CALCULATIONS or Guessing?

The dictionary defines a calculation as “a mathematical determination of the size or number of something.” Nothing tricky there.

My questions to you today are:

• How many calculations are you doing to understand your process better?

• What have you learned from these calculations?

I have an acquaintance who was once a very senior technical contributor and leader at LLNL (Lawrence Livermore National Laboratory). He routinely asked his team members to do some calculations before work began. Completing some calculations to get a feel for the situation had to be done before work started.

This is common sense, you may say, and indeed you are right. However, the power of simple “back of the envelope” calculations is vast. It can give the process builder a much better feel for how things work.

As these calculations accumulate over the course of a project, the totality of this quantitative knowledge can create an intuitive feel for the situation that cannot be gotten in other ways.

Wanting to do these calculations is a natural result of being curious about how the process really works. It is interesting and amazing to me that almost anything can be calculated to some usable degree of accuracy. The ability to calculate all kinds of thought-provoking stuff helped make me interested in engineering as a career.

I was curious how much our house weighed, so I calculated it. This is much easier than using a scale! The calculations showed my house probably weighs about 690,000 pounds, or 340 tons.

In the context of building great manufacturing processes, some things worth calculating include:

• Cpk and other quality indices

• Fluid mechanics: driving factors in operation

• Heat transfer overview: steady state situation

• Kinetics: inherent speed of chemical reactions (without mass-transfer linmitations)

• Mass balance, raw materials vs. finished product

• Mass transfer: where are the rate-limiting steps

• Percentage of non-value added time in process

• Process "Window" size: current and future targets

• Transient behavior: start-up and change over characteristic response times

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My main learning from this line of thinking is how valuable even relatively simple calculations can be in helping to develop a much better feel for how a process is really built and operates. These calculations allow one to “look under the hood” and quantify how these “invisible” processes behave. The knowledge and insight gained by this approach can help guide the construction of great and robust processes.

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YOUR CHALLENGE THIS WEEK

Please think about one or two of your key process engineering projects, either creating a new process or an improving an existing process…

• Ask your key process experts which calculations have provided them with the most insight regarding why the process works.

• Which calculations have not been done yet but would be very useful to have completed?

I’d enjoy hearing your comments about the role of calculations in creating great processes in your organization. Please send your thoughts to me at marty@martyschad.com, or call me at 508-410-8081.

All the Best,

Marty

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