Review of Problem Solving in Manufacturing, Part 5
In Part 5 of this series, I completed our discussion by explaining the final four steps in the “Logical Pathway to Problem Solving.” To review, here are the 11 elements of the process:
- Identify the problem.
- Describe and define the problem.
- List the symptoms.
- List the known changes.
- Analyze the problem.
- Hypothesize possible causes.
- Test possible causes.
- Take action(s) on the cause(s).
- Test and implement the solution.
- Implement appropriate controls.
- Celebrate, recognize success, and document.
As we continue to explore problem solving, today we will cover the importance of reason, judgement, and common sense, along with potential traps in solving intermittent and recurring problems. Again, much of what I’m presenting in this series of posts is taken directly from my first book written in 2001,  Process Problem Solving—A Guide for Maintenance and Operation’s Teams.
Applying reason, judgement, and common sense to problem solving
The most effective problem-solving tools are of little value if we don’t apply the fundamental skills of deductive reasoning, good judgement, and common sense. Even a proven process like the logical pathway will produce faulty solutions without sound thinking. With this in mind, here are my recommendations for properly exercising our “cerebral muscles” in problem solving:
- Develop a complete definition of the problem. What are we solving? What are the parameters of the problem? Defining is the most important of the fundamental problem-solving skills; it is absolutely imperative.
I was assisting a team in a project in which a motor attached to a robotic arm (used to cut fiberglass parts) had burned up and been replaced five times. My first question to the team was, “What do you mean when you say the motor burned up?” They told me the armature was shorting out. Then I asked “What did you see when you opened the motor casing?” No answer—just blank stares. No one had looked inside the casing to define the problem. When we opened the motor, we found burned-out bearings. The team redefined the problem accordingly and was able to determine that a flow switch was improperly located and that the motor bearings were not being cooled correctly.
- Develop accurate definitions of symptoms. Symptoms are signs that something has changed or gone wrong. They are the faults that we see, hear, smell, and feel. A machine that makes a funny noise, the smell of burning plastic, the feel of a vibration, and a change in appearance are all symptoms of a potential problem. Learn to rely on your senses to develop accurate descriptions of symptoms. You may even want to list out “sight, sound, smell, and feel” with corresponding descriptions of what you sense.
- Look for simultaneous symptoms. Multiple symptoms often have a common cause. When two or more symptoms occur at the same time, they may be the result of a common origin, or they may have a cause and effect relationship. For example, if two presses powered by the same compressor both fail at once, the compressor is the likely culprit.
- Independent causes may or may not occur simultaneously. When symptoms are not concurrent, they are most likely the result of distinct causes.
- Find defect-free configurations (DFCs). Configurations are individual parts linked together to perform a given function. A defect-free configuration is the combination of components in a nonfunctioning system, machine, or process that is still functioning correctly. DFCs may even be similar or identical to a malfunctioning configuration.
- Look for distinctions. When comparing a malfunctioning or nonfunctioning piece of equipment to a properly functioning piece, contrast the two and find the telling distinctions.
- List and investigate changes. A change is any event that precedes the initial onset of a symptom of a problem. Because it precedes the problem, it is a potential cause. Remember that changes do not always occur immediately prior to the onset of a problem. A change may have happened long before the first symptom(s) appeared and the first symptom may have appeared long before it was noticed.
- Test to determine cause(s). Never rely solely on instincts and hunches about the potential source of a problem. Use your experience to develop hypotheses. Then think through the problem, imagine the likely symptoms of each hypothesized cause, and then test to determine the cause(s).
Intermittent and recurring problems
Have you ever attempted to solve a problem for which symptoms appeared, disappeared, and reappeared again? This scenario is referred to as an intermittent problem, and it can be fairly frustrating to recognize and solve. The systematic approach I have provided will enable you to significantly reduce the degree of problem-solving difficulty. One key to solving intermittent and recurring problems is to spend even more time going through the process.
To find the root cause(s), you must determine the timing of the symptoms. Here are the six steps I suggest following to deal with this type of challenge:
- Document each time the symptom(s) appear and disappear. Record specific dates and times, including when the symptoms began and ended.
- Document all changes that occur prior to and immediately after the onset of the symptoms. Operator shifts, environmental conditions (e.g., temperatures, humidity), operating speeds, and material changes are all examples of potentially useful clues.
- Create a simple time-based run chart depicting start and stop times for each occurrence of the symptom(s).
- Transpose the documented changes directly onto the run chart at the appropriate date and time coordinates.
- Look for a correlation between the documented changes and the date/time that the symptoms occurred.
- Analyze the plotted results. Is there a repeating pattern? That is, do the symptoms occur at the same time every day? Is the pattern periodic? Is the pattern cyclical?
Coming in the next post
In the next post, I will discuss recurring problems and potential problem-solving traps. As always, if you have any questions or comments about any of my posts, please leave a message and I will respond.
Until next time.
 Process Problem Solving – A Guide for Maintenance and Operation’s Teams, 2001, Productivity Press
Don't miss out!
Stay on top of the latest business acumen by subscribing to the Manufacturing Breakthrough blog.