Dr. HABEEB HATTAB HABEEB Office: BN-Block, Level-3, Room-088 Email: hbuni61@yahoo

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]

http://www.dewittindustries.com/cgibin/ibrowse/images/of_12/animations/mechanical/gear/gear

http://www.dewittindustries.com/cgibin/ibrowse/images/of_12/animations/mechanical/gear/gear

University TENAGA National

College Of EngineeringMechanical Department

Academic Year – 2008-2009

Lecture Note

University TENAGA Nasional Lecturer: Habeeb Al-Ani

UNITEN

Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

CAMUniversity TENAGA Nasional Lecturer: Habeeb Al-Ani

Computer Aided Manufacturing

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Computer Aided Process Planning(CAPP)

Process Planning

Principle activity of manufacturing engineeringincludes1. Deciding which process and methods to be

used in what sequence2. Determining tooling requirements3. Selecting production equipment and

systems4. Estimating cost of production of selected

process, tooling, and equipment


Computer Aided Process Planning (CAPP)

CAPP is an automated process planning, can be divided into two main sytems1. Retrieval Systems2. Generative Systems


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.


Generatival CAPP systems

Alternative to Retrieval systems. Rather than retrieving and editing an existing plans from a data base, a generative system creates the process plan using systematic procedures that might be applied by a human planner.

In fully Generative CAPP system, a process sequence is

planned without human assistance and predefined parts.

It is a branch of artificial inteligence “Expert Systems”. Computer Programs are capable of solving complex problems that normally requires a human.


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”.



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.



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 “Inference Engine”


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..)Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

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..


(DFM/A)(cont.)

b)Designers must spend some time in manufacturing area.c)A manufacturing engineer should consult the designers.

2) One of the guide lines in designing is to make it as simple as possible, but in design for assembly, additional features are required, such as; to be technically good in manufacturing, is it safe from copying( can competitors learn the secrets of our product by reverse engineering?).


Benefits of DFM/A

1. Shorter time to bring product to the market2. Smoother transition into production3. Fewer components in final product4. Easier assembly5. Lower cost of production6. Higher product quality 7. Greater customer satisfaction


Design for Quality (DFQ)Traditional quality control has been concernedwith detecting the or quality in manufacturedproducts and taking corrective action toeliminate it.The modern view of quality controlencompasses a broader scope of activitiesincluding robust design and statistical processcontrol.


Design for Quality (DFQ)(continue)Robust Design: Product’s function andperformance is not sensitive to the variations indesign and manufacturing parameters. Itinvolves the design of both the product andprocess.Statistical Process Control(SPC): Involving theuse of statistical methods to assess and analyzethe variations in process. This method includeskeeping records of production data and charts.


Design for Life Cycle Factors associated with life cycle1)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..


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 processesLecturer: Dr. HABEEB ALANI University TENAGA Nasional

Role of Materials Understand the functional requirements of each part, choosing criteria will include1) 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 shape

with respect to the design, therefore it requires less additional process.


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 is another aspect in the price of a material.


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 appear continually 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 reduce maintenance, etc...


Role of Manufacturing Processes

Proper selection of manufacturing processes and machinery depends on various considerations like:1)Properties of the work material2)The shape and the size of the work material 3)Surface finish and dimensional tolerances4)Quantity of the production5)Functional requirements6)Process capabilities.


Manufacturing Cost

1) Material cost

2) Tooling cost

3) Fixed costs

4) Capital costs

5) Direct labor costs

6) Indirect labor costs


Manufacturing Cost (continue)Fixed costs:Electric, fuel, taxes, rent, insurance type of costs

called fixed costs. These costs are not sensitive to the production volume.

Capital costs:Investment in land, building, machinery,tooling and equipment.

Direct labor costs:Includes all labor, from the time raw materials are first handled to the time when the product is finisihed. This period is called as floor-to-floor time, and the personnel is called productive labor.

Indirect labor costs:These costs are refered to as overhead (burden rate) and charged proportionally to all products. The personnel involved in activities such as quality control, repair, maintenance, engineering, research, sales, etc called non-productive labor creates these costs.


Manufacturing Cost and Production Rate

Approximate cost divisionDesign 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 manufacturingincludes dedicated machinery which needs less direct labor. On the other hand small volume productions needs more directLabor since the machinery used is general purpose type of Machines and needs more human interaction.


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.


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.


Value Analysis

Value analysis consists of six phases• Information phase: gather data and determine cost• Analysis phase:Identify problems and

opportunities• Creativity phase:Seek ideas to solve problems• Evaluation phase: Select ideas and identify costs

involved.• Implementation phase:Take necessary actions to

accomplish the task• Review phase: Analyze to see if any adjustment is

needed


End of presentation

THANK YOU Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

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Dr. HABEEB HATTAB HABEEB Office: BN-Block, Level-3, Room-088 Email: hbuni61@yahoo