. "It used to be a high-growth sector, but in recent years growth has been flat. We've virtually exhausted the performance side of engineering thermoplastics. We now must reduce system costs and take the |haze' out of material performance properties in order for our customers to remain competitive.

"Sometimes people tend to focus on the inconveniences of conversion to a metric system, and it's unfortunate," Munoz continues. "That's not the real issue at hand." He does acknowledge that resin suppliers will be faced with a host of new communication challenges during a transition period to the ISO protocols. He says it will be a "top-down" effort, with end-user design engineers reaping the initial benefits, with processors soon to follow. SPI's Polymeric Materials Producers Div. Committee on International Standards part of the Society of the Plastics Industry (SPI), Washington, D.C., formally recommends that member companies this year begin conversion to international ISO/IEC standards for test data, and by June 1994 routinely supply information on product sheets and computer databases using the preferred ISO/IEC standards.

Pat Toner, v.p. of technical affairs for SPI's International Technical Advisory Committee, says the cautious approach to ASTM/ISO conversion being taken by some U.S. resin producers involves concerns over adopting new test standards, as well as the anticipated costs of new testing equipment and molds.

"While conceptually it may sound good for the U.S. to adopt a new set of international standards for testing, the actual implementation of such a program causes reservations," Toner says. "Depending on markets, later is better for some resin producers."

Toner states another concern for resin producers is how well metric test data would be accepted by processors and end users, and how to adjust communications and marketing efforts to provide full customer education. "The needs of the processing community and end users are an important part of the mix on this question of test standards," he says." A top-down initiative on test standards might be successful in Europe, but top-down doesn't always work in the U.S. We would prefer to have a full industry buy-in across the board. Resin producers are reluctant to adopt things if they aren't endorsed and

understood by processors and end users," he says, drawing an analogy with the U.S.'s failed effort to embrace the metric system in the early 1970s.

THE ROLE OF CAMPUS

One major first step in the international test standardization movement was the formation of a European industry consortium known as CAMPUS (Computer-Aided Material Preselection by Uniform Standards), which relies on specific ISO test methods. The CAMPUS consortium was founded by the four major German resin producers (BASF, Bayer, Hoechst and Huls) in 1987.

Today CAMPUS includes 27 major resin producers in Europe, including several U.S.-based firms such as DuPont, Dow, Exxon, GE Plastics, and Monsanto. CAMPUS was brought about by dissatisfaction with the latitude for variation inherent in German DIN and European ISO test standards. For example, DIN and ISO listed 33 different impact test methods with seven different specimen types and at least three different notch shapes.

The German "Big Four," looking to resolve this confusion, first agreed on a uniform test sample and protocol for a sample mold, molding conditions, and test methods. Next, they agreed each supplier would provide the now-comparable materials data on a computer diskette, using the same database software format.

While some U.S. industry executives refer to CAMPUS mainly as an innovative marketing tool, others believe its real significance is the agreement by material suppliers finally to provide comparable data. Most executives recognize the specificity imposed by following the CAMPUS diskette format for reporting test data, but also note that the critical issue still lies in the creation of the test data itself. They say CAMPUS does little to certify or police its information, and that the testing data still represents only the typical values obtained from ISO procedures, which are now under review. Many executives question whether a CAMPUS-like system would be successful in the U.S. and see its effects as a separate issue from ASTM/ISO harmonization.

It's important to note that any materials-data standardization effort represents a more rational, consistent measure for resin preselection screening. No matter how consistent or standardized any method is for testing the thermal and mechanical properties of resins, these data do not tell an engineer how to design a part. Final material selection for processors always involves a host of other factors and decisions. Material test data is only the initial step in that process, although the promise is that it will now be more reliable and user-friendly.

PROCESSOR BENEFITS

The test-standards harmonization effort should help both processors and resin suppliers get in line with growing trends of global business competition and recognized international quality standards. U.S. manufacturing, and the plastic processing sector in particular, is becoming keenly aware of the underlying benefits to be reaped from acceptance and recognition of such global standards (see PT, May '93, p. 54).

The two most important near-term benefits in this test-data harmonization process for processors are that it will provide access to initial better screening information that supports mold and product design functions, as well as more meaningful processing information.

Several processors recently polled for this story admit to having grown accustomed to doing business with material-property data-sheet information that offers little benefit in preselecting resins; it has become an accepted limitation of the current way of doing business, according to processors. When choosing a resin, it always comes down to processing a sample batch of material and testing the properties of a molded part in a real-world application. However, processors recognize the importance of universal testing standards as a way to facilitate preselection work.

The clear trend for processors is assuming greater responsibility for part and mold design in the very early stages of a contract. While this element always has been part of a processor's job description, it's importance has intensified in recent years (see PT, Sept. '92, p. 84; Jan. '92, p. 48; April '91, p. 84; Nov. '88, p. 44).

The increased emphasis on a processor's design and engineering capability means fundamental material performance data becomes a more critical resource. This is traditionally an admitted area of weakness on the part of material suppliers, many of whom recognize the "chaos" that stems from the lack of (or failure to adhere strictly to) clear, recognized standards for producing a test sample, test methods, and clear, consistent presentation of data.

"The Germans recognized in the mid-1980s that the real competition for designing applications in plastics is metal and other materials, not other plastics," says Ranganath Shastri, development leader at the Materials Engineering Center of Dow Plastics, Midland, Mich. "Steel and aluminum are much more standardized in terms of their material test specifications. Plastics producers traditionally have had little enthusiasm for testing standardization, in order to maintain a competitive advantage or showcase certain property values for their own resins. But today in the environment of global competition, it's a new game."

The latest versions of CAMPUS resin databases include more sophisticated design information--notably "multi-point" data in the form of charts and graphs of shear modulus vs. temperature, stress/strain curves, and secant modulus vs. strain. These contrast with elementary "single-point" data on mechanical properties such as tensile strength, flex modulus or Izod impact. Multi-point design data is rarely present on standard data sheets, although it offers designers valuable insights into a resin's fatigue life and end-use service envelope.

More information that characterizes a resin's flow and processability is another benefit of the ASTM/ISO harmonization for molders. Along with more consistent test data, processors can expect to have greater access to "multi-point" processing information--charts and graphs that depict viscosity/shear rate rheological curves, for example, in place of simple melt-flow indexes. Current CAMPUS software offers users charts and graphs that plot multi-point processing data and provides specialized test data to plug into separate mold-filling/cooling analysis programs. Until now, resin suppliers have tended to withhold the latter kind of processing information from publicly available data sheets, even though they do supply it to customers on request.

Even mold-simulation data can benefit from standardization. Shastri says different laboratories use very different methods to determine the fundamental materials data on which the simulations depend. Consequently, Shastri is heading a new task group formed last summer under ASTM D 20.30. It is drafting standard methods for determining no-flow temperature, freeze temperature, pvT data, and other key properties.

Jeff Viola, technical service applications manager for the Polystyrene Business Group of BASF Corp. in Edison, N.J., says that while design engineers have great interest in data they could incorporate in a mold-filling analysis, molding technicians prefer more "hands-on" data such as a spiral-flow test. "Machine operators are more interested in running their mold temperatures colder and ejecting parts faster. Pilot runs with material samples will always be needed. But more processors are becoming involved in part and mold design and need information like viscosity/shear-rate relationships."

SOME PROGRESS IS EVIDENT

ASTM committee leaders say many test procedures and material standards between ASTM and ISO now are comparable, including tensile and flexural modulus readings. The one major unresolved area of concern is impact strength, where notched Izod and Charpy test methods and sample preparations have yet to be made consistent. The size and shape of the notch in the test sample is a key issue, they say.

Robert MacFarlane, manager of technical communications for AlliedSignal Inc., Morristown, N.J., and vice-chairman of materials for ASTM's D-20 committee, agrees that ASTM and ISO already have made great strides to harmonize test data and procedures. As an example of this, he points to ASTM D 4181--test standards and specimen preparations for acetal--that recently were rewritten to conform to ISO.

MacFarlane, who also is chairman of ISO's TC 9 subcommittee on thermoplastics, says: "All of this effort is aimed at making it easier and more cost-effective for everyone to do business. Multiple test procedures due to a lack of standards raises costs for everyone. Years ago it was wild--resin companies were running tests just to satisfy individual customers. But now, our customers are all over the world."

Tom Murdoch, a consultant with the Plastics Marketing Group of Monsanto Co.'s technical center in Pensacola, Fla., and chairman of ASTM's 20.15.09 committee on nylon, says his group hopes to harmonize ASTM's D 4066 and ISO's 1874 standards for nylon by the end of next year. The harmonization effort is focusing on specimen preparation (molding conditions) and testing methods, such as choosing specific tensile strain rates.

"We'd be short-sighted if we only relied on ISO methods," Murdoch says. "We must have input from ASTM too, but we do need to implement ISO methods and use them in U.S. industry. Standardization is what our customers want."

Kishor S. Mehta, manager of design engineering services for the Polymers Div. of Miles Inc., Pittsburgh, says he's seen heightened interest in ISO/ASTM harmonization prospects during the last year and expects even greater progress in the coming months.

George Diehl, standards engineer for GE Plastics, says despite general eagerness to move forward on harmonization, large multinational resin producers still must proceed cautiously, coordinating efforts in the U.S., Europe and another important market with its own standard-setting bodies: Asia.

WHAT WILL HARMONY LOOK LIKE?

The most likely scenario for formally harmonizing ASTM and ISO material testing information in the U.S. is that resin firms will begin offering dual columns of information on data sheets within the next two to three years. Sources interviewed for this story decline to offer specific forecasts, but most indicated there will be some type of phasing in of ISO metric numbers.

Dale Keeler, technical associate with Dow Plastics and subcommittee chairman of ASTM D 20.22, says the fundamental issue behind the standards debate is the quest to provide useful data to processors, designers and end users. "From a scientific and cost-effective point of view, you should have only one ,correct, standard," he says. "Ultimately, if you pick the right standard, you should be able to provide better data to molders in a more cost-effective manner. But there are years of history behind test data, and some companies don't want to throw away good data just for the sake of a new standard."

"Processors want uniformity in test standards," according to Viola of BASF. "The information at first may be more difficult to learn, but it will be much more useful to processors. In the end, they will be happy, but we all must go through a learning curve."