The cost, speed and quality leaps of Lean Six Sigma are obtained
through the application of appropriate tools. Following the DMAIC
Lean Six Sigma improvement model, we will look at a number of
tools for each phase.
The definition phase
Purpose Define:
This phase of Lean Six Sigma implementation identifies the
improvement opportunities and customer deliverables and defines a
scope. At the end of the definition phase, we should have a project
charter, clearly identified stakeholders, a project team,
estimation of business implications, a customer assessment
requirements, a high-level process map, and project management and
communication plans.
Tools to define:
Stakeholder analysis:
The various stakeholders (customers, shareholders, employees) are
listed and the potential impact of the improvement project on each evaluated as substantial, average, low, or none.
SIPOC Diagram:
Of the tools applied in this stage of the improvement project,
perhaps the most widely used is the SIPOC diagram. SIPOC supports
for Suppliers, Inputs, Processes, Outputs and Clients. The diagram
provides a visual answer to the questions needed to understand
the process: who are the main stakeholders in this process? That
value it creates? Who is the owner of the process? Which are the
inputs and who provides them? What resources are consumed by the
process? What process steps create the value?
The steps involved in creating the SIPOC diagram and the
participation of team members in brainstorming and generating ideas
sessions are just as important as the resulting diagram.
VOC – Voice of the Customer:
Critical to an adequate definition of the improvement project is the
availability of data representing customer views and
requirements. These are collected using VOC tools such as interviews,
surveys, focus groups, comment cards, suggestion/complaint boxes
etc The definition of customer here includes internal and external
customers.
The use of Kano analysis covers raw quantitative and qualitative data
obtained from the above into clearer expressions of the value
Customers value the various features of the products and services you offer.
The development of critical requirements for quality makes the customer
statements, which may be imprecise, to precise requirements (valued
from the customer’s perspective) for your product or service.
The measurement phase
Purpose of the Measure:
This phase quantifies the current state of the process with respect to
at cost, speed and quality and gives an idea of the gaps to be
filled. At the end of this phase, we have a detailed map of the
process, data on key input and output variables, an analysis of the
process capability, refined project charter, and plans where
justified by new information and recommended actions to choose under
hanging fruit.
Tools to measure:
Operational definition: several measures are defined so that all
team members apply the same definitions when collecting data for the
improvement project
Process map, value stream map, complexity value stream map:
This produces a more detailed representation of the process than
the SIPOC diagram and includes information such as lead times,
processing time, resource
consumer, process operator, etc.
Cause and Effect Matrix:
This tabulates the causes against the effects and calculates the scores that
are used to classify causes. as a measure
tool, this matrix is used to select which inputs to focus on
due to its significant impact on the results of the process.
Preliminary FMEA (failure modes and effects analysis):
This tool is similar in function to the cause and effect matrix.
All possible failures at the inputs are considered, and then
weighted according to
probability of occurrence, severity of impact on products and
detection difficulty. This assessment also helps determine
which inputs the project team should focus on.
Data collection plan:
This includes decisions about which data (balanced between input and output)
output) to collect, identification of
stratification factors (these help determine patterns in the data),
sample size determination, identification of data sources,
preparation of data collection sheets and transfer of data
collection duties among team members.
Pareto charts:
This is one more tool to focus the team’s efforts on the most
important problems A Pareto chart is a bar
graph where the horizontal axis represents the categories. About him
vertical axis we can plot in descending order, the frequency of
occurrence, or cost, speed, or quality impact of each category.
Where there is a clear Pareto effect, only some of the categories
(typically 20% or less) are responsible for most of the effects
(80% or more).
Analysis of measurement systems:
The measurement-taking process undergoes standard analysis to ensure reliability, repeatability, and reproducibility. Other attributes of
the measurement system are stability, bias and discrimination.
Control charts:
A control chart is a sequence of quantitative data run charts with
three horizontal lines showing a centered mean and upper and lower
control limits. Control charts help assess the nature of
process variation. Processes under control are expected
produce data points randomly distributed around the mean but within
the calculated control limits.
Process evaluation capacity:
This tool measures process capability and assesses the capability of a
process to meet functional requirements.
There are several measures of capacity. They are all compare the
process standard deviation to the allowable range of variation as
specified by the customer.