Parametric Evaluation Of Ball Burnishing Process On Aluminium Alloy Roughness Of Al 6061 Using

Taguchi Method In Ball Burnishing Process

PRESENTED BYSANDEEP NAIR

CB.EN.P2MFG15018

ABSTRACT:Burnishing is a cold-working process in which plastic

deformation occurs by applying a pressure through a very hard and smooth ball or roller on a metallic surface.

Improvements in surface finish, surface hardness, wear resistance, fatigue resistance, yield and tensile strength and corrosion resistance can be achieved by the application of this process.

Machined surface by conventional process such as Turning and milling have inherent irregularities and defects like tool marks and scratches that cause energy dissipation (friction) and surface damage (Wear).

To Overcome These Complications, Conventional Finishing Processes Such As Grinding, Honing, And Lapping Have Been Traditionally Employed.

These methods essentially depend on chip removal to attain the desired surface finish, these machining chips may cause further surface abrasion and geometric tolerance problem especially if conducted by unskilled operators.

Burnishing process offers an attractive post-machining alternative due to its chip less and relatively simple operations

The burnishing process is made with the intention of improving the surface finish of some pieces that have been previously mechanized. It is a finishing and strengthening process.

INTRODUCTION: To ensure reliable performance and prolonged service life

of modern machinery, its components require to be manufactured not only with high dimensional and geometrical accuracy but also with high surface finish.

The surface roughness of engineering parts is a significant design specification that is known to have considerable influence on properties such as wear resistance and fatigue strength. Perfectly flat surface can never be generated.

Surfaces have always irregularities in the form of peaks and valleys. Processes by which surfaces are finished differ in its capabilities concerning finishing action, mechanical and thermal damage, residual stresses and materials.

It is seen in finishing process such as burnishing which can be achieved by applying a highly polished and hard ball onto metallic surface under pressure.

Besides producing a good surface quality, the burnishing process has additional advantages over machining processes, such as securing increased hardness, corrosion resistance and fatigue life as result of the produced compressive residual stress on the surfaces .

EXPERIMENTAL STEPUP:

TAGUCHI METHOD: Taguchi’s approach has been built on traditional concepts

of Design of Experiments (DOE), such as Full factorial, fractional factorial design and orthogonal arrays based on signal –to-noise ratio, robust design and parameter and tolerance designs.

DOE is a powerful statistical technique introduced by R.A. Fisher in England in 1920s to study the effect of multiple variables simultaneously .

The well known Taguchi technique is chosen and adopted in the present research work. In order to reduce the total number of experiments “Sir Ronald Fisher” has developed the solution: “Orthogonal Arrays”

The orthogonal array is a distillation mechanism by which the engineers can select the experimental process. The array allows the researcher engineer to vary multiple variables at one time and obtain the effects such that set of variables has an average and the dispersion.

Taguchi employs the design of experiments using specially constructed table, known as "Orthogonal Arrays” (OA) to treat the design process, such that the quality is build into the product during the product design stage.

This orthogonal array is chosen due to its capability to check the interactions among factors.The experimental results are then transferred in to a Signal to Noise (S/N) ratio.

The category the-lower-the-better was used to calculate the S/N ratio for surface roughness by using minitab 17 software.

Symbol parameter unit level1 level2 level3A Burnishing Kgf 17.1 34.2 42.75 ForceB speed Rpm 280 400 630C Feed mm/rev 0.056 0.1 0.125D Lubricants Kerosene SAE20 SAE20 W40 40With Graphite

Table.3.1-Desigh scheme of Experiment of Parameters and Level

Parameter Percentage Importance (Ball Burnishing)

EQUIPMENTS: Surface Roughness calculated using Digital

surface roughness tester.

S/N Ratio calculated using MINITAB 17 Software.

RESULTS AND DISCUSSIONS: The results, in terms of Surface Roughness were obtained

after conducting the burnishing test for all nine specimens. Each test specimen, indeed, represented one experiment in the orthogonal array (Table 5.1).

Parameter LevelExperiment No. A B C D1 1 1 1 12 1 2 2 23 1 3 3 34 2 1 2 35 2 2 3 16 2 3 1 27 3 1 3 28 3 2 1 39 3 3 2 1

Table.5.1-Experimental plan using L9 orthogonal array

The experimental results for burnishing test under the application of Four Parameter are summarized in Table 5.2.The results were analysed by employing Main effectt and the signal –to –noise ratio analyses.

The influence factor on surface roughness is feed ,then burnishing force and finally speed which as not much effect on surface roughness of alloy.

Table.5.2.-S/N Ratio for surface roughness [ smaller is better]

Experiment.no. Burnishing force Speed Feed Lubricant S.R S/N (kgf) (rpm) (mm/rev) (µm) Ratio 1 17.1 280 0.056 kerosene 0.287 10.932 2 17.1 400 0.1 SAE20W40 0.287 10.932 3 17.1 630 0.125 SAE20W40 0.326 10.327

4 34.2 280 0.1 SAE20W40 0.292 10.437 5 34.2 400 0.125 kerosene 0.327 10.303 6 34.2 630 0.056 SAE20W40 0.24 11.242 7 42.75 280 0.125 SAE20W40 0.337 10.104 8 42.75 400 0.056 SAE20W40(Gra) 0.299 10.346 9 42.75 630 0.1 Kerosene 0.364 9.631

Taguchi Analysis: C4 versus A, B, C :Response Table for Signal to Noise Ratios:(Smaller is better) Level A B C 1 10.473 10.327 11.242 2 10.932 10.346 10.104 3 9.571 10.303 9.631 Delta 1.362 0.043 1.611 Rank 2 3 1

321

11.25

11.00

10.75

10.50

10.25

10.00

9.75

9.50321 321

A

Mea

n of

SN

rat

ios

B C

Main Effects Plot for SN ratiosData Means

Signal-to-noise: Smaller is better

Fig.5.1-S/N Ratio of SR For Different Level

Response Table for means:

Level A B C 1 0.3000 0.3053 0.2753 2 0.2863 0.3043 0.3143 3 0.3333 0.3100 0.3300 Delta 0.0470 0.0057 0.0547 Rank 2 3 1

321

0.34

0.33

0.32

0.31

0.30

0.29

0.28

0.27321 321

A

Mea

n of

Mea

ns

B C

Main Effects Plot for MeansData Means

CONCLUSIONS: Database developed from the experimental analysis could be very

useful for the selection of best possible process parameters and conditions for finishing various machine components, economically.

Surface roughness up to 0.24 μm could be achieved by this process.

An optimum parameter combination for the minimum surface finish and maximum surface hardness was obtained by using the analysis of signal-to-noise (S/N) ratio. The combination of parameters and their levels for optimum surface roughness is A2B3C1D2 ( i.e. Burnishing force- 34.2 kgf, speed- 630 rpm, feed-0.056 mm/rev, lubricant- SAE 20W 40).

The experimental results confirmed the validity of the used Taguchi method for enhancing the burnishing performance and optimizing the ball burnishing parameters.

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turning and ball burnishing process”, Indian Journal of Engineering and material sciences, Vol.11, October (2004), pp.391-396

Adel Mahmood Hassan and Amer M.S. Momani,“Further improvements in some properties of shot peened components using the burnishing process”, International Journal of Machine Tools & Manufacture Vol.40 (2000) pp.1775–1786.

Aysun Sagbas, “Analysis and optimization of surface roughness in the ball burnishing process using response surface methodology and desirability function”,Advances in Engineering Software 42 (2011) 992–998

A.A. Ibrahim et.al., “Center rest balls burnishing parameters adaptation of steel components using fuzzy logic”, Journal of materials processing technology 209 (2009) 2428–2435.