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(+)+(+) Setup Minimization Improves Line Efficiency
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(+)+(+) The Quick Changeover e-letter
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(+)+(+) Published monthly by Changeover.com
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(+)+(+) Written by John R Henry, CPP
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### SEPTEMBER 2005
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If you’ve not donated to Hurricane Katrina relief yet, please do so. A few good places that will put any contribution to good use include:
Adventist Development and Relief Agency http://www.adra.org
Salvation Army http://www.salvationarmyusa.org/usn/www_usn.nsf
Catholic Charities http://www.catholiccharitiesusa.org/news/katrina.cfm
There are hundreds of others as well.
Please help.
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PackExpo Las Vegas is just around the corner. There are lots of great conferences. Perhaps the best will be one that I am presenting on “Calculating and cutting the high cost of changeover”. If you are a machine user, you need to hear why changeover is so expensive and where the costs come from. If you are a machine builder, you need to hear this even more. You will understand why your customers will happily pay for enhanced changeover capabilities.
See http://pelv2005.packexpo.com/content/solutions.html for more information and to register.
I look forward to seeing ALL of you in Las Vegas.
By the way, the Las Vegas slogan is “What happens here, stays here”. I hope conference attendees will accept a modification: “What happens in the conferences needs to be taken back to your plant and put to work!”
And, don’t forget to visit the PackNation Blog at www.packnation.com
SOME THOUGHTS ON...
STARTUP (Part I)
Changeover is the total process of converting a line or machine from running one product to another. I need to emphasize the word “total” here. The proper definition must include everything that is involved. I place a great deal of emphasis on definitions because the first step in solving any problem is figuring out exactly what it is. Sometimes, the diagnosis is harder to get right than the solution. The wrong diagnosis will result in chasing snipes.
In keeping with the concept of changeover being the total process, I divide it into what I call “The 3 Ups”. These are Clean-up, Set-up, and Start-up. In this newsletter, I want to focus on the issue of startup.
Let’s begin by defining startup. Startup is the period of time beginning when cleanup and setup are complete and the line is put back into production. The startup period lasts until the line is running at normal speed and efficiency. Typically the startup period is characterized by high reject levels, frequent machine or product jams, frequent stoppages to fine tune adjustments that had been initially made during setup. Jams, especially with liquid products, can also necessitate the stopping of the line for cleaning after a spill. In a worst case, perhaps due to machine timing issues where machine components crash, startup may also include breakdowns and emergency repairs.
Startup times can be measured in minutes and in some cases are measured in shifts (8 hours). I have found most packaging lines take at least a couple hours to settle down and run reliably. Plants with relatively short production runs may never achieve steady-state operation since, before they can get the line fine-tuned, the run is over.
Most lines will require a relatively short period (usually less than 5-10 minutes) of what I call charging or acceleration. This is the period of time when perhaps hand feeding the initial bottles into a timing screw is required. Or it may be the first few cycles on a filling machine until al the air bubbles work their way out of the lines. It also includes the time it takes the first bottle into the line to work it’s way through to the discharge. I don’t really consider this startup although I realize some will disagree with me.
The goals for cleanup and setup should be reduction to a minimum. They will seldom go away completely.
There is a single cause of startup: Variation. If there were no variation, there would be no startup. This leads us to the definition of quality as the absence of variation but that’s a subject for another newsletter.
The variation causing startup comes from two sources, variation of the product (including components and other materials) and variation of the cleanup and setup:
Liquid products often vary in viscosity depending on their temperature. If a product is compounded at 120 DegF it will run very differently if used immediately or allowed to cool to ambient temperature overnight. Compressed pharmaceutical tablets will sometime vary in hardness causing problems with breakage in the filler. Corrugated material such as used for cases is notorious for variability of size. SBS board can absorb moisture which can cause it to be less rigid. The day shift operator of the injection molding machine making caps may use less mold release than the second shift operator. Or, plant purchasing may negotiate a better price on the “same” cap but from a different supplier. In short, there are lots of causes of product variation. There are countless other examples that most of you have probably seen.
This is not to say the product/components are not within design specification. It is possible that they are not. Hopefully, there is a quality process that assures this. However, many parameters that can effect runnability may not be measured. How many quality inspections include determining the quantity of mold release, for example? Or the moisture level of the corrugated? Parameters can also change in storage. Corrugated stored in a non-climate controlled warehouse will absorb moisture. Sometimes the changes will be subtle. A carton purchased from different plants of the same supplier may use board from different parts of the country. Differences in the trees from which the board is made can sometimes cause subtle variations that can drive plant people nuts.
Problems will occur due to product being within specification but varying within the, perhaps overly generous, limits. Caps that come in on the low side of the specification will run differently from caps that come in on the high side. This can be especially difficult when the “same” caps from different suppliers are mixed.
In short, the key with the product and components is not just to be within specifications. They need to be the same every time.
Next month I will discuss variability in the cleanup and setup phases of changeover.
TIP OF THE MONTH...
REVOLVER GAUGES
Readers here know that I do not support the use of tools for routine changeover. They may not be available, time may be lost looking for them, the right tool may be used improperly or the wrong tool may be used. In some cases, policy permits operators to perform changeover tasks but not to use tools.
Gauges are tools and subject to the same problems as any other tool. For this reason, although I stress accurate measurement in setup, I do not recommend gauges. The exception is when they can be permanently mounted at the point of use.
There are a number of ways to do this but I thought I would share one that I have seen as standard items on some Italian machines. I was recently in a plant where they had been incorporated on existing American machines. In that case, the plant had built the gauges themselves.
The gauge consists of a flat, round baseplate, perhaps ½" thick and 3-4" in diameter. The plate is mounted on a bracket and spins on a center bolt. A series of holes around the circumference allows bolts to be mounted. These bolts are parallel to the center “axle” bolt. The entire assembly is permanently mounted under the component to be set.
The bolts are adjusted to provide the proper set-point for each setup and locked in place. They can be locked in with either a locking nut or with a set screw perpendicular to the bolt.
To use the gauge, the proper bolt is rotated into position and the component part brought up against it.
Other refinements include replacing the bolts with rods cut to specific lengths and ball detents to let each gauge click into position.
Don’t forget to color code!
It seems to me that this is something someone should make as a standard retrofit item but I have never seen it. If anyone knows where they can be purchased, I would be interested in hearing from you.
I am not sure how clear my description is. If anyone wants a sketch that I use in my workshops, drop me a note.
BOOK OF THE MONTH
A Revolution in Manufacturing: The SMED System by Shigeo Shingo
In the 60's Toyota was taking 8-12 hours to changeover stamping presses. Shigeo Shingo was assigned the task of reducing that time. He was able to get it under 10 minutes.
This book tells how he did this using standard industrial engineering principles and simple modifications to the process. If you are interested in changeover, it is the “must read” book on the subject.
A companion book in Productivity Press' Shopfloor Series is "Quick Changeover for Operators". It is a condensed version of the SMED book and excellent for distribution to the operators and mechanics who might find "Revolution..." a bit complex. On the other hand, never underestimate your floor people. They usually kow more than you might think.
Order it from Amazon at
http://www.amazon.com/exec/obidos/ASIN/0915299038/changeovercom-20
John R Henry CPP
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