IELM, HKUST Prof Neville Lee

IELM215Manufacturing Processes

II. Manufacture Design/Material/Process

Selection

IELM, HKUST Prof Neville Lee

Lecture Organization

1. Examples or questions of how design/material/process selection may affect the outcome of product.

2. Selection Criteria from Material points of view

3. Discussion of Mechanical Properties

IELM, HKUST Prof Neville Lee

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 MaterialReading Assignment:Material overview – p. 43-45Mechanical properties – p. 64-70 (up to sect. 2.2.3)Plastics Material – p. 191-207

IELM, HKUST Prof Neville Lee

Examples1. 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?

IELM, HKUST Prof Neville Lee

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

IELM, HKUST Prof Neville Lee

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

IELM, HKUST Prof Neville Lee

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

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee

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.

IELM, HKUST Prof Neville Lee

Suggestion of How to Select the Best Design/Material/ Process

A good starting point--what is the best material and process to use?

1. What is the lowest cost material?2. What is the lowest cost manufacturing

process?3. Does the lowest cost manufacturing

process compatible with the lowest cost material?

IELM, HKUST Prof Neville Lee

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

IELM, HKUST Prof Neville Lee

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?

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee

Examples to Utilize the Mechanical Parameters for Product Design

IELM, HKUST Prof Neville Lee

Examples to Utilize the Mechanical Parameters for Product Design

IELM, HKUST Prof Neville Lee

Ways to Improve Physical Properties 1. Through Structures

Rib structure or U shape or hollow structure can improve mechanical stiffness tremendously.

2. Through compositeCan provide light/ductile/strong/high damp

3. 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

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee

Basic Knowledge of Plastics Please read Chapter 7

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee

Different Types Of Polymer Structures

IELM, HKUST Prof Neville Lee

IELM, HKUST Prof Neville Lee