Lec 1 + Lec 2: Manfacutring process

1. ACE305: Aircraft Components
Design and Manufacture
Instructor: Dr Mohamed Elfarran
Aerospace Engineering Department
Cairo University
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Lec1 : Manufacturing
Process
Ref: Ch 1-3

2. Lecture 1
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3. The Traditional Design Process
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4. Preliminary Design Phase
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Often the first step in which a designer becomes
involved, and may not involve intense iteration. In this
phase, we deal with the entire machine:
• Define function
• Identify constraints involving cost, size, etc.
• Develop alternative conceptions of
mechanism/process combinations that can satisfy
the constraints
• Perform supporting analyses (thermodynamic, heat
transfer, fluid mechanics, kinematics, force, stress,
life, cost, compatibility with special constraints)
• Select the best mechanism
• Document the design
Alternative design concepts for cross members in
a light-duty truck floorpan assembly
Concept 1 Two longitudinal members,
one trans-verse split-end cross
member, small transverse member in
transmission tunnel, rear transverse
member similar to original, gauge
reduction.
Concept 6 Two integrated, split
transverse cross members, rear
transverse member similar to original,
reduced sheet thickness in cross
members.

5. Intermediate Design Phase
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Generally occurs after preliminary design, but the two phases may
overlap. Intermediate design always involves iterations. In this
phase, we deal with individual components of the machine:
• Identify components
• Define component functions
• Identify constraints involving cost, size, etc.
• Develop tentative conceptions of the components
mechanism/process combinations using good form synthesis
principles
• Perform supporting analyses (including analyses at each
critical point in each component)
• Select the best component designs
• Document component designs; prepare a layout drawing
A-pillar component geometries
Corner
Reinforcement
Front
Reinforcement

6. Detailed Design Phase
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Subsequent to intermediate and. In
this phase, we deal with individual
components of the machine and the
machine as a whole:
•Select manufacturing and
assembly processes
•Specify dimensions and
tolerances
•Prepare component detail
drawings
•Prepare assembly drawings
Line rendering of a pickup box assembly showing
geometric details such as wheel well openings, cross
members, and bed corrugation

7. Design Affecting Factors
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The design of a component or system may be influenced by a
number of requirements. If a requirement affects design, it is called
a design affecting factor/design consideration. For example, if the
ability to carry large loads without failure is important, we say that
strength is a design consideration. Most product development
projects involve a number of design affecting factors:
- Strength/stress - Cost - Thermal properties
- Distortion/stiffness- Processing requirements - Surface finish
- Wear - Weight - Lubrication
- Corrosion - Life - Marketability
- Safety - Noise - Maintenance
- Reliability - Aesthetic considerations - Volume
- Friction - Shape - Liability
- Usability - Size - Scrapping/recyclability

8. Economics
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Strength, safety, reliability, and cost are perhaps the most
important design considera-tions. In general the design
alternative that satisfies other design considerations at the lowest
costs is to be preferred. Issues affecting the “cost” of a design
include:
•Product development costs
•Material choice
•Manufacturing processes involved
•Economies of scale
•Tolerances specified
•Use of standard sizes and
components
Breakeven point for two different screw manufacturing
processes

9. Materials Selection
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• The designer of any product, other than
software must get involved with material
selection.
• Only occasionally will the exact grade of
material be specified by the customer.
• Even then the designer must understand
the material to be able to design the
product.

10. Materials Selection
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Decisions, decisions!
So many materials, so much information.
How do we decide?
How do we begin to choose?
First we need to look at the function of the
product – product analysis

11. Materials Selection
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Product Analysis
Every product is designed in a particular way - product
analysis enables us to understand the:
important materials, processing, economic and aesthetic decisions
which are required before any product can be manufactured.
Just what it says – analyse the product!
• What does it do?
• How does it do it?
• Where does it do it?
• Who uses it?
• What should it cost?
• What does it look like?

12. Lecture 2
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13. Introduction
• Choice of materials for a machine element depends very much on its
properties, cost, availability and such other factors. It is therefore
important to have some idea of the common engineering materials
and their properties before learning the details of design procedure.
This topic is in the domain of material science or metallurgy but some
relevant discussions are necessary at this stage.
• Common engineering materials are normally classified as metals and
non- metals. Metals may conveniently be divided into ferrous and
non-ferrous metals. Important ferrous metals for the present purpose
are:
• (i) cast iron (ii) wrought iron (iii) steel.
• Some of the important non-ferrous metals used in engineering design
are:
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14. Classification of Engineering Materials
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15. Loads
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17. Stress and loads
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18. Material Strength and Stiffness
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19. Strength and Cold Work
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