Column Editor: Myer Kutz (President, Myer Kutz Associates, Inc.)
I spent the early portion of my professional career working as a mechanical engineer. (I hold mechanical engineering degrees from MIT and RPI.) Specifically, I was involved in thermal design. Among other pursuits, I worked on temperature control of the inertial guidance system used in the Apollo program. (If the components of such a system become too hot or too cold, it steers a vehicle off course.) Like most young men, I thought I knew everything. So, for example, when I needed values of materials properties, such as the thermal conductivity of high-performance metals to use in calculations to determine operating temperatures of key components of the Apollo inertial guidance system, I believed that tables of materials properties published in something called Materials Selector were sufficient for my purposes.
Materials Selector was an annual publication of Machine Design, an advertising supported magazine that arrived on my desk free of charge, as I recall, and Materials Selector was replete with tables of materials properties data. I don’t remember caring too much about whether there was any documentation testifying to the validity of the numbers in the tables. Whatever was in the tables was good enough for me, and I had faith in the results of my calculations. It was the equivalent of using Wikipedia today, I suppose. In any case, the projects I worked on didn’t suffer any catastrophes because I used materials properties values that might not have been fully vetted. They were good enough for engineering work, as a variation of the old joke would have it. Besides, I knew that my calculations weren’t the last word. The groups I worked in ran tests to determine how things would be under operating conditions.
I used tables from Materials Selector (with permission, of course) in my first book, Temperature Control, back in 1968. Years later, when I started putting together engineering handbooks, I keenly felt a responsibility not to lead young practitioners astray. For the materials chapters in my Mechanical Engineers’ Handbook, for example, I made sure to enlist expert contributors who would provide detailed references about the origins of materials properties tables in their chapters. As time when on, industry groups such as the Aluminum Association and the Copper Development Association became involved with and even sponsored the compiling of data in chapters covering materials. Those are the chapters that tend to have the most exhaustive materials properties data, although I should say that a handbook cannot strive for completeness in this area. There are just too many variables affecting the precise value of a material’s property — the ingredients in it, how it was manufactured and the conditions under which the property was measured, to name just a few.
In the Internet age, I’m not sure how much of this vetting process matters to young engineers, who have been thought to be a principle market for engineering handbooks. The Internet is filled with materials properties information, some of it reliable, some not, of course. I’m not writing with the benefit of market research into the matter, but it wouldn’t surprise me if it were the case that practicing engineers use whatever properties data they find on a site that looks legitimate and don’t bother much with investigating the data’s provenance. That said, there’s plenty of reliable data available and current computer-based calculations using good data look and feel a whole lot more reliable than the pencil and paper scratches that I and my masters had to make do with back in the day. Let’s check out a couple of examples.
To start with, there’s ASM International’s Website, which has a ton of information about materials and the processes used in manufacturing. (In days of yore, ASM used to deal only with metals, but for some time it has provided information on plastics, composites and ceramics, as well.) Whatever information ASM provides, it becomes the gold standard. Or engineers can go to MatWeb for materials properties data. How reliable are such data? Let’s hear from MatWeb: “Most of the data in MatWeb has been supplied to us directly by companies in the supply chain — the manufacturers, or, less commonly, distributors or fabricators. Other data has been taken from standards organizations or from similar materials/known relationships by the MatWeb staff.” I found this statement when I looked at the properties of silver, MatWeb also listed three books as data sources, all from the 1990s. But never mind that, I’d guess that the data are good enough for many design purposes.
Over the last several years, publishers have told me that they’re interested in materials and chemical properties data. I tell them that my handbook contributors sometimes provide such data, but by no means can I promise that I could provide a handbook with comprehensive data. I’ve seen my handbooks open on desks where engineers were making calculations or designing something. I try to make my handbooks very useful for such purposes. But I would expect my handbook users to have to consult additional sources for materials properties data in some instances. I simply can’t include all of it.
I tell publishers that if they want to provide comprehensive data, then relying on outside handbook editors and chapter contributors won’t achieve that end. To get there, a publisher would have to employ a team of experts to put together such databases. They would have to compensate the experts, not an enticing prospect these days, when publishers tend to rely more on outside contractors than in-house employees. In addition, merely applying a publisher’s logo to data won’t guarantee that the engineering public would blithely accept such data as the equivalent of ASM’s gold standard data. But handbook editors and contributors can provide accurate and useful information about how materials are mined and made, how their properties can be improved, how materials can be used and in what situations — and how they degrade in certain conditions. In other words, how materials properties change over time as a result of how the materials are used. But it does take a village to produce comprehensive materials properties data and it doesn’t come cheap, nor does it fit a typical publisher’s current business model.