To make room for a new production machine in Building C, four smaller production machines were moved to Building D. Each of these machines performs a set of sequential operations. For example, a bin of blank bars is emptied into a chute. A robotic arm picks up a blank and inserts into a chuck; the bar is then turned down to the needed size and gets some grooves cut into it. Then the part moves to the next stage, where a multi-function head drills, chamfers, and threads several holes. Then the part moves down to the next stage where still another set of operations is performed.
All of these machines worked flawlessly before the equipment was moved. A contractor had been hired to disconnect and relocate the equipment. The maintenance department was tasked with making the connections at the new site (while also answering trouble calls and performing PMs).
Now each of the machines has something wrong, such as a sequence not being performed. It’s not the same problem with each one. The plant engineer wants you to figure out what’s wrong and what should be done to fix it, along with identifying a methodology with no trial and no error. Where do you start?
Answer to Quiz. One requirement of an equipment move is to produce or obtain good “As Installed” drawings and verify them against the installation before disconnecting anything. It’s also normal in an equipment move for the contractor to do the whole job. Trying to save money by cutting the contractor out of the reconnect is just asking for trouble. And now you have it.
It is possible the contractor wasn’t careful documenting the connections before the move and missed something, but it’s very unlikely. They would be motivated to not get blamed when things go awry. The most likely situation is the contractor handed off the drawings to someone who didn’t ensure they got to the reconnecting crew. That crew then used outdated “original” drawings that were on file. You could spend time tracking down the contractor’s drawings to see who has them, but the contractor can easily send you a copy.
Once you have the drawings, a crew will need to “greenline” (or yellow line, depending on what color of markers or pencils they will use) the drawings as each terminal and each bit of field wiring is verified against it. Whatever isn’t greenlined is what must be figured out. And it’s probably something simple, such as a sensor connection not made (and thus an operation can’t proceed).
Suppose, however, with this split responsibility, the contractor was told, “We already have those drawings, so there is no need to duplicate that effort.” If that’s the case, you’ll have to greenline from scratch. Someone will need to make the “as installed” drawings.
Once those are made, someone will need to examine those drawings to determine what’s connected that shouldn’t be and what’s not connected that should be. With any luck, the wiring itself will have labels. And in many cases, things will be obvious. For example, it will be obvious which wires go to that proximity switch and it will be obvious from looking at the switch whether it is wired or not. Where it’s not obvious, someone will need to understand what the various sections of each machine do and what the parts in each section do. An experienced operator can help with that.
You can go back to the Plant Engineer with this plan. It’s going to be either wiring per the pre-move “as installed” drawings, or reverse engineering each machine to produce those drawings now. But it won’t involve the guesswork of “trial” or the rework of “error”.
