skip to main content

Title: Wear Performance Evaluation of Minimum Quantity Lubrication with Exfoliated Graphite Nanoplatelets in Turning Titanium Alloy
This paper evaluates the performances of dry, minimum quantity lubrication (MQL), and MQL with nanofluid conditions in turning of the most common titanium (Ti) alloy, Ti-6Al-4 V, in a solution treated and aged (STA) microstructure. In particular, the nanofluid evaluated here is vegetable (rapeseed) oil mixed with small concentrations of exfoliated graphite nanoplatelets (xGnPs). This paper focuses on turning process that imposes a challenging condition to apply the oil or nanofluid droplets directly onto the tribological surfaces of a cutting tool due to the uninterrupted engagement between tool and work material during cutting. A series of turning experiments was conducted with uncoated carbide inserts, while measuring the cutting forces with a dynamometer under the dry, MQL and MQL with nanofluid conditions supplying oil droplets externally from our MQL device. The inserts are retrieved intermittently to measure the progress of flank and crater wear using a confocal microscopy. This preliminary experimental result shows that MQL and in particular MQL with the nanofluid significantly improve the machinability of Ti alloys even in turning process. However, to attain the best performance, the MQL conditions such as nozzle orientation and the concentration of xGnP must be optimized.
Authors:
Award ID(s):
1727525
Publication Date:
NSF-PAR ID:
10106633
Journal Name:
Journal of manufacturing science and engineering
Volume:
141
Issue:
8
Page Range or eLocation-ID:
081006
ISSN:
1528-8935
Sponsoring Org:
National Science Foundation
More Like this
  1. Titanium alloys typically do not contain hard inclusion phases typically observed in other metallic alloys. However, the characteristic scoring marks and more distinctive micro- and/or macro-chippings are ubiquitously observed on the flank faces of cutting tools in machining titanium alloys, which is the direct evidence of abrasive wear (hard phase(s) in the microstructure abrading and damaging the flank surface). Thus, an important question lies with the nature of the hard phases present in the titanium microstructure. In this work, we present a comprehensive study that examines the microstructural impact on flank wear attained by turning various Ti-6Al-4V bars having distinctmore »microstructures with uncoated carbide inserts. In particular, four samples with elongated, mill-annealed, solution treated & annealed and fully-lamellar microstructures were selected for our turning experiments. After turning each sample, the flank surface of each insert was observed with confocal laser scanning microscopy (CLSM) and analyzed to determine the flank wear behavior in relation to each sample' distinct microstructures. To characterize the microstructure, scanning electron microscopy (SEM) together with Orientation imaging microstructure (OIM) was used to identify and distinguish the phases present in each sample and the content and topography of each phase was correlated to the behavior of flank wear. The flank wear is also affected by the interface conditions such as temperature and pressure, which were estimated using finite element analysis (FEA) models. The temperature dependent abrasion models enable us to estimate the flank wear rate for each microstructure, and are compared with the experimentally measured wear data.« less
  2. Titanium alloys typically do not contain hard inclusion phases typically observed in other metallic alloys. However, the characteristic scoring marks and more distinctive micro- and/or macro-chippings are ubiquitously observed on the flank faces of cutting tools in machining titanium alloys, which is the direct evidence of abrasive wear (hard phase(s) in the microstructure abrading and damaging the flank surface). Thus, an important question lies with the nature of the hard phases present in the titanium microstructure. In this work, we present a comprehensive study that examines the microstructural impact on flank wear attained by turning various Ti-6Al- 4V bars havingmore »distinct microstructures with uncoated carbide inserts. In particular, four samples with elongated, mill-annealed, solution treated & annealed and fully-lamellar microstructures were selected for our turning experiments. After turning each sample, the flank surface of each insert was observed with confocal laser scanning microscopy (CLSM) and analyzed to determine the flank wear behavior in relation to each sample' distinct microstructures. To characterize the microstructure, scanning electron microscopy (SEM) together with Orientation imaging microstructure (OIM) was used to identify and distinguish the phases present in each sample and the content and topography of each phase was correlated to the behavior of flank wear. The flank wear is also affected by the interface conditions such as temperature and pressure, which were estimated using finite element analysis (FEA) models. The temperature dependent abrasion models enable us to estimate the flank wear rate for each microstructure, and are compared with the experimentally measured wear data.« less
  3. Abstract

    Minimum quantity lubrication (MQL) drilling has been known for decades, but limited knowledge is available on two-channel through-tool MQL drilling due to the lack of accessibility to production systems. A common problem in MQL drilling is the absence of a rational approach to select the oil flow rate. The limited entry and exit area, and fixed energy available to the flow make the behavior complicated. This study leverages the capabilities in Ford’s manufacturing lab to abridge the research gap. Four different oil flow rates (0 ml/h, 15 ml/h, 30 ml/h and 60 ml/h) and two different drills (twist drillmore »and straight drill) were used to find out the influence of oil flow rate on the cutting performance. Tool life, tool wear, cutting force and torque were monitored as the cutting performance indicators. It was concluded that, the common belief of higher oil flow rate providing better tool life, does not hold true for through-tool MQL drilling. The tool life for 30 ml/hr. oil flow rate appeared to be the highest compared to all the other cases for both the drills. Increasing the oil flow rate above 30 ml/hr. decreased the tool life. However, it is to be noted that the optimal oil flow rate values may be specific to the case.

    « less
  4. This paper presents a new turning system where the guided cut chip during turning is pulled using an external pulling device to attain high-performance cutting. An electro-mechanical pulling device with sensor-less chip tension monitoring function is designed to steadily pull the guided chip and robustly assist the turning operation. The effect of chip tension on the process is modeled and experimentally verified. The developed chip pulling system is utilized to achieve direct real-time control of the cutting process and zero thrust force cutting is demonstrated. Developed system effectively reduces cutting energy for improved tool life and regulates cutting forces formore »high performance turning.« less
  5. Friction is one of the key factors limiting the achievable productivity and efficiency in most machining processes. Typically, adverse effects of friction in machining has been addressed through better tool material design and use of coolants. This paper presents an innovative technique to significantly increase the efficiency of turning processes by alleviating friction forces using an assistive device. As opposed to breaking the cut chip using chip breakers, in the proposed technique, the chip is not broken but pulled using a system to realize a new turning process so-called the “chip-pulling turning”. By pulling the cut chip externally, the frictionmore »force acting along tool’s rake face could be reduced and even cancelled. This, in return, increases the shear angle and leads to efficient material removal with significantly lower process forces and energy. An electro-mechanical chip-pulling device is designed that can pull the guided chip continuously during the turning operation. Design of the chip-pulling system, proposed pulling device and its automatic control are presented. The effect of chip-pulling is validated experimentally through various cutting experiments. Furthermore, orthogonal cutting force models are used to model the effect of chip-pulling on the process.« less