Six Sigma is a structured management method that aims to improve the quality and efficiency of manufacturing processes in order to reach zero defects. First applied to industrial processes, the Six Sigma method was then extended to all types of processes, including administration, logistics, commercial and energy save.
The Six Sigma Methodology is based on two Axes
- the client’s opinions (collected through surveys for example),
- Of reliable and measurable data (indicators, etc.).
Six Sigma was created by Motorola, a US company, in 1986 to improve its manufacturing processes to satisfy its customers. The name Six Sigma was even deposited by the firm. However, the method became famous in the 1990s thanks to General Electric, which decided to use it and improve it.
The Six Sigma method encourages companies to carry out measurable and effective actions, to better satisfy their customers, to involve teams and thus improve their image.
Principles of Six Sigma Methodology
In order to satisfy customers, it is imperative to deliver quality products. In practice, it is difficult to have a constant product quality because the manufacturing processes are becoming more and more complex, making the drift inevitable.
Scraps, retouches and customer returns for non-compliance generate significant costs for the company, not to mention customer dissatisfaction and the negative impact on the brand.
The Six Sigma method offers techniques and tools to improve process reliability and eliminate variability in order to reduce defects.
Six Sigma takes its name from the Greek letter sigma σ which designates the standard deviation. “Six sigma” therefore means 6 times the standard deviation. Specifically, the method aims to ensure that all products from the same process are within a range of up to 6 sigma relative to the overall average of the products resulting from this process.
By reducing the variability of the process products, you reduce the risk of your product being rejected by the customer because it does not meet its expectations or requirements. You need to improve the process so that only products that meet customer expectations and requirements are delivered. The aim of this method is therefore to produce the desired product the first time, thus avoiding corrections and alterations, and especially the costs associated with them.
The Six Sigma methodology seeks absolute consistency in manufacturing processes because variability is a source of customer dissatisfaction. This method was therefore created to improve processes or, if improvement is not possible, to create new ones.
The method is based on the five stages of DMAIC tools (Define, Measure, Analyze, Improve, and Control in English):
- Define: define the objectives to be achieved and the needs of the client. This first step allows framing the project by determining its perimeter, the expected results, the resources and the necessary delays.
- Measure: assess current process performance and variability.
- Analyze: identify problems (where, when and how faults occur) by analyzing the data gathered and the strengths and weaknesses of the different processes.
- Improve: identify and implement improvement solutions to eliminate problems encountered. Several steps may be necessary to test and validate the most appropriate solutions.
- Control: this is the most delicate step. It is essential to follow the solutions put in place in order to avoid a reversal and to ensure quality improvement in the long term.
Advantages and Disadvantages of 6 Sigma Methodology
- The benefits of using the Six Sigma methodology include improved resource utilization and lower operating costs through process optimization.
- Since the customer is satisfied, the company succeeds in retaining it, which leads to an improvement in turnover per customer and an increase in market share. Finally, the company enters a dynamic of continuous improvement.
- Side disadvantages, Six Sigma are an approach based on measurement and figures, which is not always a reflection of the reality of the field.
- Moreover, to be successfully applied, this method must be adopted by the whole company and it is known that this can be difficult, especially in large companies.
- Finally, Six Sigma requires the collection and analysis of a large number of statistical data, which can be complicated and time-consuming. Small businesses can quickly be discouraged.
Client, process and measurement are the three key concepts on which the Six Sigma method is based. This method allows you to identify customer expectations, measure process performance against these expectations, and analyze the causes that influence performance through the use of statistical tools, implement solutions to correct the causes of non-performance and to use measurement tools to check that the solutions implemented work and improve performance. To successfully implement the Six Sigma approach, the entire company must participate and invest in training.