AFS Transactions 11

Agglomeration Behavior inGreen Molding Sands

T.A. DornNeenah Foundry CompanyNeenah, WisconsinM.D. RothwellGrede Foundries, Inc.Reedsburg, WisconsinR.W. HeineUniversity of WisconsinMadison, Wisconsin

ABSTRACT

Agglomerates of silica grains, clay and additives with waterform during green sand processing. The sand is in an agglomer-ated condition when it reaches the molding operation. Afterpouring and shakeout, the sand remains in a, more or less,agglomerated condition as it returns for further processing.This report reveals the course of agglomeration behavior as thesand is reused.

The silica sand base sieve analysis must be known to followthe course of agglomeration. Agglomerates build from the sievedistribution and fineness of the silica grain base. The number ofparticles and agglomerates that develop are shown to build onthe surface area and number of particles provided by the silica.Surface area and particle numbers are obtained by calculationfrom the sieve analysis using a conversion table. Sieve analysesof the silica sand base, the washed molding sand and %AFS clayand the unwashed dried molding sand are required. Percent AFSclay and methylene blue (MB) clay are shown to alter particleand agglomerate numbers and area.

Sands from two foundries are compared in the analysis.Increasing AFS grain fineness number (gfn) is shown to be animportant contributor to agglomeration. The base silica grainsieve analysis and gfn is shown to be a dominant factor affectingagglomeration. Attrition and thermal bonding can alter thesieve distribution. The sands were studied in the 38–43%compactibility ranges. Several questions were posed to arrive ata standardized procedure for further research.

The dominant effect of the base silica grain distribution andfineness is proven. Agglomeration increases as the percent AFSand MB clay increase. Fines accumulation on +140 to pan is anongoing process. Coarse agglomerates may also develop. Theeffect of the agglomeration condition on casting performancewas not studied.

INTRODUCTION

Particles of silica, clay and additives agglomerate during green sandprocessing. At the conclusion of mulling and aeration, the sand is inan agglomerated condition when it reaches the molding operation.Molding compresses the agglomerates into a near maximum bulkdensity. After shakeout, the agglomerates may or may not break upduring subsequent processing and return to green sand molding

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stations. The technical literature provides little description of theagglomerated condition in present day green sand.1,2 This report isaimed at describing the particle and agglomerate size distributionsthrough sieve analysis methods and their relationship to clay andfines in green sand.

SIEVE ANALYSIS

Green sands have a silica grain distribution that originates in the coresand (CS), which enters the system. The CS sieve analysis must beknown because it will appear in all subsequent green sand analyses.If a second silica sand is added, to change the base silica sieveanalysis from that of the CS, then the resulting base silica sieveanalysis should be calculated. The acronym CS is used to designatethe base silica sand sieve analysis in the system, whatever its source.Agglomeration begins from this base.

For comparison with the base silica sieve analysis, two other sieveanalyses are needed. First, is the AFS sieve analysis without clay plusthe %AFS clay totaling 100% by weight. Second, is the driedagglomerated sieve analysis. The former is designated WMS (washedmolding sand) sieve analysis. The latter is designated UWMS(unwashed molding sand) sieve analysis. In addition to CS, WMSand UWMS sieve analyses, %MB clay, %LOI (loss on ignition) and%VCM (volatile combustible material) are data needed to followagglomeration behavior.

Foundry Sand Data

Green sand data from two different foundry companies were used forthis study. The sand systems and green sand properties of thesesystems were described elsewhere.4 Molding was done with 2070DISA machines. Sand sampling and testing procedures were doneaccording to each company’s regular procedures. Screen sets werethose normally used for control testing.

Foundry A used a single base silica core sand A, in Table 1.However, sand may be transferred from other systems and, onoccasion, other silica sand has been added. Also, the samples wererandomly chosen from the beginning and end of a five-year period.One sieve analysis data set came from a supplier’s laboratory. In thiscase, the data provided a long-range look at agglomeration behaviorin a particular system with numerous inputs.

Foundry B data was randomly selected from a much shorter timeperiod, January–February and May–July 1998. In this foundry, aregular addition of silica sand was used to raise the 140-pan sizeparticles above that from the CS dilution.

Table 1 provides the silica grain base for both foundries. Thenumber of particles and their surface area is also listed. Figure 1shows the cumulative wt% versus U.S. sieve number curves, whichplainly reveal the CS gfn difference: 56.3 for foundry A and 67.2 forfoundry B. Table 1 also lists particle numbers and surface areascorresponding to the CS wt% sieve analyses. They are used inagglomeration analysis.

Agglomeration Analysis

A data set for agglomeration analysis of foundry A2070-1095 isprovided in Table 2. Data from Table 2 is first plotted as cumulativewt% retained versus U.S. sieve number for CS, WMS and UWMSanalyses in Fig. 2. Figure 2 shows the UWMS cumulative curve

12 AFS Transactions

above the WMS curve. The CS curve is between them over most ofthe range, except above 100 sieve. Figure 2 also shows 12, 20 and 30sieve agglomerates in the UWMS that are not present in the CS andWMS sands. Each of these three sands terminates at the pan wherethe sample weight is reached. Note, in Fig. 2, that the WMSterminates at a cumulative wt%, which is 100% minus the %AFSclay. This termination point, 100–14.53, is dependent on the %AFSclay in the sand.

Fig. 1. Cumulative wt% versus U.S. sieve number for CS, the basesilica grain distribution in foundry A and B sand systems. See Fig.12 for surface area and number of particles.

Fig. 2. Cumulative wt% retained of CS, WMS, UWMS versus U.S.sieve number for Table 2 data of A2070-1095. Note that %AFS claycauses the curve to terminate at 85.5% cumulative weight silica.

Table 1.Core Sand Data for Foundries A and B

Foundry A Core Sand: %AFS = 0.46; MB = 0; gfn = 56.3

Sieve Weight Number of Particles SA Part/cm2

No. %Ret %Cum Ret Cum Ret Cum

6 0 0 0 0 0 0

12 0 0 0 0 0 0

20 0 0 0 0 0 0

30 0.15 0.15 182 182 4 4

40 6.9 7.05 24301 24483 265 269

50 17.64 24.7 172700 197183 953 1222

70 38.34 63.0 1052797 1249980 2922 4144

100 30.37 93.4 2336155 3586135 3262 7405

140 5.67 99.1 1214133 4800268 857 8262

200 0.31 99.42 197817 4998085 67 8329

270 0.015 99.57 270047 5268132 46 8375

Pan 0 0 0 0 0 0

Foundry B Core Sand: %AFS = 0; MB = 0; gfn = 67.2

Sieve Weight Number of Particles SA Part/cm2

No. %Ret %Cum Ret Cum Ret Cum

6 0 0 0 0 0 0

12 0 0 0 0 0 0

20 0 0 0 0 0 0

30 0 0 0 0 0 0

40 4.7 4.7 16553 16553 181 181

50 14.7 19.4 143917 160470 794 975

70 26.8 46.2 735915 896385 2042 3017

100 31.2 77.4 2400001 3296386 3351 6368

140 18.1 95.5 3875804 7172190 2735 9103

200 4.1 99.6 2616288 9788478 892 9995

270 0.5 100.1 900155 10688633 153 10148

Pan 0 100.1 0 0 0 0

Ret = retained; Cum = cumulative; SA = surface area; Part = particles

Table 2.Analysis of WMS, UWMS Foundry A2070 -1095

and Core Sand of Table 1

Washed Molding Sand WMS –UWMS

Sieve Weight Number of Particles SA Part/cm2 # of SANo. %Ret %Cum Ret Cum Ret Cum Part cm2

6 0 0 0 0 0 0 Cum Cum

12 0 0 0 0 0 0 –46 –16

20 0 0 0 0 0 0 –462 –52

30 0.16 0.16 194 194 4 4 –2451 –96

40 3.13 3.29 11024 11218 120 124 –11854 –199

50 8.91 12.2 87232 98445 481 605 –79314 –572

70 33.75 45.95 926758 1025203 2567 3177 –316839 –1231

100 26.72 72.67 2055385 3080588 2870 6047 +200089 –509

140 7.97 80.64 1706638 4787226 1204 7251 +750405 –121

200 2.50 83.14 1595298 6382523 544 7795 1069464 –12

270 1.25 84.39 2205388 8632911 384 8179 1879727 +126

Pan 1.09 85.48 5175851 13808762 463 8642 2307121 +164

%AFS = 14.53; MB = 12.3; gfn = 67.1

Unwashed Molding Sand

Sieve Weight Number of Particles SA Part/cm2

No. %Ret %Cum Ret Cum Ret Cum

12 2.4 2.4 46 46 16 16

20 2.6 5.0 416 462 36 52

30 1.8 6.8 2183 2645 48 100

40 5.8 12.6 20427 23072 223 323

50 15.8 28.4 154687 177759 854 1177

70 42.4 70.8 1164283 1342042 3231 4408

100 20.0 90.8 1538462 2880504 2148 6556

140 5.4 96.2 1156317 4036821 816 7372

200 2.0 98.2 1276238 5313059 935 7807

270 0.8 99.0 1440248 6753154 246 8053

Pan 1.0 100.0 4798487 11501641 425 8478

gfn 56.8

Ret = retained; Cum = cumulative; SA = surface area; Part = particles

AFS Transactions 13

Figure 3 illustrates the effect of %AFS clay on position of thetermination point for three foundry A sands of 14.53, 11.53 and10.1% AFS. In each case, UWMS agglomerates are present on 12, 20and 30 sieve sands, which are not present in WMS, as in Fig. 2. TheUWMS must all terminate at 100%.

Changing from cumulative weight to cumulative numbers ofparticles or agglomerates greatly changes the graphs. The WMS andUWMS sieve analyses are converted from retained and cumulativepercent by weight, to retained and cumulative number and surfacearea of particles using the multiplying factors in Table 3. Theparticles are considered to be spheres. The multiplying factors arebased on using U.S. sieve opening sizes as the diameter of particle,or agglomerates, passing through one sieve and retained on the next.The results are like those in Reference 3, but differ because thatauthor used an average diameter for successive sieves. The order ofmagnitude is the same, but shifted accordingly. The particle numbersand areas on each sieve for the A2070-1095 sand is listed in Table 2for WMS and UWMS.

Figure 4 shows the cumulative number of CS and WMS particlesand UWMS agglomerate sieve analysis for the A2070-1095 sand.The cumulative number curves in Fig. 4 should be compared with thecumulative weight curve in Fig. 2. The cumulative weight curvealways terminates at 100% AFS clay (Fig. 2). However, the numberof particles versus sieve number curve is terminated by the totalnumber through the 270 sieve, on the pan (Fig. 4). If a 400-mesh sieveand the pan were used, the number of particles would continue toincrease.

Fig. 4. Cumulative number of CS and WMS particles and UWMSagglomerates for the A2070-1095 sand. Compare with cumulativeweight curves in Fig. 2.

Fig. 3. Cumulative wt% retained of WMS and UWMS versus +12 to+50 and +70 to pan for sands of 14.53, 11.53 and 10.1% AFS clay.

Table 3.Number and Surface Area per Gram Retained on U.S. Sieve

–Thru Sieve Sieve Cu. In. Grams Sieve Part/g+On No. Opening Part Vol per Particle 1 g/Part

–6+12 +12 0.132 in. 1.0204x10–3 5.23x10–2 19.12

–12+20 +20 0.065 in. 1.4379x10–4 6.244x10–3 160.1

–20+30 +30 0.0331 in. 1.8988x10–5 8.2458x10–4 1212.7

–30+40 +40 0.0232 in. 6.5376x10–6 2.8394x10–4 3521.9

–40+50 +50 0.0165 in. 2.3521x10–6 1.02142x10–4 9790.3

–50+70 +70 0.0117 in. 8.3861x10–7 3.6417x10–5 27459.5

–70+100 +100 0.0083 in. 2.9936x10–7 1.3000x10–5 76923.1

–100+140 +140 0.0059 in. 1.07539x10–7 4.670x10–6 214132.8

–140+200 +200 0.0041 in. 3.6087x10–8 1.5671x10–6 638119

–200+270 +270 0.0029 in. 1.2740x10–8 5.5546x10–7 1800310

–270+400 +400P 0.0021 in. 4.8495x10–9 2.106x10–7 4748487

–400 0.0015 in. 1.7673x10–9 7.675x10–8 13029920

Sieve Surface Area SA per g on Sieve cm2

No. per Particle – cm2 X Part/gram

+12 0.353 cm2 6.8

+20 8.5634x10–2 13.7

+30 2.221x10–2 26.93

+40 1.091x10–2 38.42

+50 5.518x10–3 54.02

+70 2.775x10–3 76.2

+100 1.3963x10–3 107.41

+140 7.055x10–4 151.08

+200 3.407x10–4 217.44

+270 1.7046x10–4 306.88

Pan 8.9383x10–5 424.5

Ret = retained; Cum = cumulative; SA = surface area; Part = particles; g = gram

472194 A2090

%AFSCLAY

14 AFS Transactions

These differences apply in both WMS and UWMS. Further, thefine particles are involved in the agglomeration process, to a majorextent. The WMS and UWMS number are essentially low untilparticles finer than 70 mesh occur (Fig. 2). Then, divergence of WMSand UWMS occurs with a decline in the UWMS numbers because ofagglomeration of fines with the –70 mesh particles. The CS particles

cannot increase beyond the +140 sieve because of their limitedpresence.

AFS clay and MB clay should be much involved in agglomerateformation. Figure 4 is for 14.53% AFS clay and 12.3% MB clay. InFig. 5, comparison is made with foundry A sands of 11.5 and 10.1%AFS clay and 9.57 and 8.3% MB clay. Note that particle andagglomerate numbers on sieves decline with decreasing clay per-centages. Divergence of the particle number curves beyond +70sieve is a feature of the curves in Fig. 5.

This fact is emphasized when the parameter WMS-UWMS isplotted against sieve number (Fig. 6). WMS-UWMS is measure ofthe agglomeration behavior of the sand. A large WMS-UWMS valueindicates strong agglomerating action. The +12 to +50 sieve agglom-erates shown in Fig. 3 do not appear on Fig. 6 because of scalelimitations.

Sands from foundry B show particle numbers like those offoundry A. The CS cumulative weight sieve analysis of this finersand, gfn 67.2 vs. gfn 56.3, is shown in Fig. 1. Particle number curvesof CS, WMS and UWMS for four samples are shown in Fig. 7. Notethat divergence of numbers appears beyond the 100 sieve in the finersand instead of beyond the 70 sieve in the coarser sand (Fig. 7compared to Fig. 5). Figure 8 shows that the B2070 sands respond tothe WMS-UWMS parameter, just as the A2070 sands in Fig. 6.Figures 5–8 show that agglomeration numbers change with increas-ing AFS gfn, but in the same direction.

Fig. 5. Comparison of 14.5% AFS clay, 12.5% MB clay of Fig. 4with A2070 sands of 11.5 and 10.1% AFS clay and 9.57% MB and8.3% MB. Note divergence of particle number curves beyond the+70 sieve.

Fig. 6. Divergence of WMS-UWMS particle number curves beyond+70 sieve, as suggested in Fig. 5.

Fig. 7. Cumulative numbers of CS, WMS and UWMS particles onsieve series for foundry B2070 sands. Compare with Fig. 5. Note,divergence occurs beyond 100 sieve.

AFS Transactions 15

Table 4.Percent MB Clay in UWMS Sieve Fractions

A2070 B2070Sieve UWMS WMS UWMS* MB Ret on Sieve (g) UWMS**No. %Ret %Ret %MB on Sieve Ret Cum %MB on Sieve

6 – – – – – –

12 1.2 0 11.91 1.0143 0.143 NA

20 1.44 0.16 12.15 0.175 0.318 NA

30 1.20 0.48 9.48 0.113 0.431 NA

40 8.89 4.78 6.80 0.605 1.036 NA

50 25.72 12.10 8.02 2.063 3.099 7.8

70 42.07 33.44 9.72 4.089 7.188 8.8

100 14.88 26.59 12.15 1.808 8.996 12.0

140 3.12 6.85 18.71 0.584 9.58 15.2

200 0.96 2.07 27.95 0.268 9.848 24.0

270 0.24 0.80 NA 0.067 9.915 NA

Pan 0.24 1.11 NA 0.067 9.982 NA

Sum 99.96 88.38

%AFS — 11.63

MB — — — — 9.983%

gfn 50.5 63.82

* % MB Analysis by Foundry A; ** % MB Analysis by Foundry B

Ret = retained; Cum = cumulative; SA = surface area; Part = particles; MB = methylene blue

AFS and MB Clay Analysis

The sieve fractions of UWMS were analyzed for %MB clay for bothA2070 and B2070 sands. Results are listed in Table 4. Obviously, theWMS contains no MB clay. Figure 9 shows the %MB clay in eachsieve fraction of Table 4. This MB clay distribution appears similarto the WMS-UWMS distribution in Figs. 6 and 8. Because the weightpercentage of agglomerates is maximum in the +50 to +140 sieverange, the greatest percentage of the total %MB present is on thesesieves (Table 4). As expected, the highest %MB is reported for the+200, +270 and pan, which was analyzed as a composite samplebecause of its limited weight. Probably, much of the freshly addedclay will appear on these sieves. The high percent MB on the +12,+20, +30 sieve material conforms to its disappearance when compar-ing the UWMS and WMS sieve analyses.

The total %AFS clay is comprised largely of the %MB claypresent together with fine silica and carbon. Excluding the latter, theMB is usually about 80–85% of the settling test AFS clay. The AFSclay composite undergoes agglomeration with the MB clay duringfinal mulling. The agglomerates are what respond to molding andalso heating from casting.

Surface Area

Surface area conversion factors for sieve analysis are given inTable 3. Surface areas for both CS sands are listed in Table 1, and forthe A2070-1095 sand in Table 2. Cumulative surface areas are shownin Figs. 10 and 11 for A2070-CS and B2070-CS sands. The B2070sands show higher surface area on a sieve than the A2070 sands. Thisis expected, since the gfn of B2070-CS is 67.2 versus 56.3 for theA2070-CS sands. The A2070-CS sand has a total surface area of8375 cm2 and the B2070-CS has 10148 cm2 (Table 1). These areadifferences account for the WMS and UWMS particle numberdifferences in Figs. 5–8, as well as the cumulative area curves in Fig.10 and 11. Figure 12 shows the cumulative surface area contributionand number of particles from A2070-CS and B2070-CS sands.

Agglomerates and Particles

Agglomerates result from particles sticking together during sandconditioning and molding. They spring from surface interactions ofsilica grains, clay and water. Figures 1, 5, 7, 10 and 11 reveal the orderof participation. The CS provides the beginning surface area (Figs.1, 10 and 11). Numbers of UWMS agglomerates vary little from CSand WMS numbers up to +100 sizes because the major cumulativeincrease in surface area occurs up to the +100 sieve size (Figs. 5 and7, as related to Figs. 10 and 11). In other words, the major agglom-eration increase defined as WMS-UWMS follows the major surfacearea increase up to the point of divergence indicated on Figs. 6 and8. Then the +140 to pan sizes react with clay to form fine agglomer-ates until CS fines are consumed (Figs. 10 and 11). This is wellillustrated in Figs. 10, 11 and 12. Obviously, the %MB clay and%AFS clay will also influence the extent of agglomeration.

Fig. 8. Response of B2070 sands to the WMS-UWMS parameterfor comparison with 2070 sands in Fig. 6.

Fig. 9. Percent MB clay in the UWMS sieve fractions of 2070A and2070B sands (Table 4). Compare curve shape with Figs. 6 and 8.

16 AFS Transactions

Fig. 12. Contribution of A2070-CS and B2070-CS to surface areaand number of particles.

Fig. 10. Cumulative surface area cm2 for A2070 sands corres-ponding to cumulative numbers in Fig. 5.

Fig. 11. Cumulative surface area cm2 for B2070 sands corres-ponding to cumulative numbers in Fig. 7. Compare with Fig. 10.

Extremes of particle sizes and numbers are illustrated in Fig. 13.1

The single particle size in Fig. 13 (A) can undergo little agglomera-tion, while the multiple particle size (B) can produce many agglom-erates of various sizes. Coarse agglomerates can form if there aresufficient numbers of fine particles. This was illustrated in Fig. 3. Inthat case, coarse UWMS particles on +12, +20 and +30 disappearedfrom those sieves in the WMS. Because agglomerates can developover the size range suggested in Fig. 13, they can confer moldingplasticity and mold strength when molds are made.

Fines Accumulation

Examination of Fig. 5 shows that A2070-CS has less fines on 140 topan than its WMS fines. But, Fig. 7 shows B2070-CS has more finesthan its WMS fines. This again relates to the difference in sieveanalyses and gfn of the two base sands (Table 1 and Fig. 12). Whatis another source of the higher WMS sand fines? Attrition of silicagrains in mulling, shakeout and blasting in sand processing is onesource. Thermal bonding of clay, coal ash, coked seacoal and sootparticles can build up fines or produce coarse agglomerates. Micro-scopic examination indicates both sources. Fines generation is aninherent result of both particle attrition and agglomeration. Graphs ofpercent retained versus sieve number are the simplest way to observewhether fine or coarse particles are increasing on any sieve.

Figure 14 provides a percent retained sieve analysis examplefrom the A2070 sands of Figs. 5, 6, 10 and 12. In comparison withA2070-CS, note the increased percentages of fines retained on +140,+200, +270 and pan. Decrease in the percent retained on +40 and +50percent retained is revealed, suggesting attrition. This may producethe increase on the +70 sieve. This example suggests that WMS sieveanalysis is changing from the CS base by attrition and thermalbonding plus clay addition.

AFS Transactions 17

Fig. 14. Weight percent retained sieve analysis of A2070 WMS ofFigs. 2, 3, 5 and 6. Note increase or decrease in percent retainedwhen WMS is compared with CS.

Fig. 13. Schematic illustration of particle size ranges that canparticipate in agglomeration.1

UNRESOLVED QUESTIONS

The dried unwashed sieve analysis is not presented as a standard testin the AFS Mold & Core Test Handbook (1989). Inquiry among somesand laboratories reveals differences in testing procedure as follows:

1. Point of sampling the green sand.2. Testing for AFS clay by the 20- or 25-micron method pro-

duces different results. The 20-micron method was used inthis study.

3. Assuring that both WMS and UWMS results are from thesame sample.

4. Drying of the sand for UWMS sieve analysis is not standard-ized. Some air dry for 24 hours; some bake one hour at 220–230F (104–110C); some air dry to less than 20 compactibility.

5. The screening process time is not standardized. Some screenfor 2.5 minutes, others for 5 or 15 minutes before obtainingretained sieve weights.

6. Sample size is not standardized. Percent MB clay content ofUWMS sieve fractions could be more easily gained fromlarger samples.

7. Conversion factors for relating weight to particle and agglom-erate numbers and surface area should be standardized. In thisreport, conversion factors are based on spheres having adiameter equal to the sieve opening preceding the one onwhich the particles are retained. Reference 3 used an averagevalue for successive screens. No correction for shape of grainwas made.

If the UWMS sieve analysis is to become useful, the testing andreporting procedure should be standardized.

Research on agglomeration in green sand could be fruitful towardbetter understanding of sand behavior and performance. Some sub-jects are suggested.

1. Compactibility and moisture. The examples provided weremulled to about 38–43% compactibility. Change incompactibility and related moisture content would changeagglomeration results.

2. Change in grain fineness and distribution.3. Additives or pH adjustment.4. Change in clay type from sodium bentonite in this report to

calcium bentonite or mixtures.5. Change in the sand processing system mechanisms.

6. Coated core sand dilution.7. Presence of other aggregates.8. Carbon or coke fines.

One purpose of this report is to suggest a neglected aspect of sandcontrol testing and process control measurement.

CONCLUSIONS

Agglomeration of particulates is inherent to processing green sandfor molding. Study of the extent of agglomeration requires unwasheddried sieve analysis and its percent MB clay plus the standardizedAFS clay and washed sieve analysis. Sieve analysis of the core sandentering the system should be known. From this information, severalconclusions are supported.

1. The base silica sand sieve analysis from cores or new sandadditions prevails in agglomerate formation.

2. Both percent MB and AFS clay influence the extent of agglom-eration. Higher AFS clay from higher MB clay are the majorcontributors to the extent of agglomeration. Higher percent AFS clayleads to a greater percent change in agglomerates.

3. AFS grain fineness, sieve analysis and its surface area exert adominant effect on agglomerate formation in green sands.

4. Number of particles and agglomerates varies much more than thetotal surface area of WMS, UWMS and CS of a green sand.

5. Divergence of WMS, UWMS and CS number of particles oragglomerates begins at 70, 100 or 140 sieve sizes increasing withAFS gfn.

6. Fines accumulation on +140 to pan sieves is an ongoing processarising from either grain attrition or stable fine agglomerates.

Sand performance in molding and casting may, in part, be relatedto variation in the agglomerated condition extant in the sand. Theabsence of a database of agglomeration conditions prevents suchcorrelation at this time. In this context, a standardized UWMS testprocedure is necessary. Research using the standardized proceduresmight then be fruitful.

18 AFS Transactions

ACKNOWLEDGMENTS

The managements of Grede and Neenah Foundry companies arethanked for permission to publish this report. A. Habeck, LaboratorySupervisor of Technical Services, Neenah Foundry Co. and M.Herritz, Laboratory Technician, Grede Foundry-Reedsburg are com-mended for the high quality of data they provide.

This study was funded in part by the University of WisconsinSystem Solid Waste Recovery Research Program.

REFERENCES

1. C. Ludwig, “Principles of Agglomerating Processes,” AFS Transac-tions, 1955, vol 63, p 466.

2. H.W. Dietert, “Balling and Clustering in Green Molding Sands,” AFSTransactions, 1973, vol 81, p 49.

3. M. Granlund, “Micromeritics as Applied to Foundry Sands,” AFSTransactions, 1962, vol 70, p 37.

4. F. Headington, M.D. Rothwell, R.A. Green and R.W. Heine, “Avail-able Clay Control and Mulling Efficiency,” AFS Transactions, 1998,vol 106, p 271.