DESIGN AND DEVELOPMENT SOURCEBOOK
PRODUCT PRODU CT DES DESIGN IGN FOR DIE CASTING
in Recyclable Aluminum, Magnesium, Zinc and ZA Alloys
Although great care has been taken to provide accurate and current information, neither the author(s) nor the publisher publi sher,, nor anyone else associated with this publication, shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book. The
material contained herein is not intended to provide speci c advice or recommendations for any specic situation. Any opinions expressed by the author(s) are not necessarily those of NADCA. Trademark notice: Product or corporate names may be trademarks or registered trademarks and
are used only for identi cation and explanation without intent to infringe nor endorse the product or corporation. © 2015 by North American Die Di e Casting Association, Arlington Heights, Illinois. All Rights Reserved. Neither this book nor any part may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying, photocopying,microlming, microlming, and recording, or by any information storage and retrieval system, without permission in writing form the publisher. publisher.
D E S I G N
A N D
D E V E L O P M E N T
S O U R C E B O O K
PRODUCT DESIGN FOR DIE CASTING
in Recyclable Aluminum, Magnesium, Zinc and ZA Alloys
2015 Seventh Edition Published by the North American Die Casting Association
NORTH AMERICAN DIE CAST ING ASSOCIATION ASSOCIATION
Product Design for Die Casting
i
PREFACE Product Design for Die Casting was originally prepared and published for designers,
engineers and speciers through a cooperative effort of the die casting industry and the United States Department of Commerce. It was initially nanced by contributing members of a marketing afliate of the North American Die Casting Association (NADCA), and the U.S. Department of Commerce through a grant/cooperative agreement.
Acknowledgement is made to the seless individuals, representing die casters, industry suppliers and engineers and managers, who spent many hours contributing, reviewing and verifying data. All known sources of published information on the die casting process as it applies to product design were researched. Portions of the text and some of the illustrations in this manual were adapted from Product Design and Development for Magnesium Die Castings with the permission of the Dow Chemical Company. Several illustrations are reproduced with the permission of the International Lead Zinc Research Organization. In addition to this book the North American Die Casting Association also provides die casting product design assistance through its NADCA Design program which consists of the following resources: NADCA Design web site: www.diecastingdesign.org NADCA Design seminars: www.diecastingdesign.org/seminars Phone support: 847.279.0001 E-mail support:
[email protected]
Designers, engineers and speciers are also urged to consult NADCA Product Specication Standards for Die Castings, published by the North American Die Casting Association; these standards include standard and precision tolerances (including geometric dimensioning) for current production practices under varying manufacturing conditions. The standards also include Tooling, Alloy, Engineering & Design, Quality Assurance and Commercial guidelines. For die casting produced with the semi-solid and squeeze casting processes the
publication NADCA Product Specication Standards for Die Castings Produced by the Semi-solid and Squeeze Casting Processes is available. Additional copies of this publication and other publications are available from the North American Die Casting Association: North American Die Casting Association www.diecasting.org 3250 N. Arlington Heights Rd., Ste. 101 Arlington Heights, IL 60090 Phone: 847.279.0001 Fax: 847.279.0002
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Product Design for Die Casting
PRODUCT DESIGN FOR DIE CASTING CONTENTS 1
The Die Casting Option
1
1.1
Die Casting Advantages: Summary
1
1.2
Advances in Die Casting Process Technology
1
1.3
Developments in Die Casting Alloys
2
1.4
Die Casting’s Range of Product Capabilities
2
1.5
The Economic Equation
6
1.6
The Benets of Designing for Manufacturing
6
1.7
Miniature, Heat Treated, High Vacuum, Squeeze & Semi-Solid Metal Casting
6
Serviceability & Recycling
8
1.8 2
3
4
5
Product Development
9
2.1
Working Environment
12
2.2
Structural Criteria
16
2.3
Manufacturing Economics
26
2.4
Die Casting Versus Other Processes
32
Product Design
37
3.1
Geometry Optimization
38
3.2
Assemblies
47
3.3
Machining
64
3.4
Surface Finishing
67
3.5
Prototyping
79
The Conventional Die Casting Process
87
4.1
Understanding the Die Casting Cycle
88
4.2
Characteristics of Die Casting
93
4.3
Preventing Casting Defects
94
4.4
Alloys and Properties
97
4.5
Aluminum Die Castings
98
4.6
Magnesium Alloys
106
4.7
Zinc
111
4.8
ZA Alloys
115
4.9
Early Designer-Die Caster Interaction
116
4.10
Alloy Selection
116
High Integrity Die Castings
125
5.1
High Vacuum Die Casting
125
5.2
Squeeze Casting
129
5.3
Semi-solid
130
Product Design for Die Casting
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iv
Product Design for Die Casting
1
THE DIE CASTING OPTION
When functional products are designed for volume production, the high-pressure die casting process is one of the prime production options considered by product engineers. Components can be cast at high speed from a range of durable metal alloys while faithfully capturing the most intricate design details. This ability to maintain close tolerances, often eliminating all machining, can make the process the optimum choice for lower volume production as well. The introduction of new, higher-performing die casting alloys and process technology makes old design assumptions about the limitations of the process obsolete; dimensional
specications, draft angles, as-cast atness, porosity reduction can be achieved to levels unheard of just a few years ago.
1.1 Die Casting’s Advantages: Summary This checklist summarizes the advantages of today’s die casting process from the perspective of the product designer seeking to maximize product performance and minimize product cost.
• • • • • • • • • • • • • •
Modern process technology that insures consistent quality Freedom to design intricate congurations Net-shape casting economies, even at lower volumes Wide variety of available alloys and alloy properties The rigidity, look and feel of metal Meets moderate to high-strength performance needs Moderate to high impact and dent resistance Documented fatigue strength characteristics Pressure tightness for hydraulic and pneumatic components Bearing properties that often eliminate separate bearings Excellent sound damping properties Inherent EMI shielding for electronic applications High-quality surface nish for decorative applications Meets criteria for serviceability and recyclability
1.2 Advances in Die Casting Process Technology The die casting process today has been well researched and systematically quantied in terms of thermodynamics, heat transfer and uid ow parameters. This technology has been transferred to the die casting industry, where its use has made a signicant improvement in the design of die casting dies, the die steel used in die construction, and in virtually all die casting production options.
Product Design for Die Casting
1
Chapter 1: The Die Casting Option
Die casting machines today are being tted with new, high-technology electronic systems that control production processes according to exact parameters and continuously monitor production output. Casting accuracy is greatly improved, variations from casting-to-casting are sharply reduced, and production costs are more closely controlled. Today advanced die casting systems are producing castings with extremely close tolerances and reduced draft angles (in some cases zero draft) on selected features,
eliminating nish machining operations. This casting precision has lowered the breakeven point for die casting versus low-volume production processes and increased its
economic advantages over high volume alternatives. The specic implications of these changes for the product designer are presented in this manual.
1.3 Developments in Die Casting Alloys A wide range of alloys are used for die casting today. A separate section will deal in detail with the four families that currently account for most of the functional and decorative die castings produced in the United States: aluminum, magnesium, zinc, and ZA (zinc-aluminum). Copper, tin and lead are being die cast for certain specialized applications. Ferrous die castings are also being produced on a very limited basis. Die casting alloys are precisely formulated to offer mechanical properties equivalent to medium-strength metals. They are generally several times as strong and many times more rigid than plastics, and the mechanical properties of the higher-strength die casting alloys compare favorably with powder iron, brass and low carbon steel. When compared with high-performance plastics or advanced composites, die casting alloys can often deliver the required product strength at a cost advantage. New die casting alloys have been introduced and have proven their capabilities in
full-scale production and eld use. The methods now being used to produce them have been modied to reduce impurities, improve overall metal quality, improve product reliability, and reduce energy consumption. Figure 1.1 Fog Light Housing This die cast aluminum 383 fog light housing eliminated a two piece plastic and aluminum casting assembly. The reective optics, pivot bosses and height adjustment features are included in one die cast part. The part is also leak proof and has thin weight reducing walls.
1.4 Die Casting’s Range of Product Capabilities Die castings are produced in a wide range of sizes and congurations, from precision components weighing less than one gram to a one-piece instrument panel for high performance automobiles. Integral housings for torque converters and automatic transmissions and intricate electronic components are typical of the size and complexity of die castings currently in production. 2
Product Design for Die Casting
Chapter 1: The Die Casting Option
Products from nearly every manufacturing industry make use of die castings:
• Agricultural Machinery • Automotive Vehicles • Building Hardware • Electrical and Electronic Equipment • Hand Tools • Home Appliances • Industrial Products
• Instrumentation • Lawn and Garden Equipment • Ofce Furniture • Ofce Machines • Recreational Equipment • Portable Power Tools
The following product capabilities highlight the qualities that can make die casting production the optimum product choice.
Product Design for Die Casting
