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(+)+(+)
(+)+(+) S.M.I.L.E(sm)
(+)+(+)
(+)+(+) Setup Minimization Improves Line Efficiency
(+)+(+)
(+)+(+) The Quick Changeover e-letter
(+)+(+)
(+)+(+) Published monthly by Changeover.com
(+)+(+)
(+)+(+) Written by John R Henry, CPP
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### JUNE 2005
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=============================================================
I have added a new page to the Changeover.com site. This page, called "Best
Practices" is located at www.changeover.com/ideas.htm The purpose of the
page is to illustrate some practices that have been found to be useful in
reducing changeover time and improving changeover quality.

Submissions are encouraged. What are you doing that you can share with your
colleagues around the world? Send me a photo, sketch or drawing with a
brief description and I'll be happy to add it to the page. I will post all
submissions anonymously with no ID information unless you specifically
allow me to credit you or your company.

SOME THOUGHTS ON...
EXTERNALIZATION



Those who have read Shigeo Shingo's book, "A Revolution in
Manufacturing:The SMED System" will be familiar with the concept of
externalization. Briefly, it means performing as many changeover operations
as possible while the line is running. This may not save any labor time. In
some cases, it may even take a bit more. Still, since labor costs tens of
dollars per hour and downtime costs thousands of dollars per hour, it is
very powerful concept.

I first learned about the concept years ago and have been lauding it's
value ever since. For all that, I had never had it brought home as
forcefully as happened at a client earlier this year.

I was presenting my "Achieving Lean Changeover" workshop in a packaging
plant. Earlier I had been shown 8 pouch forming machines. These use flat
film from a roll. The film is folded and sealed to form pouches for the
product. One thing I had noticed about them was that they had only a single
roll of film mounted. In the course of discussion, I asked about this as
well as how often they have to replace the rolls and how long it takes.

The rolls are replaced about 3 times per shift, on a two shift operation or
6 times in a normal day. My first thought was that perhaps the rolls could
be made larger diameter to hold more material. Going from a 12" to a 16"
diameter roll should more or less double the amount of film and thus cut
the number of roll changes in half. The problem with that is that the rolls
are pretty heavy as they are. Increasing the diameter would make them even
harder to handle.

We then discussed mounting two film rolls on the machine. One roll, in the
forward position would be in use. The second, backup roll, would be mounted
on a shaft and positioned directly behind the active roll. When the active
roll is used up, the machine is stopped, the shaft removed and the backup
roll rolled forward on it's shaft into the active position. The leading end
of the backup and tail end of the active rolls are spliced with tape and
the machine restarted. (see www.changeover.com/doubleroll.jpg for a
conceptual example)

In discussing this, the group seemed to think that it might be a good idea
but would only save a few minutes a few times per day. As readers of this
newsletter already know, my position is that downtime elimination is all
about saving a few minutes here and a few seconds there, but doing a lot of
it. In the end, these little, "nickle & dime" improvements add up to a
significant reduction.

So, in my best pedagogical manner I decided to examine how much time would
actually be saved from this improvement. First I asked how much time the
current method took. The consensus answer from the group was that it was
about 10 minutes a time. Sometimes a bit less sometimes a bit more, but
about 10 minutes on average. The typical sequence of operation was:

Wait till the roll ran out (If the operator was not right there, it
sometimes took a minute or two to notice that the machine had stopped.)

With the machine stopped, remove the shaft and empty film core

Disassemble the shaft and remove the core

Fetch the new roll from across the room

Place it on the shaft

Assemble the shaft, mount the locking collar

Lift the assembly onto the machine. This sometimes required 2 people
depending on who was doing it.

Splice the new film to the old.

Restart the machine.

As I mentioned, this happened 6 times on the typical day. Here's the math:

6 changes X 10 min/change X 240 days/yr = 14,400 minutes per year or 240
hours.
In other words, when you actually do the math, this single, repetitive,
operation goes from being nickels and dimes to a major cause of downtime.
In this case it amounted to about 6% of the total available working hours.

If a second roll, with some refinements, could be added, this time could be
easily cut to 5 minutes per roll change.

The operation becomes:

3-5 minutes before the roll comes to an end, a yellow beacon alerts the
operator to be standing by.

When the roll runs out, the machine stops automatically leaving sufficient
material for easy splicing.

As soon as the machine stops, the operator lifts the shaft/core out of
place and sets it aside.

The backup roll, previously placed on the rollstand is moved forward to the
active position.

The film ends are spliced.

The machine is restarted.

With the machine running, the empty shaft that has just been removed is
loaded with a new roll and placed on the machine as the backup roll.

Total estimated downtime is now 5 minutes. Now do the math again:

6 changes X 5 min/change X 240 days/yr = 7,200 minutes per year or 120 hours.

This relatively simple modification, costing less than $5,000 has resulted
in a gain of 120 production hours per year.

What are 120 additional production hours worth in YOUR plant?

I believe that 5 minutes per change is still too long. There are ways it
can be improved further.

Splicing is too often done in an ad hoc manner with the operator trying to
hold the two ends with one hand and apply the tape with the other. A
purpose built splicing table will make this much simpler, faster and will
reduce the chance of an improper splice jamming in the machine. The splice
table can be fabricated in house or purchased, it need not be anything
elaborate. See
http://www.webtechniquesinc.com/acc_model_SP3_splicingaid.html
for a simple example. It's not shown in this example but I would recommend
that a permanent tape dispenser be mounted above the splice table. This
should be positioned so the tape can be pulled straight out of the
dispenser onto the web.

An even more effective approach can eliminate downtime altogether. This is
to have accumulation of the last 50-100 feet of film so that splicing can
take place without stopping the machine. One manufacturer of off-the-shelf
machines for this purpose is CTC International at http://www.ctcint.com
They make a complete line of automatic and semi-automatic machines as well
as components for build-your-own.

The dual roll concept can be used on labelers, PVC banders, foil cappers,
bagging machines and any other roll fed machine. Even a very simple
implementation can eliminate large amounts of downtime over the course of a
year.

TIP OF THE MONTH...
PROGRAMMABLE AIR CYLINDERS

Air cylinders are the workhorse of the typical industrial plant. They are
used for a wide variety of simple and complex machine motions.
Historically, air cylinders have been limited to 2 positions, fully
extended and fully retracted. When intermediate positions were needed, they
were usually achieved by putting a hard stop.

In recent years, several cylinder manufacturers have developed programmable
air cylinders. These cylinders incorporate an electronic position sensor.
They allow a controller to position and lock the cylinder at any position
in it's stroke.

One useful application I saw was a machine built to form small (6" X 4" X
2", approx) chipboard trays. This automatic former was designed by the
user's engineering department and built in their maintenance shop. It was
designed for quick changeover and used programmable cylinders for almost
all position adjustments. I saw the machine both in operation and in
changeover and can say it was most impressive.



Best,

John R Henry CPP



Best,

John R Henry CPP

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