Week's Slides.pdf

7/26/2019 Week's Slides.pdf

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2000 John W. NazemetzSlide 2 Computer IntegratedManufacturing Systems

ADVANCED

MANUFACTURING

SYSTEMS DESIGN

Concurrent Engineering

Introduction to Simultaneous and

Asynchronous Engineering

Activities


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Overview


Definition

Concepts

New Products

Existing Products


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Computer Integrated

Manufacturing Systems Definition Revisited

Systems which enable the integrated,

rationalized design, development,

implementation, operation and

improvement of production facilities

and their output over the life cycle of

the product. These systems identify and

use appropriate technology to achieve

their goals at minimum cost and effort.


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--

Definition

Concurrent Engineering is a systematic

approach to the integrated, concurrent

design of products and their related

processes, including manufacturing and

support. This approach is intended to

cause the developers, from the outset,

to consider all elements of the product

life cycle from conception to disposal,

including quality, cost, schedule, and

user requirements.

(Pennell and Winner,1989)


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2000 John W. NazemetzSlide 6Computer Integrated

Manufacturing Systems


-

Definition Problems

Name Implies only Engineering Involved

Activity is Really Concurrent (

DESIGN)

CONCEPTUALIZATION

and

EVALUATION(ENGINEERING)

Require Broad View of Design

Must Assure that Correct Concepts Are

Incorporated into the Design

Must Assure that Principles ofEngineering/Nature are Followed


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Goals of Concurrent

Engineering in CIM (1) Primary Goal is to Assure

Rationalization in Early Stages to Avoid

Cost/Improve Product Operational Concept

Physical Concept

Manufacturing Concept

Maintenance Concept

Disposal Concept


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Goals of Concurrent

Engineering in CIM (2) Secondary Goal is Lead Time Reduction

Administrative Lead Time

Design and Rationalization of Product Approval and Acquisition of Facilities

Manufacturing Lead Time

Scheduling and Execution

Storage and Distribution

Measure of Exposure to Risk/Changes


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Traditional Process of

Serial Engineering Functions Separated

Functions Serially Executed

No Interaction Maintenance Usually an Afterthought

Time Consuming

Costly Product a Series of Suboptimal

Reconsiderations


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Serial Engineering

DESIGN MANUFACTURINGPLANNING

MANUFACTURING CUSTOMER

SUPPORT??


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Concurrent vs. Serial

Engineering All Viewpoints Solicited

Interdisciplinary Teams

Life Cycle Cost Considered Attempt to Embody Concept Early -

Before Committing to Detail Design

Data/Information/Knowledge ExchangePlanned and Encouraged

Cycle Time and Cost Reduced


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CONCURRENTDESIGN

A Concurrent Engineering

Model

PRODUCTMANUFACTURING

CONCEPT

PRODUCTMAINTENENCE

CONCEPT

PRODUCTFUNCTIONAL

CONCEPT

DISCIPLINE INPUTS

ENGINEERING

MARKETING

PRODUCTION

CUSTOMERS

WORKERS


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Virtual Concurrent

Engineering Always a Virtual Endeavor

Groups Are Always Geographically (and

Culturally) Distributed How Far is Too Far Apart?

Information Generated/Stored in VariousFormats and Locations

Single Plant + Customers

Multiple Plants (Same Organization) + Customers

Multiple Organizations + Customers


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Keys to Concurrent

Engineering Supportive Culture

Clear Understanding and

Documentation of Requirements Technical Competence/Experiences

Technical Tool Availability (CAx Tools)

Communication Competence Communication and Information Tool

Availability


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Advanced Manufacturing SystemsDesign

2000 John W. Nazemetz

Lecture 3 Topic :Concurrent

EngineeringSegment A Topic:Introduction to

Simultaneous and Asynchronous

Engineering

END OF SEGMENT


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Lecture 3 Topic :ConcurrentEngineering

Segment B Topic:Computer AidedProcess Planning


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Overview

Computer Aided Process Planning

The Use of Computer To Develop andAnalyze Alternative ManufacturingProcesses

Part of Design


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Computer Aided Process

Planning Definition

Use of computer and information

technologies to assist in the cost effectivedevelopment and assessment of alternativemethods of production and sequences for aspecific product specification andidentification of areas for potential

improvement in specifications from theprocess/manufacturing viewpoint.


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Manufacturing Processes

Casting and Molding Processes

Forming Processes

Chip Formation Processes Finishing Processes

Small Chip Removal Processes

Treatment (Mechanical and Chemical)Processes

Coating Processes


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Manufacturing Process

Review How To Determine Process/Cost

Process To Be Used (Shape)

Process Ability to Hold DimensionalTolerance

Surface Finish (How Determined)

Set Up Times

Machining ParameterSelection/Specification

Part Processing Times

Cost Optimization


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2000 John W. NazemetzSlide 22

Computer Integrated


Types of Process Planning Manual Process Planning

Variant Process Planning

Existing Plan Retrieval Composite (Master) Part Plans

Generative Process Planning

Computer Generated Process Plans Use of Artificial Intelligence


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Computer Integrated


Manual Process Planning Study Design and Specifications

Recall Past Relevant Experiences

Discuss Tight Specifications

Develop Alternative Process Sequences Specification/Capabilities

Volume/Tooling/Cost Requirements

Capacity Availability

Select and Document Best Process

Implement and Monitor


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Computer Integrated


Manual Process Planning -

Drawbacks Completely Dependant on Experience of

Process Planner

Number of Alternatives GeneratedLimited

Relatively Slow Process

Documentation Usually Poor

Incorporation of Past Investment inProcess Design not Assured


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Computer Integrated


Variant Process Planning

Identify/Find Similar Parts

Compare Existing Parts with Current

Delete Unneeded Part Features inRetrieved Part

Add Part Features/Process Not inRetrieved Part

Add New Design into System for LaterUse


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Computer Integrated


Variant Process Planning -

Retrieval Systems System for Associating/Locating Past

Process Plans/Designs Crucial to

Success Group Technology Based Systems

As Up Front Design Philosophy to Limit Variation

As Key to Access Previous Plans

Part Features

Process Sequence Based Systems

Problem of Pattern Recognition


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Computer Integrated



Composite (Master) Parts Develop Composite Part

Defines Characteristics of a Class of Parts

Contains all Possible Features that Can BeIncorporated in the Design of Parts in thisClass

Generally Defined Parametrically

Not All CAD Systems Support Parametric Features Manual Intervention Required in Non-Parametric

CAD Systems

Generally Assumes Infinite Capacity


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Computer Integrated



Drawbacks New Process Plan is Generally No Better

Than Retrieved Design

Use of Archived Plan Does Not AlwaysReflect Current Situation

Part Family Formation is NaturalFallout

No New Technologies are Considered inPlanning


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Computer Integrated


Generative Process Planning

Part Specification (CAD Model)

Recognize Part Features From CADModel

Generate Feasible Methods forProduction of Part Features

Evaluate Operational Feasibility

Evaluate Economics of Alternatives Specify Process

Regenerate Each Time Part is Produced


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Computer Integrated


Generative Process

Planning (2) Part Specification (CAD Model)

Must Conform to Standard

Current Standards not Unambiguous Recognize Part Features From CAD

Model

Lines, Arcs => Surfaces

Surfaces => Part Features

Part Features Have Specifications

Recognize Relations Between Part Features


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Computer Integrated


Generative Process

Planning (3) Generate Feasible Methods for

Production of Part Features

All Technically Feasible Methods ConsideredAlternate Sequences Considered

Evaluate Operational Feasibility

Map Technically Feasible Methods Against

Those Available to Company Subcontracting Difficult to Incorporate

Tooling Difficult to Incorporate


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Computer Integrated


Generative Process

Planning -Drawbacks Part Feature Recognition is Not a

Mature Technology CAD Model Data Exchange (Precision,

Format) May Depend on Missing Material

Expensive (Artificial Intelligence)

Must Be Tailored to Specific Firm

Incorporation of Proprietary ProcessesDifficult


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Advanced Manufacturing Systems

Design 2000 John W. Nazemetz


Segment B Topic:Computer AidedProcess PlanningEND OF SEGMENT


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Segment C Topic:Quantitative Analysis


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Computer Integrated


ADVANCED

MANUFACTURINGSYSTEMS DESIGN


Quantitative Analysis


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Computer Integrated


Overview

Quantitative Analysis in ConcurrentEngineering Singhs Mathematical Model

Uses Manufacturing Method/ProcessCapabilities, Tolerance Limits, Input andProcessing Costs, and Time Estimates toCompare Alternatives

Source: Singh, Nanua, Systems Approach to ComputerIntegrated Design and Manufacturing, John Wiley andSons, Inc., New York, New York, c1995


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.1, 4.2) Tolerance

Alternatives and

Process Capabilities Standard Normal

Variate of upperTolerance

Standard NormalVariate of lowerTolerance

u

jk

j

j

u

k Zt

t = tolerance limitk= tolerance system (design alt.)j= machining system

l

jk

j

j

l

k Zt


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.3)

SCrap Fraction

)](1[)( ujkl

jki

jk

s

jk

jk ZZ

YYSC

s

jk

o

jk

i

jk YYY ,, = output, input, scrap units


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.4)

Mass Balance

s

jk

o

jk

i


sjk

ojk

ijk YYY


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.5, 4.6)

Technological Coefficients (input perunit of output, scrap per unit of output)

s

jk

o

jk

i


o

jk

ijki

jkY

Yk

o

jk

sjks

jkY

Yk


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.7) Combining (Percent Acceptable in

Output Stream)

s

jk

o

jk

i


)()(

)](1[)(

1 ljku

jk

u

jk

l

jk

jk

jk

o

jk

s

jks

jkZZ

ZZ

SC

SC

Y

Yk


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.8) Combining (Ratio of Input to Output

Obtained Will be >1)

s

jk

o

jk

i


)()(

11

l

jk

u

jk

s

jko

jk

i

jki

jkZZ

kY

Yk


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.4, 4.9, 4.10) Combining to Reform Material Balance

Equations

s

jk

o

jk

i


o

jk

i

jk

i

jk YkY

ojk

sjk

sjk YkY s

jk

o

jk

i

jk YYY


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.11) Cost Equation (Cost of Output and Scrap

= Cost of Input and Processing

s

jk

o

jk

i

jk XXX ,, Unit Cost of input, output,scrap

)( ijkijk

ijk

ijk

sjk

sjk

ojk

ojk YfYYXYXYX

)( ijkYf Processing Cost per Unit


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.11) Dividing by to get output cost/unit

o

jk

i

jk

i

jk

i

jk

i

jk

o

jk

s

jk

s

jk

o

jk

o

jk

YYfYYX

YYXYX )(

o

jkY

i

jko

jk

ijks

jko

jk

sjki

jko

jk

ijko

jk fYY

YX

Y

YX

Y

YX


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.12) Or, by substituting technological

factors, unit cost of output (good units)

)( ijki

jk

s

jk

s

jk

i

jk

i

jk

o

jk YfkXkXkX


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Computer Integrated


Singhs Quantitative

Analysis (Eq. 4.13) Developing an expression for

Manufacturing Lead Time:

ojk

ijkjjj YktST

jt

jS Set-up Time

Processing time, j thmethod


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Computer Integrated


Using Singhs Quantitative

Analysis Given a Set of Production Methods

With Process Capabilities,

Unit Production Cost Estimates, Unit Production Time Estimates, and

Set up Times

and a Set of Precision Alternatives,

Assuming Precision is Relevant to CustomerDefinition of Quality

Then, Quantitative Assessment Possible.


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Computer Integrated


Problems with Singh

Quantification (1) Product Manufacturing Centric

Viewpoint

No Design Cost Data No Service/Maintenance Cost Data

No Value to Increase/Decrease in Lead Time

No Administrative Lead Time Factor

No Material/Capacity Lead Time


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Computer Integrated


Problems with Singh

Quantification (2) Product Manufacturing Centric

Viewpoint

Scrap Defined by Designer, not Customer,no Customer Definition of Quality

No Differential Cost Savings/Cost (Serial vs.Concurrent)

NOT AN ANALYSIS OF CONCURRENTENGINEERING !!! --IT IS A

DESIGN/PROCESS COMPARISION

METHOD


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Computer Integrated


Benefits of Quantification

Forces Focus upon Measurable Factors

To Extent These are the Right Factors,Drives Organizations Direction

Shows Changes/Provides Basis forComparison of Alternatives


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Computer Integrated


Concurrent ReEngineering

of Products No Real Difference in Organization and

Process Execution

Only Change is Inclusion of ExistingPlant and Facilities

Cost (Current) Known, Not Estimated


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Advanced Manufacturing Systems

Design



Segment C Topic:Quantitative Analysis

END OF SEGMENT

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