Lean Six Sigma leaps in cost, speed, and quality are achieved by applying the right tools. We conclude by reviewing some tools from the Analyze, Improve and Control phases of DMAIC.
The analysis phase
Purpose of the analysis:
When implementing Lean Six Sigma, this phase identifies and verifies the relationships between the causes and their effects. Helps in discovering factors that affect key inputs and outputs of the process. The analysis phase seeks to find patterns in the data obtained during the measurement phase to make sense of everything.
Tools for analysis:
Two variables are plotted against each other on a graph. The resulting image gives a visual indication of how well the variables are correlated.
This can be thought of as a mathematical equivalent of the scatter plot. Here an equation is derived to express the dependence of one of the variables on one or more others. The equation can then be used to predict values of the dependent variable for given values of the independent variables.
A large arrow is drawn with the effect whose causes are being analyzed shown to the right at the end of the arrow. The main categories of probable causes are shown in the branches that emanate from the main line. For each category, detailed ideas about the causes are generated and indicated in relation to the corresponding branch.
Analysis of time traps and identification of capacity restrictions:
A time trap is a process activity that inserts delays into the process and may be due to capacity constraints or other operational inefficiencies. Whatever the source of the delays, it eventually manifests as long delivery times. A capacity constraint is a thread or activity whose output per unit of time is less than that of the previous and/or subsequent thread or activity.
Without value-added analysis:
From the current value stream map, each process activity is examined to determine its contribution to customer requirements. Those that do not contribute to valuable customer outcomes and are not needed for other business reasons (eg, regulatory requirements) are removed.
The improvement phase
Purpose of Improvement:
In the previous phases, defects (variability outside of customer specifications) and waste (non-value-added activities and costs) have been identified, measured, and their causes found through analysis. The purpose of the improvement phase is to eliminate defects and waste.
Tools to improve:
To Be Process Maps: A map of the desired process is created, in which the activities identified without added value have been eliminated.
From the capacity constraint and time trap analysis performed in the analyze phase, we can determine if the main source of delay was due to long preparation times. In that case, the following steps apply.
* Document and classify installation procedures
* Improve the organization-Study of distribution of the work area and analysis of required movements. Use 5S if necessary to eliminate inefficiencies. Brainstorm opportunities for improvement in configuration steps.
* Whenever possible, convert internal procedures (setup activities that are performed with the machine turned off) to external procedures (setup activities that do not affect machine operation). In transactional situations, this means turning serial procedures into parallel ones.
* Improve the remaining internal configuration procedures.
* Eliminates the need for adjustments.
This slim tool results in a clean and organized work area, with a place for everything and everything in its place. The steps of the methodology are:
* Spell out
* To hold
The application of 5S eliminates the inefficiencies that result from lack of organization by reducing the amount of unnecessary movement and transportation.
Total Productive Maintenance
When downtime is one of the main causes of low process cycle efficiency, total productive maintenance should be applied, which aims to reduce the percentage of downtime.
Through proper design of processes and equipment, the possibility of errors (and with them the need for inspections) is eliminated. Examples are the design of online forms that cannot be submitted if data is entered incompletely or the wrong type of data is entered. Similar to this are pieces that can only be assembled one way.
Design of experiments:
This is the statistical design of experiments that allow you to determine the impact of two or more variables on another variable of interest. This tool also takes into account the interaction effects between the variables.
This is a statistical tool to test the validity of assumptions. In this case, the assumptions could relate to the impact of causes on effects. For example, if performance is suspected to be operator dependent, tests can be performed to verify whether the observed differences in performance between two operators are statistically significant.
Solution selection matrix:
There will usually be more than one possible solution identified for the problems under consideration. The selection matrix compares them using a set of weighted criteria to determine the most suitable.
The actual implementation of the agreed solutions will take the form of a project and will require the use of the usual project management tools for planning, communication, risk assessment and monitoring.
The control phase
The purpose of the control phase is to ensure that the gains from the improvement phase are integrated into the organization.
Standard Operating Procedures:
Improved process design will certainly include new operating practices. These should be codified in an operating manual that operators can refer to. Having a standard operating manual helps prevent slipping back into old inefficient practices.
Statistical Process Control:
Control charts that reflect the improved capabilities of the process should be constructed and used to monitor process performance over time.
The essence of visual management is captured in the idea that an employee should be able to walk through the work area and leave with 90% of the information. This is achieved through the 5S organization, illustrations of process steps located close to the process, SIPOC diagrams and value stream maps, the use of shadow boards, etc.
The list of tools considered in this article and the last one are just some of the several available. In any project, it is likely that only a few will be used.