Hot topic: Six Sigma and SPC

Six Sigma

(Lean) Six Sigma is  a breakthrough management strategy to improve cost, inventory and lead time. The six sigma implementation is done using the DMAIC improvement process. (Define, Measure, Analyze, Improve and Control). To understand what implementing Six Sigma means some facts about the first company to apply six sigma: Motorola.

From: The vision of Six Sigma : Mikel Harry

  • In 1979 Motorola established that “their quality stinks”.
  • In 1981 they established a training center and set their quality should improve by a factor of 10 in 1986.
  • In 1982 they implemented SPC
  • In 1984 they implemented design of experiments
  • In 1987 they adopted six sigma approach.
  • In 1987 2,4% of the corporate payroll was used for training and 40 % was devoted to quality tools and techniques
  • Employees get 150 hours of training about quality techniques in 3 years

The conclusion from the above is that implementing Six Sigma or SPC is a long term project with high commitment from top management and large investments. The tools used to implement six sigma and the approach to implement SPC are the same. If you implement SPC properly you need to establish targets for improvement, you have to apply FMEA, MSA, Process capability analysis, experimental design etc.

To understand which tools and techniques will work in which production situation you have to have knowledge about other improvement systems as well like Total Productive Maintenance (TPM), Lean Manufacturing and Theory of constraints (TOC).

How does a Six Sigma implementation benefit from DataLyzer Spectrum

If you implement Six Sigma you will also implement a good SPC system which supports all different levels of the organization. The statistical tools used during Six Sigma implementation are standard available in a good SPC system. Data entry screens with the required factors and responses can be created quickly. For more information see also the whitepaper tracking and tracing.

Most companies use Minitab during the Six Sigma implementation and when they reach the control phase they start to think about implementing a SPC system. In the mean time they have lost a lot of time creating data entry templates in Excel and gathering datasets. If a company already implements a SPC system during the design phase you will save a lot of time gathering data and creating templates.  Operators don’t need to be instructed how to enter data on Excel sheets and later in a real-time SPC system. Data can be captured automatically from gages and other external sources (CMM machines, PLC’s camera’s etc). So for the day to day analysis, responding to actions, starting CAPA processes etc you use the real time system. Implementing a good real time system in the early stages of a six sigma implementation saves you a large amount of time during all phases.

For more advanced analysis like DOE you can simply import the data into Minitab.

For further information contact our staff.

Six Sigma Calculator

In Six Sigma the quality of the process is indicated by the sigma number. If the sigma of a process is 6 it indicates that the process has 3.4 defects per million opportunities. The sigma number can be calculated based on the process average, the standard deviation and the specifications. For attribute processes the sigma number can be calculated based on the percentage of defects. With the calculation of the sigma number of a process a prerequisite is that the process has some stability and is more or less in control.

In SPC Wizard you can get the sigma number and test for stability and control. To get an indication of the sigma number of a process we offer a free calculator. You can download the free calculator here.

In SPC Wizard you can test a hypothesis if 2 data sets are different by using the F and t test directly on 2 data sets. We also offer a free F and t test calculator where you can enter the parameters of a data set. Click here to download the free F and t test calculator.

SPC Wizard for Green Belts

Green belts typically use the standard statistical techniques 95 % of their time.

These techniques include:

  • Control Charts
  • Histograms and capability analysis
  • Pareto
  • Regression analysis
  • Multi vari analysis
  • F and t test and hypothesis testing

and preferably this needs to be done on all kinds of different data sources like Excel, Access, SQL databases etc

SPC Wizard is designed for analysis with these standard statistical tools. Because SPC Wizard is used on a daily basis much effort is put in very efficient analysis of data and different features are implemented to analyze the data without having to clean up the original data set. For example in a regression analysis you can click on a point in the scatter analysis and immediately see the point in the control chart with all the subgroup information and notes by the operator and basis on the information you can instantly exclude the point from the analysis without changing the original data set. This makes analysis on a daily basis very powerful.

Companies using DataLyzer Spectrum use SPC Wizard for the analysis in the measure, analyze and improve phase and of course later for daily analysis in the Control phase.