Summary 2

6.1

Updated April-09

Lecture Notes

Chapter 6

Knowing and Understanding Your

Processes

ENTERPRISE EXCELLENCE

6.2

Updated April-09

Learning Objectives

• Understanding Process Variation

• Acquire All Process Documentation

• Process Mapping

• Value Stream Mapping

• Value Stream Analysis

• Failure Modes and Effects Analysis

6.3

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Define Phase: Knowing and Understanding

Your Processes

• The goals of the define phase is to know and understand your business processes

• The define phase is accomplished using:

• Process mapping • Process walkthroughs • and Failure Modes and Effects Analysis (FMEA)

6.4

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UNDERSTANDING PROCESS VARIATION

• Understanding variation is a key to understanding measuring your process

• As you collect the data associated with your process, you will start to better understand its variation and how it effects your process, its metrics, and controls.

• A defect is any error state that results in customer dissatisfaction or down stream rework.

• Defects will negatively impact your bottom line. By minimizing defects, companies can increase customer satisfaction and profitability.

6.5

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UNDERSTANDING PROCESS VARIATION

• Six Sigma began in the 1980s when Motorola developed this strategy to reduce defects in its products

• Sigma is the symbol for standard deviation (6σ).

• Six Sigma seeks to improve processes by reducing variation.

• Six Sigma can be defined in several ways:

 A management philosophy

 A process measurement

 A level of quality

6.6

Updated April-09

UNDERSTANDING PROCESS VARIATION

• Normal fluctuations in a process are always present to some degree. They are called common-cause variations.

• Variation observed from one processed checkout to the next is an example of common-cause variation

• Variations that are not normally present in a process are called special-cause variations. Power failures, for example, occur infrequently and unexpectedly, and they can bring checkout lines to a standstill

6.7

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UNDERSTANDING PROCESS VARIATION

• Decreasing process variation increases the process sigma

• The end result is greater customer satisfaction and lower costs

• Less variation in a process provides many benefits, including:

 Less waste and less rework

 Products and services that are higher quality, last longer, etc.

 Satisfied customers

 More stable and predictable process

6.8

Updated April-09

UNDERSTANDING PROCESS VARIATION

• A defect is any error that results in customer dissatisfaction or rework.

• Six Sigma measures the number of defects per opportunity, or DPO.

• Defects per opportunity (DPO) consists of total defects divided by total opportunities.

• The differences between the traditional three sigma and six sigma processes are shown in the graph

6.9

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UNDERSTANDING PROCESS VARIATION

6.10

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EXAMPLE

6.11

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EXAMPLE

6.12

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Sources of Variability

• Two sources of variability can be identified: systematic variability and error variability

• Systematic variability comes from the treatment performed in the experiment. It is variability between two or more groups, and it helps us to de- termine whether the treatment has had any effect

• Error variability, on the other hand, comes from unidentifiable sources. It is variability within groups, and it makes it difficult for us to determine whether the treatment has had any effect

• Figure 6.3 represents the three major causes of variability

6.13

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First-Pass Yield

• First-pass yield (FPY) is a quality metric that measures the amount of rework in a given process.

• Specifically, first-pass yield equals the number of good units the process yields divided by the number of units going into the start of the process:

6.14

Updated April-09

Rolled Throughput Yield

• Rolled throughput yield (RTY) is the probability that a single unit can pass through a series of process steps free of defects. This means that RTY takes into account rework, which makes it a better indicator of the nature of the process. To understand how it is calculated, let's begin by looking at a metric that is similar to FPY. It is known as defects per unit.

• Since most processes consist of multiple sub-processes, it is important that we understand how to calculate the DPU for an entire process. Total defects per unit (DPU value for the entire process) equals the summation of each DPU from the various sub-processes.

6.15

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Rolled Throughput Yield- Example

6.16

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Rolled Throughput Yield- Example

• The value generated from the formula can then be used to estimate the minimum additional resources required, where X is defined as the number of units that must be produced.

• Minimum additional resources = X (1 - e -TDPU)

• Example 1: You are required to produce 500 units, and your process has a TDPU of 0.1899. Based on the preceding equation, the minimum number of additional resources that will be required by this process equals:

• Minimum additional resources = 500 (1 – e -0.1899) = 500 (1 – 0.827) = 500 (0.173) = 87

• From the calculation, we now know that to produce 500 nondefective units, we need to rework and/or scrap at least an additional 87 units to get 500 perfect units out of the current process. What type of impact do you think this increase will have on labor costs, material costs, and planned cycle time?

6.17

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ACQUIRE ALL PROCESS DOCUMENTATION

• Use the following as a checklist for your pro- cess documentation:

1. Process requirements 2. Contractual requirements 3. Regulatory and safety 4. Procedures and work instructions 5. Supply chain management information 6. Process data

6.18

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Process Mapping

• Process mapping is a systems approach to documenting the steps/ activities required to complete a task. Process maps are diagrams that show levels of detail - what an organization does and how it delivers services.

6.19

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Types of Processes

• Process mapping is a systems approach to documenting the steps/ activities required to complete a task. Process maps are diagrams that show levels of detail - what an organization does and how it delivers services.

6.20

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Processes Map Symbols

6.21

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Levels of Process Mapping

• Process mapping is accomplished at four levels:

 Level 0: Enterprise level

 Level 1: Organizational/funct ional level

 Level 2: Operations level

 Level 3:

Work activity level

6.22

Updated April-09

VALUE STREAM MAPPING

• Value stream mapping (VSM) is a unique kind of process mapping that lists and relates all of the elements and actions required to bring a product/service from required inputs to delivery to the customer. The scope of the VSM needs to include the appropriate supply chain for the level of the enterprise being evaluated.

• Applications for VSM are listed in Table 6.8.

6.23

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VALUE STREAM ANALYSIS

• Value stream analysis will identify and rate the activities performed by an organization according to customer requirements and expectations.

• Value stream analysis involves identifying and evaluating three types of activities:

1. Value-added (VA) 2. Non-value-added (NVA) 3. Necessary non-value-added (NNVA)

6.24

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VALUE STREAM MAP SYMBOLS

6.25

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VALUE STREAM MAP- EXAMPLE

6.26

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FAILURE MODES AND EFFECTS ANALYSIS

• FMEA is a systematic evaluation procedure used to identify, analyze, prioritize, and document:

1. Potential failure modes 2. Their effects on a system, product, and process 3. The failure causes 4. The controls used to mitigate the causes or modes 5. A measurable level of risk 6. Potential corrective actions

6.27

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FAILURE MODES AND EFFECTS ANALYSIS

• FMEA provides information regarding: 1. Reliability 2. Maintainability 3. Safety 4. Manufacturability 5. Quality

6.28

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FAILURE MODES AND EFFECTS ANALYSIS

• FMEA is properly conducted during the concept and development stage of products and processes, it has a positive effect and will produce the following benefits:

1. Improve the quality, reliability, and safety of products

2. Increase customer satisfaction 3. Reduce product development time and cost 4. Reduce the amount of rework, repair, and scrap 5. Document and track actions taken 6. Prioritize deficiencies to focus improvement efforts

6.29

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FAILURE MODES AND EFFECTS ANALYSIS

6.30

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FMEA FORM

6.31

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• In this chapter, we have learned the following:

 Understanding Process Variation

 Acquire All Process Documentation

 Process Mapping

 Value Stream Mapping

 Value Stream Analysis

 Failure Modes and Effects Analysis

Wrap-up