A critical assessment of lubrication techniques in machining processes: a case for minimum quantity lubrication using vegetable oil-based lubricant

2013 ◽  
Vol 41 ◽  
pp. 210-221 ◽  
Author(s):  
Sunday Albert Lawal ◽  
Imtiaz Ahmed Choudhury ◽  
Yusoff Nukman
Author(s):  
Eduardo C Bianchi ◽  
Rafael L Rodriguez ◽  
Rodolfo A Hildebrandt ◽  
José C Lopes ◽  
Hamilton J de Mello ◽  
...  

Minimum Quantity Lubrication is an alternative technique to conventional techniques that are related to environmental sustainability and economic benefits. This technique promotes the substantial reduction of the amount of coolant employed in machining processes, representing a mitigation of risks to people’s health that are involved with the process. On the other hand, it has been reported in the literature that some problems of using the Minimum Quantity Lubrication technique can impair the grinding efficiency. One of these problems is associated with wheel clogging phenomenon, which is caused by inefficient chip removal from the cutting zone as well as from mixture of metal dust and oil accumulated on the wheel surface during grinding. If chips lodge inside the pores of the grinding wheel as machining progresses, they will adversely affect dimensional and geometric quality of final product. Also, this will require more frequent dressing. A solution for this problem can be an effective cleaning system of the abrasive wheel during grinding with the traditional Minimum Quantity Lubrication technique Assisted with Wheel Cleaning Jet. In this context and aiming to explore the various potential health, environmental and economic benefits that have been widely reported in the literature about the use of Minimum Quantity Lubrication technique in grinding, this study presents an application of the Minimum Quantity Lubrication technique at flow rates (30, 60 and 120 mL/h) and assisted with wheel cleaning jet (Minimum Quantity Lubrication + Assisted with Wheel Cleaning Jet) in plunge grinding of a hardened steel with an aluminum oxide wheel. Experiments were also carried out with traditional Minimum Quantity Lubrication (without wheel cleaning) and with the conventional coolant techniques for comparison. The output variables were geometrical errors (surface roughness and roundness) of the workpiece, diametric wheel wear, acoustic emission, vibration and tangential cutting force. Results showed that Minimum Quantity Lubrication + Assisted with Wheel Cleaning Jet (with wheel cleaning jet) not only outperformed the traditional Minimum Quantity Lubrication technique in all the parameters analyzed, but in some cases it proved to be compatible with the conventional coolant technique under the conditions investigated. Also, most of values of the output parameters tested decreased with increase in flow rate.


Author(s):  
Arul Kulandaivel ◽  
Senthil Kumar Santhanam

Abstract Turning operation is one of the most commonly used machining processes. However, turning of high strength materials involves high heat generation which, in turn, results in undesirable characteristics such as increased tool wear, irregular chip formation, minor variations in physical properties etc. In order to overcome these, synthetic coolants are used and supplied in excess quantities (flood type). The handling and disposal of excess coolants are tedious and relatively expensive. In this proposed work, Water Soluble Cutting Oil suspended with nanoparticles (Graphene) is used in comparatively less quantities using Minimum quantity lubrication (MQL) method to improve the quality of machining. The testing was done on Turning operation of Monel K500 considering the various parameters such as the cutting speed, feed and depth of cut for obtaining a surface roughness of 0.462μm and cutting tool temperature of 55°C for MQL-GO (Graphene oxide) process.


Author(s):  
Trung Kien Nguyen ◽  
Kyung-Hee Park ◽  
Patrick Y. Kwon

This paper studies the effect of various lamellar-type solid lubricants (graphite and hBN) that can be mixed into a lubricant to potentially improve the machinability of minimum quantity lubrication (MQL) machining. To examine this, the solid lubricants are classified into particles and platelets based on their aspect ratios as well as their respective sizes. In particular, the particles are classified into microparticles and nanoparticles based on their dimensions (average radius), while the platelets were classified, based on their average thickness, into two types: the “microplatelets” if the thickness is typically up to few tens of microns and the “nanoplatelets” if the thickness is well below a tenth of a micron (even down to few nanometers). Our previous work has shown that the mixture of an extremely small amount (about 0.1 wt. %) of the graphitic nanoplatelets and vegetable oil immensely enhanced the machinability of MQL machining. In this paper, many lubricants, each mixed with a particular variety of nano- or micro-platelets or one type of nanoparticles, were studied to reveal the effect of each solid lubricant on MQL machining. Prior to the MQL machining experiment, the tribological test was conducted to show that the nanoplatelets are overall more effective than the microplatelets and nanoparticles in minimizing wear despite of no significant difference in friction compared to pure vegetable oil. Consequently, the MQL ball-milling experiment was conducted with AISI 1045 steel yielding a similar trend. Surprisingly, the oil mixtures with the microplatelets increased flank wear, even compared to the pure oil lubricant when the tools with the smooth surface were used. Thus, the nanoscale thickness of these platelets is a critical requirement for the solid lubricants in enhancing the MQL machining process. However, maintaining the nanoscale thickness is not critical with the tools with the rough surfaces in enhancing the MQL process. Therefore, it is concluded that finding an optimum solid lubricant depends on not only the characteristics (material as well as morphology) of solid lubricants but also the characteristic of tool surface.


Author(s):  
Trung Kien Nguyen ◽  
Patrick Y. Kwon ◽  
Kyung-Hee Park

The lamellar-type solid lubricants are readily available in a form of platelets. The diameter and thickness of these platelets are typically up to tens of microns and few microns, respectively, which are classified as micro-platelets. Some of these platelets are also available as nano-platelets whose thickness is well below a micron (even to few nanometers). In the previous work, the vegetable oil mixed with nano-platelets was enormously effective for Minimum Quantity Lubrication (MQL) machining. Clearly, the micro-platelets are not as inexpensive. In addition, the mixtures with the micro-platelets are not as stable as those with the nano-platelets. This paper intends to find the effect of the thickness differential on these platelets in MQL machining. The tribometer test shows that the nano-platelets are much more effective than the micro-platelets in reducing wear without changing the friction. With the MQL ball mill experiment, the micro-platelets present in MQL oil increased the tool wear, even compared to the traditional MQL with pure oil only. Thus, the thickness of the nano-platelets holds an important characteristic to enhance MQL-based machining.


Author(s):  
Arunachalam Ramanathan ◽  
Sumaya Al Rumhi ◽  
Noor Al Hamimi ◽  
Shurooq Al Ajmi

Recently all environmental worries are calling for reducing the usage of fluids in machining operations. One of the promising solutions that appeared lately is minimum quantity lubrication (MQL). This research aimed to develop an eco-friendly cooling system for a lathe machine and assess its performance. After considering the customer needs, the needs were translated into engineering specifications in the conceptual design phase, and then the quality function deployment was developed. Three concepts were generated and evaluated considering the selection criteria, and a final concept was selected using the decision matrix method. Following this, a detailed design and fabrication of the subsystems such as the oil tank and a structure accommodate all the components. The developed system was tested on six different workpiece samples to compare the MQL system with the conventional one. In general, the MQL system resulted in lower surface roughness values as well as lower tool wear.


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