1. Chapter 9 Material Selection (Review) EIN 3390 Manufacturing Processes Summer A, 2012

2. 9.1 Introduction
Goal of manufacturing: to create products and components that perform properly
Material selection processes should be constantly reevaluated
Materials selection concerns are always changing
Environmental pollution
Recycling
Energy
Health or safety constraints
Geopolitical issues

3. 9.2 Material Selection and Manufacturing Processes
Material and manufacturing processes are extremely interdependent
Change in a material will likely cause a change in the manufacturing process needed
A successful product has gone through both proper material selection and processing selection
Figure 9-4 Schematic showing the interrelation among material, properties, processing, and performance.

4. 9.2 Material Selection and Manufacturing Processes
Material and manufacturing processes are extremely interdependent
Change in a material will likely cause a change in the manufacturing process needed
A successful product has gone through both proper material selection and processing selection
Figure 9-4 Schematic showing the interrelation among material, properties, processing, and performance.

5. 9.3 The Design Process
Design is the first stage in manufacturing processes
What it is
What properties must it possess
What material
How to make it
How many to make
What conditions will it see during use

6. Steps for Design 1. Conceptual 2. Functional 3. Production
Several concepts may be considered
2. Functional
Workable designs are developed
Detailed plan for manufacturing
Prototyping
3. Production
Full production
Production speeds and quantities

7. 9.4 Procedures for Material Selection
General sequence of product design
design→material selection→process selection→production→evaluation→redesign
Case-history method
Evaluates what has been done in the past
Modification of an existing product
Evaluates the current product and manufacturing techniques
Changes or improves upon features of the existing product
Development of a new product
Follows the full sequence of product design above

8. Factors for Materials Selections
Geometric
Mechanical Properties
Physical Properties (Electrical, Magnetic, Thermal, and Optical)
Environmental Considerations
Manufacturing Concerns
Quantity
Rate, Level of quality
Quality control and inspection
Assembly concerns
Section thickness
Standard sizes and shapes
Liability if product failure occurs
End-of-use disposal

9. 9.5 Additional Factors to Consider
Cost is often one of the biggest additional factors
Often, compromises between material properties and cost must be made
Material availability
Are there any possible misuses on the part of the consumer?
Have there been failures for similar products?
Material’s usage history
Material standardization

10. 9.6 Consideration of the Manufacturing Process
Overall attractiveness
Physical properties
Mechanical properties
Formability
Economical concerns
All processes are not compatible with all materials

11. 9.7 Ultimate Objective
Develop a combination of material and processes that is the best solution
Material or manufacturing selection normally imposes restrictions or limitations on the other
Economics, environment, energy, efficiency, recycling, inspection, and serviceability are important deciding factors

12. Decision Models
Figure 9-6 Alternative flow chart showing parallel selection of material and process.
Figure 9-5 Sequential flow chart showing activities leading to the production of a part or product.

13. Decision Models
Figure 9-6 Alternative flow chart showing parallel selection of material and process.
Figure 9-5 Sequential flow chart showing activities leading to the production of a part or product.

14. Compatibility
Figure 9-7 Compatibility chart of materials and processes. Selection of a material may restrict possible processes. Selection of a process may restrict possible materials.

15. Material Substitutions

16. Material Substitutions
Causes of product failure
Failure to know and use the best materials information
Failure to account for all reasonable material uses
Use of materials with insufficient data
Inadequate quality control
Material selection made by unqualified people

17. Select a Material with Rating Chart
List all required material properties for a product to be designed.
Screen all required properties and identify those absolute properties that must be considered for the product as “Go-No-Go” properties.
Rate each candidate material on a scale such as 1 to 5 or 1 to 10 for each required property.
Define weighted factor for each required property based on its significance.
Multiply property rating by its weighted factor and sum the results for each materials
Select the material that satisfies the “Go-No-Go” screen and has the highest sum of the relative rating numbers.

18. Select a Material with Rating Chart
Go-No-Go
Relative rating number - R
(=rating number x weighting factor) SR Sr
SR/r
Weldability
Stiffness
Stability
Fatigue
Tensile 1 4 5 14 A B C

19. Select a Material with Rating Chart
Advantages:
Potential materials can be compared in a uniform, unbiased manner
The best candidate can often be selected
There is less chance to overlook a major requirement by placing all the requirement on a single sheet.

20. Example: Selection of a Material:

21. Solution: - S: satisfactory
Finding “Go-No-Go” property: weldability
- S: satisfactory
- U: unsatisfactory
Calculating: R = Relative rating number, and r = weighting factor.
Relative rating number R = property rating number x weighting factor
Set material’s property rating number (1 – 5):
excellent = 5, very good = 4, good = 3, fair = 2, poor = 1
weighted factor for each material’s property:
- Stiffness : 1
- Stability:
- Fatigue:
- Tensile strength: 4

22. Solution (cont.) Rating chart for selecting material Weldability
Stiffness
Stability
Fatigue
Tensile Strength SR Sr
SR/Sr
Go-No-Go
screening
(1)
(4)
(5) X S
3x1
3x4
2x5 37 14
2.64 Y U
5x4
3x5 58
4.14 Z
5x5
2x4 48
3.43

23. Conclusion:
Based on the chart below, material Y has the highest rating number. However, because it does not have satisfactory weldability and this is an "absolute" requirement, it should not be selected. Material Z should be used.