For obtaining better combination of properties some of the parameters such as ageing time, solutionization temperature, ageing temperature, retrogression temperature and retrogression time are chosen meticulously. Machining studies were conducted on as-cast and RRA treated samples. The influence of cutting parameters on the surface roughness is studied. The optimum cutting parameters are evaluated through Taguchi DoE.
International Journal of Mechanical Engineering and Technology (IJMET) Volume 11, Issue 1, January 2020, pp 16-22, Article ID: IJMET_11_01_003 Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=11&IType=1 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 © IAEME Publication INFLUENCE OF CUTTING PARAMETERS ON SURFACE ROUGHNESS OF AS-CAST AND RRA TREATED AA7075 - A COMPARATIVE STUDY D Venkatesh, N D Prasanna, *Balasubramanya H S, Sanjith Girish Kamath, Daruk Lulla Ramaiah Institute of Technology, Bangalore, India *Corresponding Author: baluhs.md@gmail.com ABSTRACT Abundantly available aluminium is being used in various applications such as air craft, automotive industry etc due to its high specific strength and good corrosion resistance To achieve desired results, knowledge of the manufacturing process employed and behavior of metal under various working conditions are utmost important Several engineering applications such as fly motors, airframes, space transports, hypersonic rockets and remote ocean submersibles, and so forth demands materials with tailored set of properties that can't be obtained by employing the ordinary solid materials There is a need for lightweight materials which exhibit high strength, stiffness and high wear resistance which are primarily required in structural, aerospace and automotive industries In present work a sincere attempt has been made to study some of the important properties of heat treatable AA7075 aluminium alloy subjected to an heat treatment procedure known as Retrogression and Re-ageing (RRA) to achieve property enhancement For obtaining better combination of properties some of the parameters such as ageing time, solutionization temperature, ageing temperature, retrogression temperature and retrogression time are chosen meticulously Machining studies were conducted on as-cast and RRA treated samples The influence of cutting parameters on the surface roughness is studied The optimum cutting parameters are evaluated through Taguchi DoE Keywords: Rattan fiber, composites, manufacturing, car spoiler Cite this Article: D Venkatesh, N D Prasanna, Balasubramanya H S, Sanjith Girish Kamath, Daruk Lulla, Influence of Cutting Parameters on Surface Roughness of asCast and RRA Treated AA7075 - A Comparative Study International Journal of Mechanical Engineering and Technology 11(1), 2020, pp 16-22 http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=11&IType=1 INTRODUCTION 7xxx series lightweight aluminium are wide used in applications such as aviation, marine and defence due to their superior mechanical properties The several investigation carried out by researchers focuses on casting of alloy and evaluation of its composition, heat treatment of alloy, retrogression and re-aging of the above alloys, Corrosion studies, Impact test, http://www.iaeme.com/IJMET/index.asp 16 editor@iaeme.com Influence of Cutting Parameters on Surface Roughness of as-Cast and RRA Treated AA7075 - A Comparative Study microstructure analysis with optical microscope (OM), evaluation of mechanical properties, wear studies using optical and scanning electron microscopes, analysis of results and drawing conclusions AA 7075 is an heat treatable alloy is used in the present investigation If this alloy is subjected to heat treatment, improvement in some of the properties has been observed as suggested in some of the literature The surface finish is a critical factor in the production of machine components The surface roughness affects wear resistance and fatigue strength The efficiency of the metal cutting activity is constrained by the surface quality For light weight components and structures aluminium and magnesium are considered In aerospace applications Al-Zn castings are widely used due to their excellent combination of properties such as better castability, low thermal expansion coefficient, better strength-toweight ratio, and energy required for recycling is less Wallace et al started conducting investigation on retrogression and re-ageing in 1980, which aims out at modifications in the existing method so as to extend it to bigger parts [1] they have Also stressed on improved stress corrosion cracking resistance and strength for T6 levels for the process condition at the second retrogression hardening peak Retrogression at lower temperatures took around 360 sec to 180 min, which has influence on the properties so as to be used for bigger section parts ES-Said O S et al [2] Considered the Aluminium alloy 2024 for the investigation, subjecting it to solution treatments at 495, 505, and 515°C followed by quenching it in water It was then artificially aged at 190 and 208°C Hardness, tensile tests, Impact and fatigue tests were carried out on the heat treated alloys Based on tensile test results, fatigue tests (bendingrotation test machine) were carried out The best combination of property is seen for solution temperature of 505°C and ageing temperature of 208°C for h Taguchi strategy is a marvelous statistical framework It gives basic, proficient and orderly ways to deal with quality and cost Taguchi technique is productive strategy for planning process that works reliably and ideally over a range of conditions In present study, Taguchi DoE is used for optimizing the process parameters with only a small number of experiments [6] Taguchi design methodology optimizes the process parameters to improve the quality of parts that are fabricated Taguchi's strong plan strategy is an integral asset for the structure of an excellent framework [7] Since good surface finish is one of the important requirement in aerospace application, the present study aims at optimizing the cutting parameters Hence machinability study on this material has been carried out Trial ware conducted for as-cast, T6 temper and RRA heat treatment T6 treatment is conducted at a solutionizing temperature of 460ºC for two hours followed by water quenching at 120ºC for twenty-four hours Later it is being followed by RRA heat treatment Retrogression is carried out at 200ºC for fifty followed by water quenching and reheating the specimen at 120ºC for twenty-four hours Mechanical tests and surface roughness tests were carried out for a batch of as-cast, T6 temper and RRA treated examples The aim of the current investigation is to study the effect of cutting parameters on surface roughness on as cast and Retrogression and Re-Aged specimen and to determine the optimum cutting parameters to minimize surface roughness when machined on a conventional lathe http://www.iaeme.com/IJMET/index.asp 17 editor@iaeme.com D Venkatesh, N D Prasanna, Balasubramanya H S, Sanjith Girish Kamath, Daruk Lulla EXPERIMENTAL DETAILS The alloy chosen for this work is AA 7075 (Al-Zn-Mg) alloy It is one of the high strength alloys that can be easily heat treated The chemical composition of this alloy and its properties are given in the Table and Table Table Chemical composition of Aluminium alloy (AA7075) Table Properties of AA7075 alloy 2.1 Fabrication Setup The melting unit is shown in Fig is an electric resistance-heating furnace of 4KW heating capacity, with a controller to monitor the temperature within ±20 C accuracy The furnace can attain a maximum temperature 12000 C The melt temperature was maintained at 8100 C Figure Melting furnace For the development of the composites, AA7075 alloy ingots were first melted in a electrical resistance melting furnace in a graphite crucible The melt was stirred with a graphite stirrer continuously During stirring, speed was increased continuously till vortex was created for the homogeneous mixing of the particles in the matrix Degassifier in powdered form was added to the molten metal to remove entrapped gases Scum powder is added to the melt to remove the impurities collected at the top surface Molten metal was poured in the precoated-preheated cast iron molds and allowed to cool in air at room temperature Samples were prepared for characterization of the composite http://www.iaeme.com/IJMET/index.asp 18 editor@iaeme.com Influence of Cutting Parameters on Surface Roughness of as-Cast and RRA Treated AA7075 - A Comparative Study 2.2 Heat Treatment Heat treatment is carried out in stages namely (a) Solution heat treatment and age hardening (T6 temper) (b) Retrogression and Re-aging (RRA) As cast specimen are subjected to treatment temperature of 460°C for a duration of hours It is followed by quenching in water bath maintained at 60°C with the time delay less than 15 seconds The specimens were then subjected to age hardening treatment to improve hardening properties The specimens were subjected to precipitation heat treatment at a temperature of 120°C for a duration of 24 hours The specimens were then quenched again in water bath maintained below 600C The specimens were then subjected to retrogression heat treatment in a furnace maintained at 200°C The duration of 50min was maintained The specimens were again quenched in water bath maintained below 60°C This is followed by re-aging heat treatment process in Electrical muffle furnace at 120°C for a duration of 24 hours The specimens were then quenched in water bath maintained below 60°C 2.3 Machining Studies The experiments were designed based on three levels and three factors These experiments were conducted according to the Taguchi's beta structure and L9 array The experiments were conducted by employing conventional lathe HSS was used as the cutting tool material for machining the work pieces The work piece used has a dimension of diameter 22 mm and length of 110 mm RESULTS AND DISCUSSIONS 3.1 Machinability Tests The machinability tests were conducted as per Taguchi’s experimental style and L9 orthogonal array shown in Table.3 Cutting parameters like speed, feed rate and depth of cut were varied and surface roughness was measured for each trial for as cast and RRA heat treated samples and compared Relation between input and output parameters was studied Table Cutting conditions and response for as-cast sample ANOVA considering cutting parameters as input and surface roughness as output for as cast and RRA heat treated samples shows the influence of various cutting parameter on surface roughness, which is provided in Table and Table http://www.iaeme.com/IJMET/index.asp 19 editor@iaeme.com D Venkatesh, N D Prasanna, Balasubramanya H S, Sanjith Girish Kamath, Daruk Lulla Table ANOVA table for surface roughness of as-cast sample Table 5:ANOVA table for surface roughness of RRA samples (b) % contribution % contribution (a) Figure (a) and (b) Parameter contribution for as-cast RRA treated sample (%) Fig 2(a) shows the contribution of cutting parameter on surface roughness for as-cast specimen It is found that feed rate has the significant parameter contributing 83.38% on surface roughness It is followed by DOC Speed has least significant effect on roughness Fig 2(b) demonstrates the contribution of cutting parameters on surface roughness of RRA test sample It is found that feed rate has the most significant impact on the yield contributing to 48.65% Cutting force found to be least significant The higher contribution of error for RRA samples indicates that special care needs to be taken in carrying out RRA in industry These outcomes can be utilized to ideally decide the best arrangement of machining parameters and additionally device geometry particular so as to accomplish the most ideal surface finish http://www.iaeme.com/IJMET/index.asp 20 editor@iaeme.com Influence of Cutting Parameters on Surface Roughness of as-Cast and RRA Treated AA7075 - A Comparative Study Figure 3(a) Main effect plot for as-cast sample Figure 3(b) Main effect plot for RRA sample From Fig 3(a) shows the evident that the S/N ratio is more in the event of feed rate has a significant effect on surface roughness for both alloy and the alloy subjected to RRA treatment From this the optimum combination of the cutting parameters obtained are as shown in Table This combination can be employed to control over surface roughness Table Optimum parameter values for as-cast and RRA sample CONCLUSIONS The results of the investigation carried out to study the influence of cutting parameters on surface roughness of as cast and RRA treated AA 7075 as follows The alloy was fabricated successfully through stir casting route The samples are subjected to RRA treatment The prepared samples are turned on a conventional lathe according the cutting parameters selected from array From the machinability studies conducted using L9 orthogonal array Machinability (as indicated by surface roughness) of the AA7075 alloy deteriorates on heat treatment and the feed-rate has the maximum impact on surface roughness; as such the required surface smoothness can be obtained by a proper control of the feed-rate Main effect plot is drawn considering the SN ratio reveals the contribution of cutting parameters on surface roughness It was found that slope obtained for the feed rate is high compared to other parameters ANOVA technique shows the contribution of cutting parameters on surface roughness It is found that feed rate offers significant effect on surface roughness Feed rate contributes 83.38% of total yield for as cast and 48.65 for RRA treated condition, which is very important aspect to be considered in aerospace applications to maximize productivity REFERENCES [1] Wallace, W., Beddoes, J.C and Malherbe, M.C., Can Aero & Space Journal, Vol 27, No 3, 1981, pp 222-232 [2] ES-Said O S, Frazier W E, Lee E W The effect of retrogression and re-Ageing on the properties of 7249 aluminium alloy [J] JOM, 55(1): 2003, pp 45−48 http://www.iaeme.com/IJMET/index.asp 21 editor@iaeme.com D Venkatesh, N D Prasanna, Balasubramanya H S, Sanjith Girish Kamath, Daruk Lulla [3] Vinod Kumar Vankantia, Venkateswarlu Gantab, “Optimization of process parameters in drilling of GFRP composite using Taguchi method” Journal of Material Research and technology (JMRT)-2013 [4] Vladimir Aleksandrovich Rogov, Ghorbani Siamak “Optimization of Surface Roughness and Vibration in Turning of Aluminium Alloy AA2024 Using Taguchi Technique” International Journal of Mechanical, Aerospace, Industrial and Mechatronics Engineering (IJMAIME)- Vol:7, No:11, 2013 [5] P.L Srinivasamurthy, B.N Sarada, Karthik B.S, Shamanth S Holla “Effect of Retrogression and Reaging Heat Treatment on Microstructure and Corrosion Properties of Al-7075” International Journal of Innovative Research in Science, Engineering and Technology (IJIRSC)-Vol 2, Issue 11, November 2013 ISSN: 2319-8753 [6] S Thamizhmanii, S Saparudin, S Hasan “Analyses of surface roughness by turning process using Taguchi method” Journal of Achievements in Materials and Manufacturing Engineering (JAMME)- Volume 20 Issues 1-2, January-February 2007 [7] Saha A, Mondal S C “Optimization of process parameters in submerged arc welding using multi-objectives Taguchi method” 5th International & 26th All India Manufacturing Technology, Design and Research Conference (AIMTDR 2014) December 12th–14th, 2014, IIT Guwahati, Assam, India [8] Ng Guan yao, Mohd warikh bin abd rashid, b Zolkepli “ Effect of retrogression medium to the mechanical properties of Aluminium alloy 7075”, Applied Mechanics and Materials, Vol 165 , Issue 2012, pp 6-11 [9] Deepak Singla1, S.R Mediratta2 “Effect of load and speed on wear properties of al 7075fly ash composite material”, International Journal of Innovative Research in Science, Engineering and Technology, Vol 2, Issue 5, May 2013 [10] T Pratheep Reddy, N Amara Nageswara Rao “Wear Optimization of Al/Sic/Gr Hybrid MMC Using Taguchi and ANOVA”, International Journal of Innovative Research in Science, Engineering and Technology, Vol 3, Issue 11, November 2014 http://www.iaeme.com/IJMET/index.asp 22 editor@iaeme.com ... as- cast sample ANOVA considering cutting parameters as input and surface roughness as output for as cast and RRA heat treated samples shows the influence of various cutting parameter on surface. .. Cutting Parameters on Surface Roughness of as- Cast and RRA Treated AA7075 - A Comparative Study 2.2 Heat Treatment Heat treatment is carried out in stages namely (a) Solution heat treatment and. . .Influence of Cutting Parameters on Surface Roughness of as- Cast and RRA Treated AA7075 - A Comparative Study microstructure analysis with optical microscope (OM), evaluation of mechanical