Problems are central to lean culture and part of everyday life at production sites. A structured problem-solving approach, monitored on the field, can sustainably improve industrial performance, but which lean problem solving tools and methods should be used?

Let’s review the techniques, criteria and philosophy involved in industrial problem solving, in particular:

• The problem-solving approach
• How to analyze the root causes of a problem
• Which problem-solving methods should be used (8D method, PDCA, DMAIC, QRQC,etc.)
• The most common specific tools (5 Whys, WWWHHW, is/isn’t analysis, Yamazumi diagrams, Ishikawa diagrams, pareto diagrams, checklists, etc.)

What are the steps involved in solving a problem in the factory? 🏭

First of all, we need to clarify a basic term: what is a problem? From an industrial point of view, a problem is defined as a deviation between a given situation and the expected standard. Problem-solving involves finding the cause of the situation that isn’t providing the expected results, then implementing sustainable solutions.

Toyota formalized the process decades ago with different stages in the process:

• Initial perception of the problem: The first stage usually involves describing the problem.
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• Clarify the problem: Here, the aim is to reduce the search area as far as possible, and to document the problem well in order to find the best solution.
  > What was the expected result? What information can be gleaned from the shop floor? Can the problem be broken down into a single entity? This brainstorming stage helps you understand the ‘symptoms’ so you can ‘find a cure’ effectively.
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• Locate the cause: The aim here is to ‘rewind’ the process to understand where/when the problem came about.
  > For example, if a part is defective, the problem could be due to a quality issue, an anomaly in the raw material, or a fault at the machining stage.
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• Search for the root cause: Generally, the ‘5 Whys’ method is used during this stage. The key is to identify the source of the problem, so as to find a lasting solution rather than a superficial one. This questioning is essential.
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• Think about solutions: Once the root cause has been identified, it’s time to think about sustainable solutions (brainstorming).
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• Test solutions: This is an important step, used to confirm the hypotheses and solutions envisaged in step 5. Only a real test can validate solutions in the long term. This calls for the implementation of monitoring indicators.
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• Standardize and generalize for similar problems, to improve problem-solving efficiency in the future.
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Once the problem-solving approach has been defined, there are a number of methods for following it through, using a predefined framework. Let’s look at that now.

What lean problem solving methods should be used ?

Structured problem-solving methods enable you to identify and solve a problem, sustainably. In most cases, they follow the approach described above, and can be broken down into several stages. The best-known are :

The 8D method: The heavy artillery of problem-solving, 8D is made up of 8 steps:

• D1: Form the team
• D2: Describe the problem
• D3: Identify and implement immediate actions/security measures
• D4: Determine the causes of the problem
• D5: Decide on definitive, long-term corrective actions
• D6: Implement the solution
• D7: Prevent the problem from recurring elsewhere
• D8: Congratulate staff

The PDCA method or Deming’s Cycle, which breaks down into 4 stages:

• Plan: Analyze the data/problems and plan the actions to be taken
• Do: Deploy/implement the actions defined in step 1
• Check: Check the results of the actions that are carried out. Compare actual and expected results
• Act: Here, either the results are as expected, or the solution needs to be adjusted, in which case it’s back to the “Do” stage.

The DMAIC method :

• Define
• Measure
• Analyze
• Improve
• Check

The QRQC (Quick Response Quality Control) method:

More than a method, it’s a mindset. As the name suggests, this method guarantees a Quick Response and a comprehensive resolution of the problem (Quality Control). 

Whether you choose the 8D, PDCA, DMAIC or QRQC method to solve problems in the factory, your staff has access to them through fabriq’s shop floor management solution, guiding them in their day-to-day problem-solving. Make the most of this data by making it available to as many people as possible, so you don’t have to reinvent the wheel every time! 

The lean problem solving tools most frequently used in a factory environment

Certain tools may prove necessary to structure the different stages of the above methodologies: for example, when searching for the root cause (8D and DMAIC), using the “5 Whys” tool will help you to analyze the causes in greater depth. When describing the problem during the QRQC stage, it is sometimes essential to use WWWWHHW and is/isn’t analysis. 

Here is a non-exhaustive list of the lean problem solving tools that are most commonly used:

The 5 Whys method

Primarily used to identify the root cause, the 5 Whys method involves asking “Why?” until you get to the source of the problem. For example:

• Why was the part faulty? Answer: A machining flaw
• Why did a machining flaw occur? Answer: The machine wasn’t set up correctly
• Why weren’t the settings correct? Answer: The instructions were unclear for the situation at hand
• … and so on until the root cause of the problem is identified.

The WWWWWHH (5W2H) 

‍The aim here is to characterize the problem by asking these 7 questions: Who, What, When, Where, Why, How, How much/many (or 5W2H). This method can be combined with is/isn’t analysis.

Is/isn’t analysis

‍This also helps define the scope of the problem, which is why it can be used in conjunction with 5W2H. This tool can be used to sort elements into two categories: those that are related to what’s being analyzed, and those that aren’t.

The Yamazumi diagram

‍Chart per workstation: Each step is represented by a block and the amount of time it takes. This tool helps identify non-value-added steps and their duration. The Yamazumi chart is a powerful lean manufacturing tool for line balancing.

The Ishikawa Diagram (or Cause-Effect Diagram):

The Ishikawa diagram, also known as a cause-effect diagram or fishbone diagram, identifies the causes of a given situation.

• Define the effect that’s being observed: a defect occurrence, or an aspect of the product or process
• Draw an arrow from left to right in the direction of the effect
• Describe the main factors that are potential causes of what is being observed
• Usually the 5Ms below  (+possibly Management and Financial Means)

In fact, a multitude of tools can be used to solve complex factory problems: affinity diagrams, pareto diagrams, tree charts, etc.

Want more? Discover the 10 best practices for problem solving.