What is a Layered Process Audit?
Layered Process Audit is a quality tool designed specifically for manufacturing management. It is meant for auditing organizational processes ...
By AMREP | Posted on January 08, 2024
In our comparison article about Six sigma and Lean we gave a brief introduction to Six Sigma. Six Sigma is essentially a process improvement tool that uses statistics-driven methods to reduce defects and eliminate variation. We gave an overview of its 5 key phases, DMAIC - Define Measure Analyse Improve Control. Here, we explain these phases in detail.
The first step in Six Sigma is the Define phase. This involves scoping out the problem, improvement activity, opportunity for improvement, the project goals, and customer (internal and external) requirements.
Activity | Description | Tools Used |
---|---|---|
Establishing Purpose and Scope | Define the problem in detail, understanding its impact and scope | Brainstorming, Problem Statement |
Identifying Stakeholders | Recognize all affected parties and involve them in decision-making | Stakeholder Analysis |
Mapping the Process | Create a high-level map of the process flow | SIPOC Diagram |
Here, the principle objective is to determine the problem and situation that needs to be addressed. This involves defining the problem in a precise manner. This step ensures that the challenge has a clear objective and a defined boundary, so that the group can remain focused.
Stakeholder analysis means identifying the parties that are involved and are affected by the project. This also helps with defining roles and responsibilities in developing Six Sigma activities.
SIPC stands for Supplier, Input, Process, Output, and Customer. It is a high-level process mapping tool to help visualise a process and its inputs and outputs. It is particularly useful for identifying process-related issues and developing improvement strategies.
The Measure phase in Six Sigma is where statistics takes centre stage. It's all about quantifying the problem identified inside the Define section and establishing a baseline for improvement.
Activity | Purpose | Tools Used |
---|---|---|
Gathering and Analyzing Data | Collect relevant data to establish a performance baseline | Data Collection Methods |
Identifying Critical Data Points | Pinpoint essential data that reflects the problem's impact | Key Performance Indicators (KPIs) |
Employing Statistical Techniques | Analyze data to understand process variation and capability | Statistical Analysis Tools |
The first step is to gather statistics relevant to the problem identified. This includes figuring out what data to acquire, the way to gather it, and ensuring its accuracy. This data forms the baseline against which all future improvements can be measured. It's not about collecting numbers; it is about getting the data that can give insights into the production situation and the problem at hand.
The Measure phase focuses on identifying the most critical information points that directly reflect the impact of the problem. These key performance indicators (KPIs) are essential in understanding the nuances of the issue and in guiding the improvement efforts.
Once the data is gathered, it is time to analyze it. This is in which statistical techniques come into play. Using statistics results in a quantitative approach towards problem-solving and is essential in identifying process variations.
In the Analyze phase of Six Sigma, the focus shifts to determining the root cause of the variations and poor performance.
Technique | Purpose | Example Tools |
---|---|---|
Data Visualization | Gain insights into process behaviour and identify defects | Control Charts, Pareto Charts, Scatter Plots |
Statistical Analyses | Uncover patterns and validate assumptions | Hypothesis Testing, Correlation Analysis |
Cause-and-Effect Analysis | Map potential root causes of problems | Ishikawa (Fishbone) Diagrams |
Visualizing statistics is an effective way to benefit insights into procedure behaviour. Tools like Pareto charts, and scatter plots, use numbers to spot tendencies, outliers, and patterns. These visuals assist in identifying areas that require deeper analysis and understanding the underlying causes of defects.
This step uses statistical analysis such as hypothesis testing and correlation analysis. These techniques are essential in validating assumptions and becoming aware of variation patterns.
Also known as Ishikawa or fishbone diagrams, cause-and-impact diagrams are instrumental in mapping capacity root reasons. They assist in visualising the different factors that contribute to the problem. These diagrams are specifically useful for collaborative problem-solving group discussions.
Also, read about Six sigma vs Lean in detail
Phase four of Six Sigma, 'Improve', is the solutions development and process improvement part of Six Sigma.
Activity | Objective | Techniques Used |
---|---|---|
Brainstorming for Solutions | Generate a range of potential solutions | Control Charts, Pareto Charts, Scatter Plots |
Employing Creative Problem-Solving | Develop innovative solutions to address root causes | Design Thinking, Lateral Thinking |
Aligning Solutions with Objectives | Ensure solutions meet project goals | Alignment Checks, Feasibility Analysis |
The journey starts with brainstorming. Teams come together to generate a pool of ideas for solving the problems identified.
Creativity is fundamental in this section. Problem-solving techniques like 'thinking out of the box' or 'layout wondering' are used to develop innovative solutions. The intention is to be as adventurous as possible in finding ways to resolve problems. Sometimes, it can even involve creating new production techniques.
Every proposed solution is evaluated against the problem identified to ensure that it is within scope. Other factors considered are whether the solutions are sustainable and can lead to a long-lasting effect on eliminating variations.
Also, read about VDA 6.3 Process Audit.
The very last stage within the Six Sigma technique is the Control segment. This is focused on ensuring that defects and variation reductions are made permanent.
Activity | Goal | Tools and Techniques |
---|---|---|
Implementing and Monitoring Solutions | Ensure effective execution of solutions | Project Management Tools |
Establishing Control Mechanisms | Maintain gains and prevent regression | Standard Operating Procedures, Training |
Using Statistical Process Control (SPC) | Monitor process stability and quality | Control Charts, Process Monitoring |
This is where all the action is - the stakeholders work together to implement the solutions developed and monitor the results.
Control mechanisms are used to keep processes within the established variation limits. Regular audits and statistical process controls are key tools.
Statistical Process Control (SPC) strategies are integral to the Control segment. SPC includes the usage of statistical strategies and techniques to monitor and manipulate a process. SPC is a whole separate science in itself and involves the use of control charts and statistical analysis to limit process variation.
This structured approach ensures not just temporary fixes but permanent improvements in process variation and defect control, the ultimate goal being the total elimination of defects (which is achieved through minimising process variation). Six Sigma is widely used in our manufacturing quality enhancement solutions to ensure that the supplier’s production is kept within the buyer’s quality parameters and production requirements. Most of all, it is used to control defects at the supplier source.
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