We have previously brought you a blog post dedicated to problem solving techniques used within engineering. Naturally, this was only an introduction. The below post is a much more in-depth dive into a larger scale problem solving methodology referred to as the DMAIC process (pronounced Dee – Make). You will notice plenty of overlap from our previous problem-solving blog as a lot of the same tools are employed, the difference however is scale. Smaller issues make use of simpler quicker to use tools, whereas major issues and technical challenges would be more suited to utilising the full DMAIC process.
The DMAIC process is broken down into five key sections, Define, Measure, Analyse, Improve and Control. This structure sets you up to have the best possible chance of solving or improving the problem. It is a skill that will develop over time and is used in careers ranging from engineering to accounting.
Define
Define is the first phase of the DMAIC process and is critical in setting your project up for success, as a poorly defined problem becomes difficult to solve. The define phase is to highlight the challenge or improvement opportunity that you will work on during the project. The project title, scope and problem statement will all be set out as part of this phase. This problem statement will carry on throughout the following process steps in which you will constantly reflect on it to ensure you are staying on track.
The three main topics that fall under the define phase are discussed below:
Voice of the Customer (VOC)
First, you need to understand what drives these improvements or changes in a process from the beginning. The answer is the Voice of the Customer. This has many interpretations depending on where you are working. For example, if you were in a contract medical device company you would be dealing with the customer and their project, they are the driver of the improvement or change. Another possibility is if you were working within a large multi-national company where the driver may be your key stakeholders within the project, for example, quality, project managers or finance. The key to a successful project is to understand the need; once this is understood, you can then focus on what the scope of the project entails.
Project Charter
A project charter provides an overview of your project before the bulk of the work begins. It includes four sections:
1. Define the project vision
2. Organize the project structure
3. Have an implementation plan
4. Estimate risks, issues, and budget
Along with your project charter, an A3 board can be created under the DMAIC headings to track your project from stage to stage. Once a section is complete you can then funnel everything down to eliminate any noise that may have been created.
Value Stream Mapping
Value Stream Mapping is a lean-management method for analysing the current state and helping design a future state. This includes all aspects of the project from the manufacturing process until it reaches the customer. This is a visual aid to define areas for improvement.
Measure
Measure is the second phase of the DMAIC process. This section allows you to gather and analyse data to assess the current performance of your chosen problem. This gives you the current state or baseline for your project and will allow you to gauge improvements made.
The three main tools that are used in the measure phase are discussed below:
Process Map
Process mapping is a technique utilized in a project to visualize the steps involved in a certain activity or process. In its basic form, process mapping is a flowchart that illustrates all the inputs and outputs of an event, process, or activity. This process is to dial into each significant step and dial into the micro detail involved to identify vital areas of concern. A successful process map requires four elements:
1. A set of symbols. These symbols can mean things such as start of step, end, decision point etc.
2. A technique to ensure that everyone uses and understands the symbols.
3. Data about each process step. (Process times, operators, output etc.)
4. A drawing tool to link graphical elements into a readable map.
Capability Analysis
A capability analysis is a tool used to understand your process and predict or monitor its performance. It is used to assess the ability of a process to meet specifications and can alert you to issues within the process. When completing your capability assessment, it will demonstrate the current state of the process such as whether it is currently under control, out of control or on the edge of the process's capability - see graph below for visual representation. A key element to this tool is relevant accurate data collected over time. The data can then be assessed using software such as Minitab to generate the capability assessment.
Pareto Chart
A Pareto Chart promotes confidence that you are directing your attention and energy into the highest priority issue which if solved will have the largest positive impact on the process. A Pareto Chart is essentially a bar chart which is arranged by height in descending order. The order of the bars allows you to rank and prioritize the problems. Pareto charts are an excellent visual aid to demonstrate your data in a clear and concise manner, they are simple to read and understand which will support you when presenting your approach to the wider team.
Analyse
The analyse phase is used to identify areas highlighted in the measure phase to determine root causes. This phase allows you to interpret the data and highlight possible reasons for variation in the process or poor performance.
5 Whys
5 whys are a tool used when moving through your problem-solving project. They allow you to continually dig deeper into your proposed root causes to eventually arrive at the true cause of the issue. Each why gets evaluated as its own unique problem to allow you to ask the question again, “Why?”.
Cause and Effect Diagram (Fishbone Diagram)
A cause-and-effect diagram is a modified brainstorming tool which allows you to group potential variation under different characteristics. The cause-and-effect diagram falls under six headings material, method, manpower, environment, machine, and measurement. It serves as a great visual aid to support the problem-solving process, allowing the team to explore potential causes of a specific problem and more importantly, allows you to understand the relationship between these causes.
The above methods are spoken through in more detail in our problem-solving techniques blog which we strongly recommend you read if you haven’t already.
Improve
The fourth phase of the DMAIC process is improve. This is the section where you improve the process performance by addressing and eliminating the root causes identified earlier. Some root causes may be relatively straightforward to address, such as adding in an additional step or some new tooling. If a more complex root cause is identified a different approach may be required to determine the ideal solution. This is discussed briefly below.
Design of Experiments (DOE)
Design of experiments (DOE) is a systematic, efficient method that enables scientists and engineers to study the relationship between multiple input variables and key output variables. It is a structured approach for collecting data and making discoveries. A DOE can be introduced when there are multiple complex processes or systems which are influenced by many factors and the optimum set of parameters is currently unknown. An example might be a gluing process, where you have several inputs such as: the age of the glue, the amount applied, the person applying the glue, the humidity in the room, the cure time, the temperature in the room, the lot of glue used, the lot of the substrate used etc. Running a DOE in this instance can help with identifying the key inputs into the process that have the largest effect on a measured output (e.g., bond strength).
The below points are some key characteristics for a successful DOE:
1. Set good objectives
2. Measure responses quantitatively
3. Replicate to dampen uncontrollable variation (noise)
4. Randomize the run order
5. Block out known sources of variation
6. Know which effects (if any) will be aliased
7. Do a sequential series of experiments
8. Always confirm critical findings
When completing a DOE, Minitab is again often used in recording, demonstrating, and analysing the data.
Control
The final phase of the DMAIC process is the control phase. At this stage the change has been introduced and will be monitored to ensure performance is improved. We can now reflect on the impact the change is having on the process or product performance. The following methods help us ensure that the process performs to an acceptable standard.
Quality Control Plan
The quality control plan is a set of documents that help control the process and reduce variation. This document structure includes procedures, manufacturing forms, and visual aids along with many more. These documents help support the line with instructions on how to manufacture units along with what fixtures and components to use. This set of documents reduces risk and mistakes happening which can create rejects. Along with the creation of reject units, it is paramount that the quality control plan allows you to identify these rejects appropriately. It is very likely that these are already in place at the start of the project, but perhaps they will be updated at this stage to make them more useful/ accurate for the operators on the line.
Statistical Process Control
As mentioned throughout this blog, the statistical program Minitab has multiple options to help support you in controlling the performance of a process. The software allows you to monitor changes within the line over a period of time, allowing you to visually see the improvement after you implement changes to the process. This is a significant part of the control step as it is a visual support that allows you to easily interpret the data.
6S
6S is the cornerstone to any process and should be implemented at the earliest possible opportunity to reduce the chance of issues down the line. It is continuous practice and one which will grow and develop as the line matures.
The pillars of 6S are as follows:
Safety - Avoid unnecessary risks and act so that you and others around you stay safe.
Sort - Remove from the workplace all items that are not needed for the current operation.
Set In Order - There should be a home for everything, and everything should be in its home.
Shine - Clean the workplace extensively to eliminate all clutter and ensure that everything is ready to use.
Standardize - Use Safety, Sort, Set In Order and Shine to establish the basic standard for performance.
Sustain - There is only one right way to do the work - follow the standard until a better way is found.
Mistake Proofing (poka-yoke)
Mistake-proofing is a tool used across all areas of lean manufacturing. This technique is called poka-yoke (Japanese term). These are used in everyday life which we may not notice. A poka-yoke is any mechanism in a process that helps an equipment operator avoid mistakes and defects by preventing, correcting, or drawing attention to human errors as they occur.
Examples of Poka-yoke in our everyday lives are below:
1. Treadmill safety tag to stop the treadmill as the safety lead detaches from you.
2. Elevator doors usually have a safety sensor that detects the presence of a person, preventing the doors from closing.
3. Lawnmower safety bar on the handle cuts out the engine when not held.
The above information is a summary of the DMAIC process to support you on your career path and set yourself up for success, if you desire to learn more, please read though our other posts where we will be regularly updating with more information and advice for up-and-coming engineers.
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