Cam 13 Inference Engine

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Dr. HABEEB HATTAB HABEEB

Office: BN-Block, Level-3, Room-

088

Email: [email protected]. No.: 7292

UNITEN

University TENAGA Nasional Lecturer: Habeeb Al-Ani

Lecturer: Dr. HABEEB ALANI University TENAGA Nasional
mailto:[email protected]:[email protected]://www.dewittindustries.com/cgibin/ibrowse/images/of_12/animations/mechanical/gear/gearhttp://www.dewittindustries.com/cgibin/ibrowse/images/of_12/animations/mechanical/gear/gear


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University TENAGA National

College Of EngineeringMechanical Department

Academic Year2008-2009

Lecture Note

University TENAGA Nasional Lecturer: Habeeb Al-Ani

UNITEN



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CAMUniversity TENAGA Nasional Lecturer: Hab

eeb Al-Ani

Computer Aided Manufacturing

UNITEN



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Computer Aided Process

Planning(CAPP)


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Process Planning

Principle activity of manufacturing engineeringincludes

1. Deciding which process and methods to be

used in what sequence2. Determining tooling requirements

3. Selecting production equipment and

systems4. Estimating cost of production of selected

process, tooling, and equipment



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Computer Aided Process Planning (CAPP)

CAPP is an automated process planning, can

be divided into two main sytems1. Retrieval Systems

2. Generative Systems



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Retrieval CAPP systems

Based on group technology (GT) and part classification

and coding a standard process plan is stored in

computer files for each part code number.

GT: Similar parts identified and grouped together in

order to take advantage of their similarities in

design and production.



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Generatival CAPP systems

Alternative to Retrieval systems. Rather than retrieving and

editing an existing plans from a data base, a generativesystem creates the process plan using systematicprocedures that might be applied by a human planner.

In fully Generative CAPP system, a process sequence isplanned without human assistance and predefinedparts.

It is a branch of artificial inteligence Expert Systems.

Computer Programs are capable of solving complexproblems that normally requires a human.



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Generative CAPP systems (continue)

Several ingredients needed

1. Knowledge Base: Technical knowledge of manufacturing

and the logic used by a succesfull process planners must

be captured and coded into a computer program.

Generative CAPP systems use the knowledge base to

solve the process planning problems and to create route

sheets.



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2. Computer Compatible Part Description: Description

contains all the data needed to plan the process

sequence. For example

i. Geometric model of the part developed on a CAD

system.

ii. Group technology code number of part defining its

significant features is given.



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3. Inference Engine: A generative CAPP system

requires the capability to apply the planning logic

and process knowledge contained in the knowledge

base to a given part description. CAPP applies its

knowledge base to solve a specific problem of

planning the process for a new part. This procedure

is called InferenceEngine



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Benefits of CAPP systems

1. Process rationalization and standardization (logical

and consistent)

2. Increased productivity (greater number of process

plans to be developed)

3. Reduced lead time

4. Improved legibility

5. Interfacing with other programs (cost estimation,

etc..)



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Design for Manufacturing and Assembly (DFM/A)

To implement DFM/A, a company must make

changes in its organizaitonal structure and

design principles and guidelines.

1) Organizational changes need to be done to have

better intraction between design and MFG

personnel.

Organizational changes must contain :

a)Team formed of designer, manufacturing

engineers, quality engineers, material engineers..



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(DFM/A)(cont.)

b)Designers must spend some time in

manufacturing area.c)A manufacturing engineer should consultthe designers.

2) One of the guide lines in designing is tomake it as simple as possible, but in designfor assembly, additional features arerequired, such as; to be technically good in

manufacturing, is it safe from copying( cancompetitors learn the secrets of ourproduct by reverse engineering?).



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Benefits of DFM/A

1. Shorter time to bring product to themarket

2. Smoother transition into production

3. Fewer components in final product4. Easier assembly

5. Lower cost of production

6. Higher product quality7. Greater customer satisfaction



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Design for Quality (DFQ)

Traditional quality control has been concerned

with detecting the or quality in manufactured

products and taking corrective action to

eliminate it.The modern view of quality control

encompasses a broader scope of activities

including robust design and statistical processcontrol.



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Design for Quality (DFQ)(continue)

Robust Design: Products function and

performance is not sensitive to the variations in

design and manufacturing parameters. It

involves the design of both the product and

process.

Statistical Process Control(SPC): Involving the

use of statistical methods to assess and analyze

the variations in process. This method includes

keeping records of production data and charts.


D i f Lif C l


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Design for Life Cycle

Factors associated with life cycle

1)Delivery: Transport cost, delivery time, etc..2)Installation: Utility requirements.

3)Reliable: Service life, failure rates, etc..

4)Maintaining: Design modularity, maintenance

requirements.

5)Service: Spare parts, field service.

6)Human factors: Complexity of controls, risks, etc..

7)Upgrading: Compatibility to the future designs.

8)Disposability: Recycling of components, waste

hazards, etc..


D i f C


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Design for Cost

In manufacturing our main aim is to reduce the cost of

production. Of course we need to make the processes

easy and quality high. Choosing the best material and

manufacturing processes among all the available

materials and processes is a complex decision making.

In cost reducing there is two main factors

1) Role of materials

2) Role of manufacturing processes



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Role of Materials

Understand the functional requirements of each part,

choosing criteria will include

1) Mechanical properties of the material: Strength,

toughness, ductility, hardness, etc..

2) Physical properties of the material: Density,

melting point, thermal expansion, etc..

3) Chemical properties of the material: Oxidation,

corrosion, etc..

4) Shape of the material:Need to select the shapewith respect to the design, therefore it requires

less additional process.



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Role of Materials (continue)

5) Manufacturing properties of the material: Need to

select the suitable material for the process that is

going to be applied.

6) Material supply: Location of the plant, location of

the country, politics in the country affects the

availabitiy of the material. Therefore the cost.7) Material cost: Cost of a raw materialdepends not

only on the material itself but also on its shape,

size and condition. Also, price of a material

decreases as the volume increases.Demand isanother aspect in the price of a material.



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Role of Materials (continue)

8) Product design: Cost of material is a significant

portion of product cost. This cost can be reduced

by optimization in design or reducing thickness.

But minimization in material thickness may cause

problems in manufacturing.

9) Substitution of materials: New products appearcontinually in the market to substitude the

materials in use. The purpose of substitution is to

reduce the cost of the material, to improve

manufacturing and assembly, to reducemaintenance, etc...



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Role of Manufacturing Processes

Proper selection of manufacturing processes andmachinery depends on various considerations like:

1)Properties of the work material

2)The shape and the size of the work material

3)Surface finish and dimensional tolerances

4)Quantity of the production

5)Functional requirements

6)Process capabilities.



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Manufacturing Cost

1) Material cost

2) Tooling cost

3) Fixed costs

4) Capital costs

5) Direct labor costs

6) Indirect labor costs



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Manufacturing Cost and Production Rate

Approximate cost division

Design 5%

Material 50%

Direct labor 15%

Overhead 30%

Of course the direct labor costs changes with respect to the

manufacturing volume. High volume type of manufacturing

includes dedicated machinery which needs less direct labor.On the other hand small volume productions needs more direct

Labor since the machinery used is general purpose type of

Machines and needs more human interaction.



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Cost Reduction

Cost can be reduced by

Simplifying part design

Allowances of rougher surface finish and broader

tolerancing

Using less expensive material

Investigating the alternative ways of

manufacturing(see the figure next slide)

Using efficent machinery Since manufacturing adds value to materials by

using value analysis methods we can reduce the

cost.



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Methods of Making a Part

Various methods of making a simple part:(a) casting or powder metallurgy.(b) forging or upsetting.

(c) extrusion.

(d) machining.

(e) joining two pieces.



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Value Analysis

Value analysis consists of six phases

Information phase: gather data and determinecost

Analysis phase:Identify problems andopportunities

Creativity phase:Seek ideas to solve problems

Evaluation phase: Select ideas and identify costsinvolved.

Implementation phase:Take necessary actions toaccomplish the task

Review phase: Analyze to see if any adjustment isneeded



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L t D HABEEB ALANI U i it TENAGA N i l

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Cam 13 Inference Engine