Quality and manufacturing practitioners are most familiar with the effect of variation on product quality, and this is still the focus of the quality management and Six Sigma bodies of knowledge. Other forms of variation are, however, equally important—in terms of their ability to cause what Prussian general Carl von Clausewitz called friction, a form of muda, or waste—in production control and also many service-related activities. This article shows how variation affects the latter as well as the former applications.

Anyone involved in 3D printing/additive manufacturing (AM) knows about STL file formats. Problem is—and no offense meant—STL is dumb. It’s just a large text file, generally written in ASCII programming language, defining the surface of a closed solid using a zillion triangles. For every tiny triangle, the file lists Cartesian coordinates locating its three vertices plus a normal. You can slice it up to print, but that’s it.

The National Institute of Standards and Technology (NIST) has campuses in Maryland, Colorado, South Carolina, and Hawaii. Now, I know what you’re thinking, “Hawaiian campus? How do I get a job at NIST?”

What do you think of when you think work holding? A vise, hydraulic clamps, vacuum plates, toe clamps, magnets, glue? Absolutely, but this is only half of the equation. What about the interface between these components and the machine tool? This is equally important, if not more so because it dictates the time it takes to change your work holding, which in turn has a significant effect on your spindle uptime.