Running-In of Transmission Gears as a Reference for ImprovingGears Quality of Small and Medium Enterprises Products

Natalino Fonseca Da Silva Guterres1Department of Mechanical Engineering, Diponegoro University, Semarang2Department of Mechanical & Automotive Engineering of Pukyong National

UniversityJ1. Prof. Sudarto, Semarang, Jawa Tengah, Indonesia 50275

natalinofonseca81@gmail.com

Keywords: running-in, gears, surface roughness.

Abstract. The gears efficiency decreases due to load and unload contact,seals, lubricants, and bearings. One solution to minimize these losses isby reducing the viscosity of lubricants. This method will reduce thespeed loss. But the weight loss will increase. In order to avoid this,the ratio between the thickness of the layer of lubricant and surfaceroughness must be maintained, it can be met by smoothing gear surface.The purpose of this thesis is to analyze the influence of surfaceroughness on the running-in of gears, analyze the effect of surfacehardness on the running-in of gears and compare the quality of therunning-in between OEM products to local SME products. The testsconducted is surface roughness and chemical composition. Experimentsconducted on AHM gears and SMEs without treatment, proceed by grindingprocess and proceed by induction hardening. The process of running-inruns from 200-1200 rpm and remains at 10 kg load. During running-in,surface roughness is measured every several minutes. The coefficient offriction will be displayed on the screen automatically. Gears of SMEs hasthe highest coefficient of friction is 0.47 at 1200 rpm. While the lowestcoefficient of friction owned by SME products that proceed by grindingprocess is 0,32 at 200 rpm. SMEs gears proceed by grinding take thefastest running in 10 minutes at 1200 rpm. While SME products proceed byinduction hardening take the longest time in 80 minutes at 200 rpm. Gearsof SMEs with further treatment such as grinding and induction hardeninghas better running-in.

Introduction Gears and transmission gears are used to change the characteristics

of movement, good rotation motion changes to be linear, linear to therotation, or simply a change in the torque and speed of the shaft (roundto round). Transmission gears including an old invention which hasevolved over the centuries in terms of profile and complexity of thetransmission.

Current industry trends gears is focused on improving the efficiencyof transmission gears. The efficiency of transmission gears decreased due

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to the contact load and unloads seals, lubricants, and bearings. One wayto minimize these losses is to lower the viscosity of the lubricant.

The contact areas between the gears have a rectangular shape(rectangular) and to group them into contact problems line (line contactproblem).

Contact pressure and the contact load has an important role in thecoefficient of friction and power loss. This phase is crucial forcomponents in contact with each other in order to adjust, reduce miss-alignment and establish the proper clearance. In addition to giving aload and travel time, running-in phase is also determined by the qualityof the surface of the component before the start of this phase is given.Small and Medium Enterprises (SMEs) that produce transmission gears areexpected to produce gear that has a good quality surface roughness.

MethodologyThe study begins with the preparation of specimens gear Supra Honda

motorcycles of Honda Genuine Parts and products Small and MediumEnterprises (SMEs). Before conducting the experiment first measured theinitial surface roughness of gears in the contact area and identified thespecifications of each gear. Experiments conducted with variations of theinitial surface roughness and surface hardness on gear SME products. Theprocess of running-in runs of 200 until to 1200 rpm. During the running-in gears measured surface roughness at the contact area every minute. Thecoefficient of friction will be displayed on the screen automatically. Sothat the known value of surface roughness and friction coefficient for acertain time. After experiments analyzed the effect of surface roughnessand surface hardness of the running-in process gears.

Data ResultsChemical Composition

Of the test results of chemical composition that has been inanalyses concluded that the material composition of the steel materialcomposition SCM440H approached gear belonging to AHM.The Result Data of Running-InThe AHM product

Distance ofthe edge

tooth [mm]AHM

SMEs withouttreatment

SMEs withinductionhardening

1 80 61 812 79 60,5 78,53 79 59,5 77

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The tables 1 above are hardness test results it appears thathardness gears SMEs without treatment by 61 HRA almost evenly orhomogeneous at all points. After being subjected to induction hardeninghardness value can equal hardness AHM gear that is equal to 81 HRA, butonly as deep as 1 mm only.

The Result Data of Running-InThe AHM productTable 2 Data AHM product surface roughness after running-in at a speed of 200 rpm and a load of 10 kg.

Parameter Time [menit]0 10 20 30 50 70 90

Ra [µm] 0,586 0,457 0,367 0,342 0,303 0,296 0,243Rq [µm] 0,721 0,556 0,431 0,424 0,470 0,368 0,305

The coefficient of friction during the running-in gears AHMproducts with a speed of 200 rpm and a load of 10 kg is shown in thefigure below. From the graph shows that the coefficient of friction atfirst of 0.2 μm, rising gradually until steady state is reached 0.33 μmare at 90 minutes.

Figure 1 the coefficient of friction during the running-in the gearproduct AHM, 200 rpm 10 kg

AHM through gears running-in process at a speed of 600 rpm and aload of 10 kg was shown that the surface roughness of Ra trend decreaseswith increasing time of running-in. The value of the beginning roughnessRa is 0.550 μm and Rq is 0.662 lm. While the value of the final roughnessRa is 0.260 μm and Rq is 0.330 lm.

The coefficient of friction during the running-in gears AHMproducts with a speed of 600 rpm and a load of 10 kg. From the graphshows that the coefficient of friction at first of 0.21 μm, then rosegradually until steady state is reached in 40 minutes with steady statecoefficient of friction of 0.42 μm.through of the AHM gears running-in with the speed of 1200 rpm and a loadof 10 kg was shown that the surface roughness of Ra trend decreases with

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increasing time of running-in. The value of the beginning roughness of Rais 0.561 μm and Rq is 0.733 μm. While the value of the final roughness ofRa is 0.280 μm and Rq is 0.374 μm.

From the results of the three variable speed when made in one graphas in figure 4.4. At 200 rpm slope sloping surface roughness valuesdecrease, while at 600 rpm and 1200 rpm slope is very steep drop insurface roughness.

0 20 40 60 80 100 1200

0.20.40.60.8

Keka

sara

n [µ

m]

Figure 2 Surface roughness of Ra AHM gear on variations rpm

The SMEs Products Without TreatmentGears SMEs without treatment through a process running-in with a

speed of 200 rpm and a load of 10 kg. It appears that the trend ofsurface roughness of Ra decreases with increasing time of running-in. Thevalue of the beginning roughness of Ra is 0.868 μm and Rq is 1.317 μm.While the value of the final roughness of Ra is 0.398 μm and Rq is 0.623μm.

Gears SMEs without treatment through a process running-in with aspeed of 600 rpm and a load of 10 kg. It appears that the trend ofsurface roughness of Ra decreases with increasing time of running-in. Thevalue of the beginning roughness of Ra is 0.830 μm and Rq is 1,169 μm.While the value of the final roughness of Ra is 0.423 μm and Rq is 0,559μm.

Gears SMEs without treatment through a process running-in with thespeed of 1200 rpm and a load of 10 kg. It appears that the trend ofsurface roughness of Ra decreases with increasing time of running-in. Thevalue of the beginning roughness of Ra is 0.898 μm and Rq is 1,296 μm.While the value of the final roughness of Ra is 0.348 μm and Rq is 0.434μm.From the results of the three variable speed when made in one graph as infigure 4.8. At 200 rpm slope sloping surface roughness values decrease, while at 600 rpm and 1200 rpm slope is very steep drop in surface roughness.

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Figure 3 Surface roughness of Ra SMEs gears without treatment on thevariation rpm.

SMEs Products through a Grinding ProcessSMEs through gears grinding process after the running-in with a

speed of 200 rpm and a load of 10 kg. It appears that the trend ofdecreasing surface roughness of Ra. The value of the beginning roughnessof Ra is 0.410 μm and Rq is 0.567 μm. While the value of the finalroughness of Ra is 0.158 μm and Rq was 0.2 μm.

SMEs through gears grinding process through the process of running-in with a speed of 600 rpm and a load of 10 kg. It appears that the trendof decreasing surface roughness of Ra. The value of the beginningroughness of Ra is 0.473 μm and Rq is 0.609 μm. While the value of thefinal roughness of Ra is 0.212 μm and Rq is 0,312 μm.

SMEs through gears grinding process through the process of running-in at a speed of 1200 rpm and a load of 10 kg. It appears that the trendof decreasing surface roughness of Ra. The value of the beginningroughness of Ra is 0.390 μm and Rq is 0.481 μm. While the value of thefinal roughness of Ra is 0.259 μm and Rq is 0.326 μm.From the results of the three variable speed when made in one graph as infigure 4.12. At 200 rpm slope sloping surface roughness values decrease, while at 600 rpm and 1200 rpm slope is very steep drop in surface roughness.

0 500

0.5200 rpm600 rpm1200 rpmWaktu [menit]

Keka

sara

n pe

rmuk

aan

[µm]

Figure.4 surface roughness of Ra SMEs through gears grinding process onthe variation rpm

SMEs Products through A Process of Induction Hardening

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Roda gigi UKM melalui proses induction hardening setelah proses running-in dengan kecepatan 200 rpm dan beban 10 kg. Seperti terlihat pada tabel3 dibawah ini.

Parameter Time [menit]0 10 20 30 40 60 80

Ra [µm] 1,063

0,936

0,867

0,794

0,641

0,600

0,413

Rq [µm] 1,212

1,185

1,060

0,907

0,790

0,730

0,534

Gears SMEs through induction hardening process after the running-inwith a speed of 600 rpm and a load of 10 kg. As shown in Table 4 below.

Parameter Time [menit]0 10 20 30 40 50

Ra [µm] 1,061

0,600

0,492

0,433

0,398

0,296

Rq [µm] 1,178

0,848

0,556

0,538

0,427

0,400

Gears SMEs through induction hardening process after the running-inwith the speed of 1200 rpm and a load of 10 kg. As shown in Table 4below.

Parameter Time [menit]0 5 10 15

Ra [µm] 1,090

0,596

0,568

0,380

Rq [µm] 1,312

0,718

0,780

0,462

From the results of the three variable speed when made in one graph as inFigure 5. At 200 rpm slope sloping surface roughness values decrease, while at 600 rpm and 1200 rpm slope is very steep drop in surface roughness.

0 500

2

200 rpm600 rpm1200 rpm

Waktu [menit]

Keka

sara

n pe

rmuk

aan

[µm]

Figure 5 Surface roughness of Ra gears SMEs through the process ofinduction hardening on variations rpm.

The analysis Effects of Hardness

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Gears AHM product has a hardness which meet the internationalstandards of 80 HRA at the edge of the teeth and decreased hardnesstowards the center. The composition of the material is destined for thegears that require high hardness at the edge and tenacious in the middle.

Surface ProfileTo determine the surface topography changes gears during the running-

in taken samples of one specimen gears are SME products withouttreatment. Gears mounted not parallel to each other, so that no surfacein contact and there are not are in contact. It aims to ensure that thesurface roughness measurements are always performed at exactly the samepoint. Measurements were taken at the edge pitch and gears. Changes insurface topography on the pitch circle shown in Figure 6.

Figure 6 Changes in surface topography on the pitch circle of thegear SMEs.

On the pitch circle of the gear rolling contact occurs. Surfaceprofile changes that occurred only a few. On the outskirts of the gearchanges occur extremely large. It is caused by the sliding contact gear.Changes in surface topography on the edge of the gears is shown in Figure7.

Figure 7 Changes in surface topography on the edge of SMEs gear.

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Of the results of this study concluded that the gears SMEs throughthe process of grinding to get the most optimal results, are the smallestfriction coefficient and a running-in the fastest. Specifications SMEsthrough gears grinding process are presented in Table 5 below.Table 4.3 Specifications of research results SMEs Grinding gears

Hardness

[HRA]

Rotation

[rpm]

TheBeginni

ngFrictio

nCoefficient

Coefficient offriction SS

Longsteadystate[minutes]]

thebeginni

ngroughness [µm]

The endRoundeness [µm]

Treatment

61

200 0,18 0,32 60 0,41 0,158 Grinding at 800 rpm andfeeds 0,2 mm

600 0,2 0,38 30 0,473 0,212

1200 0,38 0,41 10 0,39 0,259Differences with SMEs without treatment 15.8% lower in the coefficient offriction and 16.7% shorter in running-in time.

ConclusionOf the results the following conclusion can be drawn that the surface

roughness values have an influence on the coefficient of friction. Thegears are high surface roughness values will cause higher the coefficientof friction. The gears SMEs that have not undergone treatment to have thehighest coefficient of friction of 0.47 with 1200 rpm (AHM of 0.42).While the lowest coefficient of friction is owned by gears SME productsthat have gone through the process of grinding that is 0.32 at a speed of200 rpm (AHM 0.33). Gears that have high hardness value will be longerreach steady state. SMEs through the gears grinding process take timefastest running-in that is 10 minutes at a speed of 1200 rpm (AHM for 15minutes). While SME products that have undergone a process of inductionhardening followed time-in the longest running of 80 minutes at a speedof 200 rpm (AHM for 90 minutes).In terms of running-in period and the coefficient of friction to achievesteady state, gears SMEs products that have undergone a process ofgrinding to be the most well even when compared with AHM product. But thequality of the gear is not only determined by two things, there arethings more important that is the surface hardness and toughnessparameters shelf life from the gears. It would be better if it is done atthe same treatment that is grinding and induction hardening which ofcourse would make the quality of the gear will be better.

ReferencesAGMA 906-A94: 1994.

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Akbarzadeh S., Khonsari M.M., 2011, “Experimental and theoritical investigation ofrunning-in,” Tribology International 44, pp. 92–100.

Akkurt S., 1995, “On the effect of surface roughness on wear of acetal-metal gear pairs,”Wear 184, pp. 107–109.

Amarnath M., Sujatha C., Swarnamani S., 2009, “Experimental studies on the effectsof reduction in gear tooth stiffness and lubricant film thickness in a spur geared system”,Tribology International 42, pp. 340-352.

Aslantas K., Tasgetiren S., 2004, “A study of spur gear pitting formation and lifeprediction”, Wear 257, pp. 1167–1175.

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Bergseth, E., Sjoberg, S., Bjorklund, S., 2012, ”Influence of real surfacetopography on the contact area ratio in differently manufactured spur gears”, TribologyInternational, Volume 56, pp. 72-80.

Blau, P.J., “On the nature of running-in, Tribology International, Volume 382005, Pages 1007-1012.

Dhanasekaran S., Gnanamoorthy R., 2008, “Gear tooth wear in sintered spur gearsunder dry running conditions,” Wear 265, pp. 81–87.

DIN EN ISO 4287: 1998.Evans, H.P., Snidle, R.W., Sharif, K.J., 2009, ”Deterministic mixed lubrication

modelling using roughness measurements in gear applications”, TribologyInternational 42, pp. 1406–1417.

Flodin, A., Andersson, S., 1997, “Simulation of mild wear in spur gears”, Wear207, pp. 16–23.

Hargreaves D.J., Planitz A., 2009, “Assessing the energy efficiency of gear oils via theFZG test machine”, Tribology International 42, pp. 918-925.

2, pp. 918-925.