Sometimes We Remove Technology

I consulted in a plant that had a large machine that cut rubber tubing into pre-determined lengths. Next to the machine, I spotted a large wire container with cut tubing lengths.  It was labeled with a red tag with the word REJECT visible from twenty feet away.  The detail on the tag revealed that the tubing contained in this container had been cut too short.  It was probably going to have to be scrapped.

I asked why the tubing had been cut too short.  Probably human error in setting the machine, I was told.  The specs were not entered correctly and no one noticed until a full container had been cut.  We formed a work group to find a way to prevent this problem from every happening again.

We discovered that the internal customers for these products were two assembly lines.  Tubing that was too long could easily be cut down to size.  Tubing that was too short could not be used because it did not reach the two points in the assembly that needed to be linked. 

We quickly came to the idea that the tubing was quite easy to cut, so why not cut it just-in-time.  The team designed a guillotine (actually a small paper cutter), mounted it on a bench with a channel and a stop that measured the tubing to the required length, making it easy to cut just one piece when it was needed.  The roll of tubing was too large to have on the assembly line.  We cut off enough to supply the line for one day and rolled it onto a smaller reel.  Our arrangement worked well for a week on the first line. After that we duplicated the process on the second line.

Later the company negotiated with the supplier and was able to get tubing in smaller rolls suitable for putting directly on the assembly line.  Within the company there was some resistance to taking a “perfectly good” machine out of service, when it was still being paid for.  When I toured plants in Japan that were practicing lean manufacturing and continuous improvement, I saw several yards filled with equipment covered by tarps.  We were told that this was equipment taken out of service by efforts to make processes lean and reliable.

Why Not Manufacture in Easy Batches?

During a workshop, a manager resisted the idea that batches are always to be avoided if possible.  He used the example of paying his bills by check (this was before the days of online bill-paying). It was easiest for him, he said, to sit down at the kitchen table, open all the bills and take them out, write all the checks, stuff all the envelopes, put stamps on all the envelopes and drop them in the mail.

I asked the group if there was anyone present who had ever sent the wrong check to a payee.  A couple of people admitted that it had happened to them.

If you practice one-piece-flow, processing one unit at a time – in this case one bill—you practically eliminate that particular mistake.  You open one envelope, read the bill, write the check, put it in the envelope with the bill stub, seal the envelope and put a stamp on it.  If you wait to put stamps on the envelopes until all have been sealed and stacked, there is more of a chance of skipping an envelope and mailing it without a stamp.

Keeping it Simple

We often overcomplicate things at work.  Complicated machines become obstacles to getting the job done.

In one factory, a large, highly automatic machine spun nuts onto threaded nipples.  The operator’s job was mostly to catch defective nut-to-nipple assemblies as they came out of the machine and set them aside for later repair.  If practically all of the assemblies were defective, because the nut had not been spun on straight and had jammed onto the nipple, he shut down the machine, tried to make adjustments to it, and generally ended up calling maintenance.  While maintenance tinkered with the machine, the operator would sit at a workbench and use channel locks to removed jammed nuts from the nipples, so that both parts could be put back into the machine. 

Sometimes, there were so many flawed assemblies, additional workers would be brought to the area, given channel locks and put to work undoing the bad assemblies.

I worked with a team of workers and managers on an improvement project that made this problem go away. We purchased two nut drivers with sockets sized to the nuts in question.  The nut drivers were of the type that activate when you press down on the nut, and stop when you release the pressure.  We mounted these upside down, side-by-side, in the center of a small workbench.  We fashioned some brackets to hold them with the sockets flush with the tabletop, through holes in the center of the workbench.  We had a bin with nuts and a bin with nipples on the workbench. The operator would take two nuts and slide them into the sockets.  He would then take two nipples and briefly press them into the nuts in the sockets. This activated the drivers to spin the nuts onto the nipples.