Erween Abd Rahim

Investigation of tool wear and surface integrity on MQL machining of Ti-6AL-4V using biodegradable oil:

Minimum quantity lubrication (MQL) machining involves the application of small quantity of lubricant to the tool–workpiece interface. This paper describes the results of an investigation on the effects of using different MQL lubricants (synthetic ester and palm oil) on the drilling of Ti-6Al-4V. Dry cutting was also performed for comparison purposes. It was found that drilling under dry conditions resulted in the shortest tool life due to severe chipping. MQL is beneficial to the measured responses such as tool life, thrust force, torque, and temperature. The outstanding performance of palm oil in reducing the value of those responses was attributed to its ability to form a thin film which promoted boundary lubrication during the machining process. The presented results indicated the substantial benefit of using palm oil in terms of microhardness, surface roughness, and subsurface deformation. This work shows that palm oil can be used as a viable alternative to a synthetic ester as a MQL lubricant.

Tool failure modes and wear mechanism of coated carbide tools when drilling Ti-6Al-4V

This paper reports on the performance of TiAlN and Supernitride coated carbide tools when drilling titanium alloy, Ti-6Al-4V. Tool life, tool failure modes and tool wear mechanisms were examined at various cutting speeds of 25, 35, 45 and 55 m/min with a constant feed rate of 0.06 mm/rev. Results showed that Supernitride coated carbide tool outperformed TiAlN coated carbide tool at most cutting speeds investigated. Non-uniform flank wear, excessive chipping and microcracking were the dominant tool failure modes under most tested conditions. Adhesion, attrition and diffusion were the operating wear mechanism on both tools when drilling Ti-6Al-4V.

Thermal-Assisted Machining of Nickel-based Alloy

Nickel-based alloy can be found in different industrial applications especially in aircraft engines and hot end components of various types of gas turbines with its high strength, strong corrosion resistance and excellent thermal fatigue properties and thermal stability compared to conventional materials. However, nickel-based alloy is one of the extremely difficult-to-cut materials. During the machining process, the interaction between the tool and the workpiece causes severe plastic deformation and intense friction at the tool-workpiece interface. Because of the increasing demands in industries, any improvement of conventional machining processes or any other deployment of additional technique is directly related to higher productivity. Thermal-assisted machining (TAM) has become an effective alternative to the conventional machining of these difficult-to-cut materials. Various types of heating methods and the beneficial effects on machining of nickel-based alloys are discussed in this chapter. Finally, TAM was proven as an efficient technique to increase the machinability of nickel-based alloys in terms of tool life, surface roughness and cutting force.

Numerical Analysis of Laser Heating for Laser Assisted Micro Milling Application

The promising processing techniques of micro scale parts are very important in products miniaturization and functions enhancement. Combination of two or more processing techniques gives better processing performance especially when dealing with difficult-to-cut materials. For that reason, the combination of laser beam and micro milling process has been widely studied and proven efficient in reducing cutting force and tool life extension. However, this process needs a precise temperature control in order to eliminate heat effect generated by laser beam irradiation. In this study, temperature distributions are determined numerically to characterize the melted zone and heat affected zone geometry. From the results, the estimation of tool and micro milling cutter distance together with the allowable depth of cut are determined.

Machinability of Titanium Alloys in Drilling

Hole making is an essential process in the structural frames of an aircraft and contributes to 40 to 60% of the total material removal operations (Brinksmeier, 1990). This process is commonly divided into short hole or deep hole drilling. Short hole drilling typically covers holes with a small depth to diameter ratio having diameter up to 30 mm and a depth of not more than 5 times the diameter. Meanwhile deep hole drilling caters for holes greater than 30 mm in diameter and the depths are usually greater than 2.5 times the hole diameter. Drilling deeper hole with conventional drills requires pecking method to enable easy flow of the chips out of the hole. Deep hole drilling is more difficult especially when hole straightness is the main concern. Therefore, a usual method is to make a circular cut using a hollow-core cutting tool. This technique allows larger hole diameter to be drilled with lesser power. In addition, holes can be produced in many forms which include through holes or blind holes (Fig. 1). Through hole is one which is drilled completely through the workpiece while a blind hole is drilled only to a certain depth.

High Speed MQL Drilling of Titanium Alloy using Synthetic Ester and Palm Oil

Minimum Quantity Lubrication (MQL) machining involves the application of a small quantity of lubricant being dispensed to the tool-workpiece interface. This paper describes the results of applying different MQL lubricant (synthetic ester and palm oil) to the high speed drilling of Ti-6Al-4V. Dry cutting conditions were also used for comparison. It was found that cutting under dry conditions resulted in the shortest tool life due to severe chipping. MQL was found beneficial to the measured factors such as tool life, thrust force, torque and temperature. In addition, the outstanding performance of palm oil in reducing the value of these factors could be attributed to its ability to form a thin film which promotes boundary lubrication during the machining process. This work shows that the palm oil can be selected as a viable alternative to synthetic ester for MQL lubricant.

An investigation of cutting mechanics in 2 dimensional ultrasonic vibration assisted milling toward chip thickness and chip formation

The purpose of this paper is to investigate the effects of 2 dimensional Ultrasonic Vibration Assisted Milling (UVAM) cutting mechanics, considering tool path trajectory and the effect on the chip thickness. The theoretical modelling of cutting mechanics is focused by considering the trajectory of the tool locus into the workpiece during the machining. The studies found the major advantages of VAM are come from the intermittent tool tip interaction phenomena between cutting tool and workpiece. The reduction of thinning chip thickness formations can be identifying advantages from vibration assisted milling in 2 dimensional. The finding will be discussing the comparison between conventional machining the potential of the advantages toward the chip thickness and chip formation in conclusion.

Numerical analysis of laser preheating for laser assisted micro milling of Inconel 718

Micro milling of super alloy materials such as nickel based alloys such as Inconel 718 is challenging due to the excellent of its mechanical properties. Therefore, new techniques have been suggested to enhance the machinability of nickel based alloys by pre-heating the workpiece’s surface to reduce its strength and ductility. The prediction of fluctuated temperature distribution generated by pulsed wave laser in laser assisted micro milling (LAMM) is crucial. The selection of processing parameter by minimize the effect on the processing characteristic is decisive to ensure the machining quality is high. Determining the effect of heat generated in underneath surface is important to make sure that the cutting tools are able to cut the material with maximum depth of cut and minimum defects in terms of tool wear and tool life. In this study the simulation was carried by using Ansys APDL. In order to confirm the actual and distribution irradiation of temperature from simulation, an experimental was done to validate the results. The experiment was conducted by using Nd:YAG laser with wavelength 1064 nm.

Determination of mist flow characteristic for MQL technique using Particle Image Velocimetry (PIV) and Computer Fluid Dynamics (CFD)

In recent years, minimum quantity lubrication (MQL) machining is regarded as a promising method for reducing machining cost and cutting fluid, while improving cutting performance. However the effectiveness and the working principle of MQL are still questionable with very few explanations provided. The aim of this study is to determine the optimum distance between the nozzle and tool tip and appropriate flow pattern of the mist flow for minimum quantity lubricant using Particle Image Velocimetry (PIV) and Computer Fluid Dynamic (CFD) for optimizing the spraying conditions thus reducing the lubricant consumption. The spray from the nozzle with outlet diameter of 2.5mm is analysed using Particle Image Velocimetry (PIV) to measure the mist flow velocity and identify the flow pattern. The input pressure of 0.2, 0.3 and 0.4MPa will be discharged throughout the experiment. Higher pressure produce more mass flow rate which helps in reducing the cutting force and cutting temperature efficiently and prolong tool life. Thus the appropriate distance can reduce lubricant consumption and increase the cooling and lubricating ability with best nozzle position. The applied distance increases the efficiencies of MQL applied during machining process.

Dissimilar Materials Laser Welding Characteristics of Stainless Steel and Titanium Alloy

Welding parameters are directly influenced by the work material properties. Thermal properties such as thermal conductivity and melting point are very important to estimate the range of power required and the allowable scanning speed. However, when two or more different materials are involved, modifying lasing parameters are not enough to counter the problems such as imbalance melting region and weak adhesion of contact surface. To counter this problem, the characteristics of welding beads formation for both materials need to be clarified. In this study, comparison of welding beads constructed using the same scanning parameters were done to understand the different and similarity of melted region for the both materials. Actual welding of the both materials were done under different offset distance to obtain a balanced melting area and well mixed melting region.