Six sigma

1. Introduction

In the late 80's and early 90's, Motorola started an initiative called Six Sigma led by Engineer Mikel Harry, who began to influence the organization to study the (focused on Deming concepts), such as a way to improve them. These variations are what are statistically known as standard deviation (around the mean), which is represented by the Greek letter sigma (). This initiative became the focal point of the Motorola improvement effort, capturing the attention of then Motorola CEO Bob Galvin.

With Galvin's support, emphasis was placed not only on variance analysis but also on continuous improvement, setting the goal of obtaining 3.4 defects (per million opportunities) in the processes; something almost close to perfection. The initiative represented a savings of $ 2.2 billion for Motorola.

This initiative reached the ears of Lawrence Bossidy, who in 1991 and after a successful career at General Electric, took the reins of Allied Signal to transform it from a troubled company into a successful machine.

During the implementation of Six Sigma in the 90s (with the push of Bossidy), Allied Signal multiplied its sales and profits dramatically. This example was followed by Texas Instruments, achieving the same success. During the summer of 1995 the CEO of GE, Jack Welch, learned of the success of this new strategy from the mouth of Lawrence Bossidy himself, leading to the biggest transformation ever started in this huge organization.

Jack Welch's drive and support transformed GE into a "Six Sigma organization," with impressive results across all of its divisions.

2. Definition of six sigma

Sigma (σ) is a letter of the Greek alphabet that corresponds to the letter “s”, which is also used in statistics to represent the standard deviation

6σ corresponds to the bandwidth of a normal distribution.

Six Sigma can be defined as a work philosophy and one that is based on a customer focus that seeks to reduce the variability of processes using measurements based on product, process and service data and that is managed through an “aggressive ”Series of indicators.

Conceptually Six Sigma is an index of process capability; It is a number that represents how capable a process is of meeting customer specifications based on the degree of variability of that process. Assuming that a process behaves according to a normal distribution with a known mean and standard deviation, it can be defined as a Six Sigma level when having a centralized nominal mean specification (admitting up to a 1.5 sigma shift), the upper limits and Specification lower than six standard deviations (hence the name Six Sigma) from this EN. In this way the process produces a defect rate of 3.4 PPM.

Six Sigma is a management philosophy, which is focused on eliminating waste caused by process variation, through a systematic and scientific / practical approach and the use of statistical tools.

"It is a methodology that combines the use of statistical tools with a disciplined problem-solving approach"

Six Sigma or Benchmark

It is used as a parameter to compare the level of quality of processes, operations, products, characteristics, equipment, machines, divisions and departments, among others.

Six Sigma - the Goal

It is also a quality goal. The goal of Six Sigma is to get very close to zero defects, error, or failure. But it is not necessarily zero. In truth, 3.4 parts per million defective units, 3.4 defects per million, 3.4 failures per million, 3.4 PPM.

Six Sigma - the Measure

It is a measure for a certain level of quality. When the number of sigmas is low, such as in two sigma processes, involving plus or minus 2 sigmas (+2 σ), the quality level is not that high. The number of non-conformance or defective units in such a process can be very high. If we compare it with a 4 sigma process (+4 σ), where it may not have more or less four sigmas, here we will have a significantly better quality level. So the higher the number of sigmas, the better the quality level.

Six Sigma - Philosophy

It is a philosophy of continuous improvement of the process (machine, labor, method, metrology, materials, environment) and reduction of its variability in the endless search for zero defects.

Six Sigma - Statistics

It is a statistic calculated for each critical quality characteristic, to evaluate performance in relation to specification or tolerance.

Six Sigma - The Strategy

It is a strategy based on the interrelation that exists between the project of a product, its manufacture, its final quality and its reliability, control cycle, inventories, repairs in the product, and defects, as well as failures in everything that is made in the process of delivering a product to a customer and the degree of influence they can have on customer satisfaction.

Six Sigma - the Vision

It is a vision of leading an organization to be the best in the industry. It is an intrepid journey in search of the reduction of variation, defects, errors and failures. It is to extend to the quality beyond the expectations of the clients. Offering more, because consumers want to buy more, as opposed to having salespeople chasing them in an attempt to convince them to buy.

3. What is Six Sigma

Six Sigma is the measurement of defects per million operations, it applies to all transactions. The lower the number of errors, the higher the quality.

Process capacity σ	Defects per Million (PPM's)	%
two	308,537	69.1515
3	66,807	13.32
4	6,210	99.38
5	233	99.98
6	3.4	99.9997

Comparison table

3.8 Sigmas	6 sigma
20,000 items lost in the mail per hour	7 items lost per hour
Failures in drinking water for at least 15 minutes a day	1 minute of failures every 7 months
5.00	1.7 wrong surgeries per week
2 incorrect landings per day	1 wrong landing every 5 years
20,000 wrong prescriptions a year	68 wrong recipes a year
No electricity service 7 hours per month	1 hour without electricity every 34 years

4. Benefits

The benefits of Six Sigma are:

Alignment between results and efficiency: improving the quality of a process implies increasing profitability for the company Application of the methodology in various areas of the company: finance, logistics, sales, systems, administration, etc., no restricting work to the productive areas of the company Possibility of making decisions based on statistical data Development of a system that promotes the link between strategic planning and statistical and quality tools Search for the Ideal Model of System Efficiency Eliminate the processes non-added value Reduce natural variation of processes to a minimum possible Robust processes, capable of delivering what the customer demands.

5. Implementation Phases

The Six Sigma Approach is based on 6 phases (DMAIC) which are:

Definition Measurement Analysis I Improvement Control

Essentially these steps involve defining, measuring, analyzing in order to discover the root causes of the problem and then improving and controlling it to prevent the problem from occurring again.

5.1 Definition

In this phase, the defect to be corrected will be defined, the process where this defect occurs, who are the client (s) of this process, the team that will be focused on solving the problem, the improvement goal, the savings that will be made. will achieve, the metrics to use and the implementation times.

5.2 Measurement

The internal processes that influence the critical characteristics for quality are identified and the defects that are generated in relation to said characteristic are measured. Defects are defined as those characteristics that are out of tolerance.

5.3 Analysis

The goal of this phase is to begin to understand why defects are generated. Brainstorming, statistical tools, etc. They are used to identify the strategic variables that cause the defects.

5.4 Improvement

In this case, the objective is to confirm the fundamental variables and then quantify their effect on the critical quality characteristics, identify the maximum acceptable ranges of these variations, ensure that the measurement systems are capable of measuring the variation in the fundamental variables, and modify the process to stay within acceptable ranges.

5.5 Control

The goal of this final phase is to ensure that the modified process now allows the fundamental variables to remain within the maximum acceptable ranges, using tools such as statistical process control, or simple checklists.

6. Tools

Some of the statistical tools that Six Sigma uses for the analysis, approach and troubleshooting of processes, are the following:

Cause and effect diagrams. Cause effect matrices. Process maps. Process value flow maps. Charts; Pareto, Histograms, Dispersion, Box, etc. Failure Mode and Effect Analysis (FMEA) Correlation Analysis Process Capability Analysis Analysis of Variance (ANOVA) Regression Analysis Hypothesis Testing Surface Response Design Experiment Design Etc.

Six Sigma also uses Lean tools for analysis and troubleshooting, such as:

Poka-yokes Value Stream Maps Kanban Kaizen Rapid Changes (SMED) Spaghetti Diagrams Visual Communication Etc.

7. Roles in Six Sigma Implementation.

4 important Roles are identified in Six Sigma Implementation, these are:

7.1 Champions (Champion)

They define projects and are accountable for the success of Six Sigma efforts, approve, fund, and detect and resolve problems.

7.2 Master Black Belts

They are full-time people who have important quantitative and capacity tasks as mentors and as leaders. They are certified once they meet two requirements: they must supervise at least ten black belts who have obtained their certification, and they must be approved by the company's champions. Selection criteria for master black belts are quantitative skills and the ability to teach and mentor. Teacher black belts receive at least two weeks of training to teach and mentor.

7.3 Black Belt

These are full-time people who lead teams and focus on the fundamental processes and report the results to the champions. Team leaders are responsible for measuring, analyzing, improving and controlling the critical processes that influence customer satisfaction or productivity growth. He obtains his certification after having successfully concluded two projects: the first under a master black belt, and the second autonomously. A successful project will be one in which the defects are reduced tenfold if the process started at least as 3 sigmas (66,000 defects per million operations), or 50 percent if the process begins at a point greater than 3 sigmas. To get certified,black belts must also be approved by the business champion team.

7.4 Green Belts

They work on black belt projects, but not full time; they work on Six Sigma projects while performing other functions in the company. After the black belt project ends, team members are expected to continue to use the Six Sigma tools as part of their regular work.

Conclusions

Six Sigma can be approached in different ways according to the expectations that each company wants to achieve, but it is necessary to have a broad vision of what the company requires since applying is a very long and expensive process. Therefore, each company must have its applications well structured and defined, since if these are not well directed the results will be null. Large companies such as GE, Motorola, Allied Signal have taken 5 to 10 years for their implementation as well as a high cost in the training of their person but thanks to the effort of the personnel dedicated to Six Sigma they have achieved great results by obtaining millionaire benefits.

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