Conventional Minimum Quantity Lubrication Research Articles

Flank Wear Characterization in Aluminum Alloy (6061 T6) With Nanofluid Minimum Quantity Lubrication Environment Using an Uncoated Carbide Tool

This study is focused on the categorical analysis of flank wear mechanisms in end milling of aluminum alloy AA6061 with minimum quantity lubrication (MQL) conditions using nanofluid. Wear mechanisms for the water-based TiO2 nanofluid with a nanoparticle volume fraction of 1.5% are compared with conventional oil-based MQL (0.48 ml/min and 0.83 ml/min) using an uncoated cemented carbide insert. Micro-abrasion, micro-attrition, and adhesion wear leading to edge chipping are identified as the main wear mechanisms. Aluminum deposits on the tool flank surface are observed. Results show that the water-based nanofluid shows potential as a capable MQL cutting media, in terms of tool wear, replacing the conventional oil-based MQL.

Improving minimum quantity lubrication in CBN grinding using compressed air wheel cleaning

The application of minimum quantity lubrication (MQL) in grinding has emerged as an alternative for reducing the abundant flow of cutting fluids, thus achieving cleaner production. Although considered an innovative technique in grinding operations, its widespread application is hindered due primarily to the high heat generation and wheel pore clogging caused by machined chips, harming the final product quality and increasing tool wear on the machine. This study sought to improve MQL use in grinding. In addition to the conventional MQL injected at the wheel/workpiece interface, a compressed air jet was used to clean the mixture of MQL oil and machined chips from clogged wheel pores. Experiments were conducted using external cylindrical plunge grinding on AISI 4340 quenched and tempered steel, and a vitrified cubic boron nitrite (CBN) wheel. The cooling-lubrication methods employed were the conventional flood coolant application, MQL (without cleaning), and MQL with a cleaning jet directed at the wheel surface at different angles of incidence. The main goal of these experiments was to verify the viability of replacing the traditional abundant flow of cutting fluid with MQL and wheel cleaning. The analyses were conducted by measuring the following output variables of the process: workpiece surface roughness and roundness errors, diametrical wheel wear, acoustic emission generated by the process, and metallographic images of the ground surface and subsurface. Results show the positive effects of implementing the cleaning jet technique as a technological improvement of minimum quantity lubrication in grinding in order to reduce the usage of cutting fluids. The MQL technique with cleaning compressed air jet, for a specific angle of incidence (30°), proved to be extremely efficient in the improvement of the surface quality and accurate workpiece shape; it also reduced wheel wear when compared to the other cooling-lubrication methods that were tested (without a cleaning jet).

Temperatures in fine grinding with minimum quantity lubrication (MQL)

Minimum quantity lubrication (MQL) is a promising new fluid delivery technique in grinding. However, the thermal behaviour of the process under such cooling conditions remains unclear. This work reports on the results of a recent investigation of MQL in fine-cut plane surface grinding. The experimental study considered three conditions: conventional low pressure fluid delivery, dry grinding and MQL delivery. Common steels EN8, M2 and EN31 were ground with a general purpose alumina wheel. Conventional fluid used was a general purpose 5% by volume emulsion; MQL fluid was a general purpose machining oil. Grinding temperatures were measured using the single-pole thermocouple method. Grinding temperatures obtained from experiment are compared with those predicted from theory. Results obtained demonstrate that MQL can deliver a comparable thermal performance to conventional flood delivery under the conditions investigated. Grinding kinematics are discussed to explain the outcomes and to improve understanding of MQL grinding performance.

An investigation of graphite nanoplatelets as lubricant in grinding

Cooling and lubrication are very critical to ensure workpiece quality in grinding due to the high friction and intense heat generation involved in the process. Liquid lubricants have traditionally been used in flood form or minimum quantity lubrication (MQL), raising however, major environmental and economic concerns. The focus of this study is to evaluate the performance of graphite nanoplatelets as a lubricant in surface grinding. The role of graphite's characteristics such as form, size and concentration; and the effect of the carrying medium and the graphite's application method are determined based on an experimental study. The results indicate that graphite nanoplatelets significantly reduce the grinding forces, specific energy, and improve surface finish during surface grinding of hardened D-2 tool steel. A comparison with results obtained in conventional MQL grinding is also provided. The proper selection of graphite, carrying medium and application method can lead to a low cost, nontoxic and simple alternative to solid lubrication or MQL grinding.