SORELMETAL®

Eighth Edition

2

A DESIGN ENGINEER’S DIGEST OF

DUCTILE IRON

INTRODUCTION

During recent years, producers and users of Ductile Iron castings haveobserved that many potential users of Ductile Iron castings are not aware ofthe wide range of properties offered by the family of Ductile Iron alloys.

Since their commercial introduction in 1948, Ductile Iron castings haveproven to be a cost effective alternative to malleable iron castings, steel cast-ings, forgings, and fabrications. This is for a multitude of reasons, some ofwhich are explained in the following pages.

Ductile Iron castings are found in every field of engineering and in everygeographic area of the world. Ductile Iron is known under different names,such as S.G. Iron or Nodular Iron. This booklet uses the term Ductile Iron,which is the most commonly referred to name in North America.

Throughout this booklet are many examples of Ductile Iron castings. Agood portion of these castings have been converted to Ductile Iron from othermaterials and manufacturing processes.

After reading the information contained in this booklet, it is hoped thedesign engineer will be sufficiently informed and encouraged to take advan-tage of the performance potential of Ductile Iron as a cost effective engineer-ing material. Ask your Ductile Iron foundry for more information and assistance.

3

PRECISION INSTRUMENTCONNECTING FRAME

Courtesy: IBM, W. Germany

4

CONTENTS

DUCTILE IRONS – WHEN AND WHY....................5

FIRST A WORD ABOUT STEEL AND IRON ......7-8

THE FAMILY OF DUCTILE IRONS ........................9

DUCTILE IRON – MORE STRENGTHFOR LESS EXPENSE ......................................14

THE DUCTILE IRON FOUNDRY ..........................36

INSPECTION ........................................................37

EXAMPLES OF DUCTILE IRON –THE DESIGNER’S CHOICE ............................38

PRINCIPLES

UTILIZE THE FREEDOM OFFERED BYTHE CASTING PROCESS................................22

UNDERSTAND THE FUNDAMENTALS OFTHE CASTING PROCESS................................24

DESIGN FOR OPTIMUM ECONOMY ..................26

DESIGN FOR CASTING SOUNDNESS ..............27

SPECIFY NO MORE DIMENSIONALACCURACY THAN NEEDED............................28

THE EFFECT OF SECTION SIZEON MECHANICAL PROPERTIES ....................29

DESIGN WITH ADEQUATE SAFETY ..................31

TRUST THE FOUNDRY........................................33

COMMUNICATE WITH THE FOUNDRY ..............34

5

DUCTILE IRONS – WHEN AND WHY

THE PLACE of Ductile Iron among engineeringmaterials is as difficult to define precisely as it is forexample for wood, plastic or aluminum. No materialscan be better than all the others. Nevertheless, thou-sands of examples prove, that Ductile Iron castingscan replace other materials and manufacturingprocesses with either an improvement in perfor-mance or lower production cost, or both.

THE DESIGNER is advised to become acquaintedwith this family of cast alloys, with the production ofcastings and with general foundry operations. Forinstance, while not all foundries produce Ductile Irongrades, virtually all castings or cast shapes can bemade from an appropriate grade of Ductile Iron.Ductile Iron will always have ductility. It is at least asstrong as cast mild steel, but can be specified atmuch higher yield strength. Material selectiondepends not necessarily on strength. Within the lim-its of the space available, this booklet attempts toacquaint you with a variety of Ductile Iron properties.

THE FINAL CHOICE may or may not be DuctileIron. The purpose of this booklet is to point out theunique combination of properties available with thismaterial thereby helping the designer make a safeand economical choice. This choice is made mucheasier due to the existence of many foundries, capa-ble of producing Ductile Irons of reliable quality.

BEST WORST

Characteristic

Castability

Ease of MachiningVibration DampingSurface HardenabilityModulus of ElasticityImpact ResistanceCorrosion ResistanceStrength/ WeightWear ResistanceCost of Manufacture

Ductile Iron

Malleable Iron

Grey Iron

0.3%C Cast Steel

White Iron

NA

NA

NA

NA

NA

RADIAL TIRE MOULD.Courtesy: Morris Bean & Co., YellowSprings, Ohio, U.S.A.

6

Dropping a 2-ton weight from a height of 9 meterscaused a slight dent in this Ductile Iron pipe but did notreduce its serviceability.

THE EXAMPLES in this digest highlight the freedomDuctile Iron offers to the designer, while providinginternal integrity. The five-stage turbo-compressorhousing shown above must be pressure tight at veryhigh testing pressures. This was accomplished, eventhough the shape of the housing is exceptionallycomplex.

Courtesy: Cast Iron Pipe Research Association, USA

HOUSINGCourtesy: Vulcan Iron Works, USA

7

FIRST A WORD...

PURE, carbon-free iron is practically never usedas a cast metal because it is soft and weak. As car-bon content increases, so does hardness andstrength. The beneficial effect of carbon, althoughcreating production problems, is advantageous toabout 0.9% carbon. These alloys are calledSTEELS. Additional problems are encountered withcarbon contents to about 2.0%, and these “semi-steels” are seldom used. WHITE IRONS, containing2 to about 3.3% carbon, can be used for highly abra-sive service, but the application is limited due to thebrittle nature of the alloy. It is a true cast iron, butmost of the contained carbon is present as iron car-bide Fe3C, a hard and brittle compound.

The carbon contents of white and MALLEABLEirons overlap. Indeed, malleable iron must solidify aswhite iron. (Hence, its production is limited to rela-tively thin castings.) A lengthy heat treatment of thewhite iron castings decomposes the Fe3C into ironand nodules of graphite. In this condition, malleableiron exhibits strength/elongation combinations from40,000 p.s.i. (280 mPa) with 18% elongation to116,000 p.s.i. (800 mPa) with about 2% elongation.

�

�

����5.0

4.0

3.0

2.0

1.0

00 1.0 2.0 3.0 4.0

Silicon Content (%)

Carb

on C

onte

nt (%

)

%C + 1/3% Si = 4.3Ductile Irons

Steels

Malleable IronsWhite Irons

Gray Irons

%C + 1/6% Si = 2.0

Ductile Iron X50

Gray Iron X50 White Iron X50

8

...ABOUT STEEL AND IRON

In gray and Ductile Irons, carbon in excess of itssolubility in solid iron is present as finely dispersedgraphite shapes, rather than as Fe3C (cementite,iron carbide). In GRAY CAST IRONS the graphiteflakes act as stress raisers and under stress helpcrack propagation (See illustration A). As a result,gray cast irons are weak, with ultimate tensilestrength is the order of 20,000 to 58,000 p.s.i. (150to 400 mPa) and with practically no elongation. Thesize of graphite flakes varies with production condi-tions and, also, with casting thickness. Normallyflake lengths are from 0.1 to 1.0 mm.

CAST IRON WITH SPHEROIDAL GRAPHITE(i.e. Ductile Iron) became an industrial reality in1948. A suitable treatment of the molten iron causesthe graphite to precipitate as spheroids, rather thanflakes. The nearly spherical shape of the graphiteremoves the “crack” effect and, in fact, the graphitespheroids act as “crack-arresters”, as shown impres-sively on the page (See illustration B).

A

B

9

THE FAMILY OF DUCTILE IRONS

The majority of Ductile Iron castings are producedin one of the following three types, all of which can beproduced in the as-cast condition without the needfor heat treatment.

• FERRITIC DUCTILE IRON (60-40-18)

Graphite spheroids in a matrix of ferrite which isbasically pure iron. High impact resistance.Relatively good thermal conductivity. High magneticpermeability. Low hysteresis loss. In some expo-sures, good corrosion resistance. Good machinability.

• PEARLITIC-FERRITIC DUCTILE IRON (80-55-06)

Graphite spheroids in a mixed matrix of ferrite andpearlite. This is the most common grade of DuctileIron. Properties are between those with “fully ferritic”or “fully pearlitic” structures. Good machinability.Usually the least expensive Ductile Iron.

• PEARLITIC DUCTILE IRON (100-70-03)

Graphite spheroids in a matrix of pearlite. Pearliteis a fine aggregate of ferrite and cementite (Fe3C).Relatively hard. Moderate ductility. High strength.Good wear resistance. Moderate impact resistance.Somewhat reduced thermal conductivity. Low mag-netic permeability. High hysteresis loss. Goodmachinability.

*Approximate ultimate tensile strength 87,000 p.s.i. (600 mPa) Hard, Brittle (Note that magnifications are different.)

MATRIX

Ferritic- MartensiticFerritic pearlitic Pearlitic (With retained Tempered ADI ADI Austenitic

Grade 60-40-18 Grade 80-55-06 Grade 100-70-03 austenite) Martensitic Grade 150-100-70 Grade 230-185-

60,000 p.s.i. 80,000 p.s.i. 100,000 p.s.i. N.A. * 115,000 p.s.i. 150,000 p.s.i. 230,000 p.s.i. 45,000 p.s.i.(414 mPa) (552 mPa) (690 mPa) (793 mPa) (1050 mPa) (1600 mPa) (310 mPa)

10

Occasionally, the designer will encounter specialsituations, and consider the special grades of theDuctile Iron alloys.

• MARTENSITIC DUCTILE IRON (Q&T)

In the “as-cast” condition the alloy is hard and brit-tle, and seldom used. However, TEMPEREDMARTENSITE has very high strength and wearresistance. A 930°F (500°C) tempering results in 300HB, a 1110°F (600°C) tempering in 250 HB hardness.

• AUSTENITIC DUCTILE IRON

They are never chosen for strength alone. Theoutstanding features are good corrosion and oxida-tion resistance, magnetic properties, strength anddimensional stability at elevated temperatures. (Alsoknown as Ductile Ni-Resist).

• AUSTEMPERED DUCTILE IRON (ADI)

This is the most recent addition to the Ductile Ironfamily and represents a new group of Ductile Ironsoffering the design engineer a remarkable combina-tion of strength, toughness and wear resistance.

ADI is almost twice as strong as the regular ASTMgrades of Ductile Iron whilst still retaining high elon-gation and toughness characteristics. In addition,ADI offers exceptional wear resistance and fatiguestrength, thus enabling designers to reduce compo-nent weight and costs for equivalent or improved per-formance.

Crop Box from Steel WeldmentBlack Clawson Foundry, Watertown, NY

200

160

120

80

40

0

1380

1100�

830�

550�

275�

ASTM grades Ductile Iron

Q&T Ductile Iron

Austempered Ductile Iron

5 10 15 20

Gray Iron

Elongation (%)

Tens

ile st

reng

th (1

03 psi)

Tens

ile st

reng

th M

Pa

Note: The orange sheet in the back of this book gives moreinformation on specifications and properties.

11

The remarkable properties of ADI are developedby a closely controlled heat treatment operation(austempering) which develops a unique matrixstructure of bainitic ferrite (60%) and retained (highcarbon) austenite.

The retained (H.C.) austenite is thermally stable toextremely low temperatures but is work hardenableand will locally transform to martensite under suitableconditions of stress. Advantage of this feature of ADIis taken by allowing the service loading stresses towork harden the load bearing services. Alternatively,surface stresses can be deliberately imposed prior toservice, e.g. by shot peening of gears or fillet rollingof crankshafts in order to achieve significantimprovements in wear resistance and fatigue life.

Presently there are no accepted standard specifi-cations for ADI, but proposals for five grades of ADIhave been made which form the basis for discussionand material selection between designers andfoundrymen.

Current ASTM A897ADA Specifications

Tensile Yield Percent Charpy BHN HardnessStrength Strength Elongation (unnotched) Range*

(KSI) (MPa) (KSI) (MPa) (ft. lb.) (J)125 0850 080 0550 10 75 100 269 - 321150 1050 100 0700 07 60 080 302 - 363175 1200 125 0850 04 45 060 341 - 444200 1400 155 1100 01 25 035 388 - 477230 1600 185 1300 0- - 0- 444 - 555

*not part of specification

The heat treatment necessary to produce ADI isessentially a two-stage operation:

Stage 1

Austenitizing in the range 1500-1700°F (815-920°C). The specific austenitizing temperatureselected is related to the subsequent austemperingtemperature and the grade of ADI required. Onceselected, the austenitizing temperature must beclosely controlled (±10°F).

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8

Typical Austenitizing & Austempering Cycles

Temp

erat

ure (

°F)

Time (h)

1,700°F (930°C)

1,500°F (815°C)

Grade 125 ADI

Grade 200 ADI

750°F (400°C) (250-320 Bhn)

450°F (230°C) 21/2 h max (400-500 Bhn)

Courtesy: General Motors Corp., Central Foundry Division,Saginaw, Michigan, USA

Austempered Ductile Iron Hypoid Axle Gears:Conversion to Cast Ductile Iron from Forged Steel gavemajor production cost saving, better machinability, quieteroperation, reduced weight.

ADI Timing Gears for Cummins B-Series dieselengines. Replaced forged and case carburised 1022 steelwith 30% cost saving.

12

Stage 2

Rapid transfer of the castings to the austemperingfurnace (usually a salt bath) where the castings areheld isothermally at the selected austempering tem-perature. Austempering temperatures are in therange 450-750°F (230-400°C) according to the prop-erties required in the castings (ADI grade). Closecontrol over temperature and time of austempering isessential.

ADI is well established as a gear material replac-ing forged steel with major production cost savings,quieter operation and reduced weight. By machiningthe gears before the austempering heat treatment,major savings in machining costs are achieved.

Austempering Temperature °F450 500 550 600 650 700

220 260 300 340 380

12

8

4

0

1600

1400

1200

1000

900°C (1650°F) Austenitizing250

200

150

Austempering Temperature °C

Elong

ation

%

Tens

ile St

reng

th, M

Pa

Tens

ile St

reng

th, k

si

13

Courtesy: Hogfors Industries Ltd., Finland

Austempered Ductile Iron gears to patented specifica-tions K9805.

Other examples of the use of ADI castings includetruck spring supports, railroad axle-box spring adap-tors, crankshafts, connecting rods, agriculturalplough shares, etc.

ADI Crankshaft for Ford turbo-charged engine–ADIcapable of meeting fatigue strength requirements at muchlower cost than forged steel.

Success in consistently achieving the optimumproperties and performance of ADI requires highquality, careful selection and control over the baseDuctile Iron, and heat treatment parameters. Thisnecessitates material of high nodule count which isfree from carbides, inclusions and shrinkage and of acomposition which minimizes the dangers of alloysegregation.

This brief summary about the DUCTILE IRONFAMILY is based on metallurgy, rather than on stan-dard specifications. A chart showing the properties ofmost of the Ductile Iron grades is enclosed on theinside back cover of this publication. All propertiesare primarily determined by chemical composition,cooling (solidification and solid cooling rate) andmatrix structure.

14

DUCTILE IRON–“MORE STRENGTH FORLESS EXPENSE”

Ductile Iron appears to have been invented (1948)with the designer in mind. The tensile strength, proofstress, and elongation combinations obtainable inDuctile Iron exceed those for ANY OTHER cast fer-rous alloy, including steel and malleable iron.

Since its introduction, the growth of Ductile Ironapplications has exceeded all expectations. World-wide production is approximately 12 million tons andis expected to reach 20 million tons by the turn of thecentury. The application of Ductile Iron is a notableengineering achievement of our age.

DISK BREAK CALIPER

Whether in an automobile component, as shownabove, a water pipe, plow, or a “robbery-proof” park-ing meter box, Ductile Iron has made major inroadsto the casting market in every industrially developedcountry. There can be little doubt, that the major moti-vating factor for this was “MORE STRENGTH FORLESS EXPENSE” compared to just about every othercast alloy. The lesser expense comes not only fromthe readily available raw materials and the efficienciesof the foundry operation, but also from reduced clean-ing and machining costs of Ductile Iron castings.

The following pages present a variety of DuctileIron case histories from around the world. Manymore examples could have been added. The DuctileIron alloys are versatile and appear to find unlimitedapplications.

WORLD PRODUCTION OF

DUCTILE IRON (Including Pipe)

1950 1960 1970 1980 1990 2000

3-5% Growth

20

16

12

8

4

0

MILL

ION

TONN

ES

15

The original design of the 1,000 H.P. pump framewas a steel fabrication. Converting to Ductile Ironachieved more uniform stress distribution, lower pro-duction cost and improved strength-to-weight ratio.The weight was reduced by 46 percent, which is par-ticularly important for remote installations where theparts must be airlifted.

Courtesy: Gardner Denver Co., USA

A camshaft thrust plate is exposed to severe abrasive wear. The reason for selecting Ductile Ironwas to combine wear resistance with machinability.

For break-in, this casting is phosphate-coated.

Courtesy: Fichtel & Sachs, Germany

Ductile Iron can readily by surface hardened to 55Rc, which provides for the superior performance ofthis catch-sleeve.

Courtesy: Dana Corp., USA

16

In the design of bearing housings, compressivestrength is an important factor. Ductile Iron, as shownin the photographs, compares favorably with steel.Additional advantages are better machinability andvibration damping.

Courtesy: S.K.F., Katrineholm, Sweden

Courtesy: Metallgesellschaft, A.G. Germany

The scaffold fittings shown above, with 2 to 5 mmwall thickness, illustrate the excellent castability ofDuctile Iron.

Courtesy: Ausherman Manufacturing Co., Inc., USA

This 5-1/2 lbs. (2-1/2 kg.) idler chain sprocket isfrom a large jack used for straightening automobileand truck frames. Designed by Kansas Jack, Inc.,McPherson, Kansas, USA and cast by AushermanManufacturing Co., Inc., this part is made of DuctileIron to USA specifications ASTM A 536 - 65-45-12 andis used in the as-cast condition.

Kansas Jack’s on-the-shelf cost, ready to use inassembly is 63% less for the Ductile Iron casting,than it was for the weldment.

Courtesy: C.A. Parsons & Co., Ltd., England

The seating ring is part of an advanced designmarine sterngear unit. Beside the need for highstrength, good corrosion resistance in a saline envi-ronment is required. The choice: austenitic DuctileIron to British Standard BS3468-AUS 202A.

17

Pistons for low speed, high pressure compressorswere originally one-piece gray iron castings with 19mm walls. As speeds increased, the need for a high-er strength, lighter weight piston was achieved bycasting the pistons in Ductile Iron and reducing wallthicknesses to 5-6 mm.

Courtesy: Gardner Denver Co., USA

Also, a design change to a two-piece weldedassembly simplified casting procedures and permit-ted further weight reduction. This saving in weightreduced inertia of the piston.

The mating surfaces and weld bevels of the pistonhalves are machined, then bolted together on anarbor and furnace heated to 1,050°F (565°C). Thepreheated assembly is welded using a shieldedmetal arc with nickel-iron electrodes (ENiFeC1). Theweld is made in three passes and the assembly heattreated to the specified 201-260 BHN.

18

Courtesy: The H.P. Deuscher Co., USA

This frame, for a 4,000 volt primary “lighting”arrester and overload switch gear, was originally castin steel. Inadequate strength often resulted inwarpage, which caused the failure of the wholeassembly.

Switching to medium-strength Ductile Iron provid-ed adequate strength and impact loading resistance.The part cost was also reduced.

Courtesy: Dorr Oliver Long, Ltd., Canada

Axle trucks for mine cars. By switching from caststeel to Ductile Iron, dimensional stability in serviceincreased. The main cost saving occurred as a resultof reducing machining.

The bracket shown below must have precisedimensions and carry heavy loads. The alternativematerial–cast steel–would be more expensivebecause of alloying, machining, and heat treatmentcosts. Ductile Iron is also superior in its dimensionalaccuracy. The casting is used in the as cast condition.

Courtesy: Sulzer Bros., Ltd., Winterthur, Switzerland

Before fabricated(assembly)

After one piece D.I. casting

Courtesy: Ferrovorm, Republic of South Africa

Mounting bracket on a mold board plow producedby Fedmech Holdings Limited. The reason forswitching to a grade 72,500 p.s.i. (500 mPa) DuctileIron casting was the many field failures of the heavi-ly welded steel part. Repeated attempts to improvethe fabricated design resulted in too many compo-nents which led to warping and dimensional accura-cy problems during welding. There was also a highreject level during fabrication of the part.

Since switching to a Ductile Iron casting therehave been no field failures.

19

AUTOMOBILES USE MANY DUCTILE IRONCASTINGS. While this booklet is too short todescribe all the reasons for the material selection,the major ones are castability, ease of machining,reliability in service, vibration damping, surface hard-enability, wide range of strength to choose from, etc.

In addition, since the modules of elasticity ofDuctile Iron is somewhat lower than that of steel, thestresses due to unavoidable misalignment are lower.Crankshafts are a good example of the utilization ofthis property.

20

SOME OF THE DUCTILE IRON CASTINGS USED IN A JAPANESE AUTOMOBILE.Courtesy: Toyota Motors Corporation, Japan

Courtesy: Von Roll, A.G., Klus, Switzerland

Housings for hydraulic control devices used mainlyon heavy machine tools. These housings, machinedfrom grade DIN 1693; GGG 60 (German Standard),(continuously cast Ductile Iron) must withstand up to500 atmospheres (7,000 psi) internal pressure.

The nuts machined from a Ductile Iron sleevecasting cost more than nuts machined from steel barstock. Still, the choice was Ductile Iron. The reason:the presence of face graphite in the Ductile Ironstructure provides for a unique self-lubricating feature in service.

Courtesy: Metalgesellschaft, A.G. Germany

21

THE PRINCIPLES OF DUCTILE IRONCASTING DESIGN

Casting design will be discussed insofar as DuctileIron is concerned. Presenting general rules wouldreach beyond the scope of this work. There are refer-ence books available that deal with Casting Design.

Familiarizing oneself with the advantages ofdesigning with Ductile Iron helps not only to achieveengineering elegance (uniform stress-flow, optimumeconomy) but also helps the designer to decidewhen the use of Ductile Iron is preferable to an alter-native material. In this regard, then, design charac-teristics may be considered to be one of the techno-logical properties of this material.

Principle No. 1–

Utilize the Freedom Offered by the CastingProcess.

The purpose of design is to achieve functional per-formance of a part at minimum cost in materials andmanufacture. An individual design is usually a com-promise between an engineering concept to satisfyspecific service requirements and a form suitable forhigh quality, low cost production.

Casting as opposed to stamping, forging or weld-ing, is the most universally practicable method ofmetal forming and offers great freedom in creatingthe shape of the part to be designed. Complexcurves and ribs or bosses may be combined with littleprocess restriction. The ability, for instance to castpump and turbine casing involutes to their desiredshape eliminates an almost impossible machiningoperation. The combination of two or more compo-nents into a single casting can dramatically reducecost and improve performance.

Courtesy: TMF, Republic of South Africa

Ductile Iron tram wheels for underground mining opera-tions, shown “as-shaken-out”. Machining time wasreduced to 1/8 that of the previous material, cast steel,while safety in service increased.

22

In spite of design freedom, difficulties are some-times encountered when transforming the engineer-ing concept into a useful casting especially when thepart was originally designed as a forging, stampingor fabrication.

Since the designer is concerned with a wide rangeof products, he is seldom wholly conversant with thecasting process and so the part is designed withoutregard for a multitude of foundry variables. This is notto suggest the designer should obtain a comprehen-sive understanding of the casting process but ratherthat he should understand the fundamentals andrefer additional queries to the founder who is a spe-cialist in the casting process.

Ideally, the designer and founder should establishclose contact during the preliminary stages of castingdesign so that the founder has an opportunity to usehis detailed knowledge of the foundry industry and ofhis own products, for mutual benefit. In this way,comments on draft designs and pattern constructionto suit specific foundry requirements, can be madewith the least inconvenience. Consequently, major(late) changes in shape, dimensional tolerances andmaterial specification may never arise. All these fac-tors will probably be reflected in lower casting pricessince the price of a casting is not simply a function ofits weight but rather of the complexity of its shapeand how this affects the cost of patterns, cores,molds, cleaning and casting yield.

The process of deciding to design and producecastings may be summarized as follows:

Preliminary

decision to use a castingdetailed designinquiry, quotation, order

Production

pattern manufacturesample/prototype casting productionbulk casting production

Very often only superficial contact is establishedbetween designer and founder until sample or proto-type castings are produced. Occasionally, significantchanges are requested at this stage by the designer,or the founder. The designer may have the impres-sion he did not quite receive what he ordered and thefounder may realize that a few relatively minorchanges to the casting shape may make the castingmuch simpler and therefore cheaper to produce with-out affecting performance of the casting. For whatev-er reason, changes at this stage may mean lengthy,costly delays.

It is therefore essential to involve the founder fromthe beginning in the technical aspects of detaileddesign and minimize the occurrence of costly delaysduring the production stages.

23

Principle No. 2–

Understanding the Fundamentals of the Casting Process

Most modifications to the “ideal” casting shape,aimed at optimum production economy, arise fromthe understanding of the casting process. Thisrequired knowledge may be summarized as follows:

The first step in the casting process is to producethe pattern, a nearly exact reproduction of the wholecasting, usually in wood or metal. The pattern is thensectioned (a) usually in one or more parallel planes.The sections, one after the other, are placed intomolding boxes or flasks and the box is tightly filledwith bonded, firm sand (b) (c). The pattern creates acavity after withdrawal (d). This cavity will be filledlater with liquid iron to form the casting.

Cavities in the mold other than that of the castingcavity are needed for two purposes; 1, to deliver theliquid iron from the top of the assembled mold to thecasting cavity, 2, to replace the volume lost due tothe shrinkage of the liquid iron from the pouring tem-perature to the freezing temperature. The first set ofcavities or channels is called the gating system whilethe “feeding” cavities are called risers. As a rule, boththe gating system and the risers are integral parts ofthe pattern.

The liquid iron first passes through the gating system, then, through one or more openings (gates)into the mold cavity, and finally, the entire mold cavi-ty including the risers fills with liquid iron. While pass-ing through all the channels and filling the mold, thetemperature of the liquid iron decreases. The thinnerthe casting walls, the greater the temperature loss.This increases markedly the danger of defects due toimproper fusion.

24

������������ ������������

�����

���������

a b c d

Internal cavities in the casting must be producedby placing properly shaped inserts, called cores,usually made from bonded sand, into the mold cavi-ty. The core materials must be subsequentlyremoved and, therefore, the internal cavity mustcommunicate with the outside of the casting. Thecore also must be well-supported and anchored bythe mold to avoid flotation or deformation duringmold filling due to the difference between the densi-ty of the core and that of the liquid iron. One anchorpoint is the theoretical minimum. Normally at leasttwo anchor points (core prints) are required.

Cores are also required when, due to configura-tion, the pattern cannot be withdrawn from the mold.Such cores can be readily made, but they add con-siderably to the cost of production. For this reason,the designer should be aware that undercuts preventpattern withdrawal. Small cores exhibit relatively lowstrength especially at the temperature of liquid iron.For this reason, if holes of small cross section arerequired in the casting, it may be less expensive tomachine the holes than to form them by the use ofsmall (weak) cores. Channels of small cross sectionmay be cast integrally by placing appropriatelyshaped steel tubing in the mold cavity in a core-likefashion. A portion of the steel tubing wall will fusewith the liquid Ductile Iron.

The volume changes that occur during the coolingand solidification of Ductile Iron are unlike those inany other alloy. The volume of the liquid decreases

with decreasing temperature until slightly above thesolidification temperature. Upon further cooling, thecontraction stops and a definite volumetric expansionstarts. Unfortunately, the expansion phase prevailsthrough only part, but not all of the solidificationprocess. The expansion gives way to another contrac-tion phase, “secondary shrinkage”, which continuesuntil all of the liquid is transformed to solid.

It is the craft of the foundryman to use the above-described pattern of volume changes to obtain soundcastings. The temperature of the liquid iron should behigh enough to provide for complete fusion of theseparate streams and to avoid the entrapment ofsmall gas bubbles. Each section thickness has itsoptimum pouring temperature range within whichperfectly sound castings can be made. Ductile Ironcastings with 3 mm thick walls may need to bepoured as hot as 2,640°F (1,450°C), while 100 mmthick castings can be poured at between 2,300-2,400°F (1,260-1,320°C). Difficulties may arise whenlarge differences in section thickness exist in onecasting. Such castings can be made sound, with considerable extra effort. The foundry will be pleasedto explain.

It is in the best interest of both casting producerand user to design with as little difference in wallthicknesses as possible. It may be more economicalto mechanically assemble two or more castings thanto produce a one-piece casting with widely varyingsection thicknesses.

25

Principle No. 3–

Design for Optimum Economy

The price of a casting quoted by the foundry is relatively unimportant both to the ultimate user and tothe designer. Instead, the contribution of the castingcost to the total cost should be considered. Thisincorporates items such as machining, shippingcosts, ease of repair, service life, and others.

Every step in the manufacturing process affectstotal production economy and each of these is influ-enced by the designer. A complete review here is nei-ther necessary nor possible. Instead, four major factorsinfluencing economy will be discussed. One additionalfactor, dimensional tolerance, will be discussed later.

Factor #1 Strength required

The grade of Ductile Iron selected will have a con-siderable effect on economy. With reference to theclassification on the insert, grade 65-45-12 is theleast expensive especially if machining costs are ofsome consideration. Grade 80-55-06 costs approxi-mately the same to cast but is somewhat less easyto machine. Grade 100-70-03 is still relatively inex-pensive and should be selected where its highstrength and good wear resistance are utilized.Grades 60-40-18 and 120-90-02 are the most expen-sive to cast, but either may be the most economicalchoice if the particular material characteristics are of value in service. The evaluation of the very expensive austenitic grades of Ductile Iron must be

considered individually on the basis of their excellentcorrosion, erosion and oxidation resistance, perfor-mance at elevated temperatures, magnetic proper-ties, low thermal expansivity and other unique features.

Factor #2 Machining cost

Machining costs are frequently of major importance from the point of view of economy.Strength, weight, service life, and other considera-tions may be overruled on occasion to minimizemachining cost. The grades easiest to machine are 3 and 4, followed by 5, then 2. Grade 1 is the leastmachinable although its machinability is superior tosteels with the same hardness. The machinability ofaustenitic Ductile Irons is generally superior to that ofstainless steels.

Factor #3 Cooling rate

It will be shown how cooling rate (section thick-ness) affects the properties of Ductile Iron. Rapidcooling promotes a hard and brittle structure which isdifficult-to-machine. In terms of wall thickness, 6 mmor heavier sections are relatively easy to producewithout any embrittlement or unduly high hardness.Thinner walls are increasingly more difficult to pro-duce without such deterioration in the as-cast condi-tion. The brittleness and high hardness can be elim-inated through heat treatment, but such treatment isexpensive and also results in distortion to variousdegrees. Whenever practical, cast wall thicknessshould be at least 6 mm to facilitate as-cast delivery.Heat treatment increases casting cost by 10 to 30%.

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Factor #4 Design Simplicity

It is well known that the simplest design is the bestdesign. It is also the most economical. A healthycompromise between contour simplicity and uniformstress distribution usually requires less expensivepattern equipment and few or no cores. The con-struction and maintenance of pattern and core boxesand core-making itself all contribute to product cost.Again, talk to the foundry.

The effect of large differences in section size oncasting soundness was briefly discussed earlier.Heavy bosses or walls adjoining thin sections requirespecial treatment on the part of the foundry (risers,chills). This means additional cost and is detrimentalto casting yield. The impact of casting yield onfoundry production economy is the most important ofall variables including the material selected and heattreatment. The freezing pattern and feeding require-ments are also influenced by the geometry of thedesign. More on this later.

SCAFFOLD FITTING

One advantage of usingcastings is the clear marking ofnames, direction of rotation,etc. Even the date, or heat, orproduction hour can be easilymarked on the surface.

Courtesy: Metallgesellschaft, A.G. Germany

Principle No. 4–

Design for Casting Soundness

Thanks to the volumetric expansion which occursduring part of the solidification process, a sound,pressure tight casting is easier to produce fromDuctile Iron than from any other metal or alloy exceptordinary gray cast iron. Still, feeding requirements varywith casting shape and size–variables under the controlof the designer. Unlike steel, brass and most otheralloys, the designer and foundry processes forDuctile Iron should aim at simultaneous solidificationof the whole casting. This requirement is opposite to thedesire for directional solidification which applies to steel.

Design aimed at simultaneous solidification mini-mizes and sometimes eliminates the need for riserswith corresponding improvement of casting yield.Conversely, parts of a Ductile Iron casting which coolmuch slower than the rest may become defectiveunless the foundryman provides extra (and expen-sive) feeding. Some examples of such isolated “hotspots” are as follows:

Cast-on heavy bossesCast-on heavy test couponsSharp internal cornersJoints between equally thick wallsMultiple joints (2 is better than 3, 3 is better than

4, etc.)Joints at acute angles (90° is best)Isolated heavy sections.

Which could be lightened without reducing loadcarrying capacity.

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Courtesy: Hitachi Ltd., Katsura, Japan

Automobile clutch pressure plate. High strength, relia-bility, and ease of machining led to the section of DuctileIron for the part shown. It is exposed to heavy alternatingloads.

One simple qualitative method for evaluating thedegree of success toward a uniform solidificationpattern is to inscribe circles into selected sections ofthe design. If the diameters of the circles are all thesame, as they would be in a straight wall, optimumconditions prevail. Sudden increases in the circlesize (to twice or more of the diameter in an adjoiningsection) require special attention by the foundry.

Principle No. 5–

Specify No More Dimensional Accuracy thanNeeded

Due to the nature of the casting process, thedimensional accuracy of raw castings is more difficultto control than, for example, machining to size.

Principal dimensional inaccuracies in Ductile Ironarise from the following sources:

a. Inherent inaccuracies in the machined dimensionsof the pattern and core box.

b. Deformation of core(s) in liquid iron.c. Inaccuracies due to the presence of parting line(s).d. Relief of cast-in stresses, if and when castings are

heat treated.

With the exception of source a. the inaccuraciesare dependent on the physical size of the casting.The larger the casting the more inaccuracy expect-ed. Dimensional inaccuracies from mold deformationduring pattern withdrawal are minimized throughproper tapering of the pattern (draft). A minimumdraft of 1:100 suffices only for very shallow patterns.Deep patterns may need to be drafted as much as5:100 for maximum accuracy.

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The following is presented as an approximateguide to the dimensional accuracies to be expectedin Ductile Iron castings.

Approximate Dimensional Tolerances on DuctileIron Castings in Green Sand

Specified Dimension Tolerance ±in Millimeters in Millimeters

0- 25 1.025- 125 2.0

125- 250 2.5250- 500 4.0500-1,000 6.0

1,000-2,500 8.0

Additional points to be considered:a. The values given refer to 80-to-90 mold hardness

range (green sand). Softer molds yield lowerdimensional accuracy.

b. Accuracy can be increased at additional costthrough the use of very hard molds such as drysand, chemically bonded sand, etc. Even moreaccurate castings can be produced in semi-precision and precision molds. The investmentcasting process provides about the utmost accuracy obtainable with approximate tolerancesof ±0.003 x specified dimension. Production costsincrease with increased demand for accuracy.

c. Accuracy can be improved by a factor of approx-imately two if the (large) number of castings to beproduced permits an experimental production runfollowed by reworking of the pattern equipment.

Principle No. 6–

The Effect of Section Size on MechanicalProperties

Data included in this work, like most publisheddata on Ductile Iron properties, are valid for approxi-mately 20 to 50 mm thick castings. Standard specifi-cations are normally set for 25 mm keel block or Y-block test castings. Some standard specificationsrecognize the effect of section size (cooling rate) bylowering minimum required values, usually for elon-gation, with larger test castings or for samples cutfrom the casting.

The effect of section size on properties is theresult of changes in microscopic structure as the latteris influenced by cooling rate. Three prominent effectsof cooling rate on microscopic structure are:

a. Very high cooling rates do not permit all the insol-uble carbon to precipitate in the form of spheroidalgraphite. Instead, various amounts of a hard andbrittle component, iron carbide (Fe3C) will form.

b. Very slow cooling results in large diameter, irregularly-shaped spheroids of graphite up to 1.5 mm in diameter.

c. Varying the cooling rate in the 1560-480°F (850-250°C) temperature range from very fast to veryslow produces different structures from marten-site (very fast cooling) through pearlite, pearlite-ferrite to all ferrite (slow cooling).

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The presence or absence of carbides and the typeof matrix obtained in any given section can be con-trolled by alloying or heat treatment. They need notbe discussed here as long as the effects are recog-nized by the designer. The size of the spheroidalgraphite, on the other hand, can be influenced by,amongst other things, the cooling rate of the castingwhich in turn can be determined by the shape ordesign of the casting. These effects should be con-sidered in design calculations.

Providing the shape of the graphite is approxi-mately spheroidal, there is negligible deterioration ofchemical, physical and technological properties.However, published data vary over a very widerange. Some tenative information on the mechanicalproperties to expect in carbide-free Ductile Iron of dif-ferent section sizes is given above. If more preciseknowledge of these or other properties is essential

for design calculations, the designer must requestthe foundry to produce test castings which will cool atapproximately the same rate as the product casting.Mechanical tests on these test castings will yield themost accurate prediction of the properties in theproduct casting.

Courtesy: Cleaver-Brooks Company, Division of Aqua-Chem, Inc., USA

This manufacturer specified Ductile Iron pressure vesselsections over gray iron for its new line of cast iron boilers.Ductile Iron to ASTM specification A 395-80 (60-40-18) wasselected for its superior tensile, yield and thermal fatiguestrengths. For boiler applications these properties areimportant since they provide improved resistance to pressure vessel failures caused by thermal shock or otherstresses. Ductile Iron’s excellent corrosion and wearresistance was another factor in Cleaver-Brooks materialselection.

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0 100 14,500

200 300 43,500

400 500 72,000

600 700 101,500

800 (mPa) (p.s.i.)

Section thickness

very thick

thick

thin

very thin

Cooling rate

very slow

slow

normal

fast

Ductile Iron grade 60-40-18 High ductility Ductile Iron grade 65-45-12 Ductile Iron grade 80-55-06 Ductile Iron grade 100-70-03 Ductile Iron grade 120-90-02 High Strength

0.2% proof stress

The need to redesign an ammonia valve line gaveHenry Valve Co. of Illinois the opportunity to make the con-version from gray iron to Ductile Iron as shown. Size (thin-ner valve walls) and weight reductions (45% reduction)were achieved without sacrificing performance.

Principle No. 7–

Design with Adequate Safety

Both automobile steering knuckles and plow-shares are made in Ductile Iron. It is obvious thesecastings have different safety requirements. Safetyrequirements vary within wide limits, with the abovetwo examples representing extremes.

The designer is in command of all controls neces-sary to achieve whatever degree of safety is needed.These controls, however, need to be applied judi-ciously, because increasing part safety invariablyincreases cost. The controls available are:

a. Approximating the ultimate load carrying capaci-ty of the material to various predetermineddegrees. Under static loads the maximum per-missible stress equals the yield strength. Usualdesign stresses vary from 50 to 75% of the yieldstrength (0.2% offset proof stress). Parts exposedto frequently varying loads should be designed onthe basis of the endurance limit. Design stressesof 50 to 100% of the endurance limit are custom-ary, corresponding to a very high, and low marginof safety, respectively.

b. Estimating the effect of potential emergency overloads involves the determination of the mostlikely failure mechanism. Emergency operatingconditions can seldom be foreseen. Neverless,the occurrence of such conditions should be con-sidered. Excessive static or dynamic loads maycause failure either through deformation of the

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part beyond utility or by fracture. Depending onthe type of service, one failure mechanism willprove to be safer than the other. For example, ina pressure-tight container an unexpected majorincrease in the internal pressure may burst thecasting or it may permanently deform it. A perma-nent deformation will probably be the safer failuremechanism. This is one example of relatively fewapplications where ductility is the desired designproperty. Another example is that of a gear. Asudden unexpected load may break or bend oneor more teeth. In this case, breakage will probablybe safer since the structure will be able to continue operating, albeit poorly, until replace-ment is effected.

The indiscriminate use of the high ductilitygrade (Grade 60-40-18) cannot be upheld evenfrom the point of view of safety. Grade 80-55-06can withstand 70 to 80% higher loads; Grade120-90-02 can withstand two-and-a-half timesmore load, either static or dynamic, than Grade60-40-18. Beyond these limits, Grades 120-90-02, 100-70-03 and 80-55-06 will fail through frac-ture while Grade 65-45-12 and especially Grade60-40-18 will fail through permanent deformationunder much lighter loads. If safety so dictates, thelow strength, high ductility grades should be cho-sen but each application must be evaluated indi-vidually.

c. Specifying destructive and non-destructive testson a given number of castings, and the frequencyand thoroughness of testing is directly proportional

to the degree of safety expected from the casting.For the so-called “safety critical” parts, 100% non-destructive testing is often required even thoughsuch extensive testing is very expensive.Radiographic, eddy current, magnetic and ultra-sonic and sonic frequency methods are availablefor non-destructive testing.

Courtesy: Salzgitter Huttenwerk, A.G., Salzgitter, Germany

Housing for low pressure section of a 300 MW turbine.Total weight: 48 tons. The success of Ductile Iron for thisapplication is attributed to its good elevated temperaturestrength, and particularly, its high temperature yieldstrength. Castings allow the design engineer to generateinternal contours, which are nearly impossible to machine.

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Principle No. 8–

Trust the Foundry

Foundrymen producing Ductile Iron are well awareof choices in manufacturing processes, effects ofchemical composition, the effects of heat treatment,and the in-plant controls necessary, to produce aserviceable casting.

If the designer prescribes how the castings shouldbe manufactured he obviously trespasses thefoundryman’s domain. The designer representing thebuyer will probably succeed in this interference, butgains nothing by it and often ends up paying more forthe castings than he would have, had he left thechoice of manufacturing process to the foundryman.

The most common unnecessary instructions arethose on chemical composition, heat treatment, andquality control.

For instance, it is well known that increasing sili-con content increases impact transition temperature.If the designer decides that a certain minimumimpact test value is desired at a given temperature,he should specify that, rather than the silicon con-tent. Most properties can be obtained via heat treat-ment but, provided proper production controls areexercised, they can be obtained as-cast as well. Itshould remain the foundryman’s choice to delivercastings as-cast or heat treated as long as the cast-ing properties meet specifications.

Tight quality control needs to be exercisedthroughout the entire casting process, particularlywhen producing a high performance material likeDuctile Iron.

Whether or not the specified properties have beenmet should not be a matter of trust. It is not only theright but also the duty of the designer to eitherrequest or to perform tests as extensive as (safety)considerations require, in order to be satisfied thatthe casting indeed exhibits the properties expected.

Courtesy: Parten Machinery Co., Minneapolis, MN

This one-piece ductile carriage wheel replaces four former parts. In the redesign to ductile, total cost droppedfrom $251 per unit to $75. Machining was cut from $189 to$38, and the number of production operations droppedfrom 7 to 3. The 100-70-03 Ductile Iron was specifiedbecause of its good response to Tufftride treatment.

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Principle No. 9–

Communicate with the Foundry

It may seem an admission of defeat to again sug-gest, after all the casting design principles describedpreviously, that the designer should confer with thefoundryman before finalizing his plans. However, thissuggestion constitutes the last principle of designingcastings in Ductile Iron.

No designer will be an expert foundryman afterhaving read the brief fundamentals of the castingprocess and the particulars pertaining to Ductile Iron.Following these fundamentals will hopefully assist inavoiding major design errors. Deciding on fine detailsof potentially large significance in economy and per-formance requires a more profound understanding ofboth the casting process and the particular foundryinvolved.

The best time to meet with the foundryman is dur-ing the design of the “raw” or “ideal” part. The foundrywill be anxious to cooperate in determining whetheror not any modifications are needed to facilitate cast-ing production. The suggested modifications will notnecessarily be acceptable to the designer, but bothsides will most certainly gain from the communica-tion. The foundryman will also be pleased to showyou his foundry in operation, the capabilities of hismolding line and his core making facilities. You maybe able to see some good examples of castings similarto your design.

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Courtesy: Pontiac Motor Division, General Motors Corp.

Redesigned automobile crankshaft, used inthe Pontiac 2.5 liter L4 engine. According to thedesigners, the new nodular (ductile) iron castingis 10 lbs. or 23% lighter than the one it replaced.This was accomplished without sacrificing thecrankshaft’s durability or integrity.

Courtesy: Daniel Industries, Inc., USA

This Ductile Iron casting houses the operator for a spe-cial plug valve performing the function of two valves. Thenew housing was redesigned from a steel fabrication intoDuctile Iron, saving Daniel Industries $2,300,000 annually.

Material and fabricating costs dropped from $467 per unitto $67. Another benefit of the redesign was better appear-ance, and reduced manufacturing problems.

This support provides vertical and horizontal safetyspring attachments for a coulter blade and arm assembly,used on moldboard plows. The new Ductile Iron and steelcomposite design replaced a weld fabrication, reducingtotal cost 37%, for a first-year saving of $167,500. Cited bythe designer as additional advantages of the redesignwere improved reliability and appearance. By carefulattention to design, a Ductile Iron casting was convention-ally welded to a sheet steel stamping. In the design, provi-sion was made for an internal welding ear to be added tothe casting in order to place the weld material in shear atthe tension side of the joint.

Courtesy: John Deere Plow & Planter Works

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World’s heaviest Ductile Iron casting weighting 160tons. Frame for 40MN press. Dimensions 11300 x 3800 x3000 mm.

Courtesy: Siempelkamp Giesserei GmbH & Co. , Krefeld, West Germany

THE DUCTILE IRON FOUNDRY

The popularity of the Ductile Iron family of alloysarises from their versatility and good economy.Practical observations and adaptations by thousandsof producing foundries have made the production ofDuctile Iron castings, routine. Making Ductile Ironcastings resembles the production of other ferrouscastings–experience and craftsmanship are integralparts of founding.

A “small, but adequate” addition of magnesium isthe basic step in changing graphite shape from flaketo spheroidal. This treatment of the liquid iron is usu-ally done with ferrosilicon-magnesium alloy. Equallyimportant is the inoculation of the treated alloy by anaddition of ferrosilicon when filling the pouring ladle.

The control over alloy composition involvesapproximately twenty elements. The determination ofall is not absolutely necessary which highlights theneed for reliable charge materials. Routine determi-nation of carbon and silicon contents in the furnaceis essential even in the smallest operation.

The successful foundry invariably has an established practice of careful production and qualitycontrol. As stated earlier, such control is not thedesigner’s responsibility. However, if the foundry isnot equipped with the most basic quality controlequipment, or else, fails to use it, the integrity of thecastings is suspect.

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INSPECTION

Inspection is principally the domain of the designerand customer. Yet, to some degree, the foundrymanwill get involved. First, he will inspect the castings forexternal appearance and dimensions. Microscopicexamination will verify the spheroidization and matrixstructure. Often this will suffice if the sample is takenaccording to the wishes of the designer. The fre-quency of such sampling should also be established.

Some of the routine tests which may be specified,providing these are justified by the anticipated ser-vice conditions of the casting, are listed below:

a) Mechanical Property tests:

(i) Determination of ultimate tensile strength, yieldstrength (proof stress), elongation, hardness

(ii) Determination of impact resistance

(iii) Determination of dimensional accuracy (possiblywith jigs)

Mechanical property tests can be carried out atelevated, room or sub-zero temperatures and partic-ularly in the case of impact resistance, the test tem-perature should always be specified.

Additionally, the surface and sub-surface condi-tions of a casting may be assessed by the following:

b) Methods to reveal the presence of surface defects:

(i) Visual inspection

(ii) Dye penetrant inspection

(iii) Magnetic (fluorescent) particle inspection

c). Methods to reveal the presence of sub-surface defects:

(i) X-Radiography (Gamma Radiography)

(ii) Ultrasonic inspection

The integrity of a casting is determined by the pro-duction process parameters. Specifying any of theabove tests will not improve the integrity of the cast-ing but it will increase the delivered cost. It is rea-sonable to expect the foundry to exercise basic controlof process quality, as previously outlined, and to moni-tor product quality by measuring hardness, microstruc-ture and to visually inspect casting surface finish.When this basic control and inspection is exercisedcontinuously, the foundryman is well disposed to pro-duce castings which consistently meet specifications.

Courtesy: Siempelkamp, Krefield, West Germany

Ductile Iron casting weighing 85 tons, used for the stor-age and transportation of spent nuclear fuel element rods.International Atomic Energy Authority (IAEA) controlsapply to these castings and they were able to satisfyextremely demanding approval tests.

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Axle housingsBody bolstersBrake cylindersCaliper brakeCamshaftsClutch drumsConnecting rodsCrankshaftsCultivatorCylinder bushingsExhaust manifoldsFront wheel forks

Gears and pinionsHitch bracketsMotorcycle clutch

componentsPiston ringsPlowsharesSteering boxesTire moldsTow bar couplingsWheel hubsYokes

DUCTILE IRON–THE DESIGNER’S CHOICE

Ductile Iron castings have replaced gray iron, mal-leable iron and steel castings in many applications,giving better performance, often at lower cost.

Heavy, welded, steel fabrications up to medium sizecan virtually always be replaced by Ductile Iron cast-ings. Here are just some of the current applications:

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Automotive and Agricultural

AnchorsBridge bearingsBulldozer partsCable couplerCapstansCar journal boxesCharge bucketsChute platesCoke car platesConveyor framesCouplers

Crawler sprocketsElevator bucketsFurnace skidsHoist drumsIdlersPipe flangesPropellersRailway wheelsRollersRunway drainsTrack crossovers

Other Transportation Modes

Actuating camsArmature spidersBarstockBell cranksBoiler segmentsBriquetting ramsCantilever headsClamp cylindersCoal crusher gearsCommutator drumsCompressor bodiesCrusher hammersDamper framesDie blocksDredge sprocketsExtension clampsForging diesFrames and jibsFurnace gratesGirth gearsGyratory crushersHeater coilsHot forming diesInsulator capsLawn mower frames and

partsLightning arresters

Machine framesMandrelsMeter componentsNuclear fuel containersOil manifoldsOverhead switch gearPile driver headsPipe forming diesPress roll bodiesPump bodiesRatchetsResistance gridsRocker bracketsRollsRubber moldsSawmill bedsShaftsShear framesSpindlesSuspension bracketsTank coversThread guidesTunnel segmentsTurret headsTypewriter framesVise framesWood augers

General Engineering