Quality Process and Quality Results

How do we assure that our customers receive the highest possible quality in our products?  The first thing that comes to many people’s minds is that we need to have plenty of inspection.  Defective products will get made and we need to catch them before they get to the customer.

Unfortunately, inspection (as well as various kinds of testing) does not catch every defect. No inspection process catches every defect.  Many let 20%, 30% and more escape.  Inspections can also catch products that turn out not to be defective.

In workshops, we demonstrate the unreliability of inspection by having each participant independently count the number of a certain letter (for example, “e”) that can be found in a text. All counters do not come up with the same number. If the letter were a defect, some would not be caught in the inspection process.

Inspection does not add value.  It only catches some of the defective products and leads us to other work that does not add value either, but does add cost.

Takt Time

One of the concepts used by companies that are moving toward leaner operations is takt time.  It is also a concept that is often misunderstood in companies that have had a little exposure to lean processes and have picked up the term.

Takt time is the beat at which we should make a product or component to be in synch with the needs of the customer. The customer may be an internal customer such as a downstream process, or it may be an external customer, a dealer or an end user. Takt is a German word for beat when the subject is music.  The baton used by a band or orchestra leader is called a taktstock.

Let us suppose that a customer of any type needs 900 units, widgets of some kind.  The factory works an 8-hour shift, but a half hour a day goes into breaks and other planned downtime, leaving 7.5 available hours.  Seven and a half hours times 60 minutes, times 60 seconds, equals 27,000 seconds of available time in a shift.  If we divide 27,000 seconds into 900 units, we find that our takt time is 30 seconds per unit.  To be perfectly synchronized with the customers requirements for a day, we need to produce one widget every 30 seconds and each operation in the process should take exactly 30 seconds.

Treating People As If They Were Robots

I have consulted to a number of plants with recently acquired robots.  Often the robots didn’t work very well.  In some cases the robots were doing work that made little sense.  In one case, the robot was taking a stamped part from a hanging line and putting it on a belt. It was so unreliable that a worker had to stand by to catch parts that were about to be dropped by the robot. Having the hanging line descend to just above the belt could have removed each part without a robot.

In a factory in Brazil, a robot cell had been installed to weld some parts together. A second cell was in the process of being installed.  Management was very proud of it’s new technology.  They had a five minute video of the robots in the dining room.  The bright orange robotic arms waved through the air and set forth a shower of sparks with each weld. The dramatic video played endlessly, for all lunch breaks on all shifts to see. 

Not a week had gone by since the robots were installed when they didn’t break down and required repair. No one in the plant could do the repair and the technicians who could do the repair were four hours away.  When they arrived it often took an entire shift to get the robots up and running again.