Final Class Project

DOCUMENT NOT INTENDED FOR PUBLIC RELEASE OR DISTRIBUTION

Disclaimer and Acknowledgements

This document is the result of an academic assignment for the Fall 2011 AME 30362Design Methodology class in the Aerospace and Mechanical Engineering Department at theUniversity of Notre Dame taught by Dr. Stephen Batill. The following page is a copy ofthe project assignment. The following list of students indicates their contribution to thisproject:

Project coordinated by Waylon Chen, Kyle Kinnary, John Moran, and Emily Reinec-cius.

Chapter 1 by Matthew Cirillo, Brianna Curtis, Matthew Nagy, Jeff OBrien (GroupLeader), and Hayley Reese.

Chapter 2 by Michael George, Jason Lovell, Keith Nord (Group Leader), Yichao Pan,and Mary Beth Tribble.

Chapter 3 by Kevin Eller, Eras Noel, Michael Rose, Jonathan Rosini, and RebeccaSees (Group Leader).

Chapter 4 by Thomas Kennedy, Jennie Kim, Sean OConnor, Joanna Whitfield (GroupLeader), and Matt Wilcox.

Chapter 5 by Stephen Biddle (Group Leader), Alex Boll, Garrett Campbell, ChrisCharnock, and Houston Clarke.

Chapter 6 by Kane Kimler, Kevin Klima, Matthew Lemanski, Nathan Trembley (GroupLeader), and Nathaniel Walden.

Chapter 7 by Chris Borchers, John Calash, Julian Corona, Christine Dunphy, and MegForesman (Group Leader).

Chapter 8 by Joseph Arambula, Damon Henderson (Group Leader), Thomas McGarry,Chelsae Plageman, and Davin Sakamoto.

Chapter 9 by Ayla Bicoy, Richard Kim, Samantha Niver, Chris Payne, and DanielShaffer (Group Leader).

Chapter 10 by Angelo Brown, Charles Hunter, Emily Legault, Andy McCourt, andBrian Robillard (Group Leader).

Marketing presentation by Kyle Collins (Group Leader), John DeLacio, Emily Gore,Pat Hertenstein, and James Jones.

Editing, Compilation, and Graphical Design by Doug Carder, Oliver Chmell, JasonRunkle (Group Leader), Dave Simone, and Breanna Stachowski.

Every effort has been made to properly cite and acknowledge all sources, but the natureof the project makes it impossible (at present) to ensure that no work has been inappropri-ately included or improperly cited. As such, this document should not be reprinted, sold, orotherwise distributed except in situations protected by fair use law. All opinions containedinside this document are those of the authors and do not necessarily reflect the values andbeliefs of the University of Notre Dame. Examples of specific companies in the text aremeant to provide benchmarks and are not meant to defame, humiliate, denounce, or injurethe reputation or image of these companies.

Last Edited: December 6, 2011 at 10:34am


Revised: 8/17/11

UNIVERSITY OF NOTRE DAME DEPARTMENT OF AEROSPACE AND MECHANICAL ENGINEERING

AME30362: Design Methodology, Fall 2011

Project 4 Sustainable Design Guidelines Project Due Dates: Interim due dates to be determined as part of project Product Submission Tues. Nov. 15, 2010 This all-class project has two goals: 1) develop a product that can assist you and other mechanical engineers in the design of sustainable products or systems, 2) work as part of a large project team to design and produce a useful product. The concepts of sustainability and sustainable design have received much attention in the recent past and all indications are their importance will only increase. This project will provide you with insights and skills to contribute to this important discussion. At the onset of this project it must be stressed that the term sustainability is interpreted in many different ways and it includes what can be highly emotional and complex social, economic, scientific and ethical issues. Project Description: The class will work together to design, develop and publish a document in both conventional print and web-compatible electronic formats. The project will be conducted in multiple phases and each student will contribute in various ways to the project. You will follow a process similar to a collaborative product design project. The phases will be:

1. Project formulation a. Research: Each individual will prepare a one-page project prospectus b. Organization: A group of 4 project coordinators will be selected at the beginning of the

semester. They will work with the instructor, TA consultant and classmates to plan, organize, manage and evaluate this project.

2. Develop and evaluate product concepts and select a concept for implementation. 3. Implement and assess the product.

Similar to many engineering projects, the deadline date and available human resources are set but the details on the required tasks and desired outcomes will evolve as the project develops. Project Requirements: Class Requirements: The class will develop a document suitable for both print and web presentation that provides useful design guidelines for mechanical engineers in the development of sustainable products and systems. The deadline for completion of the document will be Tuesday, Nov. 15, 2011. It will be submitted in both hardcopy and electronic form. A formal presentation of the final product will be conducted in class on Thursday, Dec. 8, 2011. Individual Requirements:

1. Contribute in some readily identifiable and assessable way to the project through its planning, organization, and/or implementation.

2. Prepare and submit a 1-page project prospectus (typed, 12 font) for evaluation by the project coordinators. This 1-page document (due by 11:00 a.m. Tues. Sept. 6, 2011) in .pdf format by email to [email protected]) and in hardcopy submitted in class must include in a readily identifiable way:

a. A list of proposed sustainability issues or topics to include in the guidelines (at least 3) b. A concept description of the form and content of the product, i.e. the design guidelines. c. A list of potential information sources for the proposed topics in sustainable design. d. A prioritized list of the top three ways in which you would like to contribute to the project.

3. Contribute as part of an assigned sub-group to develop content for the product in compliance with the guidelines provided by the project coordinators.

4. Prepare and submit a confidential peer review assessing the contributions to the project of those individuals in your sub-group. The evaluation form will be developed as part of the project.


Contents

Table of Contents i

List of Figures vii

List of Tables ix

1 The Need For Sustainability 2

1 The Current State of Design . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Sustainable Design Methodologies . . . . . . . . . . . . . . . . . . . . . . . . 5

3 The Cradle to Cradle Philosophy . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.3.1 Rooted in Nature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.3.2 Cradle to Cradle Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.3.3 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4 Document Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.4.1 Product Material Selection . . . . . . . . . . . . . . . . . . . . . . . . 10

1.4.2 Conscientious Manufacturing Design . . . . . . . . . . . . . . . . . . 10

1.4.3 Post Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2 Metal Alloys 13

1 Carbon Alloy Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.1.1 Material Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.1.2 Material Production and Recycling . . . . . . . . . . . . . . . . . . . 15

2.1.3 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2 Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16



2.2.3 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3 Tool & Die Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18



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CONTENTS

2.3.3 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4 Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20



2.4.3 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

5 Titanium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22



2.5.3 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

6 Magnesium Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24


2.6.2 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

7 Copper Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26


2.7.2 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

8 Nickel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26


2.8.2 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

9 Zinc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29


2.9.2 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

3 Plastics 34

1 Material Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

3.1.1 Molecular Properties of Plastics . . . . . . . . . . . . . . . . . . . . . 34

3.1.2 Types of Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

3.1.3 Properties of Plastics to Consider . . . . . . . . . . . . . . . . . . . . 35

2 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.2.1 Mechanical Creation of Plastic Products . . . . . . . . . . . . . . . . 37

3.2.2 Chemical Creation of Plastics . . . . . . . . . . . . . . . . . . . . . . 38

3.2.3 Creation of Bioplastics . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3 Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.3.1 Economics of Processing Plastics . . . . . . . . . . . . . . . . . . . . 42

4 Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

5 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.5.1 Sustainable Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.5.2 Problems with Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . 46

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CONTENTS

3.5.3 The Plastic Scorecard . . . . . . . . . . . . . . . . . . . . . . . . . . 46

4 Ceramics, Composites and Elastomers 50

1 Ceramics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50



4.1.3 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

2 Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54



4.2.3 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

3 Elastomers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57



4.3.3 Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

5 Machining and Tools 62

1 Guidelines to Streamline Machining Processes . . . . . . . . . . . . . . . . . . 62

2 Designing for Maximum Reusable Material . . . . . . . . . . . . . . . . . . . 63

5.2.1 Input Energy and Pollutant Production . . . . . . . . . . . . . . . . . 63

5.2.2 Plant and Machining Selection . . . . . . . . . . . . . . . . . . . . . . 66

3 Elimination and Recapturing of Waste . . . . . . . . . . . . . . . . . . . . . . 66

5.3.1 Inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

5.3.2 Over Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.3.3 Over Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.3.4 Recovery of Materials and Energy . . . . . . . . . . . . . . . . . . . . 67

4 Proper Procedures for Machining . . . . . . . . . . . . . . . . . . . . . . . . . 67

6 Sustainability in Production 71

1 Sustainability in Different Production Methods . . . . . . . . . . . . . . . . . 71

6.1.1 Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

6.1.2 Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

2 Six Sigma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

6.2.1 Origins of Six Sigma . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

6.2.2 Certification and Use of Six Sigma . . . . . . . . . . . . . . . . . . . 74

3 Lean Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

6.3.1 A Brief History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

6.3.2 Implementation of Lean Production . . . . . . . . . . . . . . . . . . . 75

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CONTENTS

4 Demand Forecasting Management and Inventory Management . . . . . . . . . 76

6.4.1 Demand Management and Forecasting . . . . . . . . . . . . . . . . . 76

6.4.2 Inventory Management . . . . . . . . . . . . . . . . . . . . . . . . . . 77

5 Manufacturing Conscientious Design - Examples of Conscientious Production 78

6.5.1 Suncor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

6.5.2 Rio Tinto Alcan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

6.5.3 S.C. Johnson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

6.5.4 General Electric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

7 Assembly and Disassembly 83

1 Common Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

2 Built In Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

3 Temporary Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

4 Adhesives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

5 Designed Assembly Connector Concepts . . . . . . . . . . . . . . . . . . . . . 86

7.5.1 Mistake-Proof Assembly Parts . . . . . . . . . . . . . . . . . . . . . . 86

7.5.2 Oriented Parts and Oriented Handling . . . . . . . . . . . . . . . . . 87

7.5.3 Ease and Efficiency of Assembly Design . . . . . . . . . . . . . . . . . 90

7.5.4 Modular Parts within Products . . . . . . . . . . . . . . . . . . . . . 90

8 Packaging 94

1 General Guidelines for Sustainable Package Design . . . . . . . . . . . . . . . 94

8.1.1 Sustainable Packaging Metrics . . . . . . . . . . . . . . . . . . . . . . 97

8.1.2 Product Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

8.1.3 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

8.1.4 Resource Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

2 Food and Beverage Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

8.2.1 Beverages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

8.2.2 Dairy and Cheese . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

8.2.3 Dry Foods and Snacks . . . . . . . . . . . . . . . . . . . . . . . . . . 103

8.2.4 Meats and Seafood . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

8.2.5 Produce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

8.2.6 Ready Meals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

8.2.7 Food Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

3 Consumables Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

8.3.1 Excess Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

8.3.2 Change in Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

8.3.3 Reuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

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CONTENTS

8.3.4 Customer Focus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

9 Waste Management 110

1 Office and Human Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . 110

9.1.1 Paper Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

9.1.2 Electronic, Medical, and Chemical Waste . . . . . . . . . . . . . . . . 112

9.1.3 Food Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

2 Post Product Life Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . 114

9.2.1 Recycling at End of Life . . . . . . . . . . . . . . . . . . . . . . . . . 114

9.2.2 Recycling Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

9.2.3 Non-toxic Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

9.2.4 Frequently Discarded Components . . . . . . . . . . . . . . . . . . . 116

3 Bulk Waste Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

9.3.1 Manufacturing Waste Management . . . . . . . . . . . . . . . . . . . 116

9.3.2 Construction and Demolition Waste Management . . . . . . . . . . . 118

4 Big Picture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

9.4.1 Waste as a Source of Energy . . . . . . . . . . . . . . . . . . . . . . . 118

9.4.2 Waste Generation Monitoring Methods . . . . . . . . . . . . . . . . . 120

10 Green Label Benchmarks and Evaluation 124

1 Information Companies must Provide . . . . . . . . . . . . . . . . . . . . . . 124

10.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

10.1.2 Energy Used in Production of Each Product . . . . . . . . . . . . . . 125

10.1.3 Carbon Footprint Left By the Product . . . . . . . . . . . . . . . . . 125

10.1.4 Percentage of Recyclable Content . . . . . . . . . . . . . . . . . . . . 125

10.1.5 List of Materials Used . . . . . . . . . . . . . . . . . . . . . . . . . . 126

10.1.6 Waste Created By Each Product . . . . . . . . . . . . . . . . . . . . 126

10.1.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

2 Product Life Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

10.2.1 Product Life Considerations . . . . . . . . . . . . . . . . . . . . . . . 127

10.2.2 Setting the Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

3 Examples of Selected Lifespan Requirements . . . . . . . . . . . . . . . . . . . 128

10.3.1 Example: Compact Fluorescent Lamp (CFL) . . . . . . . . . . . . . . 128

10.3.2 Lifetime Performance Standard Examples . . . . . . . . . . . . . . . 128

4 Maximum Energy Consumption during Production . . . . . . . . . . . . . . . 130

10.4.1 Measuring energy consumption . . . . . . . . . . . . . . . . . . . . . 131

10.4.2 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

10.4.3 Implementing limitations . . . . . . . . . . . . . . . . . . . . . . . . . 131

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CONTENTS

5 Emissions Levels During Production . . . . . . . . . . . . . . . . . . . . . . . 132

10.5.1 Carbon Monoxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

10.5.2 Lead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

10.5.3 Ozone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

10.5.4 Particulate Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

10.5.5 Nitrogen Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

10.5.6 Sulfur Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

6 Green Standards for Sources of Raw Materials . . . . . . . . . . . . . . . . . . 133

10.6.1 Ecosystems in Danger . . . . . . . . . . . . . . . . . . . . . . . . . . 134

10.6.2 Standards of Protection . . . . . . . . . . . . . . . . . . . . . . . . . 135

Bibliography 148

vi


List of Figures

1.1 Total aluminum can waste vs. time [5] . . . . . . . . . . . . . . . . . . . . . . 3

1.2 Typical material composition of trash . . . . . . . . . . . . . . . . . . . . . . 4

1.3 Ideal waste distribution with perfect recycling and composting . . . . . . . . 5

1.4 Cyclic nature of cradle to cradle design [9] . . . . . . . . . . . . . . . . . . . . 7

2.1 Recyclable aluminum scrap [23] . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.2 Titanium sponge and rounds stock [24] . . . . . . . . . . . . . . . . . . . . . . 24

3.1 Extrusion [36] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3.2 Injection molding [37] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

3.3 Blow molding [38] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

3.4 Rotational molding [39] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

3.5 Effects of chemicals on plastic wear . . . . . . . . . . . . . . . . . . . . . . . 42

3.6 Cost comparison of material processing . . . . . . . . . . . . . . . . . . . . . 43

3.7 Plastic scorecard example [47] . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

4.1 RWTH ceramics lifetime testing [50] . . . . . . . . . . . . . . . . . . . . . . . 52

4.2 Recycling versus cost for various materials [52] . . . . . . . . . . . . . . . . . . 53

4.3 Hybrid composite material [56] . . . . . . . . . . . . . . . . . . . . . . . . . . 55

5.1 Water Cooled and Lubricated Mill [71] . . . . . . . . . . . . . . . . . . . . . . 68

6.1 ERP System Function Map [90] . . . . . . . . . . . . . . . . . . . . . . . . . . 77

6.2 Forms of Inventory [91] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

7.1 Different snap fit types for disassembly [98] . . . . . . . . . . . . . . . . . . . 84

7.2 These wood circular symmetric pins can be installed with any rotation [108] . 87

7.3 These asymmetrical computer ports do not allow incorrect connectors or in-correct orientation of the connetor which removes ambiguity [109] . . . . . . . 88

7.4 Notches and hole pattern angles only permit one orientation for assembly [110] 88

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LIST OF FIGURES

7.5 Table top utilizing incremental pins to keep table level while offering varyingheight options [111] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

7.6 This specific spacer was used to allow for multiple motor sizes to fit withinthe same case molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

8.1 Bar & Knell lamps [113] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

8.2 Harley Davidson reusable steel packaging [114] . . . . . . . . . . . . . . . . . . 96

8.3 Waterproof envelope [114] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

8.4 Air-cushioned packaging [114] . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

8.5 Optimum pack design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

8.6 Three levels of packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

8.7 Packaging life cycles [112] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

9.1 Fujitsu ScanSnap scanner [136] . . . . . . . . . . . . . . . . . . . . . . . . . . 111

9.2 Epson WorkForce scanner [136] . . . . . . . . . . . . . . . . . . . . . . . . . . 112

9.3 Recycling computers [137] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

9.4 EnergyStar logo [140] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

9.5 Diagram of incineration [149] . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

9.6 Diagram of Gasification [150] . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

10.1 Energy consumption from Annual Energy Review [156] . . . . . . . . . . . . . 130

10.2 End-use sector total consumption and shares from Annual Energy Review [156] 131

10.3 Global view of the worlds most endangered forests [157] . . . . . . . . . . . . 134

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List of Tables

1.1 Human and ecological health criteria for MBDCs materials assessment pro-tocol [9] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.1 Quick-reference table of sustainable metals . . . . . . . . . . . . . . . . . . . 14

2.2 Steel properties [12] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.3 Properties of Various Aluminum Alloys at Room Temperature [12] . . . . . . 21

2.4 Properties and typical forms of various wrought magnesium alloys . . . . . . 25

2.5 Properties and typical applications of various wrought copper and brasses [27] 27

2.6 Properties and typical applications of various wrought bronzes [27] . . . . . . 28

2.7 Properties and typical applications of various nickel alloys (all alloy names aretrade names) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3.1 Densities of common plastics [44] . . . . . . . . . . . . . . . . . . . . . . . . . 44

4.1 Material properties of ceramics [49] . . . . . . . . . . . . . . . . . . . . . . . . 51

4.2 Basic properties of elastomers [62] . . . . . . . . . . . . . . . . . . . . . . . . . 58

5.1 Sector energy consumption and energy intensity in 2002 [68] . . . . . . . . . . 64

5.2 Energy-related CAP emissions by sector in 2002 (units TPY: tons per year) [68] 65

6.1 Energy Consumption for different Steel Production Methods (GJ/ton prod-uct) [78] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

6.2 Six Sigma Levels of Certification [81] . . . . . . . . . . . . . . . . . . . . . . . 74

9.1 List of recyclable materials adapted from EPA [141] . . . . . . . . . . . . . . . 115

9.2 Sustainable Benefits of Waste Processing Methods [145] . . . . . . . . . . . . . 117

10.1 Product Label Template . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

10.2 Qualified CFL Warranty and Lifetime Statements Chart from Energy Star . 128

10.3 Stains and finishes lifespan requirements from Green Seal . . . . . . . . . . . 129

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LIST OF TABLES

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Chapter 1

The Need For Sustainability

Currently, the world is facing a crisis of design.

Civilization was blessed with a generous, but finite amount of resources which man hasfound innumerable ways to convert into tools that increase health and happiness. While thisis certainly to be celebrated, the crisis lies in the attitude with which these resources havebeen employed. What was at first seemingly endless is now clearly finite as more and more ofthe world attains a higher standard of living and adopts the consumerism that accompaniesit. What is needed is a change in attitude, a different approach to design in which not onlyform and function are considered, but also the greater impact of design decisions, the wayin which products affect not only their immediate consumer, but also the quality of life ofothers, the availability of resources to future generations, and the overall health of the planet.

By picking this handbook up, you are taking a first step toward easing this crisis andmoving toward a newer, more sustainable method of design. While much of the content inthis handbook is far from dramatic, it provides you, the designer, with the necessary infor-mation so that reasoned and equitable decisions can be made regarding the environmentalimpact of the engineering profession. Seemingly minor choices like material selection andassembly techniques have the power in aggregate to push society further down the path ofresource exhaustion or to chart a new course of sustainable, harmonious resource use. Sowhile replacing internal fasteners with snap fits or deliberately choosing recyclable materialsmay seem unlikely to have a significant impact on the global environment, collectively, thesedecisions add up. By educating a new crop of engineers and designers to make environmen-tally responsible decisions, a sustainable approach to product development will allow societyto make the best use of its resources in the present and to maximize their use for generationsto come.

This chapter begins by examining just how dire the current state of design and resourcemanagement is, identifying the moral imperative that engineers have to change their thinkingand develop a more sustainable process. Next, several existing approaches to sustainabledesign are considered, summarizing some of the work that has already been undertaken.Then, the philosophy of cradle-to-cradle design, the approach applied in this handbook,is explained, stressing the importance of examining a products entire life cycle, from theharvesting of resources to eventual disposal. Lastly, a brief summary of this documentscontents is provided along with some suggestions as to how this text is intended to be used.

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CHAPTER 1. THE NEED FOR SUSTAINABILITY

The Current State of Design

As discussed above, the way in which society views and utilizes natural resources is rapidlydeveloping into a crisis. As the consumption of energy and consumer goods continues to in-crease in the developed world and an ever-growing portion of the globe adopts Western-styleconsumer practices, the sheer scale of production and the amount of resources being usedcreates the potential for vast environmental damage. According to the United States Envi-ronmental Protection Agency, In the past 50 years, humans have consumed more resourcesthan in all previous history [1]. But increased consumption by itself is not the problem; thereal damage is done in the way that this incredible consumption is achieved. The NaturalResources Defense Council reports that mankind collectively adds six to eight billion tonsof carbon to the atmosphere each year by burning fossil fuels and destroying forests [2]. Notonly does this cause global warming that could raise the earths temperature by up to 10 Fby 2050, but also over 80 % of the worlds forests are now gone because of mans impact [3]!Turning to the seas, millions of pounds of toxic chemicals like lead, mercury and pesticidespour into waterways each year, contaminating wildlife, seafood and drinking water. Thedamage has been so extensive that more than 40 % of fresh water is no longer drinkable [2].It is clear that current agricultural, industrial and consumer processes are not only consumingvast amounts of natural resources, they are also resulting in the unintentional destruction ofadditional resources. And the impact extends to wildlife, as well: currently 50 to 100 speciesof plants and animals become extinct every day because of a loss of habitat and detrimentalhuman influences [4].

Figure 1.1: Total aluminum can waste vs. time [5]

But the process of production is not the only factor contributing to this crisis; thecreation of waste, the disposal of consumer goods, and other end-of-life issues are also creatingmajor environmental problems. Excessive packaging for consumer products accounts for30 % of what Americans throw away every day, made worse by a low recycling rate [2]. For

3



example, airlines alone throw away enough aluminum cans each year to build 57 brand newBoeing 747s [5]. In total over the last 30 years, Americans have thrown away over 900 billioncans, worth over $25 billion, and this number is increasing annually as seen in Figure 1.1 [6].

And it is not just cans alone that are improperly wasted: 25 % of what Americans throwaway are organic products that could be composted instead of thrown in the landfill [7]. Amore detailed breakdown of exactly what is going into the nations landfills can be seen inFigure 1.2.

Figure 1.2: Typical material composition of trash

This figure can be compared to Rubbish Boys Disposal Services ideal waste destinationdistribution (see Figure 1.3) for the waste identified in Figure 1.2. Only 40 % of waste shouldbe destined for landfills, although the percentage observed is much higher.

Many of these problems are rooted in the way products are designed. Of all thingspeople buy, 99 % are not in use after 6 months [3]. This can be partially attributed tothe fact that designers create products to fail so they can make more money by sellingthem again. An obvious example would be portable consumer electronics like the iPod andcellphones. Manufacturers put a battery in these devices that lasts roughly 2 years. After2 years the iPod is out of warranty, and Apple does not offer a service to replace the battery.They expect the consumer to buy a new and improved version rather than continue withtheir still functional devices. Cell phone distributors employ a similar scheme, offering newerfree phones with a new 2-year contract. These practices are extremely detrimental to theenvironment as the old devices still function; they only need replacement batteries or abattery that will actually last as long as the product will.

Clearly man is not living in harmony with the environment, and our natural resourcescannot continue to support us at the rate at which we are abusing them. This is why itis critical to turn to the public, and, even more importantly, to the people who design andmanufacture consumer products to address the issue of sustainability before it is too late.Because of the rapidly fading nature of our natural resources, the growing problem of storingwaste, and the flaws inherent in the way products are designed, there is a moral imperativeto improve the design of consumer goods and more generally to transform the way engineers

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Figure 1.3: Ideal waste distribution with perfect recycling and composting

approach design. The environmental impacts of each design decision must be given dueconsideration just as the functional and aesthetic effects of design choices are evaluated.While it may not be possible to radically alter the approach to design immediately, it iscritical that steps toward change are undertaken now.

Sustainable Design Methodologies

Sustainable design is a design method that strives to minimize the negative impact of humanactivities on the environment. Its goal is to conserve energy and natural resources as well aspreserve habitats by mimicking and taking advantage of the environment as in the utilizationof sun and wind energy. Sustainable design can include measures such as reuse or recyclingor larger measures like the design of walk-only communities or efficient public transportation.

Formal systems and design methodologies for sustainability exist in a variety of fieldssuch as agriculture, architecture and graphic design. Architecture possesses by far the mostfully developed set of green design guidelines. LEED Certification of green buildings isa prime example of architectures documented methodologies. To qualify as a sustainabledesign, buildings must include features such as green roofs and natural ventilation, and agoverning body exists to determine whether a structure satisfies the multiple tiers of LEEDrequirements [8]. Unfortunately, this program is limited to building applications, and thereis no broadly accepted equivalent for mechanical design.

While there are few formal guidelines for sustainable mechanical design, considerablework is being done in the area. The American Society of Mechanical Engineers holds annualconferences on sustainability in design, and considerable literature has been produced on

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the subject. One of the leading discussions of the topic is William McDonough and MichaelBraungarts book Cradle to Cradle. Cradle to cradle offers a holistic approach to design whichexamines a products life from resource harvest through disposal. This handbook seeks topresent a technical description of the cradle to cradle philosophy and its applications tomechanical design.

The Cradle to Cradle Philosophy

The idea of cradle to cradle design was created in the 1970s by Walter R. Stahel. It was notuntil 2002 with the publication of the book, Cradle to Cradle by William McDonough andMichael Braungart, that cradle to cradle design was effectively described. The book alsoprovided ways to implement their methods.

1.3.1 Rooted in Nature

Cradle to cradle design is a biometric approach to design. Its goal is to imitate nature bymaking manufacturing processes similar to natural processes, as shown in Figure 1.4. Natureoperates in a cyclic manner. Plants provide food for animals, whose wastes provide nutrientsfor the soil which feeds the plants. There are no wastes. Most design involves a linear processwhere manufacturing creates a product which is purchased by a customer and is then thrownout as waste, and remains in a landfill. Cradle to cradle design can be used in a variety ofareas such as industrial design, manufacturing, buildings, economics, and social systems.

The principles of cradle to cradle are based on parallel principles observed in nature:

Waste Equals Food

The first key principle taken from nature is the concept that waste equals food. In a cradle-to-cradle system, waste really is not waste at all, but rather, it is merely a reduction tothe building blocks of the original product. In order to make this a reality in mechanicaldesign, designers and engineers must perform scientific testing to choose materials that arefundamentally safe (for both humans and the environment) and sustaining in order to createa closed-loop material flow [9].

These building block materials can be either biological or technical (synthetic.) Bio-logical nutrients, like textiles and packaging, are those made from natural fibers that canbiodegrade safely and restore soil after use [9]. Technical nutrients, like carpet yarns, arethose made from synthetics. They can be continually depolymerized and repolymerized andprovide more complex elements that are reusable indefinitely.

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Figure 1.4: Cyclic nature of cradle to cradle design [9]

Use Current Solar Income

In order for cradle-to-cradle systems to be sustainable and essentially waste-free they must befueled by a clean, safe, and renewable source of energy. From the natural world, it is obviousto see that solar and wind energy are the most innate sources of energy. The utilization ofsolar energy could include both direct solar energy collection and just making more effectiveuse of the sun as a natural light, also known as daylighting.

Celebrate Diversity

In nature, every organism finds a way to adapt to its environment. Every organism is uniqueand it is this uniqueness that helps it to effectively survive in its natural habitat. Conversely,modern engineering largely conforms to the idea and championing of the standardized one-size-fits-all products for everyone in every environment in every situation. However, as provenin nature, embracing and celebrating diversity and distinctiveness is both more effective andsustainable. The more characteristics the environment and the individual can be consideredand exploited, the more efficient the design.

1.3.2 Cradle to Cradle Goals

Products can also be cradle to cradle certified. The certification program focuses on, usingsafe materials that can be disassembled and recycled as technical nutrients or composted as

7



biological nutrients [9]. The criteria for certification are material health, material reutiliza-tion, renewable energy use, water stewardship, and social responsibility.

A major concern is the safety of the materials used in products. Cradle to cradle designensures that only materials that are safe and healthy for humans and the environment areused. In nature, even the dangerous materials such as animal venom, which in small dosescan be useful, are nowhere near as damaging as man-made materials such as nuclear waste,which can remain dangerous for years. The material health of a product is graded based ona color coded system where green mean there is little to no risk, yellow is moderate risk, redis high risk, and grey means the product cannot be categorized. The table below indicateshow materials are evaluated for safety:

Table 1.1: Human and ecological health criteria for MBDCs materials as-sessment protocol [9]

Human Health Criteria Ecological Health Criteria

Carcinogenicity Algae ToxicityTeratogenicity Bioaccumulation

Reproductive Toxicity Climatic RelevanceMutagenicity Content of Halogenated Organic Compounds

Endocrine Disruption Daphnia ToxicityAcute Toxicity Fish Toxicity

Chronic Toxicity Heavy Metal ContentIrritation of Skin/Mucous Membranes Persistence/Biodegradation

Sensitization OtherOther Relevant Data

Material reutilization involves eliminating waste by recycling product for future use.In effect, a product should have multiple life cycles, where the end of one life cycle is thebeginning of another life cycle. The maker of the product should also have a plan to makesure the product is actually recycled and not just thrown into a landfill. The product is givena material reutilization score during certification that determines the level of certification.

Cradle to cradle design also encourages the use of renewable energy. These forms ofenergy include solar, wind, and geothermal energy. Renewable energy should be used in themanufacturing and assembly of the product. Higher levels of certification require that atleast 50 % of the energy used for design and assembly comes from solar sources.

Water stewardship means any water used in the manufacturing process of the productmust not be polluted. It must leave the process just as clean as it was when it entered theprocess or cleaner if possible. When the product is manufactured, the water supply shouldnot be depleted, which means the lake or river should not become smaller in size over time.

One of the key characteristics of cradle to cradle design is social responsibility. Prod-ucts should be made in ways that respect the health, safety, and rights of others and theenvironment. When a product is made, it should be made in an ethical way. Companies areeven encouraged to have a third party assess their manufacturing processes to insure theyare in compliance with the social responsibility aspect of cradle to cradle certification.

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1.3.3 Implementation

In order to implement cradle to cradle design, existing products should be evaluated. Theircomponents need to be listed and broken down into their base chemicals. All of the chemicalsneed to be categorized based on their health hazards. The chemicals need to be evaluatedfor their human and environmental impacts throughout their entire life cycles. Then theyneed to be evaluated for their renewability and recyclability.

Once all the evaluations of the product are complete changes should be made to themanufacturing of the product based on the data. The high risk chemicals listed shouldimmediately be taken out of the product and replaced with safer chemicals. The medium riskchemicals should eventually be taken out of the product and replaced with safer chemicals.The low/no risk chemicals should be kept in the product. The manufacturer should find away to make the product fully recyclable or biodegradable and to make the product usingonly renewable energy.

Most likely, implementation of cradle to cradle design will take time. The first attemptat cradle to cradle will probably not remotely resemble the final attempt. In order to fullyrealize cradle to cradle design, long term goals should be set by the manufacturer and metover time. Sometimes, the manufacturers will have to wait until market conditions, such asmaterial prices, are favorable in order to make cradle to cradle design cost effective. The keypart is making the decision to implement cradle to cradle design and beginning to make thenecessary changes in the manufacturing process.

Document Outline

The intended purpose of this document is to provide a design resource for engineers thataddresses sustainable design and the implementation of cradle to cradle design philosophy.This document will provide guidelines for mechanical engineers to aid in the development ofsustainable products and systems. It is usable both as a textbook for student use and as areference that can be called upon as needed in the workplace.

The Green Label Benchmark is introduced, and the standards for are explained. In-formation necessary for a product to receive the green label is laid out, as well as certainareas of standard requirements, such as product life, energy usage, lifetime performance,and emission levels during production. Several pollutants are considered, including carbonmonoxide, lead, and nitrogen dioxide. Consideration is given to the sites that raw materialsmay be taken from, and potential ecological troubles that could follow.

Decision processes particularly important to sustainability include the selection of prod-uct material, the consideration given to the manufacturing of the product, and the consid-eration given to relevant post-production characteristics. These are the topics that will begiven the greatest focus in this document.

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1.4.1 Product Material Selection

Potential product materials include metals, plastics, and ceramics, each of which raisesunique sustainability challenges. The individual properties of a variety of materials areconsidered, and the sustainability implications of each are evaluated.

Several metals and metal alloys are considered, including stainless steels, aluminumalloys, copper alloys, and zinc, among others. The use of plastics is discussed, and differingtypes of plastics such as PVC and Polycarbonate are evaluated, along with discussion ofmaterial use and production processes such as extrusion and injection molding. In addition,several other types of engineering materials, such as ceramics, composites, and elastomers, arealso addressed. The material properties and sustainability characteristics of these materialsare then assessed.

1.4.2 Conscientious Manufacturing Design

Manufacturing characteristics to be considered for effective sustainable design include thetools and machinery used in fabrication of a product, the assembly process, and the produc-tion system as a whole.

Streamlining of the machining process is a topic of discussion, as well as consideration ofreusable material, minimal waste byproducts, and proper machining procedures. The impor-tance of the production process is emphasized, and production methods such as Six Sigmaapplication, lean production strategies, demand forecasting, and inventory management canall prove useful as sustainability strategies. Several examples of conscientious productionprocesses that have been successfully implemented are then presented.

Finally, there is a discussion on accounting for assembly and disassembly in the designprocess. A variety of assembly methods are discussed and evaluated, including screws, wash-ers, rivets, snap fits, press fits, welds, staples, and adhesives, such as glue or tape. Eachassembly method is assessed and considered in the context of sustainable design, and recom-mendations are made on the importance of design for assembly, especially for sustainability.

1.4.3 Post Production

Finally, issues relevant to post production processing will be discussed, including the pack-aging of the product and the recyclability or disposability of the product.

Waste disposal is considered, along with the difficulties of the disposal of electronic, med-ical, or chemical waste. Recyclability is a key issue in sustainable design, and is addressed,along with consideration given to to waste management and methods of waste disposal, suchas incineration or gasification.

In addition to waste disposal, another key post production issue is the packaging usedon a product. Design guidelines are given to address topics such as reusability, recyclability,cost- effectiveness, and the goal of a closed-loop system. Separate guidelines are given forthe packaging of food, beverages, or consumables.

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12


Chapter 2

Metal Alloys

When designing to reduce negative impacts on the environment, it is important to havean understanding of available metal alloys and their properties. Metal products contributeconsiderably to the sustainable design movement. High recycled content, recyclability, fullydeveloped distribution networks, and energy efficiency are all reasons to consider metal asa sustainable material choice when designing products of any class. In order to effectivelyutilize metals as a sustainable design choice, the designer must have a basic understandingof possible uses for each metal type and how often and effectively they are recycled. Thefollowing sections contain material property data and sustainability statistics for several ofthe most commonly used metals in consumer products.

Quick-Reference Table

Table 2.1 summarizes some of the key statistics that should be considered when decidingwhich metal to choose for a sustainable design application. A list of possible material choicesfor your product should be identified based off yield strength requirements, and then thefinal choice should be made by quantitatively comparing the corresponding sustainabilitystatistics . Two of the most important factors that should be considered when making thisdecision are the energy required to produce the material, and the ease and practicality ofrecycling the material once the product has reached the end of its life. These somewhatabstract concepts of sustainability can be quantitatively defined by looking at how ofteneach material is recycled and the amount of energy that is saved by recylcling it. Aluminumis one of the most sustainable metal choices because of its vast range of applications and the95 % decrease in production energy. Copper is also a top contender because it is extensivelyrecycled and it takes approximately 85 % less energy to produce recycled copper than itdoes to produce new copper from ore. As a rule of thumb, the majority of metal alloys aresustainable choices because of the prevalent recycling options available and the increasedproduct lifetime achieved by using them. More general information about specific metaltypes can be found in the following sections.

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CHAPTER 2. METAL ALLOYS

Table 2.1: Quick-reference table of sustainable metals

MetalLife Recycled Energy Reduction Other Benefits

(years) (%) (%) (per ton recycled)

Carbon Steels - - - -

Stainless Steels 80-500 80-90 - 1100 kg Fe saved

Tooling Steels 500 71 75 1100 kg Fe saved

Aluminum 1-20 75 95 14 MWh saved

Titanium > 500 5 - -

Magnesium - 45 - -

Copper - 95 85% -

Zinc - 70 76 -

Carbon Alloy Steels

2.1.1 Material Properties

Steel, an iron alloy with carbon content up to 2.1 %, is one of the most common materialsavailable worldwide. The many classes of steel are generally distinguished by their alloyingcontent, and the most popular of these is carbon steel, in which carbon is the main oronly alloying element. Over 85 % of steel produced in the United States is carbon steel.Carbon steels are further classified by relative carbon content. Increasing the carbon contentgenerally increases the strength of the steel, but lowers its ductility and its melting point.There are many production and treatment practices in the steelmaking process (notablyheat treatment and deoxidation) intended to change the properties of the steel for a desiredeffect, but carbon content variations normally have a much greater effect on the mechanicalproperties.

1. Mild and Low-Carbon Steel: up to 0.3 % C

Common, inexpensive, and ductile. Often flat-rolled for use in automobile bodiesand structural steel.

2. Medium-Carbon Steel: 0.3 % to 0.6 % C

Good resistance to wear; often used in axles, gears, and rails.3. High-Carbon Steel: 0.6 % to 1.0 % C

Very strong yet brittle, responds well to heat treatment, and often used in springsand high-strength wires.

4. Ultrahigh-Carbon Steel: 1.0 % to 2.0 % C

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Experimental alloys used in specialty products, often produced via powder met-allurgy.

Steel with above 2.1 % carbon content is instead considered cast iron. When steel is alloyedwith any variety of non-carbon elements, it is considered alloy steel. The most commonelements used as alloyants are manganese, nickel, molybdenum, and chromium. The use ofthese alloys is generally to affect the mechanical properties such as strength, hardness, hard-enability, magnetism, or heat resistance. The sheer number of possible alloying combinationsand concentrations allows specialized steels to be developed for many specific applications.

2.1.2 Material Production and Recycling

Since steel is one of the most easily recycled materials and is 100 % recyclable, modernsteel production relies heavily on scrap steel, making approximately two-thirds of new steelfrom recycled material. An electric arc furnace is the most common secondary steelmakingprocess, in which the steel is melted for reuse. Electric arc furnaces allow production touse nearly 100 % scrap metal. By contrast, primary steelmaking with raw materials usesbasic oxygen furnaces, a process that requires significantly more energy and resources perunit weight produced. In fact, one ton of steel recycled saves 1.5 tons of mined iron ore,0.5 tons of coal, and 75 % in energy consumption [10]. Electric arc furnaces are additionallyadvantageous because they can be started and stopped quickly, whereas blast furnaces usedin primary steelmaking are never shut down and are unable to vary production quantitiesaccording to demand.

The Steel Recycling Institute (SRI) reported a 2009 overall steel recycling rate of 103 %.Recycling rates are calculated not as part of a whole, but as a ratio of influx of recyclablematerial to new production. Since this is calculated year-to-year it is inflated by recenteconomic and production trends, but overall rates have been approximately 70 % to 80 %over the last decade. More specific recycling rates show steel from automobiles at 106 %,structural steel at 97.5 %, and construction reinforcement steel at 70 % [11].

2.1.3 Sustainability

Steel is infinitely recyclable, meaning it maintains its mechanical properties indefinitely.As such, recycling is such a large component of the steel industry because, unlike manyother sustainable practices, it is financially beneficial to both the consumer and the supplier.Despite the many benefits and the efficiency of modern steel recycling, there are neverthelesssome adverse effects. These notably include the production of slag, a byproduct of steelproduction due to impurities in the metal. This is part of the smelting process and istherefore present in both primary and secondary steelmaking.

The progression of technology in steel production continues to refine alloys for use inspecific cases. One method of reducing the environmental impact when using steel is tochoose a stronger alloy, or one which has been treated, that allows for less metal to beused overall. This concept has been implemented in many industries and materials already

15



from soft drink cans to automobile bodies to reduce the total weight of the product withoutsacrificing the integrity of the material.

Stainless Steels


Stainless steels, by definition, consist of metal that has been alloyed with a minimum of10 % chromium by weight. The alloying of chromium with steel makes stainless steel highlycorrosion resistant and gives it a shiny protective layer on the surface which reforms ifscratched. In addition to being corrosion resistant, stainless steels are ductile and strongwith ultimate tensile strengths up to 620 MPa and elongations of up to 60 % [12]. Stainlesssteels can be alloyed with other metals and a few common types of stainless steels are listedbelow.

1. Austenitic steels

Nonmagnetic and comparatively ductile2. Ferritic steels

Magnetic with high chromium content3. Martensitic steels

Comparatively strong, hard, and fatigue resistant at the expensive of corrosionresistance

4. Precipitation-hardening steels

Strong and ductile5. Duplex-structure steels

Strong with good corrosion resistance properties

Stainless steels have a projected life of 80 years to 550 years, depending on the use and typeof the stainless steel selected, before pitting becomes a serious issue [13]. Stainless steels havea wide range of uses varying from nuts and bolts to fishing tackle and oil rig equipment [12].For a summary of further material property data see Table 2.2.

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Table 2.2: Steel properties [12]

AISI(UNS)

UltimateTensileStrength(MPa)

YieldStrength(MPa)

Ductility(%EL)

Characteristics and TypicalApplications

303(S30300)

550 to 620 240 to 260 50 to 53 Screw-machine products, shafts, valves,bolts, bushings, and nuts; aircraft fittings;rivets; screws; studs.

304(S30400)

565 to 620 240 to 290 55 to 60 Chemical and food-processing equipment,brewing equipments, cryogenic vessels,gutters, down-spouts, and flashings

316(S31600)

550 to 590 210 to 290 55 to 60 High corrosion resistance and high creepstrength. Chemical and pulp-handlingequipment, photographic equipment,brandy vats, fertilizer parts, ketchup-cooking kettles, and yeast tubs

410(S41000)

480 to 520 240 to 310 25 to 35 Machine parts, pump shafts, bolts, bush-ings, coal chutes, cutlery, fishing tackle,hardware, jet engine parts, mining machin-ery, rifle barrels, screws, and valves

416(S41600)

480 to 520 275 20 to 30 Aircraft fittings, bolts, nuts, fire extin-guisher inserts, rivets and screws.

17




Stainless steel is obtained through the alloying of steel and chromium. Steel is obtainedthrough the mining of iron. Mining and processing iron has traditional environmental impactissues and produces wastewater and hazardous air emissions [14]. Chromium is obtainedthrough the mining of chromium ore, which is very abundant on Earth [15]. Stainless steelis claimed for recycling at two different stages of its lifecycle. It can be recycled as newscrap or old scrap. New scrap is reclaimed stainless steel from manufacturing processes andaccounts for 35 % of the recycled material. Old scrap is composed of returned materialsclaimed from products at the end of their life and metal obtained through scrap brokersat landfills. This type of scrap accounts for 25 % of the recycled material. The remaining40 % of the recycled material are additional raw materials and other recycled metals thatare added to the recycling process [16]. When recycled, stainless steel is melted down, castinto ingots, and sometimes rolled so that it can be repurposed [17].


In general, the production and life-cycle of stainless steels have a very low impact on the en-vironment as they are easily and efficiently recycled. This makes stainless steels a very smartmaterial choice for sustainable design. On average 60 % of the production of new stainlesssteel involves recycled materials, and stainless steels themselves are 100 % recyclable. In2006, for example, 28 million tons of stainless steel was produced. In this process 14 milliontons of recycled stainless steel and other metals were used. The only reason stainless steelsare not composed of more than 60 % recycled materials is that historical consumption of themetal does not keep pace with current demand [16]. Currently, it is estimated that around80 % to 90 % of stainless steels are recycled at the end of their life. [16]. Energy reductionby recycling is difficult to quantify because recycling is an integral part of the production ofstainless steel. The production of new stainless steel always involves using recycled stainlesssteel [18]. Recycling 1 ton of stainless steel saves 1100 kg of iron ore, 630 kg of coal, and55 kg of limestone [17]. In addition, stainless steel can be recycled indefinitely without losingany material properties [16]. For this reason they are considered environmentally friendlyand are a highly recommended choice for a sustainable metal, especially when high strengthproperties are desired.

Tool & Die Steels


Tool and die steels are steels that are commonly used for manufacturing and productionpurposes. They have high strength, impact toughness, and wear resistance. There are manydifferent types of tool and die steels and several are listed below.

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1. High-speed steels

Molybdenum and tungsten type; often alloyed with other elements Designed for use at high operating temperatures with high strength and hardness

2. Hot-work steels

Designed for elevated temperature use Very high toughness, wear resistance, crack formation resistance

3. Cold-work steels

Designed for cold-working processes High wear and crack formation resistance

4. Shock-resisting steels

Very high impact toughness

Tool and die steels are often alloyed with molybdenum, tungsten, chromium, vanadium, andcobalt [12].


Tool and die steels are carbon steels that are alloyed with other elements. Therefore thecreation of tool and die steels are related to the creation of carbon steel. Carbon steelis produced using iron ore and carbon. Iron ore is in abundant supply on Earth and isobtained through mining. The overall production of carbon steel poses environmental threatsincluding the production of wastewater and hazardous air emissions [14]. Recycling processesare similar to carbon steel recycling. Metals are collected from new and old scrap and areseparated according to properties. They are then melted and formed into ingots throughcasting to be reused [19]. Typically tool and die steels are recycled through the use of anelectric arc furnace [20].


In high-speed steels, approximately 60 % to 70 % of newly produced metal is made ofscrap [21]. Although they are alloyed with other materials, tool and die steels are madeprimarily of carbon steel. As such they share many of the same sustainability properties ascarbon steel. Carbon steel is a very recyclable metal, although as always, the productionphase causes harm to the environment because it involves the processing of iron ore. Asmentioned previously, carbon steel is a very good choice for a sustainable material as itis easy to recycle and is in abundant supply. Recycling tool and die steels is especiallyimportant so that the alloyed materials contained within can be reused. These metals, suchas tungsten and vanadium are relatively scarce and difficult to obtain, so recycling is both

19



economical and important to saving natural resources [17]. Recycling carbon steel uses 75 %less energy than creating new carbon steel [19]. Therefore, recycling tool and die steels saveseven more energy because the difficult to obtain alloys are already present. When tooland die steels are needed there is little choice in sustainability. What is more important isrecycling tool and die steels at the end of their usable life.

Aluminum Alloys


Aluminum is one of the most commonly used non-ferrous materials in manufacturing. This isdue to its high strength-to-weight ratio, good corrosion resistance, high thermal and electricalconductivity, nontoxicity, appearance, and its formability and machinability. In addition,aluminum is nonmagnetic, which in some applications is beneficial. There is a wide rangeof aluminum alloys, each with distinct properties. There are two main types of aluminumalloys:

Those hardenable by heat treatment (designated by the letter T, e.g. Al 6061-T6) Those hardenable by cold working (designated by the letter H, e.g. Al 5052-H34).

Additionally, aluminum may be annealed and this is designated by the letter O. Basic prop-erties for various aluminum alloys can be found in Table 2.3.

Aluminum is formed via rolling, extrusion, drawing, and forging and can be machinedand welded. Due to its versatility, aluminum is used in a wide range of products. A fewproducts that are made of aluminum alloys are aircraft and automobile components, beveragecans, foil, and sporting equipment such as baseball bats [12].


Aluminum is produced through an electometallurgical process; this energy-intensive processmakes recycling even more appealing. To obtain aluminum, bauxite ore is mined and refinedinto the oxide, alumina. Alumina, electricity, and cryolite, a molten electrolyte, are combinedin a cell and as a result, molten aluminum metal and carbon dioxide are produced. Themolten metal is cast into ingots which may then be used for various manufacturing processessuch as castings or extrusions. The ingots may also be shaped into mill products such assheets, plates, bars, and round stocks which may be processed further by a customer in thefuture [22].

As is the case for other non-ferrous metals, a general outline of the recycling processfor aluminum is as follows: (1) bale the material into a large block (2) shear the materialinto manageable sizes (3) separate ferrous and non-ferrous metals using a rotating magneticdrum, and (4) melt the non-ferrous metal, pour into a cast, and shape into an ingot [19]. More

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Table 2.3: Properties of Various Aluminum Alloys at Room Temperature [12]

Alloy (UNS) Temper UltimateTensile

Strength(MPa)

YieldStrength

(MPa)

Ductility(%EL)

1100 (A91100) O 90 35 35 to 451100 H14 125 120 9 to 20

1350 (A91350) O 85 30 231350 H19 185 165 1.5

2024 (A92024) O 190 75 20 to 222024 T4 470 325 19 to 20

3003 (A93003) O 110 40 30 to 403003 H14 150 145 8 to 16

5052 (A95052) O 190 90 25 to 305052 H34 260 215 10 to 24

6061 (A96061) O 125 55 25 to 306061 T6 310 275 12 to 17

7075 (A97075) O 230 105 16 to 177075 T6 570 500 118090 T8X 480 400 4 to 5

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specifically for aluminum, however, depending on the type to be recycled and its intendedsecondary purpose, one of the following processes may be completed [22]:

Used Beverage Container (UBC) Processing: Old aluminum cans and scrap from thecan-making process are recycled into new can sheet.

Secondary Specification Aluminum Alloys: Scrap from various sources is used to makean alloyed ingot to the customers specifications.

Remelt Secondary Ingot (RSI): Aluminum scrap is melted down and formed into aningot without a specific chemical composition.

Deoxidation ingot production: Aluminum scrap is used to form various shapes thatare used for steel deoxidizing in the steel-making process.

Dross processing: Aluminum is collected either mechanically or chemically from thedross that forms during melting processes. This aluminum is returned to the customereither as molten metal or a RSI.


The biggest environmental concern for aluminum producers is the perflourocarboon (PFC)emission from smelting. Recycling aluminum is important not only because of the reductionof PFC emissions but also for the considerably less energy used to recycle scrap rather thanproduce new aluminum.

There are many benefits to using recycled aluminum. First of all, by recycling, 95 %less energy is used than by producing aluminum from raw materials. By recycling one tonof aluminum, the following are saved [19]:

8 tons of bauxite (an aluminum ore, the main source of aluminum) 14,000 kWh of energy 40 barrels of oil 251 kJ of energy 7.6 cubic meters of landfillThe environmental impact at the end of life for aluminum products is fairly low due to

the prevalence and ease of recycling the material. Figure 2.1 shows aluminum scrap readyfor recycling. From automobiles to beverage cans, there is a high rate of recycling (90 %and 57 % in the US respectively) of aluminum throughout the wide spectrum of productsit is used in [22]. According to the Bureau for International Recyling, of an estimated totalof 700 million tonnes(sic) of aluminium produced since commercial manufacturing beganin the 1880s, about 75 % of this is still being used as secondary raw material today. Inaddition, 63 % of all aluminum beverage cans made are recycled worldwide, making it themost recycled container [19].

Aluminum and its alloys are very durable due to their good mechanical and chemicalproperties. As a result, the materials lifetime greatly depends on its use. The aluminumfound in an automobile will have a considerably different lifetime (e.g. years) than a beveragecan (e.g. weeks to months).

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Figure 2.1: Recyclable aluminum scrap [23]

Titanium


Titaniums use in commercial products began relatively recently (circa 1950s). Due to itshigh strength-to-weight ratio and good corrosion resistance at room and elevated tempera-tures, it is commonly used in aircraft, racing cars, and marine craft. In addition, titaniumis bio-compatible, making it very useful in medical devices such as orthopaedic implants.Alloys are available in either powder or wrought forms. There are several different titaniumalloys with varying mechanical properties, and their yield strengths, in fact, vary from 95MPa to 1210 MPa. It can be formed, machined, and joined. Care must be taken during man-ufacturing to ensure that there is no surface contamination by hydrogen, oxygen, or nitrogen.This surface contamination could have a negative effect on mechanical properties [12].


Producing titanium is an expensive process. The cost of production is a limiting factor in itspopularity when compared to other materials. Titanium ingots are traditionally producedusing vacuum arc remelting (VAR). More recently, cold-heart melting (CHM) and plasma-arc melting (PAM) have also been used due to their ability to remove high density inclusions.Titanium production is expensive due to the use of these melting processes.

The following general steps are taken to turn titanium ore into an ingot ready for furtherprocessing: (1) reduce titanium ore to form an impure porous form of titanium metal (tita-nium sponge) (2) purify the sponge (3) melt the sponge or the sponge and alloy elements toform an ingot.

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Figure 2.2: Titanium sponge and rounds stock [24]

The ingots can be made into sheets, bars, plates, or round stock as needed [25]. Forexample, on the left of Figure 2.2 is titanium sponge, and on the right, titanium round stockis shown.

As is typical for non-ferrous metals, titanium is recycled by melting the titanium scrap.All types of scrap can be remelted. Prior to remelting the scrap, however, it must becleaned and all surface scales must be removed in order to avoid defects in the ingot beingproduced [25].


The durability of titanium greatly depends on the processing that it is subjected to. However,when titanium is made well it can have a considerably long life given its excellent corrosionresistance and strength [25].

Although there is a considerable amount of titanium scrap produced during the pro-duction of titanium components, typically little of it is recycled and reformed into titaniumingots. In fact, only around 5 % of titanium ingot production comes from old scrap [26]

Magnesium Alloys


Magnesium is the lightest engineering metal available; its alloys are used in structural andnonstructural applications where weight is of primary importance. Magnesium is also analloying element in various nonferrous metals.

Properties: light weight, good vibration-damping characteristics, high strength-to-weight ratios

24



Available Forms: Because it is not sufficiently strong in its pure form, magnesiumis alloyed with various elements (see Table 2.4) to impart certain specific properties.These alloys are available as either castings or wrought products, such as extrudedbars and shapes, forgings, and rolled plates and sheets.

Table 2.4: Properties and typical forms of various wrought magnesiumalloys

Composition(wt%)

Type TS(MPa)

y(MPa)

Duc-tility(%EL)

TypicalForms

Alloy Al Zn Mn ZrAZ31B 3 1 0.2 F 260 200 15 Extrusions

H24 290 220 15 Sheets andplates

AZ80A 8.5 0.5 0.2 T5 380 380 7 Extrusionsand forgings

HK31A* 0.7 H24 255 255 8 Sheets andplates

ZK60A 5.7 0.55 T5 365 365 11 Extrusionsand forgings

* HK31A also contains 3 wt% Th

Applications: aircraft and missile components, material-handling equipment, portablepower tools (such as drills and sanders), luggage, bicycles, sporting goods, printing andtextile machinery, and general lightweight components.

Miscellaneous: Because magnesium alloys oxidize rapidly, they are a potential hazard,and precautions must be taken when machining, grinding, or sand casting magnesium alloys.However, products made of magnesium and its alloys are not a fire hazard.


New magnesium-base scrap typically is categorized into one of six types.

Type 1 is high-grade clean scrap, generally such material as drippings, gates, andrunners from die-casting operations that is uncontaminated with oils.

Type 2 is clean scrap that contains steel or aluminum, but no brass or copper. Type 3 is painted scrap castings that may contain steel or aluminum, but no brass or

copper. Type 4 is unclean metal scrap that is oily or contaminated. Type 5 is chips, machinings that may be oily or wet, or swarf. Type 6 is residues (crucible sludge, dross, etc.) that are free of silica sand.

25



The most desirable type of scrap is type 1. Most of the type 1 scrap is generatedduring die-casting magnesium alloys; this typically represents 40 % to 60 % of the totalcast weight, most of which consists of runners that feed the die cavity as it is injectedwith magnesium. This scrap is either reprocessed at the die-casting facility or sold to ascrap processor. The other types of scrap are either sold to a scrap processor or are useddirectly in steel desulfurization. In addition to magnesium-base scrap, significant quantitiesof magnesium are contained in aluminum alloys that also can be recycled. In 2002, over45 % of the supplied magnesium in the United States was generated from recycling [26].

Copper Alloys


First produced in about 4000 B.C., copper and its alloys have properties somewhat similarto those of aluminum alloys.

Properties: high electrical and thermal conductivity; good resistance to corrosion andwear; easily processed by various forming, machining, casting, and joining techniques;high recyclability

Available Forms: Brass, which is an alloy of copper and zinc, was one of the earliestalloys developed and has numerous applications (see Table 2.5). Bronze is an alloy ofcopper and tin (see Table 2.6). Other bronzes include:

aluminum bronze, an alloy of copper and aluminum, tin bronze, beryllium bronze (a beryllium copper), and phosphor bronze; the latter two have good strength and high hardness for appli-

cations such as springs and bearings.

Applications: electrical and electronic components, springs, cartridges for small arms,plumbing, heat exchangers, and marine hardware, as well as some consumer goods,such as cooking utensils, jewelry, and other decorative objects.


Coppers recycling value is so high that premium-grade scrap holds at least 95 % of thevalue of the primary metal from newly mined ore. Recycling copper saves up to 85 % ofthe energy used in primary production. In order to extract copper from copper ore, theenergy required is approximately 108 J/kg. Recycling copper uses much less energy, about1.06 107 J/kg. By using copper scrap, we reduce CO2 emissions by 65 %. Almost 40 % ofthe worlds demand for copper is met using recycled material [28].

26



Table 2.5: Properties and typical applications of various wrought copperand brasses [27]

Type(UNS)

NominalCompo-sition(wt%)

TensileStrength

(MPa)

YieldStrength

(MPa)

Ductil-ity

(%EL)

Typical Applications

Oxygen-free

electronic(C10100)

99.99 Cu 220-450 70-365 55-4 Bus bars, waveguides,hollow conductors, lead inwires, coaxial cables andtubes, microwave tubes,

rectifiers.Red Brass(C23000)

85.0 Cu,15.0 Zn

270-272 70-435 55-3 Weather stripping, conduit,sockets, fasteners, fire

extinguishers, condenserand heat-exchanger tubing.

Low Brass(C24000)

80.0 Cu,20.0 Zn

300-850 80-450 55-3 Battery caps, bellows,musical instruments, clock

dials, flexible hose.Free-

cuttingbrass

(C36000)

61.5 Cu,3.0 Pb,35.5 Zn

340-470 125-310 53-18 Gears, pinions, automatichigh-speed screw-machine

parts

NavalBrass

(C46400to

C46700)

60.0 Cu,39.25 Zn,0.75 Sn

380-610 170-455 50-17 Aircraft turnbuckle barrels,balls, bolts, marine

hardware, valve stems,condenser plates.

27



Table 2.6: Properties and typical applications of various wrought bronzes [27]

Type(UNS)

NominalComposi-

tion(wt%)

TensileStrength

(MPa)

YieldStrength

(MPa)

Ductil-ity

(%EL)


Architec-tural

Bronze(C38500)

57.0 Cu,3.0 Pb,40.0 Zn

415 140(as ex-truded)

30 Architectural extrusions,storefronts, thresholds,

trim, butts, hinges.

Phosphorbronze, 5

% A(C51500)

95.0 Cu,5.0 Sn,trace P

325-960 130-550 64-2 Bellows, clutch disks, cotterpins, diaphragms, fasteners,

wire brushes, chemicalhardware, textile

machinery.Free-

cuttingphosphor

bronze(C54400)

88.0 Cu,4.0 Pb,

4.0 Zn, 4.0 Sn

300-520 130-435 50-15 Bearings, bushings, gears,pinions, shafts, thrustwashers, valve parts.

Low-silicon

bronze, B(C65100)

98.5 Cu,1.5 Si

275-655 100-475 55-11 Hydraulic pressure lines,bolts, marine hardware,

electrical conduits,heat-exchanger tubing.

Nickel-silver,65-18

(C74500)

65.0 Cu,17.0 Zn,18.0 Ni

390-710 170-620 45-3 Rivets, screws, zippers,camera parts, base for silverplate, nameplates, etching

stock

28



Nickel


Nickel is a major alloying element that imparts strength, toughness, and corrosion resistanceto metals.

Properties: high strength and toughness (at elevated temperatures for nickel-basedalloys), good resistance to corrosion and wear, magnetic

Available Forms: A variety of nickel alloys that have a range of strengths at differenttemperatures are shown in Table 2.7. Monel is a nickel-copper alloy, and Inconel is anickel-chromium alloy. Hastelloy, a nick-molybdenum-chromium alloy, has good cor-rosion resistance and high strength at elevated temperatures. Nichrome, an alloy ofnickel, chromium, and iron, has high oxidation and electrical resistance and is com-monly used for electrical-heating elements. Invar, an alloy of iron and nickel, has a lowcoefficient of thermal expansion and has been used in precision scientific instrumentsand camera/optics applications.

Applications: Nickel-base alloys are used for high-temperature applications, such as jet-engine

components, rockets, and nuclear power plants, as well as in food-handling andchemical processing equipment, coins, and marine applications.

Because nickel is magnetic, its alloys are also used in electromagnetic applicationssuch as solenoids.

The principal use of nickel is in electroplating for resistance to corrosion and wearand for appearance.

Nickel (III) oxide is used as the cathode in many rechargeable batteries, includingnickel-cadmium, nickel-iron, nickel hydrogen, and nickel-metal hydride, and usedby certain manufacturers in Li-ion batteries.


Austenitic stainless steel scrap is the largest source of secondary nickel for the United States,accounting for about 86 % of nickel reclaimed in 2002. An additional 4 % came from therecycling of alloy steel scrap. The remaining 10 % comprised copper-nickel and aluminum-nickel alloy scrap and pure nickel scrap. Scrap availability is expected to grow along withstainless steel production [26]. In addition, 80 % of nickel produced today comes from recycledmaterial [29].

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Table 2.7: Properties and typical applications of various nickel alloys (allalloy names are trade names)

Alloy(Condition)

NominalComp.(wt%)

TS(MPA)

Y(MPa)

Ductility(wt%)


Nickel 200(annealed)

None 380 to550

100 to275

60-40 Chemical- andfood-processing industry,

aerospace equipment,electronic parts.

Duranickel301 (age

hardened)

4.4 Al,0.6 Ti

1300 900 28 Springs, plastic-extrusionequipment, molds for

glass.Monel

R-405 (hotrolled)

30 Cu 525 230 35 Screw-machine products,water-meter parts.

MonelK-500 (agehardened)

29 Cu,3 Al

1050 750 20 Pump shafts, valvestems, springs.

Inconel 600(annealed)

15 Cr,8.0 Fe

640 210 48 Gas-turbine parts,heat-treating equipment,electronic parts, nuclear

reactors.Hastelloy

C-4(solution

treated andquenched)

16 Cr,15 Mo

785 400 54 High-temperaturestability, resistance to

stress-corrosion cracking.

30



Zinc


Zinc, which has a bluish-white color, is the fourth most industrially utilized metal, after iron,aluminum, and copper.

Properties: high resistance to corrosion and wear; good formability characteristics;high recyclability

Applications: For galvanizing iron, steel sheet, and wire, Zinc serves as the anode and pro-

tects the steel (cathode) from corrosive attack should the coating be scratched orpunctured.

Zinc-base alloys are used extensively in die casting for making products such asfuel pumps and grills for automobiles, components for household appliances (suchas vacuum cleaners, washing machines, and kitchen equipment), machine parts,and photoengraving plates. Major alloying elements in zinc are aluminum, copper,and magnesium. They impart strength and provide dimensional control duringcasting of the metal.

Zinc is also used as an alloying element; brass, for example, is an alloy of copperand zinc.

Another use for zinc is in superplastic alloys, which have good formability charac-teristics by virtue of their capacity to undergo large deformation without failure.


The average car contains up to 10 kg of zinc in its galvanized body panels. When they arediscarded, these panels can be readily made into new parts of comparable quality. Totalrecovery of zinc within the non-ferrous metals industry amounts to 2.9 million tons, of which1.5 million ar

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