Motion in manufacturing is a complex topic. Even motion within the confines of fabricating is a complex topic. There are different types of motions and different ways to either ensure the quality of the motion or to measure it.
Here’s an example. Putting the nozzle of a laser cutter so close to the sheet metal seems like a bad idea, but of course there are many advantages to doing so. To deliver a solid product, with an unmarked surface and a healthy cutting head, you need to coordinate the fast-moving nozzle with the inert sheet metal. Many laser cutter manufacturers do this using the principle of capacitance, measured in farads. It’s a measurement of how much charge is necessary before a current is induced in the “gap” between plates, or in this case between the sheet metal and the nozzle.
It’s an ingenious way to measure the distance—the less distance, the easier for the charge to cross. Now suppose there are irregularities in the sheet. It’s fine, the nozzle gets inferred distance readings constantly from the capacitance values, and moves vertically, accordingly.
So from a sports point of view, it’s a bit like golf—a thing moves, and a thing stays still. The challenge in golf is to strike the thing that doesn’t move with the thing that does move. Despite one inert half of the equation, it’s a damned hard and sometimes frustrating experience. Of course, we’re trying to not hit something. It might seem backwards but remember that in golf the less you hit something the more likely you are to win.
Moving it up a notch brings us to baseball, a sport in which you fling a piece of wood around your body trying to hit a horsehide ball that curves, dips, flutters, and uses different speeds—almost as if the guy who throws it doesn’t want you to hit it. The idea is, using your eyes and your muscles, attempt to make the wood thing meet the horsehide thing right in front of you—and you’re standing 90 degrees away from the pitcher. It is little wonder people who hit the ball at least 3 times out of 10 plate appearances go into the Hall of Fame.
It’s a bit like trying to coordinate two moving objects of interest in the fabricating world. For example, you might have an occasion to weld something on a workholder that rotates, plus the robot welder must move inboard at a certain point to make a pie-slice-shaped weld. This is extremely difficult but when you see this type of coordination it becomes a rather hypnotically pleasant thing.
Despite all the IF, THEN, and ELSE things that happen on an assembly line, use that same second example, but place it in a cell type system, with multiple welds going on at the same time, independent from each other yet dependent on the entire job segment to finish before a car can move to the next station in the plant. It’s a bit more like football game, with assignments, multiple relationships of coverage (man to man and zone, and different on each play), and finally the car is done with all the different welds.
If this sounds like time and motion study stuff, well, maybe it is. It seems like sort of a passé pursuit these days, but truly besides time, motion, and power, there are very few things left to manage in fabricating (I mean here the verb fabricating—there are still lots of nouns to manage!). More to come on this topic (also, see our look at time here: https://fifthwavemfg.com/time-slices-2023-thinner-more-frequent/ and here: https://fifthwavemfg.com/design-changes-in-the-time-of-robots/).