Investigation of cutting force and temperature of end-milling Ti–6Al–4V with different minimum quantity lubrication (MQL) parameters

Abstract

Different parameters (air pressure, quantity of minimum quantity lubrication (MQL) oil, position of nozzle, etc.) of an MQL system have different effects on the milling force and milling temperature. The cutting force and cutting temperature, which are closely related to lubrication and coolant, play significant roles in improving/reducing the cutting quality of a workpiece and extending/shortening the tool life. The present work investigates experimentally the effects of different MQL parameters (air pressure, quantity of oil consumed, and position of the nozzle) in end-milling titanium alloy (Ti–6Al–4V). The experimental results show that the penetrating ability of MQL oil mist has a significant effect on the milling forces and milling temperatures. When the values of air pressure and spraying distance were either too large or too small, it is not good for oil mist to penetrate into the contact zones. The spraying angle of the nozzle position has a minimal impact on the penetration ability. Conversely, the amount of oil delivery is the most important part of MQL application. The minimum quantity of oil consumption can be obtained. The results will help to select optimum MQL parameters in end-milling titanium alloy.

Minimum Quantity Lubrication Assisted Turning - An Overview

“…Increase in air pressure causes a decrease in droplet diameter and thus helps the aerosol to penetrate in the tool-chip interface. However, beyond a certain value of air pressure, the aerosol effect starts detoriating due to spring back of high speed droplets from the chip tool interface (Liu et al, 2011). The air pressure in MQL varies from 4 to 6.5 kgf/cm 2 (Silva et al, 2005), so a value close to the mid level of this range i.e.…”

Evaluation of a Novel Controlled Cutting Fluid Impinging Supply System When Machining Titanium Alloys

“…Tool wear values were found to be about 1.6% less with feed direction in MQL compared to 6.15% with jet cooling. Liu et al [42] found that an MQL spraying nozzle position of 135 • and a spraying distance of 25 mm helped to reduce cutting temperature by 2.5 and 20 • C compared to 90 • nozzle angle and 45 mm spraying distance, respectively. Another recent work by [43] has investigated the effect of a new sensor-based cutting fluid supply system on machined surface quality using minimum quantity fluid MQF cooling.…”

Experimental analysis of system parameters for minimum cutting fluid consumption when machining Ti-6Al-4V using a novel supply system

“…Additionally, the proximity of the nozzle positioned at an angle of 15°from the tool-workpiece contact point contributed in minimising the fluid particle dispersion caused by tool rotation, which allowed them to adhere to the tool and workpiece surfaces effectively and to persist in working as a lubricant in the machining zone. Conversely, at the nozzle positions of 45°or 60°, more cutting fluid particles are driven away from the tool surface whilst the cutting tool rotates in a cyclic loop process [66]. In addition, nozzle placement at an angle of 45°or 60°against feed direction tends to offer enough space to assist in chip evacuation and this helped to minimise the interference between the impinging jet and the removed chip, which led to better lubricating and cooling ability and consequently improved machined surfaces.…”

“…According to Bernoulli's equation (Eq. 4) [66], the hydraulic head (h) (where in this case, the impinging distance is equal to the hydraulic head) has an effect on jet velocity, and this consequently affected fluid penetration efficiency. The cutting fluid jet velocity (V j ) increases as the impinging distance decreases.…”

“…The cutting fluid jet velocity (V j ) increases as the impinging distance decreases. However, too short impinging distance has a negative effect on the cutting fluid droplets owing to their high levels of rebounding from the workpiece and cutter surfaces [66]. Therefore, impinging distance should be controlled at an optimal level, as the impact of shorter impinging distance would be to conspicuously affect the workpiece temperature, burr formation and average surface roughness.…”