Matt Hrivnak

Kaizen: There's always another future state


One of the single most effective projects that I worked on in the past five years was also the simplest; in fact, I proposed this change in my first week of work.

During my interview, the engineering director took me for a walk through the plant.  It was obvious that a lot of changes needed to be made.  He complained, “Every time we have a defect in this cell, we have to scrap the whole lot, 50 pieces.”  I was shocked that a man with a title of “Engineering Director, North America,” could not see the solutions that were right in front of him.

My initial reaction was to ask a question, “Have you tried reducing your lot size?  Maybe cutting your lots in half?”  His response was even more dumbfounding, “What do you think that would do?”

So, I went on to describe all of the benefits of Single Piece Flow, and added the obvious fact that if the company requires the entire lot to be scrapped because of one defect, then you would only be scrapping 25 instead of 50 every time that one occurred.  He really got the point once I asked him to think about it on a larger scale, “How many would you have to scrap if you had a lot size of 1,000?”  Of course, he said, “1,000.”

When I got there, the process looked something like this:

There was an obvious disconnect between each process, even though the stations were literally five feet apart.  Each station operated as its own entity, not caring whether or not it was receiving or shipping defective products.  The operators were there simply to put in their time and collect their money.  They cared nothing for the products they were making and took no pride in quality workmanship.  If something failed at one of the inspection stations, then the entire lot was scrapped – big deal – they did whatever someone told them to do for eight hours and that was it – product or no product.

As you can see by looking at the diagram of the process, they had incorporated inspection stations.  Inspection is a large portion of waste in many manufacturing processes. Sure, it may be necessary in some instances, but the inspection should still be dealt with in-process instead of having it as its own workstation.

By having inspection as three entirely separate workstations, defects accumulated in lots of 50 waiting in queue and valuable resources were tied up in labor, fixed overhead and much desired floor space.

As a result, I suggested eliminating inspection from the process.  Well, I should say, I suggested eliminating the wasteful aspects of inspection. Because we are dealing with electrical devices that are tested to a standard, the cables must be checked during manufacturing to certify the product as passing the standard, so the inspection needs to be in there somewhere.

I suggested that we put the inspection testing equipment within the previous station’s area (i.e. the pre-inspection station, e.g. wire insertion, pre-mold, mold), to be checked one at a time as they are made.  The results showed instantly!

  • In each of the cases, the inspection operator was eliminated and added to other cells for more value added work.
  • Each of the pre-inspection stations would make one unit and test it instantly.  If there was a problem, it was solved immediately and no other cables would be tainted by the same issue.
  • Additionally, in all cases, the inspection portion of the manufacturing could be done (by the testing apparatus) while the operator was preparing the next sample.

At this point, we also rearranged the cell so that it was in the classic ‘U’ shape which cut the travel distance by 100’.  It had been segmented into two lines, with two operations being 110’ apart from another, this was shortened to 10’.

Single Piece Flow - 1st change

The bottleneck of the entire line was the Pre-Mold operation which was considerably slower than the other processes (the Wire Stripping and Crimping operations were very slow also, but each had 3 workstations, as these were inexpensive compared to a molding machine).  This was also the highest offender when it came to quality issues.  At this step, the individual wires were consistently getting snipped by the mold, causing complete electrical failure of the connector.

Before the improvements, it was easy for this process to make upwards of 200 bad cables before the Inspection station got around to discovering their was a problem! Because it was the bottleneck, it was absolutely imperative to always keep the Pre-Mold operation filled with work.  To achieve this, we setup a sequenced pull system that started with a supermarket between the Wire Insertion w/ Inspection operation and the Pre-Mold operation.  To keep the supermarket fed, we introduced FIFO lanes upstream.  The supermarket handled multiple varieties of cables because the Insertion operation was the first step in the system where product variety appeared.

In the operations upstream from there we used FIFO lanes because the product mix was entirely the same.  Each was held to a maximum storage amount; the supermarket with 5 and the FIFO lanes with 2.With the addition of the FIFO lanes and the supermarket, we were able to work at the pace of the bottleneck.

Granted we were able to speed up the processing of the bottleneck through a SMED event, which required machine design from the maintenance department, but it was still the bottleneck regardless.  To simplify things for a relatively naïve (in a lean sense) manufacturing group, we made the Pre-Mold operation the pacemaker and scheduled all work through that one point.

Efforts to justify the purchase of another molding machine for that area were just not cost effective. (As part of the SMED, we added a second bottom half to the mold which could be loaded while the current cable was being molded.  After the current one finished, the top half lifted up and the other bottom half slid into place, and the molding continued while the other bottom half was unloaded and reloaded for the next cable.)

Single Piece Flow - Final

Since we were so constrained by the Pre-Mold operation, we were able to use the same operators that ran the operations upstream from Pre-Mold to run the operations on the back end of the system.The results speak for themselves:

  • Output of quality products increased from 1.20 units/hour to 5.56 units/hour.
  • Quality problems and rework was down by 90%.
  • The number of associates went from 14 to 9, allowing those additional 5 people to be moved to areas where they could perform more value added work.
  • Associates saw the real effects of their work, taking on more responsibility and having more respect for themselves, the jobs that they perform and the products that they produce.

 

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