Evolutionary Operation, EVOP :: Overview Click here to go to the homepage
What is it?
Introduced in the 1950s by George Box, EVOP is an ongoing mode of using an operating full-scale process, so that information on how to improve the process is generated from a simple experimental design while production is underway. To avoid appreciable changes in the characteristics of the product, only small changes are made in the levels of the process variables. EVOP is designed to be run by process operators on a full-scale manufacturing process while it continues to produce satisfactory products.
Why is it important?
Classic experimental design and Taguchi methods are revolutionary methodologies which help us to establish an optimum combination of the design factors and their proper levels for the manufacturing process. They are very powerful tools; but they cost money, time, manpower and require special training to conduct the experiments. In most cases, they interrupt production. Experimental design should be used in the design stage and trouble shooting to solve specific quality problem. It cannot be a routine operation. EVOP is a tool in which a continuous investigative routine becomes the basic mode of operation for the plant and replaces normal static operation.
When to use it?
The basic idea is to replace the static operation of a process by a continuous and systematic scheme of slight perturbations in the control variables. The effect of these perturbations is evaluated and the process is shifted in the direction of improvement.
How to use it?
There are one/two/three factor EVOP designs.
Single Factor EVOP Design:
1 If X were to be current production level, usually this is set as the new center of specification and is determined by designed experimentation.
2 Choose acceptable levels, X-D and X+D (within the specification limits) which still produces satisfactory products.
3 Evaluate the quality of the process at all three production levels (X, X-D and X+D) and choose one that produces the highest quality of product.

Two Factor EVOP Design:

1 If X is the first factor at the current production level, Y is the second factor at the current production level - evaluate the quality of the output at all different combinations of X & Y including the D. The combination that produces the highest quality is the new center point and repeat EVOP for the next cycle of continuous improvement.

Then there is the three-factor EVOP which goes on same lines as above but with three factors.



What's on the web?
1 EVOP Design of Experiments
SAE paper 2003-01-1015 by Donald Lynch
2 EVOP software
Demo Available
3 Book
Evolutionary Operation: A Statistical Method for Process Improvement
George E. P. Box, Norman R. Draper
ISBN: 0-471-25551-3
4 Book
Creative Evolutionary Systems
Peter J. Bentley, David W. Corne
Morgan Kaufmann Publishers
  Pl let us know if you found this brief overview useful
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