3D Surface Roughness and Wear Measurement, Analysis and Inspection

What is ASME B46.1?

When we start up a surface measurement system or launch a roughness software program, we’re often met with a vast array of parameters, filters, and other controls. The task of keeping these consistent and meaningful across industry and around the world is a task that falls to surface texture standards committees.

The American Society of Mechanical Engineers (ASME) has been producing standards for much of its nearly 150-year history. The ASME B46.1 standard was first developed in the 1940s to govern “the geometric irregularities of surfaces.” B46.1 defines surface roughness, waviness, and lay, as well as parameters for specifying and controlling surface texture.

ASME B46.1 is the primary standard used in the United States, particularly in defense-related industries. It is, however, only one of several primary standards. The International Standards Committee also maintain standards that relate to surface roughness and texture, as do groups within many individual countries (e.g., the Japanese Industrial Standards Committee, JIS).

The B46.1 standard has been updated and expanded many times, up to its current version, ASME B46.1-2019. When I began working in industry, the 1985 version was the latest and greatest. That standard was only 12 pages long and only recognized a handful of parameters: Ra, a peak-to-valley height parameter, and W (waviness)!

As computers became prevalent, surface texture analysis also grew and developed. The 1995 version of ASME B46.1, which took over ten years to produce, brought forward many of the parameters that we commonly use today. The latest 2019 edition has grown to over 145 pages, covering dozens of surface texture parameters and analyses.

Because so many drawings and processes are governed by B46.1, the committees that meet to update it must proceed methodically and deliberately—which is why ten years or more may elapse between versions. I’ve had the pleasure of being involved in the development of the standard for several decades now. The work and discussions that go into refining this content have been endlessly rewarding and have kept me on the leading edge of developments in the world of texture measurement.

While all of the texture standards address similar questions and provide the same types of guidance, they do differ in fundamental ways as well. Therefore, a production drawing must specify which standard, and which version of the standard, are to be followed when measuring and analyzing surface texture. Whether it’s an ASME, ISO, JIS, or other standard, you must understand and follow the intricacies in order to obtain reliable, verifiable, data.

Interested in learning more? Consider our in-person Surface Roughness, Texture, and Tribology class (Spring dates to be announced soon!) The class is also available online, as a full course and as individual modules, at udemy.com.