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The Ductile Iron News

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To Promote the production and application of ductile iron castings Issue 3, 2005

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• Ductile Iron Society AwardsScholarships

ARTICLES

• Ductile Iron Treatment Optimization

• Green Sand - The Process of theFuture

PDF ARTICLES

• Applications for AustemperedDuctile Iron Castings

• An ADI Alternative for a HeavyDuty Truck Lower Control Arm

• Ten Steps to Improving CastingYield in Ductile Iron Foundries

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The Ductile Iron Society Learns About Non-Destructive Testing From

Hickman, Williamsand

The Modal Shop

View Ductile Iron Related Publications

Located in Strongsville, Ohio, USA15400 Pearl Road, Suite 234; Strongsville,Ohio 44136 Billing Address: 2802 Fisher Road, Columbus, Ohio 43204 Phone (440) 665-3686; Fax (440) 878-0070email:[email protected]

http://www.farrarusa.com/index.html

http://www.ductile.org/

mailto:[email protected]

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The Modal ShopPart Quality Inspection Application:

NDT - Resonant Acoustic Method

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Ultra-Nod Nodularity Tester Developed byHickman, Williams & Company

Ultrasonic velocity nodularity tester developedby: Hickman, Williams & Company.Uses small coupons for rapid nodularitycheck.Excellent for process control for Ductile Iron production.Accurate, fast, repeatable.Minimal training required.Rugged construction. Stainless steel tank, heavy wall steelframe, copper plumbing.Used on foundry floor close to the molten metal processingarea.Manual load/unload.Go/No Go system.Customized to fit individual foundry controls.Can be linked with the foundry process control and datacollection.No sample cutting, polishing and microscope reading.Sampling cups can be provided.

Sold Exclusively By: Hickman, Williams & Company

Equipment Group Division330 Detroit Ave. Suite D

Monroe, Mi 48162Phone: (734) 243-6110 Fax: (734) 243-6131

www.hicwilco.comemail: [email protected]

Coupon Accept/Reject Screen

Test Tank with Fixture


http://www.hicwilco.com/


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Velocity vs. Nodularity in DI

Typical Coupons and Mold

Velocity % Nodularity Velocity* % Nodularity<2199 79 2230 952230 80 2237 972207 83 2240 982210 86 2244 992214 89 2246 1002222 92 >2247 100

Note: The above table is for reference only. Each foundry needsto develop its own calibration values for nodularity acceptance.

*Absolute values for example 0.2203 inches per microseconds.

View Located in Strongsville, Ohio, USA


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Ductile Iron Society Awards Scholarships

At the 2005 FEF College/Industry Conference, three MillisScholarships were awarded. The awards went to Jeremy McLimansfrom the University of Wisconsin at Plattville, Sara Weigle fromTri-State University, and Andrew Admiston from Tennessee Tech.

Each received $2,500 with which to help pay for their education.

The year 2006 will mark fifteen years that The Millis Scholarshiphas been helping students to continue their education and become apart of the foundry industry. The Millis Fund was established withindustry donations in memory of Keith D. Millis, the inventor ofductile iron. If you would like to contribute to the fund andcontinue to help the foundry people for the future, contact JackHall at the Ductile Iron Society.(440) 734-8040 or [email protected].

A total of 337 people—236 industry and university people attendedthis year’s conference, along with 101 student delegatesrepresenting 25 FEF accredited schools and 2 FEF affiliatedschools. This unique conference brought together top industryexecutives, FEF Board Members, Key Professors, universityofficials and top student delegates—all interested in metal casting.Bill Barrett of Neenah Foundry was the conference chairman.

The Industry Information Session held on Thursday, November 10,offered students an up-close and personal look at the industry. Italso gave the 42 participating companies, the most cost-effectiveway to see some of the top metal casting students in the country allin one place.

During the General Session on Friday, the Keynote address wasgiven by Paul Mikkola, President and Chief Executive of MetalCasting Technology, Inc., New Hampshire. This year’s threepanelists included Dan Kintner, Engineering Staff at Honda ofAmerica, Ohio and an FEF scholar from the Pittsburg State;Rodney Burkhardt, Assistant Plant Manager at Metal Technologies,Wisconsin and an FEF scholar from Western Michigan; and SandyLoftus Calabrese, Production Superintendent with General Motorsin Indiana and an FEF scholar from the Michigan Tech.

The FEF Annual Banquet was held at the Drake Hotel in Chicagoon Friday night, November 11. Special FEF recognition awardswere presented to: Foundry of the year—Honda of America Mfg.in Ohio, Supplier of the year—Applied Process in Michigan; andSociety/Association of the year—the North American Die CastingAssociation. FEF’s highest award, the E.J. Walsh Award, waspresented at the banquet as well. The award went to PresidentLifetime Patron, Conner Warren, retired from Citation Corporation,Alabama. Also, at the banquet, both the students and industryattendees enjoyed internationally acclaimed speaker, Dan Clark


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(sponsored by Ashland Specialty Chemical).

It was also announced at the Annual Banquet that FEF is holdingits first charitable eBay auction. Items contributed to FEF areavailable for bidding from November 11 through December 12,2005.

During the Edward C. Hoenicke Memorial Luncheon, the AFS/FEFBoard Award of $6000 was given to FEF Key Professor, RayRummell, Cal State-Chico.

The Awards and Recognition Breakfast speaker was ProfessorEmeritus (and former FEF Key Professor) of Kent State Universityin Kent, Ohio, Scott Layman. Following his comments, 17scholarships were awarded to the student delegates who hadsubmitted applications for these awards (see reverse side).

The total scholarships and awards that were presented during this2-day conference equaled $58,500.

Next year’s College Industry Conference will be in Chicago onNovember 16-18, 2006. More information on this conference, orany of the FEF activities, can be obtained from the FEF office at1695 N. Penny Ln., Schaumburg, IL 60173, Phone 847/490-9200,Fax 847/890-6270, email [email protected], web pagehttp://www.fefoffice.org.

CIC Student Delegate Scholarships—November 12, 2005

AFS-Saginaw Valley Scholarship Brent Fogal Michigan TechAFS Southwestern Ohio Scholarship Stephanie Collins Ohio StateClifford Chier-Badger Mining Corp. Karen Deason Univ. of WindsorRon & Glenn Birtwistle Mem. Scholarship Nicholas Hutchinson Cal Poly - PomonaRon & Glenn Birtwistle Mem. Scholarship Sarah Weigle Tri-State Univ.Donald Brunner Schol.-ThyssenKrupp Waupaca William Rowden Univ. of Missouri-RollaJohn Deere Scholarship Dave Ongena Kettering Univ.Tony & Elda Dorfmueller Scholarship Lizeth Medina Alatorre Inst. Tecnologico de SaltilloWm. E. Conway Schol.-Fairmount Minerals Dustin Wiess Kettering Univ.William M. Grimes Schol.-Gartland Foundry Matthew Arvin Purdue-IndianapolisGeorge Isaac Scholarship Greg Gauerke Univ. of Wisconsin-PlattevilleBurleigh Jacobs Scholarship-Grede Dale Linder Univ. of Wisconsin-PlattevilleJames P. & Katherine Keating Scholarship Erin Boyle Univ. of WindsorChester V. Nass Memorial Scholarship Jacob Davis Mississippi StateRobert W. Reesman Mem. Scholarship Dan Rudolph Penn StateTransportation Technologies Industries Inc. Samuel Read Pittsburg StateRobert V. Wolf Mem. Scholarship Darryl Webber Univ. of Missouri-Rolla

Special Scholarships – November 11, 2005

David Laine Scholarship Stephanie Kuhn Univ. of Wisconsin-MadisonDavid Laine Scholarship Matthew Minnich Tri-State Univ.David Laine Scholarship Alex Monroe Univ. of IowaDavid Laine Scholarship Dave Ongena Kettering Univ.David Laine Scholarship Jeff Root Ohio StateKeith D. Millis Scholarship Andrew Edmiston Tennessee TechKeith D. Millis Scholarship Jeremy McLimans Univ. of Wisconsin-PlattevilleKeith D. Millis Scholarship Sarah Weigle Tri-State Univ.Ron Ruddle Memorial Scholarship Benjamin Schultz Univ. of Wisconsin-Milwaukee

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Ductile Iron Treatment OptimizationAl AlagarsamyCitation Corporation, Birmingham, Alabama

Introduction:Ductile iron production has come a long way since its discoveryduring the 1940s. Even though magnesium and rare earths haveboth been shown to produce spheroidal graphite, magnesium is theelement of choice commercially. There are many methods used toconvert base iron to ductile iron. The result of ductile ironconversion is measured or evaluated by the following factors:

Nodularity - maximize

Nodule count - maximize

Chill carbides - minimize

Inverse chill - minimize

Shrinkage porosity- minimize

Inclusions - minimize

Unique properties of magnesiumMagnesium has a low boiling point, high reactivity with oxygenand low solubility in iron making reliable additions to iron difficult.To minimize Mg reactivity calcium is added to the master alloy.Magnesium content of the alloy is also restricted to lower thereactivity. To increase solubility silicon is raised in the vicinity ofthe alloy by using ferrosilicon as cover material. To satisfy differentneeds many alloys were developed with combinations of Mg andrare earths.

Different treatment processMany different treatment processes have evolved over the years toachieve better quality ductile iron at the lowest cost. Manyvariables affected the selection of a particular treatment process.Some of the factors are:

Base melt quality including sulfur content

Temperature of treatment, holding and pouring

Delays in metal handling

Casting section modulus

Ease of late inoculation

These factors affect the treatment technique due to the uniqueproperties of magnesium and resulted in the following processes,which are still used in commercial production:


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Open ladle

Tundish

Flow thru processes

Pure magnesium processes-Converters, plunging, pressurevessels

Wire feeders

In-mold process

Nodularity and nodule countIt has been shown by many that the nodule shape is best when themagnesium residual is just enough as too much will deteriorate thenodule shape from fully spheroidal. Nodule count can bemaximized by sound base iron melting practice and goodinoculation practice. Cooling rate affects both the nodule count andthe nodule shape. Fast solidifying iron results in better noduleshape than slowly cooled iron for the same magnesium residuals.Larger sections require increased magnesium residual and lateinoculation reduces the magnesium requirement. When rare earthsare added to the iron the amount of magnesium required is alsoreduced. As some of the magnesium measured is in the form ofmagnesium sulfide, final iron sulfur level affects the magnesiumneeded to result in nodular graphite. All of these effects are shownin the figure 1.

Figure 1. relationship between final sulfur and magnesium affectedby other factors

Combination of rare earths and magnesiumOver the years it was noticed that some tramp elements affected thegraphite shape. Increasing magnesium was not able to counteractthe effect of tramp elements like Pb, Ti, Bi etc. Rare earths werefound to neutralize these elements and restore the graphite shape tonodular form. Hence rare earths were added either with orincorporated in master alloys. For irons treated with puremagnesium Rare Earths could be added as misch metal or rareearth containing inoculants. Rare earths, like magnesium, willcombine with sulfur and oxygen. They are also additive tomagnesium in nodularizing effect. Because of this, one has to lookat magnesium and rare earths content in total and not separately in



determining amounts needed for best properties. As the rare earthsare heavier than magnesium it takes 5.8 times more rare earths thanmagnesium, by weight, to combine with sulfur and oxygen.

The Atomic weights of rare earths are about 140, and that ofmagnesium is 24. Combination of magnesium and rare earthsresulting in various shapes of graphite is shown in figure 2. Whenrare earths are added with magnesium alloy the analyzed rare earthsinclude that portion combined with oxygen and sulfur, similar tomagnesium analysis.

Figure 2. Mg and rare earth combination and graphite shapes.

Types and amount of rare earths in the magnesium alloy variedover the years depending on the economics. As rare earths are moreexpensive than magnesium alloy and it takes quite bit more tocombine with oxygen and sulfur it is necessary to examine therelationship of rare earths in ductile iron manufacturing. There ismuch anecdotal information regarding the use of rare earths and itseffect on the graphite shape. A minimum amount is necessary toneutralize any residual tramp elements that may be present in theiron. It has been shown that proper addition of rare earths increasenodule count. When cerium in the magnesium alloy is used inexcess resulting in a residual of over 0.01%, pro-eutectoid graphiteparticles tend to be larger and may result in graphite floatation andexploded graphite, especially when the sulfur is low and the CE ison the high side. When rare earths are added after the magnesiumtreatment along with the stream inoculant then the level of ceriumthat causes graphite nodule enlargement and floatation is muchlower than the 0.01%. It is closer to 0.004%. The difference may bedue to the fact that the rare earths in the first case are combinedwith sulfur and oxygen and most of the rare earths are uncombinedin solution in the second case. This will lead one to envision themagnesium and rare earth relationship differently if the rare earthsare added after the magnesium treatment where most of the oxygenand sulfur are tied up with magnesium. This may be represented inthe revised areas for various shapes of graphite in figure 3.Obviously the levels of Mg and rare earths do not stay the samethroughout the pour in a batch system due to fading of activeelements with time. From figure 3 there is no vermicular graphiteshown when there is no rare earths in the iron. Ductile iron with



only magnesium will revert to grey iron without going through avermicular graphite form.

Figure3. Graphite shapes, Mg and rare earth levels

Fading of magnesium and rare earthsFading of the elements Mg and rare earths (mainly Ce, La and Pr)is due to several factors. Magnesium can evaporate due to highvapor pressure at the melt temperatures. Both Mg and rare earthswill react with combined oxygen present in the iron as oxides of Si,Mn and Fe. Sulfides of these elements breakdown to form oxidesand the freed sulfur will react with free Mg and rare earths. All ofthese mechanisms are active in any treated ductile iron melt.

The rate of fading will increase if the iron bath contains highamounts of slag, if the temperature of the melt is high and the if themelt is exposed to turbulence either in the furnace, or in the ladlewhen it is tilted back and forth. Protective atmospheres and cleanfull ladles held without disturbances minimize fading as shown infigure 4. Due to this fading event, treated iron needs to be pouredbefore the levels of Mg and rare earths fall below that necessary forthe castings being poured.

If the iron is held in a pressure pour furnace under nitrogen or inertatmosphere, the iron will have a longer life. In pressure pourfurnaces sulfur tends to be lower due to the time factor hencemagnesium level could be lower and still produce good ductileiron. Of course the late inoculation in the form of streaminoculation helps to improve nodularity, which helps in reducingthe level of magnesium.

One of the problems seen in the industry is if pouring ladles are notemptied at the end of pouring, the remaining iron cools down andsolidifies as grey iron. This may cause problems for the next timeas this iron will fade faster than normal.

Inoculant fading is different from magnesium fading. Inoculantfading results in lower nodule count, chilled edges (carbides) andinverse chill. It can also result in lower nodularity even when thereis adequate Mg and rare earths for the section thickness and sulfur



levels.

Each foundry should establish the maximum time the iron can bepoured for their circumstances.

Figure 4. Fading of Mg, Ce and La in treated iron reheated in thefurnace as well as held in a covered ladle, sampled periodically ina 16 minute total time interval.

Quality of ductile iron – cleanlinessThere is more to ductile iron quality than just nodularity. Inclusionsresulting from sand and slag that are readily seen and recognized asmacro inclusions will decrease mechanical properties. Ductile ironquality as measured by impact properties, fatigue endurance limitand machinability are affected by cleanliness of the iron.

Micro inclusions such as nitrides, and carbides are detrimental tomachinability and ductility of castings.

Even though solubility of calcium is limited in ductile iron, Cacontent of the magnesium alloys is limited to a low level in theproduction heavy section castings.

Increased Ca in ferro alloys contribute to ladle build up andincreased inclusions in the castings. Dross formation in ductile ironwas studied by Prof. Heine and Prof. Loper extensively andreported in the literature. They have shown that there is atemperature at which the dross formation is accelerated and ironshould be poured above this temperature. This process is reversible.

If a colder iron containing dross is heated back up the iron becomesclearer as the temperature is raised above the dross formationtemperature. Carbon and reactive elements in the iron combinewith the oxides of silicon, manganese and iron and reduce them totheir elemental form.

Industry has also recognized that pouring colder will causeexcessive dross formation and may result in scrapped castings. Butmelting hotter has its own problems. Super heating the iron above2750oF results in reduction in the number of nuclei within the baseiron which is finally prone to inverse chill formation. This effect iscommonly referred to as ‘Monday morning iron’. Besides affectingiron metallurgically, melting at high temperatures reduces lininglife as carbon reacts with silica in the lining to form silicon.



Carbon-silicon temperature equilibrium curves with areas ofchemistry for various cast irons are shown in the figure 5. If iron ismelted above the equilibrium temperature lining wear will occur,and if the temperature of the melt is below the equilibriumtemperature then dross formation is encouraged.

Hence Prof. R.W. Heine exhorted foundrymen to “Melt Cold andPour Hot”. By following this principle least amount of damage willbe done to the metallurgy of iron during melting and pouring.

Figure 5. Equilibrium diagram and areas for different grades ofcast irons

To verify this axiom experiments were conducted at the DaimlerChrysler casting lab by Phil Seaton. In these experiments iron wasmelted at around 2500F and then treated with a 5% magnesiumalloy containing about 2% balanced rare earths (Ce, La, Nd, Pr).After treatment the iron was poured back into the melting furnaceand micro lug and chemistry samples were taken. The iron wasthen heated in the furnace to raise the temperature to around 2600Fand that temperature was maintained thereafter. Every few minutesmicro and spectro samples were taken. Total elapsed time from thetime iron was treated to last sample (7) was poured is 17 minutes.The micro lugs were open mold rectangular bars as shown in thefigure 6. The surface appearance of the micro lugs varied fromsevere slag inclusions in sample 1 to a very clean surface in sample7. At low pouring temperatures the iron is mixed with plenty of slaginclusions which do not separate easily from the melt. As thetemperature is increased the slag separates from the melt moreeasily and the carbon, Mg and rare earths reduce oxides of Si, Mnand Fe to their elemental form. This effect can be seen in the figure7, which shows the manganese content of the iron increase withheating of the iron suggesting that MnO in the slag has beenreduced to elemental manganese. Reduction of manganesecontinues for at least 15 minutes. This may indicate that finelydispersed oxide particles continue to be reduced by carbon andother active elements and some of these reactions will produce gasbubbles, which may be trapped underneath freezing skin. We canexpect this kind of actions taking place even in the mold as moreoxides are introduced due turbulent mold filling.



Figure 6. Samples taken from furnace where treated iron isreheated to 2600oF.

Good quality ductile iron as measured in the pouring ladle can stillbe damaged during the mold filling process. If the pouring stream isfragmented, especially if stopper rod and nozzles are used, theseparated streams cool fast and the iron temperature can go belowthe dross formation temperature quickly. In the running systemsand gates, iron will become colder and may spray into the moldcausing an increase in oxidation and dross formation. This drosscould be embedded in the iron and will reduce dynamic propertiesas well as machinability.

Apart form the dross formation there are other elements that affectthe properties adversely.

It is important to lower residual elements that contribute tolowering the dynamic properties even if they do not affect staticproperties. Magnesium and rare earths in excess of that is requiredto form nodular graphite affect the quality of iron adversely. Theytend to decrease nodularity, increase the tendency for carbides andshrinkage.

Figure7. Increase in manganese content upon reheating the treated



iron.

Economical optimizationFor making clean ductile iron with very low residuals thefollowing procedure seems practical and economical.

The magnesium alloy should preferably be of lowermagnesium such as 4 to 5% with low rare earth content in thealloy. Steel cover may not be necessary with low temperatureand low magnesium level in the alloy.

Tap temperature should be kept as low as possible stillmaintaining a high enough pouring temperature (above2500oF).

Post inoculation with ferrosilicon containing Ca and rareearths should be used to neutralize detrimental elements aswell as to increase nodule count.

If late inoculation (stream) is used then care must me takento limit the rare earths contributed by the inoculant as the rareearths that are not combined with sulfur and oxygen are verypotent in affecting the shape of the graphite nodules.

Magnesium residual and rare earth levels should beoptimized at the lowest levels still achieving good nodularity.

Limit the fading time so that there will not be muchdifference in the magnesium level between the first and thelast mold poured.

Treatment size should be commensurate with mold pourweight so that the fade time does not exceed 12 minutes forbatch processing.

Further readingMajor aspects of processing cast iron – Honorary lecture – Prof.R.W. Heine, AFS Transactions 1994.

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Green Sand - The Process of the FutureProduction of High Quality Castings with a Reduction in

Emissions of Green Sand(Information Prepared for the Ductile Iron Society)

Victor S. LaFayHill and Griffith Company

AbstractA reduction in emission characteristics during pouring, cooling, andshakeout can be accomplished while producing high quality ductileiron castings in green sand! The metal casting process can produceemissions that are generated by the thermal decomposition oforganic material in greensand and if cores are present,decomposition of the core binder. Through changes in the blendedminerals in the green sand molds and selection of the green sandrelease agents, significant reductions in VOCs, HAPs, carbonmonoxide, and carbon dioxide emissions can be accomplished. Thisreduction in emissions has been determined during actual metalcasting with advanced analytical methods and equipment that havebeen developed by Technikon for the Casting Emission ReductionProgram (CERP) in Sacramento, California.

IntroductionDuring the last few years, a number of development studies havebeen completed at various foundries, technical centers, universities,and research facilities on the emission characteristics of foundryprocesses. A series of studies has been completed at Technikon,which operates CERP, which supplies valuable information thatwas utilized to develop the significant reduction in the emissioncharacteristics of the green sand process. These studies review thecharacteristics of the emissions that were the result of the metalcasting process from the green sand, green sand release agents,contribution of the emission characteristics from the core process(and the subsequent return of the core material into the green sand)and the greensand release agents. Each one of these processescontributes uniquely to the emission characteristics, so they wereinvestigated individually.

This information will review the alternative materials that can beutilized by the foundry industry to reduce the emissioncharacteristics of green sand while producing high quality ductileiron castings and potentially with reduced costs! There are anumber of materials that can be used as either a supplement toseacoal or as a replacement for seacoal. Since seacoal is theprimary source of carbonaceous materials utilized for green sand inNorth America, the logic of supplements or replacement is the focalpoint of the technology advancements. These technologicaladvancements have been evaluated and successfully implementedin many ductile iron foundries in North America.

Review of Seacoal and Seacoal SupplementsCarbonaceous additives have been widely used in green sand


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molding for many years successfully! The primary additive that isused in the foundry industry is seacoal along with a variety ofsupplements that enhance the characteristics of the seacoal. Theadvantages of blending seacoal with the selected supplements havebeen documented in many foundry publications and discussed inconferences where metal casting technology is reviewed.Historically the selection of the supplements to seacoal wasprimarily based upon casting quality considerations not emissioncharacteristics (until recently). With particular importance placedupon the sulfur content when producing ductile iron castings. Thephysical properties of the seacoal and seacoal supplements arereviewed in table 1.

Test (%) Seacoal Anthracite Met. Coke Gilsonite Cau. LigniteMoisture 3 3 1 1 14Volatile 37 12 10 83 43Fixed Carbon 52 73 79 13 31Ash 7 12 10 2 11Sulfur 0.7 0.6 0.8 0.3 0.6

Table 1: Typical properties of carbonaceous additives

Review of Green Sand Release AgentsMore than 3 millions gallons of green sand release agents are usedin North America. Regardless of the type of metal poured (steel,ductile iron, gray iron, brass, etc.) every green sand mold producedfor the metal casting process requires the application of a greensand release agent. Most foundries simply use them “because theyalways have”! However, these materials have become scrutinizedbecause they contribute to the emission characteristics of greensand during the metal casting process. They can not be simplyoverlooked.

Table 2 contains information concerning the physicalcharacteristics of green sand release agents that are commonly usedin the foundry industry.

PhysicalProperty

PetroleumBased

Vegetable OilBased

BlendedPetroleum &Vegetable Oil

Water Based

Flash Point (F)Close Cup >200 >200 >200 Water vapor ext.

flameViscosity (cps) 10 45 15 175Specific Gravity(g/ml) 0.8 0.9 0.9 0.9

VOC (lbs/gal)EPA method 24 3.8 0.3 2.9 3.6

Biodegradability No No Yes Yes

Table 2: Typical properties of green sand release agents

Investigations that Contributed to the Final Conclusions

Contribution of Green Sand Emission Characteristics WithoutSeacoal and Release Agents

A series of investigations was completed to evaluate thecontribution of green sand release agents on the emissioncharacteristics that occurs during the metal casting process. Thematerials that were investigated included: petroleum oil based greensand release agent, vegetable oil based green sand release agent,and water based green sand release agent containing graphite.These products are commercially available and widely used



materials that can be used in molding machines and sprayapplication devices.

For this investigation, there are a number of specific details thatrequire discussion. The first consideration was the selection of thecasting that was used in the metal casting process. The teamselected the star casting design that was produced on an OsbornMolding Machine (Figures 1, 2, and 3).

Fig. 1 Osborn Molding Operation

Fig. 2 Star Castings (4 on pattern)

Fig. 3 Individual Star Casting

The molding sand was prepared without seacoal and contained onlya blend of 5:2 ratio of Western (Sodium) Bentonite and Southern(Calcium) Bentonite at 7% with 40 to 45% compactability. Withoutthe Seacoal present, the investigators had the opportunity to



determine the contribution of the green sand release agents to theemission characteristics. In this series of investigations, 40 gramsof green sand release agent was added to the surface of the patternso that each of the materials could be investigated under the sameconditions (Figures 4 & 5).

Fig. 4 Green Sand Release Agent on Pattern

Fig. 5 Release Agent (Transferred) on Mold

The following graphical emissions data was collected from pouring,cooling and shakeout of this combination of materials (Figure 6).

Fig. 6 Emission Characteristics of Green Sand Release Agents

Test Evaluation Utilizing Information From Additional Studies at



CERP

In order to significantly reduce the emission characteristics fromfoundry molding sand, core sand, and subsequent return of the coresand into molding sand, the reduction in selected materials,addition of minerals into the core sand, and changes in the moldingprocess have to occur. For this investigation the following materialswere utilized:

1. A water-based green sand release agent containing graphitewas used. The graphite would eliminate the need fordevelopment of lustrous carbon on the mold metal interfaceduring the metal casting process.

2. All of the Seacoal was removed from the molding sand.Cellulose was added to the green sand to reduce mold wallmovement.

3. A predominately Western (Sodium) Bentonite sand systemwas used with the addition of a molding sand additive toenhance the performance of the bentonite.

4. A blended aluminum silicate mineral was added to thephenolic urethane core sand mixture at a 5% level.

A casting study was completed utilizing this mix of materials. Thegreen sand molds (without seacoal) were prepared with 96.5%Western (sodium) Bentonite, 3% Cellulose, 0.5% Soda Ash, and240 ounces (per ton of prepared preblend) of a polymeric additivethat is utilized to enhance performance of the Bentonite at 7% witha 40 to 45% compactability. The cores were produced with aphenolic urethane binder system at 1.4% binder with the additionof a blended aluminum silicate mineral additive. The molding sandand cores were prepared and cast in a controlled environment toevaluate the emission characteristics of the combined processes(Figures 7 and 8).

Fig. 7 Prepared Molds and Cores



Fig. 8 CERP Testing

Figures 9 and 10 show the emission results from this casting studyin graphical form.

Fig. 9 Emission Results Summary fromTest Mix vs. Selected Baseline

Fig. 10 Target Analyte Emission Results from Test Mix vs. Selected Baseline

Casting Quality

The step core pattern used in the emission testing did not provide a



good opportunity for surface finish comparison. The followingphotos (Figures 11 through 16) compare the seacoal baselinecastings (Test FK) compared to graphite pattern release agentcastings (Test FV). This test did not include the greensand additivepackage that should improve surface finish further. Added testing isplanned by CERP to further profile the quality implications of thesemixtures.

Fig. 11 FK001 Best Casting Surface

Fig. 12 FV005 Best Casting Surface

Fig. 13 FK005 Median Casting Surface



Fig. 14 FV008 Median Casting Surface

Fig. 15 FK004 Worst Casting Surface

Fig. 16 FV011 Worst Casting Surface

Investigations That Contributed to the Final Conclusions

Contribution of Green Sand Emissions With Seacoal and SeacoalSupplements

A series of investigations was completed to evaluate thecontribution of greens sand release agents with seacoal and seacoalsupplements on the emission characteristics that occur during themetal casting process. For this investigation, the same methods andequipment was used (as previously discussed) in the studies todetermine the impact that seacoal and seacoal supplements have onemissions. In all of these studies, the same petroleum based greensand release was investigated except for a specific study that wasused in comparison with a water based release agent containinggraphite.

Figure 17 is a comparison of HAP’s between materials evaluated.These materials include; a seacoal baseline study, low volatile coalblend (specifically an anthracite/seacoal blend), causticized lignite,blended minerals (containing seacoal/graphite/iron oxide), AOadded water to a seacoal blend, and a series of blends containingno seacoal. These materials were evaluated at the CERP facilityand the entire series of reports are available at the CERP website.These reports include the complete testing results of emission fromthe pouring, cooling and shakeout and a review of casting quality.



Fig. 17 Comparison of Seacoal & Seacoal Supplements (HAP)

Investigations That Contributed to the Final Conclusions

Understanding the Resulting Comparisons of OtherDecompositions Products

In addition to the previously discussed emission data from themetal casting process, recently collected data concerning the CO,CO2, NOx, and SO2 was completed. During previously discussedevaluations the equipment and methods were not available for theseevaluations. Recently CERP added the equipment and protocols toevaluate these test methods. Figure 18 contains the collectedinformation.

Figure 18 Comparison of Seacoal and Other Materials

Final Conclusions and NAL CONCLUSIONS ANDSUGGESTIONSDuctile iron castings can be produced utilizing the information andtechnology discussed. A number of ductile iron foundries havetaken advantage of this information and changed their preblend,altered the type of green sand release agents, and improvedmethods to produce high quality castings while reducing theemission characteristics.

The results from these evaluations show that:

1. Casting surface quality is comparable to that achieved with atraditional greensand with seacoal.

2. In order to reduce the CO & CO2 content of molding sand



the reduction in seacoal should occur. This can beaccomplished by the addition of a water based green sandrelease agent containing graphite.

3. The reduction in emission characteristics of green sandduring pouring, cooling, and shakeout can be accomplishedusing a number of methods (with varying results):

a. Utilizing seacoal and seacoal supplements.

b. Utilizing green sand release agents with loweremission characteristics.

c. Utilizing water based green sand release agentscontaining graphite.

a. With seacoal and seacoalsupplements.

b. Without seacoal all together.

Overall, the data clearly show that significant emission reductionscan be achieved without sacrificing casting surface quality.

AcknowledgmentsThe authors would like to thank the Hill and Griffith Company,Technikon, LLC and CERP for their permission to publish thisinformation.

ReferencesLaFay, Neltner, “Forget Southern! Go Western with Green SandBinders,” Modern Casting, (October 2002)LaFay, Neltner, “Green Sand without Seacoal,” AFS Transactions(2004-111)LaFay, Neltner, “Understanding Emissions in Green SandMolding,” Modern Casting (Website Article) (April 2002)LaFay, Neltner, “Understanding the Application of Green SandRelease Agents,” AFS Transactions (2002-064)LaFay, Crandell, Glowacki, Knight, “Significant Reduction in theEmission Characteristics of the Green Sand Process”, AFSTransactions (2004-125)LaFay, Crandell, “Reduction and/or Eliminating Seacoal in GreenSand Systems”, AFS EHS Conference 2005.

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APPLICATIONS FOR AUSTEMPERED

DUCTILE IRON CASTINGS Don Reimer

Farrar Corporation Norwich, Kansas

Following is a discussion of several castings produced in Austempered Ductile Iron by Farrar Corporation. Each application has certain requirements that can be satisfied by ADI. What determines when a casting should be produced as Austempered Ductile Iron? Following are several examples of applications where properties of ADI fit well into the requirement of the casting components. These properties include high strength-to-weight ratio, good toughness, good wear resistance, good machinability prior to heat treatment, relatively low cost compared to other materials with like properties, and can be cast to near net shape which eliminates machining operations.

A company producing overhead conveying equipment had always used steel forgings for the component parts. When the tooling for a Side Link Pusher Dog was worn and needed replaced an opportunity arose for ADI. A quotation for the same part in ADI showed the customer that not only was the tooling much less expensive, but the parts were less as well. One reason for the parts to be less expensive was that a lubricating hole could be cast into the part rather than being machined into the forging. Fortunately one of their engineers was receptive to a change and the first ADI part was produced by Farrar Corporation. Since that time there have been many other conversions within this industry to Austempered Ductile Iron. Now, ADI is the first choice of material rather than steel forgings or weldments.

Examples of components in the overhead conveying equipment now made out of Austempered Ductile Iron are shown above. ADI is chosen because of its toughness, strength, and wear resistance. The 80-55-06 Ductile Iron trolley bodies and side plates are the only casting components not made of ADI. This material has proven to be a dependable and economical choice for the overhead conveying industry.

Taking a closer look above at the Leading Trolley and the Trailing Trolley, the actuators are of ADI material primarily for the wear resistance and strength. The retractable actuator of one system rides up on the accumulating actuator of the next system. The retractable dog is activated by the actuator and is engaged for movement of the system by the pusher dogs. The load pin holds the load being conveyed, and the spherical washers help to keep the load and the pins from binding as it travels up and down the conveyor system. Obviously strength is of primary concern for the load pins.

Another industry where the choice of material is Austempered Ductile Iron is in construction equipment, and in particular trenching equipment. Strength and wear resistance are definitely required for the components of this type of equipment where they must work in a hostile environment of abrasive dirt and sand. Another important advantage is being able to cast to near net shape. The only machining required on the gear below is a small amount of clean up on the inside diameter. The gear is driving an auger that moves the dirt to either side of the trench, thus working in a pretty nasty environment.

Bit holders are used in equipment that trench in hard, rocky soil, so strength and wear are quite important. Many of the bit holders are cast to shape with no machine work required. The bit holders were originally a fabricated part with a great deal of machine work required. A casting has proven to be quite cost effective in this application.

Below are two more applications on crawler tractors for construction equipment. The drive sprockets and rollers used on the track system are both ADI castings. Again, the advantages of strength, toughness, and wear resistance are of utmost importance.

A person might wonder what component of a lawn mower could possibly have an ADI casting requirement. In this commercial type lawn mower, two drive gearboxes are required and they each have a gear, which is made of ADI.

The gear shown above also serves as the axle for the driving wheels. It is a conversion from steel weldments, which was very difficult for the manufacturer to hold necessary tolerances. Consequently it was noisy and unreliable. As a casting, all of the machining, except grinding the bearing surfaces, is done prior to heat-treating. Extremely close tolerances can be maintained, thus eliminating gearbox noise and is very reliable for the customer. This gear and axle utilizes all the important properties offered by ADI. The entire gearbox shown above is cast, machined, and assembled by Farrar Corporation.

The last example of an ADI casting is one that is sure to be familiar to all foundrymen. Using ADI for the wear plate in an inclined conveyor has increased the amount of wear provided by gray iron castings. It also provides ductility and toughness that cannot be provided by a chrome iron wear plate.

We have shown a few examples of Austempered Ductile Iron castings that are being produced by Farrar Corporation. Some of the examples may be for applications not normally considered to be a candidate for ADI. We must always be mindful first of all of the advantages of castings over many other processes. Then we must be able to take the advantages of a casting and add the excellent properties afforded by ADI. We now have a process producing a casting with equal or superior physical properties, that can be produced at a cost to our customer lower than many other materials and/or processes currently being used.

2002 World Conference on ADI

An ADI Alternative for a Heavy Duty Truck Lower Control Arm

Philip B. Seaton DaimlerChrysler Corporation

Dr. Xiao-Ming Li

Citation Corporation

ABSTRACT An austempered ductile iron lower control arm for the 2003 MY heavy duty Dodge Ram pickup truck was designed and tested by Citation Corp. as an alternative to the planned stamped steel weldment. This paper covers the design, casting and initial testing of the part. The design and testing of the stamped part was well underway before it was decided to pursue the cast design. Incorrect loading on the initial analysis led to a delay in developing an acceptable ADI part and the opportunity for vehicle testing was missed. As a result, the stamping was chosen for the production application, but the process of developing an austempered suspension was a valuable learning experience for everyone involved. INTRODUCTION The choice of a stamped steel weldment (Ref. Figure 1 and Figure 2) for the lower control arm was well established before a casting alternative was considered. It was felt the loads involved would require too heavy of section sizes for a casting to be competitive. During the development of the stamping it became necessary to use heavier gage steel to meet the performance requirements. Citation Corp. recognized an opportunity for this component as a casting that would yield cost and weight savings compared to the stamped design.

Figure 1 : Stamped steel welded design Citation’s analysis showed a conventional D4512 iron would require sections that resulted in the part not meeting the weight requirements. At this point Citation approached DaimlerChrysler Cast Metals Engineering & Prototyping to discuss the feasibility of an ADI design. It was decided that DaimlerChrysler would build a pattern to the Citation supplied design and prototype parts would be cast by DaimlerChrysler Cast Metals. Citation would then austemper, machine and test the components.


Figure 2: Stamped and joined lower control arm for the heavy duty Ram. BACKGROUND Until recently there has been little interest in the application of ADI to automotive and light truck suspension components. Two relatively recent low volume applications include the upper control arm of the independent rear suspension of the Ford Mustang Cobra and the Cadillac limousine. For high volume applications the emphasis has been on converting ductile iron components to aluminum for weight savings at higher cost, but with the current climate of cost reduction it seems ADI with 3 times the strength and 2.3 times the stiffness of aluminum, may be a cost effective and weight competitive alternative. DESIGN CRITERIA The initial design criteria of the lower control included these elements:

DESIGN CRITERIA

WEIGHT 33 lbs.

LOAD REQUIREMENTS 3G Vertical + 2G Brake

COST Under $45 assembled

Figure 3: Design Criteria

PRODUCT ENGINEERING AND MANAGEMENT The basic steps Citation follows in a development program such as this include: • Design for manufacturing and assembly • Optimization for cost, weight and performance • Structural analysis and component validation • Process simulation for optimal quality and

productivity • Project management to ensure seamless planning

and execution. INITIAL CONCEPT As stated earlier, conventional D4512 ductile iron would not meet the design weight criteria. A design concept using austempered ductile iron was developed and analyzed.

COMPARISON OF MECHANICAL PROPERTIES

PROPERTY ASTM D4512 ASTM A897 125-80-10

TENSILE (ksi) 65 125

YIELD (ksi) 45 80

ELONGATION (%) 12 10

Figure 4: ASTM minimum mechanical properties Analysis of the initial design concept showed the part met the FEA static criteria for the 3G vertical + 2G brake load conditions. Assembled weight of the initial design was 28 lbs. Figure 4: Initial castinFFFFFF Figure 5: Initial concept design


PROCESS SIMULATION Citation also carried out process simulation of the prototype design to understand the soundness of the cast component from a manufacturing perspective. Figure 6a & Figure 6b show the typical temperature distribution during mold fill and solidification process. The simulation results indicated no significant shrinkage or porosity in the casting. Areas of minor porosity might exist as would be expected from any cast component. Figure 6a: Temperature distribution during mold fill Figure 6b: Temperature distribution during solidification Radiographic inspection performed on the prototype castings at DaimlerChrysler confirmed the simulation results. Some minor porosity (Level 1 or 2) was found at the predicted locations in cast component. This minor porosity was deemed acceptable to the function of the part. PROTOTYPE CASTING Once a design had been developed and analyzed the next step was to produce prototype castings. Citation worked with the DaimlerChrysler Woodshop and Cast

Metals Engineering & Prototyping to build the prototype pattern (Figure 7) and cast the parts. Physical testing of the part resulted in premature failure. Analysis of the failure showed no unusual casting abnormalities that may have contributed to the failure. Further investigation revealed the design loads were incorrect. The revised load for analysis was actually found to be a 4G vertical load. An analysis at the higher loads was required.

Figure 7: Prototype pattern. Cope side. Molds were made with nobake sand and poured with the following chemistry(Figure 8):

CHEMISTRY

C Si Mn P S Mo Cu Ni

3.56 2.38 .28 .03 .01 .02 .64 .49

Figure 8: Typical chemistry As cast hardness readings were found to be 229 HB to 241 HB with a matrix of approximately 50% pearlite.


The castings were heat treated (Figure 9) by Applied Process with this cycle:

HEAT TREAT CYCLE

AUSTENITIZE 1625 F

AUSTEMPER 675 F

Figure 9: Heat treat cycle Typical properties (Figure 10) on the austempered parts were:

AUSTEMPERED PROPERTIES

HARDNESS 302 HB

TENSILE 115 ksi

YIELD 88 ksi

ELONGATION 11%

Figure 10: Typical properties on test bars from castings MACHINING Though machining was not the focus of this program several general comments can be made: • Requires slower speeds and deeper cuts • Use indexable carbide tools • Machine before austempering when possible • Holes that cannot be drilled with indexable carbide

tools must be drilled before heat treat • Tapped holes need to be tapped before heat treating • Dimensional change due to austempering is

repeatable, but is part specific and requires study TESTING Assembled parts tested on a half car simulator failed prematurely (Figure 11). Investigation into the failure revealed improper loads were used for the concept design and analysis. The test condition was actually a 4G vertical load rather than a 3G load.

Figure 11: Failure on half car simulator Analysis (Figure 12) of the design with the new loads confirmed the location of the failure. Figure 12: Analysis using the 4G load identified the “hot spots” in the design The failure with the assignable cause of incorrect design loads led to the development of a new design (Figure 13). Primarily the gusset areas where the failure occurred was blended more completely into the hat section and radii increased.


Figure 13: Revised design Analysis (Figure 14) using the 4G loads showed the reduced stresses in the revised design. Figure 14: Revised design structural analysis In order to validate the design, fatigue bench testing was performed (Figure 15).

Figure 15: Fatigue testing at the revised loads confirmed the analysis.

B10 Life = 134,886 (cycle)

B10 Life = 36,083 (cycle)

Figure 16: Weibull analysis comparison


A Weibull (Figure 16) analysis comparison of the original design versus the revised design showed at least a three times increase in durability life. The next step would be further verification of the design in the half car simulator. However, the delay caused by the initial use of incorrect loads caused the program to miss the original test schedule. It is planned to complete the validation testing and confirm the feasibility of ADI as a material choice for suspension components. Even with the added weight required with the revised design the ADI lower control arm compared favorably to the stamped part (Figure 17).

STAMPING ADI CASTING

WEIGHT 33 lbs. 31 lbs.

WEIGHT PER VEHICLE 66 lbs. 62 lbs.

DURABILITY Pass Pass

COST PER ASSEMBLY $ 2% Less

TOOLING $ 54% Less

Figure 17: Comparison of stamped and joined component to an ADI casting SUMMARY Even though this part did not go into production it provided valuable information on feasibility of ADI for automotive and light truck suspension components. This experience will aid in future applications of ADI and it’s potential as an aluminum alternative offering improved properties at lower cost and competitive weight. ACKNOWLEDGMENTS We would like to acknowledge the following individuals and groups for aiding in this project: Christian DePauli - Citation Dan Tonge - Citation Harold Hopkinson - Citation DaimlerChrysler Woodshop DaimlerChrysler Cast Metals Engineering and Prototyping Applied Process Inc Citation Custom Products Albion

REFERENCES Warrick, R.J., Althoff, P., Druschitz, A.P., Lemke, J.P., Zimmerman, K., Mani, P.H., Rackers, M.L., Austempered Ductile Iron Castings for Chassis Applications, SAE Paper 2000-01-1290. Voigt, R.C., Austempered Ductile Iron – Processing and Properties, Cast Metals, Volume 2, Number 2, 1989. Keough, J.R., Hayrynen, K.L., Automotive Applications of Austempered Ductile Iron, SAE Paper 2000-01-0764 Keough, J.R., Austempered Materials and Their Applications to Drive Line and Suspension Components, SAE Paper 2000-01-2563 Paxton, J., An Alternative to a Stamped Control Arm, Ductile Iron Society presentation at DCTC, March, 20, 2001.

Ten Steps to Improving Casting Yield in Ductile Iron Foundries

Norberto T. Rizzo Downes Dana de Venezuela S.H. Foundry Division

Valencia, Venezuela

Ramon D. Duque Sudesh Kannan

SELEE Corporation Hendersonville, NC, USA

ABSTRACT Ten steps for increasing yield in ductile iron castings are proposed. These include use of ceramic foam, shorter gating systems, non-turbulent gating system design, thinner runners and ingates, and proper and efficient use of risers. Many of these techniques have been reported in the literature. It is suggested that cost-savings achieved by application of these steps can be significantly higher than those achieved by conventional scrap reduction procedures. Two case studies outlining the use of these principles with yield improvements are shown. INTRODUCTION Several gray iron foundries are slowly adding ductile iron castings to their repertoire. Shrinkage and proper micro-structure problems are often their key challenges. There is also a misconception that ductile iron castings are often associated with large risers. It is common to see the bulky gating designs of gray foundries combined with large risers contributing to reduced casting yield in many ductile iron castings. On the other hand, the primary customer for these foundries (the automotive industry) continues to make increased demand for cost reductions and quality improvements. Globalization brings additional factors into play in these areas. The production engineer in a foundry has now become involved significantly in the commercial and economic aspects of running a foundry. The foundry process has significant variables and often optimization of competing factors is essential to meet the goals of productivity and quality. These efforts, in turn, lead to improved profitability of the foundry business unit. This paper outlines ten principles of gating and riser design that could help the foundryman to show dramatic improvements in casting yield and thus reduce his costs. YIELD IMPROVEMENTS VERSUS SCRAP RATE REDUCTION Conventional attempts at reducing costs are often focused on scrap reduction. Yield is often indicated as the ratio of the casting weight to the total pour weight. In a hypothetical case, let us consider a casting that has yield of 48%. If the current scrap level associated with the casting is around 5%, the effective yield is around 45.6 % (48% *(100-5/100) =45.6%). Let us assume that the yield of that specific casting is increased (by the principles outlined in this paper) to 73% and there is an associated scrap equal to 10%. The resultant effective yield (considering loss due to scrap) is around 65.7% (73% *(100-10/100)= 65.7%). Thus, the overall effect of yield improvement can be a more significant cost reduction tool in spite of an increase in scrap levels. The authors do not minimize the importance of quality improvements and scrap reductions. Scrap reduction through process control and continuous improvement is essential for the survival for most foundries. It is merely suggested that yield improvement should also be given due consideration. Metal weight to mold ratio is often considered important since it indicates the volume utilization of the mold for a given casting. The increased volumes of cores used in a mold also lead to increased costs. All yield improvement efforts should include ways to get additional castings per mold and minimize the volume of cores used in each mold.

TEN STEPS TO ACHIEVE HIGH YIELD The following ten steps or ideas assist in reducing the gating system dimensions and volume and result in higher yields without compromising casting quality. Two case studies at the end of the paper illustrate applications of these principles. 1) Use of Ceramic Foam Filters Conventional application of filters is based on reducing the incidence of scrap related to inclusions. However, the proper use of ceramic foam filters in the runner system can help reduce the length of the runner and gates [1]. Flow modification can

help reduce turbulence in the gating system and consequently the formation of reoxidation slag. Long runners and ingates are not needed to act as slag traps. Significant yield increases can, thus, be achieved by shorter runners and ingates. 2) Use of Stable Raw Materials Optimum performance is obtained from use of raw materials that minimize variations in the process. For example, use of caruburisers that have a crystalline structure, homogeneous, pure or preferably of natural origin and free of any major impurities leads to good control of carbon content in the iron [2]. Good control over carbon content, in turn, leads to better control of shrinkage volume. Figure 1 shows typical ranges of carbon and silicon for sound castings [7].

Figure 1: Carbon and silicon ranges for sound ductile iron castings [7].

3) Use of Trapezoidal Gate Cross-Sections to Minimize Turbulent Flow As mentioned above, the use of a ceramic foam filter minimizes the need to use runner and ingate sections as slag traps. Table I compares the gating elements of rectangular, trapezoidal (base= a height =3a, top= a/3 to a/5) and triangular cross-section along with corresponding modulus, Reynold’s numbers and weight of these cross-sections. The top row has cross-sections that have constant weight per unit length. It can be seen that the classic rectangular cross-section has the maximum turbulence (as shown by a high Reynold’s number)[3]. The lower row consists of gating cross-sections with the same Reynold’s numbers (same associated level of turbulence). The weight of the triangular cross-section ingate is the lowest. However, the triangular cross-section is not preferred by most foundrymen since there is a risk of mold erosion in the corners. The very low modulus of the corners can also negatively affect the solidification characteristics of the triangular ingate. Therefore, these analyses suggest that a trapezoidal cross-section shown above can give a balance between good flow characteristics and lower weight.

Table 1: Comparison among the different types of runners. (Flow = 2.5 Kg/sec.)

4) Optimizing Pour Times and Pouring Sequence Conventional gating designs often focus on simultaneous filling of all cavities in a mold. This results in large sprues and runner systems needed to deliver the required flow rates. It is suggested that designs that permit sequential filling of cavities can reduce the need for high flow rates, consequently, the gating system can be leaner in size [4]. 5) Optimum Gating/Runner Modulus to Control Temperature Loss It is generally known that shrinkage will increase as pouring temperatures decrease. The modulii of the gating channels must be kept in mind, since high values (thicker and heavier runners and ingates) decrease the yield. However, too low values

(very thin runners and ingates) will cause gating elements to solidify rapidly and cause localized shrinkage in the castings. Care must be taken to ensure that significant metal temperature loss does not take place in the gating system. 6) The Use of Risers to Compensate Expansion Risers must be considered as compensators (for shrinkage volume). The supply of molten metal needed for filling the casting comes from the ingates. The objective is to avoid the over pressurization that generates the expansion during the solidification producing the formation of secondary shrinkage. The application of this concept allows the use of small risers improving the casting yield [5,6]. Periodic sectioning and examination of the risers is essential to verify that the risers are working as designed. The volume of metal fed by each riser should be determined. 7) Placing Risers at Optimal Locations It is important to analyze the critical sections of a casting to ensure that solidification progresses in a logical fashion. The use of risers at key locations to ensure a sound casting cross-section is essential. Figure 2 shows sectional views of a carrier housing casting and the basis for locating risers. The modulii of various sections are grouped together for feeding by two risers. Feeding distance of each riser should be considered when deciding on the location and position of the risers.

Figure 2: Positioning of risers based on modulii of important casting cross-sections.

8) Use of a Riser for More than One Casting (Whenever Possible) When a system allows, a design factor that allows for improvement of the yield, is sharing a riser with several castings, since its function is based on its modulus; and only the size needs to be adjusted to achieve the required feeding volume to the castings. 9) The Use of Top Risers In vertical molding systems, it is relatively simple to locate the top risers, but in a horizontal molding system, the situation is more complicated. The application of these kinds of risers in both cases, allows the handling of appropriate feeding volume (based on the difference between the riser height and the cope height) with smaller size riser contributing to increased yield. 10) The Use of Hot Risers Hot risers are very efficient. The volume of metal that can be delivered to the casting is significantly larger than the volume supplied by a cold riser. Consequently, the riser volume tends to be smaller. As mentioned earlier, periodic examination of riser sections is necessary to determine the efficiency and effectiveness of the risers. CASE STUDIES While these case studies are specific to vertically parted molds, the principles can be used in horizontally parted molds also.

Example A Carrier Housing Casting Figure 3 shows the initial and final gating designs for a carrier housing casting. Initial yield was 64% with three cavities per mold. The ten principles outlined above were applied to this mold. The main changes include placing a ceramic foam filter under the sprue, thinner ingates and reduced cores. The use of smaller top risers also helped in yield improvements. A final yield of 80% with four castings per mold was achieved.

Net Weight: 45.0 KgTotal Weight:70.30Kg3 Castings64% Yield

Net Weight: 60.0 Kg.Total Weight: 75.0 Kg.4 Castings80% Yield

Disa line 2070

CARRIER HOUSING

4x0.93 Kg*

Before After

(*) Only riser weight

3x2.7 Kg*

Net Weight: 45.0 KgTotal Weight:70.30Kg3 Castings64% Yield

Net Weight: 60.0 Kg.Total Weight: 75.0 Kg.4 Castings80% Yield

Disa line 2070

CARRIER HOUSING

4x0.93 Kg*

Before After


3x2.7 Kg*

Figure 3: Illustration of a carrier housing casting. Example B Differential Case Casting Figure 4 shows the initial and final gating designs for a differential case casting. Initial yield was 59% with only eight castings per mold. The runner and in-gate cross-sections were calculated based on Reynold’s numbers (as outlined in Table I). In addition to placing a ceramic foam filter, extensive redesign of the hot risers were performed. The hot risers at the middle level were 10% smaller as compared to the hot risers at the top level and 10% larger than the bottom level. The design, thus, used the advantages of metallostatic pressure at the lower levels. The average weight of the riser reduced from 1.2 Kg to 0.8 Kg. The final yield was 71% with 12 castings per mold.

Net Weight: 43.2 KgTotal Weight: 73.2 Kg8 Castings59% YieldWithout filter

Net Weight : 52.8 KgTotal Weight : 74.36 Kg12 Castings71% YieldWith filter

Disa line 2070

Big prints Small prints

DIFFERENTIAL CASE

2x1.62 Kg*

2x1.22 Kg*

2x0.91 Kg*

4 x 3.5 Kg*

Before After


Net Weight: 43.2 KgTotal Weight: 73.2 Kg8 Castings59% YieldWithout filter

Net Weight : 52.8 KgTotal Weight : 74.36 Kg12 Castings71% YieldWith filter

Disa line 2070

Big prints Small prints

DIFFERENTIAL CASE

2x1.62 Kg*

2x1.22 Kg*

2x0.91 Kg*

4 x 3.5 Kg*

Before After


Figure 4: Illustration of differential case casting. CONCLUSIONS Ten principles to improve yield in ductile iron castings have been outlined. Process improvements for scrap reduction are important. Process control is essential for consistent quality. The focus of this paper has been to suggest the possible benefits of cost reduction that can be achieved by yield improvements. ACKNOWLEDGMENTS The authors would like to thank their respective companies for the resources provided and permission given to publish this work. Special thanks are due to Ms. Annie Demps of SELEE Corporation for her assistance in preparation of this manuscript. We also wish to thank Mr. Luis Labrador, Mr. Gustavo Tirado, and Ms. Gabriela Toro of C.A. Danaven, Div. S.H. REFERENCES 1. Aubrey L.S., Brockmeyer J.W..Wieser P.F., “Removal from Ductile Iron with Ceramic Foam Filters” Transation 85-21 pp71-76. (1985) 2.Lloyd Thomas “ Economic and Operational Considerations in the Use of Carbon Charging Materials in Ferrous Metal Casting” .BCIRA Broadsheet No.132, 1986 3. F.J. Bradley, J.A. Hoopes, S. Kannan, J.V. Balakrishna, S.Heinemann, “ A hdyraulics-based model of fluid flow in horizontal gating systems”, AFS Transactions 92-101, p 917-923 4. C.R.Loper. Jr. AFS Transactions “Sequential Filling off Mold Cavities”. 1981 (81-07) AFS Gating and Risering of Cast Iron Vol. 1 Pg, 1-4

5. S.I. Karsay DUCTILE IRON III, GA TING AND RISERING, Qit-Fer Titane.inc (1981). 6. S. I. Karsay, ENCYCLOPAEDIA OF DES IGN LOGIC, Qit-Fer Titane.inc (1981). 7. DUCTILE IRON Handbook, American Foundrymen’s Society Inc., (1999).


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News BriefsMEETINGS - BUSINESS - PEOPLE

MEETINGS

The Ductile Iron Society 2006 Annual Meeting will be held onJune 21-23, 2006 at the Wynfrey Hotel at the Riverchase Galleria,in Birmingham, Alabama. The meeting will feature visits toCitation Foam Castings and Glidewell Specialties Foundry.

The Ductile Iron Society 2006 Fall Meeting will be held inMonterey, Mexico in October. The meeting will feature tours ofBlackhawk de Mexico, CIFUNSA and Grede Proeza along with afull technical program. The exact dates and the host hotel will beannounced later.

BUSINESS

Ashland Casting Solutions new EXPRESS LAB ready to roll

DUBLIN, Ohio – A new mobile laboratory, EXPRESS LAB,featuring specific capabilities for the foundry industry, is beingintroduced by Ashland Casting Solutions, a business group ofAshland Specialty Chemical, a division of Ashland Inc. (NYSE:ASH). EXPRESS LAB features on-site capabilities to measure thephysical attributes of sand systems and the performance capabilitiesof resin systems used in metal castings. This service providesfoundry operators with real-time results to help improve processcontrol and reduce scrap.

“By introducing EXPRESS LAB to the castings industry, we candeliver the highest level of expertise possible to foundry locationsthroughout North America. EXPRESS LAB packages distinctcapabilities into applications aimed at improving bottom-lineperformance that can be delivered to the foundry on site,” saidMike Swartzlander, vice president, Ashland Specialty Chemical,and general manager, Ashland Casting Solutions.

Some of EXPRESS LAB’s featured capabilities include structuredtesting that is applied to core sand analysis, molding sand analysisand casting performance evaluation. EXPRESS LAB can also beused to provide on-site instruction from ISO 9002 certified trainersso employees can receive expert hands-on experience and learn thelatest in quality control procedures.

To find out more about EXPRESS LAB contact Steve Smith,casting manufacturing representative, Ashland Casting Solutions at(614) 790-3058.

Ashland Casting Solutions, a business group of Ashland SpecialtyChemical, is a leader in supplying products, technologies, andservices to the global metal casting marketplace. The group hasoperations (including licensees and joint ventures) in 21 countries.


susan

Rectangle



Ashland Specialty Chemical, a division of Ashland Inc., is aleading, worldwide supplier of specialty chemicals servingindustries including adhesives, automotive, composites, metalcasting, merchant marine, paint, paper, plastics, watercraft andwater treatment. Visit www.ashspec.com to learn more about theseoperations.

Ashland Inc. (NYSE: ASH) is a Fortune 500 chemical andtransportation construction company providing products, servicesand customer solutions throughout the world. To learn more aboutAshland, visit www.ashland.com.

Intermet Plants Earn Quality and Performance Awards fromCustomers

TROY, Mich., November 11, 2005 — INTERMET Corporation, adiversified manufacturer of cast-metal components, todayannounced that several of its casting plants in the United States andEurope have earned prestigious quality awards from customers.

INTERMET’s Archer Creek Foundry in Lynchburg, Virginia,received a Certificate of Achievement award from Toyota MotorManufacturing North America, Inc. (TMMNA). The award waspresented in conjunction with the 2005 TMMNA Annual BusinessMeeting and Awards Ceremony held in Covington, Ky. The ArcherCreek Foundry earned the award for meeting Toyota quality anddelivery standards for an entire year. This is the fifth time in nineyears that the Archer Creek plant has received recognition fromToyota for performance achievements in quality and/or delivery.

INTERMET’s Stevensville PCPC™ Plant in Stevensville,Michigan, received an award from Delphi Energy & ChassisSystems’ Saginaw Operations. The aluminum casting plant waspresented with the 2005 “Best Supplier” award in recognition fordemonstrating excellence and exceeding Delphi’s expectations. TheStevensville facility produces aluminum steering knuckles forDelphi using INTERMET’s innovative PCPC (Pressure-Counter-Pressure Casting) process.

INTERMET’s Monroe City (Missouri) Aluminum Plant recentlywas given the Hitachi Automotive Supplier Performance Award inrecognition for achievement in the areas of quality, deliveryperformance, cost management and dedicated support during 2004.Hitachi issued ten awards for supplier performance and the MonroeCity Plant was the only die caster to receive this honor. Previously,Monroe City was recognized with this award in 2001 and 2002.

Finally, INTERMET’s Neunkirchen Foundry in Neunkirchen,Germany, received awards from Federal-Mogul Corporation for“Zero Defect” performance and “Delivery Excellence.” The awardswere given as part of Federal-Mogul’s TVA program, whichassesses suppliers in delivery, quality, innovation and a proactiveapproach to supply-chain cost reductions. The Neunkirchen plantsupplies ductile-iron brake components to Federal-Mogul.

“These awards hold special significance for us since they recognizeINTERMET as a worldwide leader in product quality anddelivery,” said INTERMET CEO Gary F. Ruff. “They are the resultof much hard work by our employees, attention to details, and use



of established systems. They also reconfirm our primary objective,which is to provide complete customer satisfaction. We lookforward to elevating this performance in the future for allINTERMET customers.”

About INTERMET: With headquarters in Troy, Michigan,INTERMET Corporation is a manufacturer of powertrain,chassis/suspension and structural cast components for theautomotive industry. The company has approximately 5,200employees worldwide. More information is available on the Internetat www.intermet.com.

PEOPLE

Milwaukee, Wisconsin - Grede Foundries, Inc., has appointed BobTroyer to the position of Vice President of Business Developmentof Grede Foundries, Inc.

Troyer received a BA Business Administration from the Universityof Wisconsin-Milwaukee. He joined Grede in 1993 as ProductManager at its Corporate office in Milwaukee, Wisconsin, and iscurrently serving as Director of Marketing.

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