Lean Six Sigma cost, speed and quality jumps are obtained
by applying the right tools. Following the DMAIC
Lean Six Sigma improvement model, we will analyze a number of
tools of each phase.
The definition phase
Purpose of defining:
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
statute, 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 different stakeholders (customers, shareholders, employees) are
listed and the potential impact of the improvement project on each of them evaluated as substantial, average, low or null.
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, Supplies, 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? What
value that creates? Who is the owner of the process? Which are the
inputs and who provides them? What resources does the
process? What steps in the process create the value?
The steps involved in creating the SIPOC diagram and the
participation of team members in brainstorming and generating ideas
The sessions are as important as the resulting diagram.
VOC – Voice of the Customer:
Critical for a proper 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.
Using Kano analysis hides raw quantitative and qualitative data
obtained from the above in clearer expressions of the value
Customers place on various features of products and services that you offer.
Developing Critical Quality Requirements Converts 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
cost, speed and quality and provides insight into the gaps that are due
full. 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, bylaws and refined project 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 wait times,
processing times, resource
consumptions, process operator, etc.
Cause effect matrix:
This tabulates causes versus effects and calculates the scores that
they 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 has a similar function to the cause and effect matrix.
All possible input failures are considered, and then
weighted according to
to the probability of occurrence, severity of the impact on the products and
difficulty of detection. This assessment also helps determine
what inputs the project team should focus on.
Data collection plan:
This includes decisions about what data (balanced between input and
output) to collect, identification of
stratification factors (these help determine patterns in the data),
determination of sample size, identification of data sources,
preparation of data collection and data allocation sheets
collection duties among team members.
Pareto charts:
This is one more tool to focus the team’s efforts on the most
major problems. A Pareto chart is a bar
graph where the horizontal axis represents categories. Have
vertical axis we can plot in descending order, the frequency of
occurrence or impact on the cost, speed or quality 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).
Measurement systems analysis:
The measurement 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 middle centered and top and bottom
control limits. Control charts help to 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 capacity assessment:
This tool measures the capacity of the process and assesses the capacity of a
process to meet functional requirements.
There are several measures of capacity. They all compare
Process the standard deviation to the allowable range of variation as
specified by the customer.