Posts Tagged ‘Constraint exploitation’

The Element of Time

Friday, September 24th, 2010

As we all know there is variation everywhere and in everything. This includes people pencils, traffic at an intersection, customer needs, goods, services, and of course processes. If you can not predict this variation, I can bet you are compensating for it and that compensation is costing you money!!

In Six Sigma we use statistics to recognize and thus assess and understand that variation so we can predict it ahead of time. This reduces our costs and increases customer satisfaction. Statistics can help you “Picture” variation. Many times we look at data that we gather in various ways but some times we forget about the element of time. At any given point things may look great but over time many times things vary. This variation can not be seen in what we call a histogram of all the data or any other kind of plot that does not use time on one of the axis. For example below (Figure 1) is a plot of Systolic blood pressure of one individual over four months. This plots shows where the average Systolic Blood Pressure would be if it was Normal, Marginally High, or High. In this individuals case it does not look that great.

As you can see this individuals Systolic pressure is all over the place and does not look like a normal distribution. It may be Bi or Multi modal (two or more things effecting the results making several peaks in the Histogram).  From this we can not draw to much of a conclusion but to tell him to see a doctor. Or should we??

If I take that same data and plot over time we get the following graphic.

Now clearly you can see a shift in the blood pressure over the 4 months. All for the better. We might not want the person to see the doctor but find out what might have cause this improvement. A different solution just because we looked at the data in a time sequence chart.

What these two graphs tell us is that if you have collected data over any given time period I’d suggest that you plot it in what is called an x or individuals chart (Figure 2 above) over time and see what you see in patterns there. In fact many times I plot the data in several different ways just to see what I can find. What kinds of patterns I see that can lead me to why the data varies so much.

If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.


Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090

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Posted in Introduction to Six Sigma, Six Sigma Tools | No Comments »

Exploiting the Process Constraint

Thursday, June 3rd, 2010

Exploit ConstraintOnce you have identified your constraints, the next step in constraint management is to exploit them. This mean to utilize them to their maximum extent. To exploit the constraint we have to take a look at a few things first.

  1. We need to look at the existing work in process (WIP) and throughput levels and compare them to the goals or proposed levels or TAKT time for the constraint.
  2. We need to look at the line flow requirements and compare it to the constraint capacity.

These two will give you a feel for how bad things are. Look closely at these comparisons and them do the following things:

  1. Develop a layout depicting buffer locations and sizes. Remember that buffers are one of the Seven Types of Wastes so try to maintain them as low as possible, but never let the constraint run out of raw materials to perform its tasks.
  2. Determine equipment needs. Here we look at if we can find other equipment to help the constraint move product faster. This may include buying more of the same equipment and creating another parallel operation to increase product flow to meet the demand.
  3. Once you have the first two done then adjust the process flow rate to match the capacity of the constraint. This will reduce materials from piling up at the constraint and making thing confusing.
  4. Rebalance operations. Not all products you produce require all operations in the process so something may bypass the constraint or can have other thing performed on it before it needs to go through the constraint. Ignore local efficiencies. Building more products at other operations just to keep people busy does not increase sales it only increases expenses.
  5. Ensure that an operator is always at the constraint working the product through it. Do this by staggering lunches and breaks, and cross training to ensure multiple people can work the constraint. Treat the person working the constraint like a heart surgeon. Everything is always there ready for them to do their job. They don’t have to go looking or wait for anything!!
  6. Establish procedures to ensure the constraint “NEVER RUNS DRY”. This includes material flow management, buffers, inventories, early deliveries, and expediting material so that they are always there at the constraint, ready for use.
  7. Every constraint needs to be a planned maintenance #1 priority so when maintenance is preformed it take the minimum amount of time away from running product on the operation. Notice I said a planned maintenance NOT no maintenance. I do not remember how many times I have heard that “we could not afford to stop for maintenance” but they ended up having to stop for repairs caused by no maintenance. Those repairs took, on average, 10 times longer to do. Maintenance is cheap and can be done off hours on constraint equipment.

Well there you have how to exploit a constraint in your processes. Next week I will address subordination of a constraint the third of five steps in constraint management. As always if, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.


Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090

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Posted in Leading Six Sigma, Six Sigma Tools | 2 Comments »