guide to machining carpenter specialty alloys guide to machining carpenter special ty all o ys

170 Pages·2005·6.8 MB·English

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GUIDE TO MACHINING CARPENTER SPECIALTY ALLOYS
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Carpenter Technology Corporation L
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Wyomissing, PA 19610 U.S.A. Y

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1-800-654-6543 L
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Visit us at www.cartech.com O
For on-line purchasing in the U.S., Y
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visit www.carpenterdirect.com
GUIDE TO MACHINING CARPENTER SPECIALTY ALLOYS
Carpenter Technology Corporation
Wyomissing, Pennsylvania 19610 U.S.A.
Copyright 2002 CRS Holdings, Inc.
All Rights Reserved. Printed in U.S.A.
9-02/7.5M
The information and data presented herein are suggested starting point values and are not a guarantee
of maximum or minimum values. Applications specifically suggested for material described herein
are made solely for the purpose of illustration to enable the reader to make his/her own evaluation
and are not intended as warranties, either express or implied, of fitness for these or other purposes.
There is no representation that the recipient of this literature will receive updated editions as they
become available. Unless otherwise noted, all registered trademarks are property of CRS Holdings,
Inc., a subsidiary of Carpenter Technology Corporation. ISO 9000 and QS-9000 Registered
Headquarters - Reading, PA
Guide to Machining
CARPENTER SPECIALTY ALLOYS
Contents
Introduction .............................................................................1
General Stainless Material and Machining Characteristics ....3
Classification of Stainless Steels ..............................................5
Basic Families and Designations ........................................5
Austenitic Alloys .........................................................5
Ferritic Alloys ...............................................................7
Martensitic Alloys ......................................................7
Duplex Alloys .............................................................8
Precipitation-Hardenable Alloys .................................8
Free-Machining Alloys ......................................................9
Project 70+® Stainless Enhanced-Machining Alloys ........12
Machinability of Stainless Steels ...........................................15
Definitions of Machinability ..............................................15
General Machining Properties ..........................................16
Austenitic Alloys ........................................................16
Ferritic and Martensitic Alloys ...................................18
Duplex Alloys .............................................................19
Precipitation-Hardenable Alloys .................................20
Relative Machinability of Stainless Steels
and Other Alloys ..................................................................22
The Carpenter Selectaloy® Method .........................................23
Criteria for Selecting .........................................................23
Selecting for Corrosion Resistance ...................................26
Selecting for Mechanical Strength ....................................26
Enhanced Selectaloy® Diagram ........................................27
Nitrogen Strengthened Grades .........................................27
Other Grades to Consider .................................................29
Guide to Machining
CARPENTER SPECIALTY ALLOYS
Traditional Machining Operations ..........................................31
General Considerations and Guidelines ............................31
Turning ... Speeds & Feeds—Turning can be found on pages 37 to 40
Turning Parameters ...........................................................35
Single-Point Turning Tools .................................................35
Cutoff Tools ......................................................................41
Form Tools ........................................................................41
Shaving Tools ....................................................................42
Trouble-Shooting Check Chart ..........................................43
Drilling ... Speeds & Feeds—Drilling can be found on pages 48 and 49
General Guidelines ............................................................45
Drilling Parameters ...........................................................46
Grinding of Drills ...............................................................46
Small-Diameter Drills ........................................................47
Special Drills .....................................................................49
Trouble-Shooting Check Chart ..........................................51
Tapping ... Speeds & Feeds—Tapping can be found on pages 57 and 58
Types of Holes and Taps ...................................................55
Percent of Thread .............................................................58
Grinding of Taps ................................................................60
Trouble-Shooting Check Chart ..........................................61
Threading ... Speeds & Feeds—Threading can be found on page 65 to 66
Die Threading ....................................................................63
Types of Chasers and Geometries ....................................63
Die-Threading Parameters and Cutting Fluid ....................65
Percent of Thread .............................................................66
Thread Rolling ...................................................................67
Trouble-Shooting Check Chart ..........................................68
Guide to Machining
CARPENTER SPECIALTY ALLOYS
Milling ... Speeds & Feeds - Milling can be found on pages 71 and 72
Types of Milling Cutters ....................................................69
Grinding of Milling Cutters ................................................70
Milling Parameters and Cutting Fluid ................................73
Trouble-Shooting Check Chart ..........................................74
Broaching ... Speeds & Feeds - Broaching can be found on pages 79 and 80
General Guidelines ............................................................77
Broach Design and Grinding .............................................77
Trouble-Shooting Check Chart ..........................................81
Reaming ... Speeds & Feeds - Reaming can be found on pages 85 and 86
General Guidelines ............................................................83
Types of Reamers .............................................................83
Grinding and Care of Reamers ..........................................84
Reaming Parameters ........................................................87
Alignment .........................................................................87
Trouble-Shooting Check Chart ..........................................88
Sawing ... Speeds & Feeds - Sawing can be found on page 90
General Guidelines ............................................................89
Sawing Parameters ...........................................................89
Grinding
Wheels ...........................................................................91
Grinding Parameters .......................................................91
Guide to Machining
CARPENTER SPECIALTY ALLOYS
Other Specialty Metals ... Speeds & Feeds—Other Carpenter Specialty
Alloys can be found on pages 93 to 112
These include:
• Carpenter Tool Steels
• Carpenter High Temperature Alloys
— Nickel-Base and Cobalt-Base
• Carpenter Electronic Alloys
Cutting Fluids ...............................................................page 113
• Stainless Steel Cutting Oils
• Emulsifiable Fluids
• General Practices
Cleaning and Passivating ...............................................page 119
• Cleaning Before Heat Treating
• Passivating
• Citric Acid Passivation
Nontraditional Machining Operations .............pages 123 to 136
• Abrasive Jet Machining
• Abrasive Water Jet Machining
• Electrochemical Machining
• Electrochemical Grinding
• Electrical Discharge Machining
• Electron Beam Machining
• Laser Beam Machining
• Plasma Arc Machining
• Chemical Machining
Guide to Machining
CARPENTER SPECIALTY ALLOYS
Helpful Tables ...................................................pages 137 to 167
• Automatic Machining Efficiency Index Table
• Machine Hours Per 1,000 Pieces
• Approximate Stock Required to Make 1,000 Pieces
• Weights of Steel Bars Per Lineal Foot
• Decimal Sizes of Drills & Length of Drill Points
• Drills for Tapped Holes
• Table of Cutting Speeds
• Fractions, Decimal & Metric Equivalents
• Hardness Conversion Table
• Wire Gauges
• Formulas
Introduction
Carpenter Technology Corporation (“Carpenter”) is a materials
company making specialty alloys and engineered parts for dozens
of industries with hundreds of applications. Specialty Alloys
Operations, our specialty steel and alloy manufacturer and
distributor, comprises the core business. Dynamet Incorporated,
a Carpenter company, produces bar and coil products from titanium
and other alloys. Carpenter Powder Products makes and sells tool
and high speed steels and specialty alloy powder products. The
Engineered Products Group is a consortium of companies that
makes precision drawn products, complex ceramic parts, thin-
wall tubing and other engineered materials.
Since 1928, when Carpenter introduced the world’s first free-
machining stainless steel, we have been concentrating on the
business of making stainless and other specialty alloys more
useful and more profitable to industry.
Our record of accomplishment in this endeavor has been gratifying.
Through never-ending research, exacting quality controls and rigid
production techniques, we have led the field in the introduction
of new and improved specialty alloys and services to help industry
improve product quality and reduce fabricating costs.
The Carpenter list of "firsts" is impressive. It includes the first
free-machining stainless, Type 416 . . . the first free-machining
chrome-nickel stainless, Type 303 . . . the first free-machining Invar,
Free-Cut Invar "36"® alloy . . . and this evidence of leadership
continues with the widespread acceptance of the Project 70®
stainless and Project 7000® stainless grades and now
Project 70+® stainless.
Through these constant efforts to improve specialty alloy quality,
we have built every known production and performance advantage
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into every machining bar we produce. But no specialty steel can
be so good that it will perform satisfactorily in the shop when it
s mishandled or misunderstood.
The purpose of this book is to help you, the fabricator, get
every benefit out of the Carpenter specialty alloys you machine.
The machining tables are intended to provide you with suggested
starting feeds and speeds. Machine setup, tooling and other fac-
tors beyond Carpenter’s control will affect actual performance.
A section on machining Carpenter tool steels, high temperature
alloys, and electronic alloys is also included. These are tabbed
together under "Other Specialty Metals."
If the answer to your particular machining problem cannot be
found here, we hope you will call us at 1-800-654-6543 for help.
Or, refer to our online technical information database at
www.cartech.com. Registration is free.
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General Stainless Material and Machining
Characteristics
Stainless steels do not constitute a single, well-defined material;
but, instead, consist of several families of alloys, each generally
having its own characteristic microstructure, type of alloying and
range of properties. To complicate the matter, further compositional
differences within each family produce an often bewildering variety
of alloys suited to a wide range of applications. The common thread
among the alloys is the presence of a minimum of about 11 percent
chromium to provide the excellent corrosion and oxidation resistance
which is the chief characteristic of the materials.
Because of the wide variety of stainless steels available, a
simple characterization of their machinability can be somewhat
misleading. As shown in later sections of this booklet, the machin-
ability of stainless steels varies from low to very high, depending
on the final choice of alloy. In general, however, stainless steels are
considered more difficult to machine than certain other materials,
such as aluminum or low-carbon steels. Stainless steels have been
characterized as “gummy” during cutting, showing a tendency to
produce long, stringy chips, which seize or form a built-up edge
(BUE) on the tool. Machine operators may cite reduced tool life
and degraded surface finish as consequences. These broad observa-
tions are due to the following properties, which are possessed by
stainless steels to different extents:
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