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MATERIALS SELECTION AND

FAILURE ANALYSIS

Materials & process selection to manufacture a product is

tedious task, >80000 materials & >1000 process to choose

from It starts with DESIGN

What is Design?

The process of translating a new idea of a market need into

detailed information from which a product can be

manufactured (Reason = Market need)

Fig. 1: Interrelationship among design, materials, and processing (ASM

Handbook, Volume 20: Materials Selection and Design, G.E. Dieter, editor, p 243-254, DOI: 10.1361/asmhba0002450)

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Design Process defines a market need and selects concepts

(ideas) to satisfy that need

The concepts are refined to embodiments, i.e. sketch

Detailed design and generation of working drawings

Figure 2

Fig. 2: Schematic of the design process with design tools on the left and

materials and process selection on the right. At the concept stage of design, the

emphasis is on breadth; in the later stages, it is on precision. FEM, finite

element modelling; DFM, design for manufacturing; DFA, design for assembly

(ASM Handbook, Volume 20: Materials Selection and Design, G.E. Dieter, editor, p 243-254, DOI: 10.1361/asmhba0002450)

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Some of information required

Approximate data required for the top

Precise & detailed data required for

materials & process here

Fig. 3: The design flow-chart. Materials and process information is required at

every step-breadth at the top, detail at the bottom

Fig. 4: Data for materials and processes takes a spectrum of forms, ranging from

numeric data for standard properties (like density) to experience derived from past

applications. One challenge in constructing selection tools is that of making the

maximum use of all forms of data. M.F. Ashby Mats. & Design, 25, 51-67, 2004 (both)

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Design has Four Principal attributes

1- Function (what does it do)

2- Appearance

3- Manufacturing method

4- Cost

Function:

1- Define it precisely 2- Design synthesis basic idea to do the function, the

constraints

3- Decision making, e.g. dimensions, dimension tolerances, materials, manufacturing process

4- Analysis

Fig. 5

Appearance

If in view, must look attractive as possible, e.g. vacuum

cleaner, car, and should be in harmony with surrounding

Cost:

Initial selection due to properties but final decisions always

involves considerations of cost which in most cases will be

the dominant criterion. The total cost of a manufactured

article in service is made up of several parts, (Figs. 6)

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Fig 5: Design flowchart, Charles & Crane book(2nd edition, 1989)

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Fig. 6: Cost analysis, Charles & Crane book (2nd edition, 1989)

Product development: Before marketing or erecting the

new plant, wise to do field trial or pilot plant studies,

overdesign the early batches to get good reputation in the

market, then optimize, Overdesign means over price, but it

is a judgment to be done.

Reduce specification once it has been established as a good

product.

Process of optimization: Evaluating improvement by

feedback from production depts., accountants and users

need ~20% improvement to justify changes in specification

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MATERIALS AND MANUFACTURING

METHODS AVAILABLE TO ENGINEERS

As part of design are the materials and manufacturing process

selections;

M.F. Ashby Mats. & Design, 25, 51-67, 2004 (both)

Fig7:

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Fig. 8: Hierarchy of metals available to Engineers (Reza Ghomashchi Book, UniSA 1999)

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Fig. 9: Hierarchy of ceramics available to Engineers (R.Ghomashchi,1999)

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L. Edwards & M. Endean, Manufacturing with Materials, Butterworth-Heinemann,1995

Fig. 10: Hierarchy of

Polymers available to

Engineers

R. Ghomashchi, 1999

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Fig. 11: Hierarchy of Composites available to Engineers (R. Ghomashchi, 1999)

Fig.12: Materials chart, M.F. Ashby , Butterworth-Heinemann ,2003

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Table 1: Several examples of materials applications in a variety of products (R. Ghomashchi, 1999)

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MANUFACTURING PROCESSES (Techniques)

Fig. 14: Schematic diagram to show the interrelationships amongst

materials processing, microstructure and properties (R. Ghomashchi, 1999)

Fig. 13: Manufacturing processes (R. Ghomashchi, 1999)

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Fig. 15: Manufacturing processes

Casting (R. Ghomashchi, 1999)

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Fig. 16: Manufacturing Processes Forming (R.Ghomashchi, 1999)

Fig. 17: Manufacturing Processes Powder processing (R.Ghomashchi, 1999)

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Fig. 18: Manufacturing Processes Machining (R.Ghomashchi, 1999)

Fig. 19: Manufacturing Processes Joining (R.Ghomashchi, 1999)

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Fig. 20: Manufacturing processes

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Main references used in this section

1- Ashby 2004, M.F. Ashby, Y.J.M. Brechet, D. Cebon, L. Salvo, Selection strategies for materials and processes, Mats. & Design, 25, 51-67, 2004

2- Charles & Crane book(2nd edition, 1989), J.A. Charles, F.A.A Crane, Selection and use of engineering materials, 2nd edition, Butterworths,1989

3- R. Ghomashchi Book, 1999, M.R. Ghomashchi, An introduction to Engineering Materials, University of South Australia, 1999.

4- L. Edwards & M. Endean, (Editors)Manufacturing with Materials, Butterworth-Heinemann,1995, Open University

5- M.F. Ashby, Butterworth-Heinemann ,2003, Materials selection in Mechanical Design, 2

nd edition, 2003

All Slides are from: L. Edwards & M. Endean, Manufacturing with Materials, Butterworth-Heinemann,1995

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Notes: