Every organization desires to make the most of its resources and produce the greatest defect-free and quality performance yields. For this purpose, the Six Sigma framework was developed and is constantly employed by businesses worldwide. This article examines Six Sigma's role as a process/product improvement tool.
What is it?
Six Sigma (6σ) is a set of techniques and tools for process improvement.
It is a management tool that helps organizations eliminate product and process defects. It applies a series of statistical analyses to find defects and deviations from an accepted quality standard. It then establishes the cause of these deviations. This way, the necessary changes can be made to significantly improve the quality and performance of the product/process.
Typically, a company generates about 50,000 defects per million products (a 5% error rate). The Six Sigma method aims to reduce the defects to less than 2 per billion products (near 0% error rate).
The term sigma actually comes from the field of statistics. A sigma (σ) denotes a standard deviation (kind of the average errors versus the expected number, i.e., mean or the average). Under the normal distribution curve (it is called 'normal' for a reason, i.e., it is a probability distribution that frequently occurs in nature), the rough probability of product defects is as follows:
70% of the values fall within 1 sigma from the mean ==> 1 defect per 3 products.
95% of the values fall within 2 sigma from the mean ==> 1 defect per 20 products.
99% of the values fall within 3 sigma from the mean ==> 1 defect per 400 products.
99.99% of the values fall within 4 sigma from the mean ==> 1 defect per 15,000 products.
99.9999% of the values fall within 5 sigma from the mean ==> 1 defect per 2 million products.
99.9999999% of the values fall within 6 sigma from the mean ==> 1 defect per 500 million products.
There are two principal methods of Six Sigma, namely:
DMAIC (Define, Measure, Analyze, Improve, Control), which is used to improve existing business processes. It comprises five steps:
Define the goals and processes to be improved. These goals should be consistent with the customer's demand and the business strategy.
Measure the key aspect of the current process and collect the relevant data.
Analyze the data to understand the cause-and-effect relationship. Then, determine the relationships and ensure all the factors have been considered.
Improve and optimize the processes based on the analysis.
Set up a control system to ensure any deviations a corrected before they create defects. For example, set up pilot runs and better tests before extending the approach and continuously monitor the process.
DMADV (Define, Measure, Analyze, Design, Verify), which is used to create new products or new processes. It also comprises five steps:
Define the goals. These goals should be consistent with the customer's demand and the business strategy.
Measure and identify CTQs (critical to quality factors). Also, identify and quantify the product's capabilities, the critical elements of the production process, and any significant risks.
Analyze the best design alternatives, create a high-level design, and select the best one.
Design the details, then implement and improve the design. This phase may require simulations.
Verify the designs, for example, by using piloting and beta testing. Also, implement the production process and ensure it is managed and improved continuously.
Since the Six Sigma methodology can help companies to reduce defects, improve product quality, increase process efficiencies, and cut costs, many companies are interested in implementing Six Sigma. Motorola, for example, attributed over $17 billion per year in savings to Six Sigma.
When do we use it?
The Six Sigma framework serves as a quality control and performance improvement tool. The instances where it provides significant value include:
When there is a report of defects in a business's products. It could come from a customer complaint or an observation on the production floor.
When there is a significant drop in profits due to high wastage. Six Sigma can curb wastage and the resulting cost implications by detecting the errors in the process and fixing them.
When you are about to introduce a new product to the market. Six Sigma can provide rigorous testing measures to ensure that the products can be produced in good quality with minimum defects.
When you seek improvement to the performance of a previous product rollout. Six Sigma helps to direct your effort to ensure that the product is of the highest quality.
What business questions is it helping us to answer?
The Six Sigma tool is designed to answer the "What, "How," "Why," and "Where" questions:
What is the problem with the product, processes, strategies, and resources used to deliver it?
How does the problem affect the product? For example, does it affect performance or cause difficulty for users?
Why is this problem occurring? What is the root cause of the defects, and what measures should be taken to address them?
Where will the amendments matter? What changes will provide tremendous improvement to the product?
What steps can be taken to prevent a repeat of the previous problem?
How do we use it?
You can follow the steps discussed below to use the six sigma tool effectively.
Define
The first step is the problem definition step. It is where you identify the objectives you want to achieve using the six sigma tool. You can use internal and external feedback (e.g., from customers) to help you identify the problems.
Measure
Next, you measure the data, compare the product's performance with its desired performance, and examine its impacts on the state of your operation.
Analyze
Then, you find out the root causes behind the challenges/problems. To uncover the underlying issues, examine the processes, human inputs, material resources, and operations.
Improve
This is where you devise improvement ideas and new processes to improve performance. Determine the changes needed to increase value or efficiency. Don't forget to consider the financial and non-financial implications of the solutions.
Control
Finally, you work out measures to prevent the problem from reoccurring. Put measures in place to monitor product quality, continuous improvement, and customer satisfaction.
Practical Example
A geolocation software company uses the six sigma framework to address the reported cases of glitches following its recent software update.
In the "Define" stage, the company verifies customer feedback and determines the objectives. Then, it identifies the glitch areas and their impact on the user/customer experience.
The "Measure" stage examines the glitches' impact on the company's sales and performance. It also compares its performance against an accepted standard.
Then, it deploys a software engineering team to find the root cause of the problem with its software. This is the "Analyze" stage, where it traces the glitches to a problem within its source code.
Next is the "Improve" stage, where it develops a supplementary program and writes it into the existing software. This helps to clear the glitches and correct any problems within its source code.
In the "Control" stage, the company creates a channel that responds to any potential glitch. It also introduces a diagnostic toolkit and a self-correction program that'll mop up glitches before they can surface in real-time. This way, software users can avoid future issues and enjoy an improved user experience.
Advantages
Six Sigma is data-driven, making it reliable in producing consistent results.
Six Sigma provides lasting solutions by preventing future reoccurrences of the problem.
Six Sigma can be used to tackle existing issues before they pose a serious problem in the long run.
Six Sigma saves your business from wastages and amendments.
Six Sigma is good at improving product quality, leading to higher customer satisfaction and a favorable brand reputation.
Disadvantages
The effectiveness of Six Sigma depends on the skills of the implementor. Inadequacies on the part of management, staff, and customers will affect the process and outcome.
Without a thorough understanding of Six Sigma's technical tools and deep knowledge of the business's problem areas, the implementors cannot bring the true potential of Six Sigma.
The downtime that results from the Six Sigma application is costly for high-volume, continuously operating factories.
Six Sigma requires considerable human input and other resources to take shape.
Six Sigma relies on data. Poor data quality will hamper the six sigma implementation.
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