analysis of failure and performance improvement of hammer

Analysis of Failure and Performance Improvement of Hammer Mill Hammers 11

Analysis of Failure and Performance Improvement of HammerMill Hammers

Ajuwa, Christopher I., Duru, Augustine Chibuike, Uyaelumuo,Anthony Emeka

ANALYSIS OF FAILURE AND PERFORMANCE IMPROVEMENT OFHAMMER MILL HAMMERS

Ajuwa, Christopher I.,1 Duru, Augustine Chibuike2, Uyaelumuo, Anthony Emeka2

1Department of Mechanical Engineering, College of Engineering, Federal University of Petroleum Resources, Warri, Nigeria2Department of Mechanical Engineering, Faculty of Engineering, Chukwuemeka OdumegwuUniversity

ABSTRACTThis work focuses on the determination of the causes of the frequent failure of the crushinghammer of the hammer mill and to improve on its lifespan. Failure analysis test based on thedestructive and non destructive tests were conducted on the samples of the failed hammer millhammers collected. Samples which were not heat treated were taken as control and differentsamples of the specimens which were heat treated, quenched and tempered in different mediawere tested to determine the best result. Tensile test, hardness test conducted revealed that thematerial lacked the appreciable hardness to withstand the impact force for crushing. The heattreated materials changed the microstructure and mechanical properties of the material. Thechemical composition test revealed that the material lacked the required percentage compositionof some essential elements for strength and impact enhancement. The main causes of the hammerwear identified were impact, followed by erosion wear by many fine grains. Improving thegeometric profile; redesigning non-clearance hammer to prevent abrasive sliding and decreaseclearance between the impact granularity and the undersurface may prolong the lifespan. It wasrecommended that the addition of 12 manganese and 1.2 percent carbon to steel or alternativelysteel bounded tungsten carbides F3002 which is expensive followed by controlled heat treatmentwill help improve the lifespan of the hammer of the hammer mill.

Keywords: Failure, Hammer, Hammer Mills, Tensile, Hardness

INTRODUCTIONProper selection of the most suitable materialsfor different parts of a machine, particularly ahammer mill is of paramount importance basedon the desired mechanical properties; this is toenhance efficiency and durability of themachine. Frequent breakdown of industrialmachines reduces production output andsubsequently reduces income of the company.This frequent breakdown of the hammer millsof these three companies aforementioned hasprompted this study. There is an envisaged needto investigate the causes of this frequent failureof the hammer mills and a lasting solution tothis problem proffered.

A conventional hammer mill is a deviceconsisting of a rotating head with free swinginghammers, which reduce rock, grains or similarlyhard objects to a predetermined size through aperforated screen (Science-tech Dictionary,2003). Hammer mills are widely used in the

agricultural, wood, mining, and chemicalindustries.

According to Okpala (1990), majority ofNigerians live in the rural areas.Anifowoshe (1990) also said that Nigerians arepredominantly engaged in agriculture andproduce grains at constant basis; therefore,efficient design and manufacture of a hammermill are indispensible.

Nigeria is blessed with equatorial (Morgan andMoss, 1965), Tropical (Clayton, 1958), Guinea(Jones, 1963), Sudan (Olajire, 1991) and Sahel(Pande et al., 1993) climatic zones; thus makingher suitable for the profitable cultivation andproduction of a wide variety of grains andtubers (FAOSTAT, 2004). Biewar (1990),Igbeka and Olumeko (1996), Adejumo and Raji(2007) said that the farmers rely on ancient andantiquated methods that are inefficient forstoring the grains and tubers and these lead tolarge storage losses due to rodents, damp, fungi

12 COOU Interdisciplinary Research Journal



and natural decay. Dixon et al. (2001) andTaylor et al. (2006) said that the grains andtubers in their unprocessed states are bulky,difficult to transport and fetch very low prices inthe market. Killick (1990) and Umoh (2003)sees that it is a major cause of poverty amongstrural farmers. That encourages rural urbanmigration (UNEP, 2006). Thus, to guaranteeaccess to food (Simon et al., 2003) and(Sanchez et al., 2005), reduce rural-urbanmigration and encourage sustainabledevelopment (Barber, 2003) and (Altieri, 2004),the processing of agricultural products likegrains and tubers or solid minerals like claysand feldspars into more valuable products bythe use of hammer mills must be encouragedand fostered.

Conventional hammer mills that are extensivelyemployed in the processing of solid mineralsand grains suffer from a number of weaknessesthat greatly hamper their productivity,efficiency and effectiveness. These weaknessesinclude the following:

a. The conventional hammer mill cannotproduce material whose particle size isless than 400m. For the most commonlyprocessed solid minerals like kaolin,dolomite and feldspar, the particle sizesproduced are relatively large and theycannot be directly used in thepharmaceutical, paint, textile, tyre,chemical, paper and glass industries or forgrains as flour to make bread, biscuit andfoo-foo for local consumption (Beintemaand Stads, 2004), and (Eyo, 2008).

b. The fineness of the particles produceddepend on the hole size of the screen sieveemployed. Large particles can block theholes of the sieve screen thereby, reducingthe output of the hammer mill.

c. Milling rates fall rapidly as the moisturecontent of the raw material increases.

d. To maintain the output, the screen sievesare continuously changed. Hence, itrequires the acquisition of a lot of

expensive accessories which cannot beproduced locally.

e. Excessive dust particles are usuallyreleased into the atmosphere wherehammer mills are operating. Thisconstitutes a health hazard for the humanoperators and environmental pollution forthe surrounding plants, animals andhuman communities.

The defects and shortcoming of currently usedhammer mills have meant that most hammermill operators and owners in Nigeria arerunning their businesses at marginal profitlevels. This is because virtually all the hammermills being utilized are old designs. Thesemachines were originally designed andmanufactured in Britain and the United States ofAmerica in the early 1930s (Lynch andRowland, 2005). They were brought intoNigeria by the tin mining companies in Jos andwere copied by local artisans. Since then, therehave been no significant improvements in theirdesigns or method of operation. The lack ofinnovation in the areas of design and operatingprinciples of hammer mills has constituted thegreatest hindrance facing the growth of solidminerals and grains processing industries inNigeria.

MATERIALS AND METHODMaterialsThe equipment used includes, hardness testingmachine, tensile testing machine, leitz massspectrophotometer, high powered metallurgicalmicroscopic, grinding machine, mounting press,polishing machine, oxyacetylene gas weldingmachine, lathe machine, veneer caliper, hacksaw, sand paper and grinding machine.

MethodCollection of SamplesSicaro Vegetable Oil Company PLC was usedas the case study for this research work becausethe company uses hammer mill for processingpalm kernel and soya bean seed into vegetableoil and soya bean oil. Scraped hammers were




collected from the breakdown hammer mill forfailure analysis tests. A total of five samples ofthe scraped hammers were collected for thedifferent failure analysis tests.

Preparation of Specimen for TestFive samples were collected from the failedhammer mill hammers (Plate 1).

Sample 2

Sample 3

Sample 4

Sample 5

Plate 1: Samples 1, 2,3,4,5Two test pieces were cut out to the requireddimension from each of the five hammerscollected for hardness test, microstructural test,tensile test and chemical composition test.These were turned with a lathe machine to around bar of uniform cross section of 28mmlength and 5mm diameter for the tensile test.This is shown in Plate2. A total of 10 tensile testsamples were machined.

Plate 2: Tensile test specimens

Five specimen from each of the hammers werelabeled specimens 1, 2, 3, 4, 5. These specimens

Sample 1

Sample 2

Sample 3

Sample 3

Sample 1




were untreated that is without heat treatment.The remaining five specimens were selected anddifferent heat treatments were done on them.The specimens were labeled specimen 1a, 2a,3a, 4a, and 5a respectively (Plate 2).

Specimens Ia was heated to red hot of about7000C without melting it using the heat fromoxyacetylene gas welding machine. The flamefrom oxyacetylene gas welding machine wasreduced to generate carbon which is allowed todiffuse in this specimen. This specimen wasimmediately dipped into oil and allowed to cool(carburized and quenched in oil). The samplewas also heated again but this time not to redhot of about 4500C and carbon was allowed todiffuse into the specimen. The sample wasdipped into oil and allowed to cool (carburizedand tempered). Specimen 1a was, therefore,heated to martensitic temperature, carburized,and tempered in oil.

Specimen 2a was heated to red hot of about7000C without melting it using the heat fromoxyacetylene gas welding machine. The flamefrom oxyacetylene gas welding machine wasreduced to generate carbon which is allowed todiffuse in this specimen. This specimen wasimmediately dipped into water and allowed towater quench (carburized and quenched inwater). The specimen was also heated again butthis time not to red hot to about 4500C andcarbon was allowed to diffuse into thespecimen. The specimen was dipped into waterand allowed to cool (carburized and tempered).Specimen 2a was, therefore, heated tomartensitic temperature, carburized, andtempered in water.

Specimen 3a was heated to red hot of about7000C without melting it using the heat fromoxyacetylene gas welding machine. The flamefrom oxyacetylene gas welding machine wasreduced to generate carbon which is allowed todiffuse in this specimen. This sample wasimmediately dipped into water and allowed towater quench (carburized and quenched in

water). Specimen 3a was, therefore, heated tomartensitic temperature, carburized, andquenched in water.

Tensile TestThe tensile testing machine used for this testwas the Extensiometer. The diagram ofextensiometer is shown in Plate 3.

Plate 3: ExtensiometerA plain graph sheet was worn round the rotatingdrum and held with a masking tape. Thespecimen was inserted into the pairs of thechuck and griped. The mercury which recordsthe force to zero extension was set to the zerolevel. Cursor was attached on the scale to thezero level. The wheel was rotated to introducethe force which expands/elongates thespecimen. As the wheel was rotated anotherperson directed the cursor and which mademarks on the graph following the direction ofthe mercury. When the specimen broke, therotation was stopped.

The gauge lengths are 28mm and the initialdiameters Di are 5mm. The final diameters afterthe breaking force were measured using thevermier caliper. The extensions were measuredfrom the graph. This was done by measuring thelength in millimeter using a ruler and dividingthe value measured by 16 which is themagnification of steel from the tensile graph.Note that every material has its ownmagnification from the tensile test graph.

On the vertical axis of the graph were measuredthe values of forces in kilo newton that is 1cmrepresents 2000N on the vertical axis. Thereforeeach division on the vertical axis represents200newtons. Assume here that toughness of the




material is the total area under a stress straincurve and that ductility is a measure of thepercentage elongation.The cross sectional area of the specimen iscalculated as;Area is calculated as 1 d2

4

Area = 1 x 3.142 x 5x54= 19.6mm2

Chemical Composition TestLeitz MPV-L Spectrophotometer was used todetermine the chemical composition of thespecimen. Heat was directed to two portions ofthe specimen and the chemical properties ofspecimen were analyzed by the Leitz MPV-LSpectrophotometer and the information read onthe computer screen and printed out. Plate 4shows the Chemical composition test specimenand Plate 5 shows the Leitz MPV-Lspectrophotometer

Plate 4: Chemical composition test specimen

Plate 5: Leitz MPV-L spectrophotometer

Hardness TestTwo specimens each were cut out from each ofthe hammers. Five specimens were not heattreated and taken as a control. Five otherspecimens were carried out using the followingheat treatments on them.

Specimen 2a was heated to red hot of about7000C without melting it using the heat fromoxyacetylene gas welding machine. The flamefrom oxyacetylene gas welding machine wasreduced to generate carbon which is allowed todiffuse in this specimen. This specimen wasimmediately dipped into oil and allowed to cool(carburized and quenched in oil).

Specimen 4a was heated to red hot of about7000C without melting it using the heat fromoxyacetylene gas welding machine. The flamefrom oxyacetylene gas welding machine wasreduced to generate carbon which is allowed todiffuse in this specimen. This specimen wasimmediately dipped into oil and allowed to cool(carburized and quenched in oil). The specimenwas also heated again but this time not to redhot of about 4500C and carbon was allowed todiffuse into the specimen. The sample wasdipped into oil and allowed to cool (carburizedand tempered). Specimen 4a was, therefore,heated to martensitic temperature, carburized,and tempered in oil.

Specimen 3a was heated to red hot 7000Cwithout melting it using the heat fromoxyacetylene gas welding machine. The flamefrom oxyacetylene gas welding machine wasreduced to generate carbon which is allowed todiffuse in this specimen. This specimen wasexposed and allowed to be air cool (carburizedand normalized).

Specimen 5a was heated to red hot (7000C)without melting it using the heat fromoxyacetylene gas welding machine. The flamefrom oxyacetylene gas welding machine wasreduced to generate carbon which is allowed todiffuse in this specimen. This specimen wasimmediately dipped into water and allowed tocool (carburized and quenched in water). The




sample was also heated again but this time notto red hot (4500C) and carbon was allowed todiffuse into the specimen. The specimen wasdipped into water and allowed to cool(carburized and tempered). Specimen 5a was,therefore, heated to martensitic temperature,carburized, and tempered in oil. Specimen 5awas quenched in water and tempered.

The Rockwell hardness testing machine (Plate6) was used for the research. The specimen wasintroduced into the anvil of hardness tester and

raised to touch the indenter. A minor load of 10kg was first applied by pressing the lever, whichcauses an initial penetration and holds theindenter in place. Then, the dial was set to zeroand the major working loads of 100kg taggedHRB in the conversion table were applied.Upon removal of the major load, the depthreading is taken while the minor load is still on.The hardness number may then be read directlyfrom the scale on the dial gauge.Plate 6: Rockwell hardness tester

RESULTS AND DISCUSSIONSResults of Tensile TestThe results for the tensile tests are presented in Tables 1 to 6 and their corresponding graphs are shownin Figures 1 to 2.

Table 1: Data for specimen 4 (untreated)Force (N) Extension (mm) Stress (N/mm2) Strain Type of stress0 0 0 0 Normal2000 0.625 102.04 0.022 Normal5200 1.19 265.3 0.043 Normal9100 2.38 464.3 0.085 Lower yield stress9600 2.13 489.8 0.076 Upper yield stress10000 3.56 510.2 0.13 Breaking stress10600 3.13 540.8 0.11 UTS

Plate 6: Rockwell hardness tester




Table 2: Data for specimen 5 (untreated)Force (N) Extension (mm) Stress (N/mm2) Strain Type of stress0 0 0 0 Normal2000 0.5 102.04 0.018 Normal4000 0.93 204.1 0.033 Normal7800 2.25 397.9 0.08 Lower yield stress8400 1.88 428.6 0.067 Upper yield stress9200 8.0 469.4 0.29 Breaking stress12000 6.25 612.2 0.22 UTS

Table 3: Data for specimen 3 (untreated)Force (N) Extension (mm) Stress (N/mm2) Strain Type of stress0 0 0 0 Normal2000 0.5 102.04 0.018 Normal4000 0.81 204.1 0.033 Normal7800 1.88 397.9 0.08 Lower yield stress8200 1.81 418.3 0.067 Upper yield stress9000 6.75 459.2 0.29 Breaking stress11800 5.63 602 0.22 UTS

Table 4: Data for specimen 3 (Quenched in water)Force (N) Extension (mm) Stress (N/mm2) Strain Type of stress0 0 0 0 Normal2000 0.31 102.04 0.011 Normal4000 0.44 204.1 0.016 Normal7000 1.19 357.1 0.043 Lower yield stress8200 0.94 418.4 0.034 Upper yield stress10400 5.7 530 0.203 Breaking stress11200 5.0 571.4 0.18 UTS

Table 5: Data for specimen 1 (Quenched in oil and tempered)Force (N) Extension (mm) Stress (N/mm2) Strain Type of stress0 0 0 0 Normal2000 0.5 102.04 0.018 Normal4000 0.88 204.1 0.031 Normal5200 1.6 265.3 0.057 Lower yield stress5800 1.3 295.9 0.046 Upper yield stress6800 8.3 346.9 0.296 Breaking stress8200 7.5 418.4 0.27 UTS

Table 6: Data for specimen 2 (Tempered in water)Force (N) Extension (mm) Stress (N/mm2) Strain Type of stress0 0 0 0 Normal2000 0.38 102.04 0.014 Normal4000 0.88 204.1 0.031 Normal5600 1.8 285.7 0.064 Lower yield stress6200 1.3 316.3 0.046 Upper yield stress6000 4.0 306.1 0.143 Breaking stress7000 3.6 451.1 0.13 UTS




Figure 1: Force/extension graph for data values for specimens

Figure 2: Stress/Strain graph for data values for specimens

DISCUSSION OF RESULTS OF TENSILETESTThe parameters which are of importance to theengineer during design construction in the

stress/strain curve are the ultimate tensilestrength, the yield strength, the percentageelongation and the percentage reduction in area.

0

2000

4000

6000

8000

10000

12000

14000

0 2 4 6 8 10

Forc

e (N

)

Extension (mm)

Specimen 4 (Untreated)



Specimen 3 (Quenched inwater)

Specimen 1 (Quenched inoil and tempered)

Specimen 2 (Tempered inwater)

0

100

200

300

400

500

600

700

0 0.1 0.2 0.3 0.4

Stre

ss (N

/mm

2 )

Strain




Specimen 3 (Quenchedin water)

Specimen 1 (Quenchedin oil and tempered)

Specimen 2 (Temperedin water)




Specimen 4 (untreated) gave the followingvalues: upper yield stress of 489.8N/mm2, loweryield stress of 464.3N/mm2, UTS of540.8N/mm2, ductility (elongation of 12.85%and percentage reduction in area of 37.7%).

Specimen 5 (untreated) gave the followingvalues: upper yield stress of 428.6N/mm2, loweryield stress of 397.9N/mm2, UTS of612.2N/mm2, ductility (elongation of 28.5% andpercentage reduction in area of 12.1%).

Specimen 3 (untreated) gave the followingvalues: upper yield stress of 489.8N/mm2, loweryield stress of 464.3N/mm2, UTS of602.N/mm2, ductility (elongation of 23.9% andpercentage reduction in area of 12.1%).

Specimen 3 (quenched in water) gave thefollowing values; upper yield stress of418.4N/mm2, lower yield stress of 357.1N/mm2,UTS of 571.4.N/mm2, ductility (elongation of20.0% and percentage reduction in area of51.0%).

Specimen 1 (quenched in oil and tempered)gave the following values: upper yield stress of295.9N/mm2, lower yield stress of 265.3N/mm2,UTS of 418.4N/mm2, ductility (elongation of29.6% and percentage reduction in area of12.1%).

Specimen 2 (tempered in water) gave thefollowing values: upper yield stress of316.3N/mm2, lower yield stress of 285.7N/mm2,UTS of 415.1N/mm2, ductility (elongation of15.4% and percentage reduction in area of35.7%).

It can be inferred here that heat treatmentreduced the UTS, upper yield and lower yieldstress and the ductility of the material. The

material that gave the highest UTS of612N/mm2 is specimen 5 (untreated) and thehighest ductility (elongation) 29.6% was givenby specimen 1 (quenched and tempered in oil).In the experiment conducted by Huang et al.(2009), the parameters recommended forhammer material is austenitic manganese steelpresented in Table 3. Table 4 shows that therequired yield stress for hammers material is394MPa and the UTS is 1229.75MPa. Theelongation (ductility) was given as 50%. Thesematerials tested did not attain theserecommended values. This means that anothermeans of strength improvement principle shouldbe applied that is alloying. The application of aproper alloy in its correct proportion andcontrolled heat treatment will improve thestrength of the material.

Discussion of the MicrostructuralExamination ResultsThe result of the microstructural result indicatesa multiphase internal structure of the material.This multiphase structure indicates that thematerial is made of many elements alloyedtogether and this is indicated by the manycolours in the structure. Ferrite indicated bywhite and pearlite indicated by black.

The untreated specimen indicated a loosestructure and that shows less hardness of thematerials. The heat treatment helped in reducingthe grain sizes and this is noticed in closeness ofgrains of the specimens heat treated. Specimen4 (quenched in oil and tempered) shows a muchcloseness of the grains to the boundaries. Thereis, therefore, the precipitation of iron andmanganese carbide, at grain boundariesfollowed by the appearance of a new constituentwhich extends to the interior of the grain.

The Results of Hardness TestThe results of hardness test presented in Table 1.7 and the corresponding graphs are shown in Figure 3to 5.




Table 7: Relationship between Rockwell and Brinell hardness numberSpecimen Rockwell Hardness

number (kg/mm2)Brinell Hardnessnumber (kg/mm2)

Specimen 2 70 122.5Specimen 3 75 132.5Specimen 4 79 142.5Specimen 5 quenched in water and tempered 77 137.5Specimn 4 (quenched in oil and tempered) 73 127.5Specimen 2 (quenched in oil) 71 122.5Specimen 3 (air cooled) 69 120

Figure: 3: Bar chart showing Rockwell values against specimen (control)

Figure 4: Bar chart showing Rockwell hardness number against specimen Heat treated

70

75

79

646668707274767880

Specimen 2 Specimen 3 Specimen 4Roc

kwel

l Har

dnes

s num

ber

Specimen (untreated)

Bar chart showing Rockwell Hardness Number againstspecimens (untreated)

Specimen 2

Specimen 3

Specimen 4

64

66

68

70

72

74

76

78

Spec 5temperedin water

Spec 4tempered

in oil

Spec 2Quenched

in oil

Air cooled

Roc

kwel

l Har

dnes

s Num

ber

Specimen Heat treated

Bar chart showing Rockwell hardness number against specimen Heattreated

Spec 5 tempered in water

Spec 4 tempered in oil

Spec 2 Quenched in oil

Air cooled




DISCUSSION OF HARDNESS TESTRESULTThe result of the Rockwell hardness testconducted shows that specimen 4 (untreated)has the highest Rockwell hardness number of 79(BHN of 142.5). Heat treatment reduced and theaffected the hardness of the materials. Specimen3 (air cooled) has the least Rockwell hardnessnumber of 69 (BHN of 120). This shows thatthe samples tested lacked the appreciablehardness for crushing. As stated by Huang et al.(2009), the recommended Brinell hardness

number for hammer mill hammers is BHN of600.

Therefore, the hammers tested should behardened to improve their hardness by alloying.Alloying will reduce the shock resistance andenhance abrasive (or wear) resistance. Heattreatment changes the internal structure,microstructure, with the resultant change inphysical, mechanical or metallurgicalproperties.

Figure 5: Relationship between Rockwell and Brinell hardness number for untreated specimensand heat treated specimens

115

120

125

130

135

140

145

65 70 75 80

Bri

nell

Har

dnes

s Num

ber

(kg/

mm

2 )

Rockwell Hardness Number (kg/mm2)

Brinell Hardness number(kg/mm2) Untreated

Brinell Hardness number(kg/mm2) Heat Treated




Chemical Composition ResultThe result of the chemical composition test is shown in Table 8.

Table 8: Chemical composition test result

Discussion of the Result of ChemicalComposition TestThe chemical composition result indicates thathammer mill materials are composed of thefollowing elements essential components:

Iron, Fe = 97.9%Carbon, C = 0.606%Manganese Mn = 0.587%Nickel, Ni = 0.061%Silicon, Si = 0.275%Chromium, Cr = 0.025%

From Table 1 it shows that the material iscomposed of a high carbon steel of low carbon

content. The range of carbon content for highcarbon steel indicated is between 0.55-1.8% C.A study conducted by Fadhula et al (2007)reported that the best material for the hammermill hammers is austenite manganese steel ofthe compositions see Table 2.3.

Iron, Fe = 81.96%Carbon, C = 1.059%Manganese Mn = 11.34%Nickel, Ni = 0.1366%Silicon, Si = 0.3694%Chromium, Cr = 0.1366%




The hammer mill hammers, therefore, need tobe alloyed to attain the compositions of austenicmanganese steel recommended by Huang et al.(2009), for hammer mill materials. There shouldbe controlled heat treatment so that theformation of austenite begins by theprecipitation of iron and manganese carbide atthe grain boundaries.

CONCLUSIONThis work ‘Analysis of Failure and PerformanceImprovement of Hammer Mill Hammers’involved testing the mechanical properties ofthe material using the destructive and nondestructive tests. The results of the differenttests conducted revealed that sample was madewith inferior or substandard material.

From Table 3, specimen 5 (untreated) has thehighest UTS of 612.2N/mm2 than the otheruntreated specimens and heat treated specimens.This shows that though the specimens weremade of the same materials but there weredislocations during the production processessince the materials were supposed to have thesame results in UTS, yield strength andductility. Specimen 1 (tempered in oil) has thehighest ductility and percentage elongation of29.6%. Specimen 4 (untreated) has the highestRockwell hardness number of 79.

This shows that the hammers were made withsubstandard material and therefore, lacked therequired mechanical properties. Therecommended material used for the manufactureof modern hammer mill hammers is theaustenitic manganese steel (ZGMn13-4) whichis a type of wear resistance material. The Brinellhardness number is about HB600 and theelongation is about 50% based on the tensile testresult. The unique properties of Hadfield’saustenitic manganese steel with composition1.2% carbon and 12-14% manganese are highstrength and high toughness, resistance to wearand heavy impact loading that makes the steelvery useful in various applications as rail road,grinding mill liners, crusher jaws and cones,impact hammer and even bullet proof helmets(Frank, 1986).

A standard industrial practice to strengthenHadfield’s austenitic manganese steel is bysolution annealing which is to heat-treat thematerial at 1000-10900C for up to 1 hourfollowed by a water quench (Taylor, 1986) and(Sant and Smith, 1985). This partialdecomposition of austenite depends on the timeand temperature of the tempering condition.

RECOMMENDATIONBased on the observations made in the research,the following measures which will improve theperformance improvement of the hammer millhammers are recommended:

Hammer mill hammer material should be madeof high strength, high toughness, resistance towear and heavy impact loading that will nullifythe impact failure and erosive wear.

To avoid hammer abrasion and erosion, we candesign non-clearance hammers, and decreasethe clearance between the impact granularityand the bottom surface of hammers.

Austenitic manganese steel of composition1.2% carbon and 12-14% manganese should berecommended for the manufacture of hammermill hammers. This is because this material hasthe desirable mechanical properties require for acrushing hammer.

Adequate and controlled heat treatment shouldbe applied to cause the solid solution of the ironand manganese carbide to be precipitated in thegrain boundaries of the pure austenite.

REFERENCESAdejumo, B. and Raji, A. (2007): “Technical

Appraisal of Grain Storage Systems in theNigerian Sudan Savannah”. AgriculturalEngineering International: The CIGRJournal Invited Overview, No. 11 vol. ix pp1-12.

Anifowoshe, T. (1990): “Food Production-problems and Prospects” Geo Journal 20(3): 243-247.




Barber, J. (2003): “Production, Consumption andthe World Summit on SustainableDevelopment”. Environment, Developmentand Sustainability, 5(1-2): 63-93.

Beintema, N. and Stads, G. (2004): “Sub-SaharanAfrican Agricultural Research: RecentInvestment Trends”. Outlook onAgriculture, 33 (4): 239-246.

Biewar, B. (1990). “Existing on-farm GrainStorage Facilities in Nigeria and SuggestedImprovements” Journal of AgriculturalMechanization in Asia, African and LatinAmerica, Vol.21, N0 .2, pp 58-60.

Clayton, W. (1958). “Secondary Vegetation andthe Transition to Savannah near Ibadan”.Journal of Ecology, 46 (2):217-238.

Dixon, J. Gulliver A. and Gibbon, D. (2011).“Farming Systems and Poverty: ImprovingFarmers Livelihoods in a Changing World”.FAO, Rome and the World BankWashington D.C.

Eyo, O. (2008), “Macroeconomic Environmentand Agricultural Growth in Nigeria”. WorldJournal of Agricultural Sciences. 4(6): 781-786.

Fadhila, R., Jaharah, A.G., Omar, M.Z., Haron,C.H.C., Ghazali, M.J., Manaf, A. andAzhari, C.H. (2007). “Austenite Formationof Steel-3401 subjected to Rapid CoolingProcess”. Journal of Mechanical andMaterial Engineering, vol. 2, No. 2. 150-153

FAOSTAT (2004): Food and AgricultureStatistical Database. faostat.fao.org.

Huang Jun-ping, ZHOU Hong-yi, BAI Zhan-wei,YIN YI-zhong (2009): Failure analysis ofcrush hammer based on damage fractureenergy. Journal of Chongqing University(English Edition) ISSN 1671-8224 8 (2)105-111.

Igbeka, J. and Olumeko, D. (1996): “An Appraisalof Village Level Grain Storage Practices inNigeria”. Journal of AgriculturalMechanization in Asia, Africa and LatinAmerica 27 (1): 29-33.

Jones, E. (1963): “The Forest Outliers in theGuinea Zone of Northern Nigeria” Journalof Ecology, 51 (2): 415-434.

Killick, (1990): “Markets and Government inAgricultural and Industrial Adjustment”.ODI Working Paper 3, London, Pp 11-15.

Lynch, A. and Rowland, C. (2005): “The Historyof Grinding”. Society of Mining, Metallurgyand Exploration, SME 2005, pp115-294.

Morgan, W. and Moss, R. (1965): “Savanna andForest in Western Nigeria”. Journal of theInternational African Institute 35(3): 286-125

Okpala, A. (1990): “Nigeria Population Growthand its Implications for EconomicDevelopment”. Scand Journal DevelopmentAltem, 9(4):63-77.

Olajire, J. (1991): “Evidence of Climatic Changein Nigeria based on Annual series ofRainfall of Different Amounts, 191-198”.Journal of climatic Change (Springer) 19(3): 319-330.

Pande, S., Harikrishnan, R., Alegbejo, M.,Muoghogho, K., Karunakar, R., and Ajayi,O. (1993): “Prevalence of SorghumDiseases in Nigeria”. International Journalof Pest Management, 39 (3): 297-303.

Sanchez, P., Swaminathan, M, Dobie, P. andYuksel, N. (2005): “Halving Hunger: It canbe done”. UN Millennium project 2005Task Force on Hunger, New York TaskForce on Hunger, New York UNDP andLondon: Earth scan.

Sci-Tech Dictionary (2003): “Hammer mill”McGraw-Hill Dictionary of Scientific andTechnical Terms. McGraw-Hill Companies,Inc, 2003. Answers.com 24 Oct 2009htt:///www.answers.com/topic/hammermill.

Simon, D., McGregor, D., Nsiah-Gyabaah, K.,and Thompson, D. (2003): “PovertyElimination, North-South ResearchCollaboration and the Politics ofParticipatory Development”. Developmentin Practice, 13 (1): 40-56.

Spangenberg, J. (2002): “InstitutionalSustainability Indicators: An Analysis of theInstitutions in Agenda 21 and Draft Set ofIndicators for Monitoring their Effectively”.Sustainable Development, 10 (1):103-115.

Taylor, J., Schober, T. and Bean, S. (2006):“African Cereal Grains” Journal CerealScience. 44 (1): 252-271.

analysis of failure and performance improvement of hammer

Documents