1. IELM215 Manufacturing Processes
II. Manufacture Design/Material/Process Selection

2. Lecture Organization
Examples or questions of how design/material/process selection may affect the outcome of product.
Selection Criteria from Material points of view
Discussion of Mechanical Properties

3. Lecture Organization (cont.)
4. Examples of How to Utilize the Mechanical Parameters for Product Design
5. Ways to Improve Mechanical Properties
6. Discussion on Plastics Material
Reading Assignment:
Material overview – p
Mechanical properties – p (up to sect )
Plastics Material – p

4. Examples 1. Which would you choose to make a telescope (pen) barrel?
Molding vs. Machining
Plastics vs. Metal
(Hint: the answer depends on the volume).
2. Gold is pretty and would not oxidize, but expensive. Iron is strong and cheap, but not pretty and oxidizes. Which would you choose for the elevator door for an expensive hotel? Any other suggestions?

5. Examples (cont.)
4. If you work for a car manufacturer, there is a lot of pressure to lower the cost and to improve the fuel economy. Are there any suggestions that you can tell your boss?
5. Plastics bag is cheap and is easy to seal. However, it is permeable to air but cannot keep food for a long time. Aluminum foil is not permeable to air but cannot seal easily and is more expensive. Would you have a good solution for a peanut packaging company?
6. How do you design a table that is light and yet still very strong

6. Selection Criteria Meet the functional requirements
Lowest overall cost
Material cost
Equipment cost
Operation cost such as facility and energy cost
Quality
Speed to market

7. Factors to be considered
Material selection
Types of Materials
Properties
Cost
Process requirements
Process selection
Tolerance requirement
Equipment / Facility requirement
Speed of production
Labor & operating cost
Alternative structural design

10. Selection Criteria From Material Points Of View
Please name the four major types of engineering material commonly used for manufacturing
What are there major characteristics, or advantages and disadvantages?
What are the main physical parameters which one should consider in selection of the material?
Electrical – conductivity
Magnetic – for motor etc.
Optical properties
Chemical – corrosion resistance
Thermal – conductivity, melting point etc
Mechanical – strength, hardness etc.

11. Suggestion of How to Select the Best Design/Material/ Process
A good starting point--what is the best material and process to use?
What is the lowest cost material?
What is the lowest cost manufacturing process?
Does the lowest cost manufacturing process compatible with the lowest cost material?

12. Quick Look At Mechanical Property
For a material, do you know the difference between strong, hard, ductile or brittle, elastics?
Roughly speaking:
Large E (modulus) – stiff
Large E and Y – hard
Large Y (yield stress) and UTS (ultimate tensile strength) – strong
Long ΔL before Y (yield) – elastic ductile
Short ΔL before Y (yield) – brittle

13. Quick Look At Mechanical Property (cont.)
Let say you need to design something, how do you determine if the design is strong enough? Or how would you select the material?
Please see the following two examples in II.4. There will also be exercise to ensure you know the material.
Do you know how to use the mechanical properties table?

18. Examples to Utilize the Mechanical Parameters for Product Design

19. Examples to Utilize the Mechanical Parameters for Product Design

20. Ways to Improve Physical Properties
Through Structures
Rib structure or U shape or hollow structure can improve mechanical stiffness tremendously.
Through composite
Can provide light/ductile/strong/high damp
Through coating process
There are many examples:
Cosmetics – Lip sticks
Reflective – CD
Corrosion resistance – Paint
Lubrication – Grease or oil
Non sticking – Teflon
Wear resistance – Diamond

22. Basic Knowledge of Plastics
Please read Chapter 7

24. Different Types Of Polymer Structures