Review of Problem Solving for Manufacturing, Part 6
In Part 6, I presented the reasons for using reason, judgement, and common sense throughout the problem-solving process. I also provided eight fundamental steps for exercising our “cerebral muscles” and becoming stronger problem solvers with experience. They are as follows:
- Develop a complete definition of the problem.
- Develop accurate definitions of symptoms.
- Look for simultaneous symptoms.
- Independent causes may or may not occur simultaneously.
- Find defect-free configurations (DFCs).
- Look for distinctions.
- List and investigate changes.
- Always test to determine cause(s).
I finished the post with an explanation of intermittent and recurring problems and a process for dealing with the challenges of solving them.
Today, we will further explore recurring problems and discuss potential problem-solving traps. As I have stated in previous posts, 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.
Once in a while, when a piece of equipment has supposedly been repaired, the same problem recurs with precisely the same symptoms it had before. Recurring problems are always the direct result of inadequate or incomplete problem-solving techniques applied in the first attempt at a solution. Problems typically recur for one of these reasons:
- The root cause of the problem was not previously found; therefore, only a symptom was treated.
- The repair was inadequate or incomplete.
- The diagnosis was made incorrectly, based on insufficient or inadequate information.
- The root cause was deliberately avoided. Sometimes people avoid problems they don’t know how to solve or repairs they don’t know how to make. Even worse, sometimes people are too tired or disinterested to work conscientiously.
- The repair was cost or time prohibitive, so a temporary, cheaper, or quicker repair was made instead. Shortcuts almost always cost more time and money in the long run.
Potential problem-solving traps
Even when we have the best fundamentals, processes, and tools at our disposal, problem-solving does not always go according to plan. Often, obstacles get in the way, or an unexpected variable diverts the problem-solver on a wild goose chase. I refer to these as “problem-solving traps.” Since you can’t eliminate them from your future challenges, it pays to become aware of the most typical types of traps, and what you can do to mitigate their risks:
- Erroneous information, facts, or data supplied by someone else involved. Misinformation can be supplied deliberately in an attempt to sabotage the process for personal gain (e.g., to get time off for equipment downtime). It can also be supplied unintentionally by someone just trying to be helpful, who doesn’t understand the value of accurate information. Be wary of generalized statements such as “It’s always been like this” or “I think it happened last week.” Be even more dubious about emotionally charged or hyperbolic statements like “This piece of garbage always screws things up!” Whenever you’re in doubt, collect new data or seek new information from other sources.
- Defective replacement parts from the supplier. As trusting people, we may assume that if we install a replacement part from the package it came in, that it must be functional. This is not always the case! If you are reasonably certain that a part is defective, and you install a replacement that doesn’t fix the problem, my advice is to remove the replacement and have it tested for functionality.
- Defective measurement tools or gauges. A team I worked with had a large hydraulic press with a hot oil problem. They tried everything to solve it, but could not locate its root cause. They made one fatal mistake in assuming that all of the gauges on the press were functioning properly and that the pressure readings were accurate (one of the known causes for hot oil is excessive pressure). When I explained this trap to them, they checked all of the gauges and found that the pressure gauge readouts were not accurate. They were too low. The team replaced the defective gauge, adjusted the pressure into the normal operating range, and the problem was solved. Incorrect data is actually more dangerous than no data because it leads you down the wrong path.
- Defective input material. Out-of-spec raw material can create a trap. Raw material characteristics that affect the final product can lead you to the wrong conclusions. For example, if the viscosity of a material is outside of the acceptable range, the material will exhibit different flow properties inside the mold. A team I worked with tried to solve a surface quality issue, and because the tag on the batch of SMC had an acceptable viscosity value, the team assumed this was not the root cause. However, when they retested the material, they found that the viscosity was too high. This high value created a material flow problem that was the root cause. Wrong assumptions about defective input materials will lead to a defective end product. When in doubt, retest!
- Incorrect drawings or schematics. How often have modifications been made to your equipment without a corresponding update to the related drawings or schematics? Even subtle changes to the process wiring or hydraulics must be added to the drawings in a timely manner. Without these updates, drawings and schematics become a trap for future problem solvers.
- Incorrect logic on your part. Even if you have undergone a thorough problem-solving process, it is still possible that some of your premises or assumptions could be erroneous. That is why it is good practice to have someone review your thoughts and conclusions. Far from being a sign of weakness, involving someone else in a review shows foresight.
Coming in the next post
In the next post, I will discuss two key problem solving tools that use cause and effect diagrams and causal chains. As always, if you have any questions or comments about any of my posts, leave me a message and I will respond.
Until next time.
 Process Problem Solving – A Guide for Maintenance and Operation’s Teams, 2001, Productivity Press
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