Elsevier

Journal of Cleaner Production

Volume 19, Issues 17–18, November–December 2011, Pages 2049-2056
Journal of Cleaner Production

Evaluation of vegetable based cutting fluids with extreme pressure and cutting parameters in turning of AISI 304L by Taguchi method

https://doi.org/10.1016/j.jclepro.2011.07.013Get rights and content

Abstract

Many problems such as health and environment issues are identified with the use of cutting fluids (CFs). There has been a high demand for developing new environmentally friendly CFs such as vegetable based cutting fluids (VBCFs) to reduce these harmful effects. In this study, performances of six CFs, four different VBCFs from sunflower and canola oils with different ratios of extreme pressure (EP) additives, and two commercial types of CFs (semi-synthetic and mineral) are evaluated for reducing of surface roughness, and cutting and feed forces during turning of AISI 304L austenitic stainless steel with carbide insert tool. Taguchi’s mixed level parameter design (L18) is used for the experimental design. Cutting fluid, spindle speed, feed rate and depth of cut are considered as machining parameters. Regression analyses are applied to predict surface roughness, and cutting and feed forces. ANOVA is used to determine effects of the machining parameters and CFs on surface roughness, cutting and feed forces. In turning of AISI 304L, effects of feed rate and depth of cut are found to be more effective than CFs and spindle speed on reducing forces and improving the surface finish. Performances of VBCFs and commercial CFs are also compared and results generally show that sunflower and canola based CFs perform better than the others.

Introduction

In metal cutting industry, cutting fluids (CFs) have a crucial importance among machining factors, due to their lubricant, cooling and chip removal properties. Functions such as improving tool life and machining process efficiency, enhancing surface integrity and part accuracy, reducing cutting forces and vibrations are obtained by using CFs.

Mineral, synthetic and semi-synthetic CFs involve in the ecological cycle with air, soil and water and their toxicity effect damages the ecosystem (Birova et al., 2002). Especially when CFs evaporate and distribute as a vapour and micro particles, they cause serious health problems such as lung cancer, respiratory diseases, dermatological and genetic diseases (Bennett, 1983). Vegetable based cutting fluids (VBCFs), minimum quantity lubrication (MQL) and near dry machining have higher potential of use under these limitations. In MQL, consumption of the CFs is reduced and the MQL has been used extensively in the literature (Marksberry, 2007, Fratila, 2009, Sanchez et al., 2010, Fratila and Caizar, 2011). VBCFs are environmentally friendly, renewable, less toxic and they reduce the waste treatment costs due to their inherently higher biodegradability. Machining industries concerned for development of preventive legislation and the increase interest for almost green products reduce the soil pollution by biodegradability which makes the manufacturing processes as a clean process (Alves and Oliveira, 2006). Biodegradability is the most important measure of the environmental compatibility of CFs. Alves and Oliveira (2008) developed a new CF from castor oil and carried out a biodegradation test for the CF which was carried out in dark at 20–25 °C for 28 days. In the biodegradability test, the CF exhibited high degradation rates and mineral oil were degraded under these conditions to 20–60% thus, mineral oil was not regarded as readily biodegradable (Alves and Oliveira, 2008). In an another study, it was reported that vegetable based synthetic ester and rapeseed vegetable oil had 100% biodegradable, while neat type of cutting oil had 20–30% biodegradable (Wakabayashi et al., 2003). These advantages of VBCFs make them better alternative lubricants as compared to mineral, synthetic and semi-synthetic CFs (Shashidhara and Jayaram, 2010, Ozcelik et al., 2011). However, VBCFs have low oxidation and thermal stability which might reduce their potential as industrial lubricants. On the contrary, formulated VBCFs with extreme pressure (EP) additives in comparison to other types of CFs displayed a lower coefficient of friction, equivalent scuffing load capacity and better pitting resistance in the cutting zone (Fox and Stachowiak, 2007).

Chemical additives used in the composition of CFs have a wide variety of functions. The most important ones of these functions can be considered as lubrication with EP, emulsifiers, corrosion prevention, pH regulation, binding, anti-foaming, odour prevention, improving the flash point, spreading and wetting. Performances of CFs with EP additives are generally expected to be better in terms of reducing tool wear, surface roughness and cutting forces, improving surface integrity, part accuracy and tool life with respect to CFs without EP additive(s). Jayal and Balaji (2009) studied effects of different CF application methods on tool wear during machining of AISI 1045. Rao and Srikant (2006) investigated for role of different ingredients in CFs. The emulsifier of sodium petroleum sulphonate (SPS) was mixed in different proportions with the oil and lubrication-cooling properties were tested. The rise in the content of SPS increased kinematic viscosity, thermal conductivity, pH and decreased flash and fire points. The results indicated that main properties of CFs improved with increase in the emulsifier additive of SPS. Srikant et al. (2009) explored the role of emulsifier on the effectiveness of the CF by measurements of cutting temperatures, cutting forces, tool wear and surface roughness. All performance criterions showed better performance with an increase in the emulsifier content up to 15% but hardly any improvements were observed after that. Xavior and Adithan (2009) studied performance of CFs (coconut oil, emulsion and neat cutting oils) during turning of AISI 304 with carbide tool. Tool wear and surface roughness were measured as a performance criterion. Taguchi’s experimental method and ANOVA were applied and results indicated that coconut oil performed better than the other two CFs. Ozcelik et al. (2011) investigated for four CFs including two different VBCFs developed from refined sunflower oil, and commercial semi-synthetic and mineral CFs for surface roughness during drilling of AISI 304 with HSSE tool. Comparison of performance results showed that VBCFs were better than commercial types of CFs. Clarens et al. (2004) compared the relative performance of vegetable and petroleum base CFs using the tapping torque test method. The performance of naphthenic mineral oil, a 50/50 blend of naphthenic and paraffinic mineral oil, soybean oil and canola oil (75% of oleic content) were compared. They were tested as straight CFs, formulated as soluble and semi-synthetic CFs, to understand the impacts of emulsification on base oil performance. Canola and soybean straight CFs featured similar efficiencies and soybean based CF showed higher efficiency in the semi-synthetic form. It was observed that an emulsion particle size had an effect on tapping torque efficiency.

Commercial mineral and synthetic based CFs are widely used in modern manufacturing industry. Today, investigation of the VBCFs performances in machining is well established (Ozcelik et al., 2011, Jayal and Balaji, 2009, Xavior and Adithan, 2009, Clarens et al., 2004). Unfortunately, limited work has been published regarding the development of VBCFs for machining and performance of EP additives in machining. The purpose of this study is to investigate the role of EP additive on VBCFs in terms of surface roughness (Ra), cutting and feed forces (Fc and Ff) during turning of AISI 304L. Regression, S/N ratio and ANOVA analysis are carried out to obtain significant parameters influencing on surface roughness, cutting and feed forces.

Section snippets

Experimental details

In this study, AISI 304L with a Vickers hardness of 315 is used as a workpiece material. Dimension of the workpiece is Ø80 mm × 250 mm. The measured values for chemical composition of workpiece are given in Table 1. Machining tests are performed by single point turning of AISI 304L steel in the cylindrical form. In the experiments, Tezsan 7.5 kW maximum power universal lathe is used. Tests are conducted with titanium nitride (TiN) coated cemented carbide inserts which reduces coefficient of

Statistical analyses of experimental results and discussion

Analyses of S/N and variance (ANOVA), regression equations and confirmation tests are applied for statistical analyses of experimental results. An analysis of S/N is important for optimum points. The objective of ANOVA is to investigate which design parameters significantly affect for the surface roughness, and cutting and feed forces. Regression equations are developed for prediction of responses and confirmation tests. The level of confidence for the analysis is 95% (the level significance is

Conclusions

This study focuses on Taguchi experimental method for investigating of influence of the new developed VBCFs with EP on the surface roughness and forces during turning of AISI 304L. In the turning experiments, different spindle speed, feed rate and depth of cut values as machining parameters and VBCFs with 8% and 12% of EP are utilized. Multiple regression analysis is performed to indicate the fitness of experimental measurements. Regression models obtained from the surface roughness (R2 > 0.98),

Acknowledgement

The author thanks to TUBITAK for supporting of this project (project no: 107M164).

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