Having problems with message search?
(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)+(+)+(+)+(+)+(+)
(+)+(+)
(+)+(+) S.M.I.L.E(sm)
(+)+(+)
(+)+(+) Setup Minimization Improves Line Efficiency
(+)+(+)
(+)+(+) The Lean Changeover e-letter
(+)+(+)
(+)+(+) Published monthly by Changeover.com
(+)+(+)
(+)+(+) Written by John R Henry, CPP
(+)+(+)
(+)+(+)
(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)+(+)+(+)+(+)+(+)
(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)(+)+(+)+(+)+(+)+(+)+(+)
###############################
###############################
###
### NOVEMBER 2005
###
###############################
###############################
============================================================
This newsletter is a free service of Changeover.com. Visit our website at
http://www.changeover.com or contact us at
john@...
Please feel free to forward this newsletter to anyone you think might be
interested
To subscribe send a blank e-mail to: quickchangeover-subscribe@yahoogroups.com
To unsubscribe send a blank e-mail to:
quickchangeover-unsubscribe@yahoogroups.com
Past issues are indexed and archived at www.changeover.com/newsletter.htm
=============================================================
Mark Garvey is president of Garvey Conveyor and I have heard him speak several times on throughput. He has a very interesting and useful approach to it. He was kind enough to contribute an article on it which appears below. This article originally appeared in print in East Asia Magazine. Mark can be contacted through his website at www.garvey.com
Thanks for sharing, Mark!
SOME THOUGHTS ON...
THE SIMPLE TASK OF MAXIMIZING THRUPUT
By Mark Garvey
President Garvey Corporation www.garvey.com
Maximizing the Thruput of a bottling line is really not as complex as you might think.
In today’s environment of tremendous competitive pressures, brought about by the development of the Mega-Buyers such as Wal-Mart and Cosco, producers of consumer products, such as bottlers, are forced to take extraordinary measures to reduce their costs and increase their thruput. Often times the people responsible for making the productivity improvements fall prey to the logic that if I improve the performance of a specific machine the overall production line will benefit. There is no guarantee that improvement will be the result and often times the overall thruput of a line can suffer as a result of efficiency gain on a specific machine. In order to understand how that is possible lets take a look at how a production line operates.
Production lines are closely analogous to a chain, a group of machines performing a sequence of events to produce a product. Each machine is a link in that chain. In order for the line to produce, all machines must be running simultaneously. No link can be broken. If that happens the line will stop and nothing is produced.
A chain is made up of almost identical links. However, if it breaks, it will only break in one place, the weakest link. In a production line, different machines will breakdown at different times. So where is the weakest link? This concept is what confuses people into thinking that the weakest link (also known as the Constraint) moves. It does not. The weakest link (the Constraint) will always be one machine.
Individual machines on a line will have basically two conditions. Either they will be running or they will not be running. The average time that a machine runs is known as the Mean Time Between Failures (MTBF). The average time a machine is not running because of a failure is called Mean Time to Repair (MTR). If you add the two component times together you get the Total Time (TT). By dividing the Mean Time Between Failure by the Total Time, the result is the Probability of Run (POR).
MTBF/TT = POR
If you multiply the POR by the rate of the machine you will get the Net Output.
The machine with the lowest Net Output will be the Constraint. Remember there can only be one. Once you have identified the Constraint, improving the overall thruput of the line, simply becomes a matter of isolating and protecting the Constraint from the failures of the other machines. This is achieved by keeping a store of product (Buffer) just upstream of the Constraint that will keep the Constraint running in the event of a malfunction of an upstream machine. Additionally, space must be provided to store product (Buffer) just downstream of the Constraint allowing the Constraint to continue to run when a malfunction occurs downstream.
If the Buffers are sized properly they will be able to supply or store enough product to account for the vast majority of malfunctions. When properly executed, the Constraint never has to stop when it is able to run. As a result, the line is producing all it can produce. That is 100% thruput.
Production lines are not a balancing act.
In order for the line to operate effectively, the machines need to be out of balance. It is virtually impossible to have everything in balance on the line. Just like it is impossible to have a chain with all equally weak links. Everything upstream and downstream of the Constraint must run faster. By default they must. Therefore the more imbalance you build into a line the more effective the Buffers will work. This is because the recovery time of the Buffers will be faster, and the faster you can recover the Buffers after a malfunction the faster you will have the full protection for the Constraint. The more imbalance you have the less sensitivity you have to the given efficiency of a non-constraint machine.
Once the line has been properly buffered, when malfunctions occur, the Constraint will continue to run without interruption. This maximizes the lines thruput.
How am I doing boss?
How do you measure the performance of the operators? If the objective is to produce as many cases per shift as possible then why not measure what insures that objective. For the operators upstream of the Constraint, their job is to never let the Buffer run empty. For the operators downstream of the Constraint, their job is to never let the Buffer fill up. If they reach that objective the line thuput has been maximized.
What if I need more?
If more production is needed, the net output of the Constraint must be increased. If the capacity of the Constraint is increased, the gain I get is limited to the net output of the next slowest machine. Therefore, if I double the capacity of the Constraint, and my next lowest machine is only 10% higher, the overall gain will only be 10%. However, to get the 10%, I must relocate the Buffers to the optimum locations.
So what’s the bottom line?
After analyzing hundreds of lines, over thirty years, in the beverage, food, pharmaceutical, personal care, automotive, and wine industries, we have found that the average increases in thruput between a line that is properly buffered versus one which is not buffered is 28%. Compared to lines that are buffered, but not in the optimum locations, the gains are in the 12 to 15% range. Those are enormous improvements. Consider what a 28% gain in thruput generates in cash flow. The numbers are staggering.
How can this help me?
We have set up a web site that will allow you to enter the data about your line and find the optimum locations and sizes for Buffers and what the resulting gains should be. It’s free and takes about 20 minutes to learn. Feel free to visit and use our www.Garvey.com and click on the link to www.Thruput.com. There you can sign on to the thruput calculator and see for yourself what your lines are truly capable of producing.
TIP OF THE MONTH...
LEAF GAUGES
As readers here will know, I am a fanatic about setting machines to specific setpoints. I generally do not like gauges because they share the same problems any other tool has. I believe that tools should be eliminated from changeover to the maximum extent possible.
There is an exception and that is when the gauge can be permanently mounted. Recently, I described a revolver gauge. Another alternative is what I call a leaf gauge.
In a leaf gauge a channel shaped piece is permanently mounted on the machine, generally on the stationary component. A series of gauges or leaves, each specific to a changeover setting, are mounted on the channel with a pin. It winds up looking something like a jackknife. To use the gauge, the appropriate leaf is swung into position, the movable component adjusted to just touch and the leaf swung back down out of the way. I don’t know if this is a real clear explanation so will be happy to send a sketch on request.
BOOK OF THE MONTH
THE GOAL by Elihu Goldratt
Mark Garvey has been speaking and working for years on improving line throughput. His inspiration, he once told me, has been heavily influenced by this book. I can understand why. The book clearly lays out the problems and solutions for improving plant and line throughput. Written in the form of a story, it is easy to read and follow. If you’ve not yet read it, you need to.
Click here for more information from Amazon.com (Clicking the links helps support the newsletter):
www.amazon.com/exec/obidos/ASIN/0884270610/changeovercom-20
If you liked The Goal, he has some others that are equally good:
Beyond the Goal By Elihu Goldratt (Audio CD)
www.amazon.com/exec/obidos/asin/1596590238/changeover.com-20
Critical Chain By Elihu Goldratt
www.amazon.com/exec/obidos/asin/0884271536/changeover.com-20
It’s Not Luck By Elihu Goldratt
www.amazon.com/exec/obidos/asin/0884271153/changeover.com-20
The Haystack Syndrome By Elihu Goldratt
www.amazon.com/exec/obidos/asin/0884270890/changeover.com-20
John R Henry CPP
Send Email