Papers by Keyword: Chip Morphology

Abstract: Additively manufactured titanium alloys such as Ti-6Al-4V have been used as functional components in industry due to their excellent mechanical properties. However, the machining of these alloys is a challenge due to their enhanced tensile/yield strength, low elastic modulus, poor thermal conductivity, and microstructural anisotropy. Thermal assisted machining (TAM), as a hybrid manufacturing technology, can improve the machinability of additively manufactured alloys. The main aim of this paper is to investigate the effect of temperature buildup on the machinability of additively manufactured Ti alloy with different build directions in the TAM process. It was found that the surface integrity was notably enhanced by preheating, and it was the best at 90° build orientation. Serrated chips were generated at room temperature, and curlier chips were formed in high-preheating machining environment. By analyzing the surface quality, the influence of the build-up orientation on the surface quality at different temperatures was evaluated.

Abstract: This analyses evaluates the cutting force , surface roughness, chip morphology, chip–tool interface temperature, tool life, and Single use of a coated carbide tool and double liquid nitrogen jets for friendly superalloy that is extremely difficult to cut being turned (Ti-6Al4V). The rake face was the only focus of the single jet, while the rake and flank surfaces were concurrently hit by the duplex jets. Liquid nitrogen jets provided the highest machining quality, reducing cutting force , temp, hardness, and, apparently, tool life. When equated to dry and single jet assist, the double liquid nitrogen jets increased life of the tool by 60% and 30%. In spite of this, chip manufacture has not changed. Using duplex liquid nitrogen jets to extend tool life, reduce tool costs, lower temperatures, improve surface quality, and most importantly, promote machinability of Ti-6Al-4V superalloy has been accepted as a sustainably booster.

Abstract: This study evaluates the impacts of machining parameters on the milling of general-purpose poly (methyl methacrylate) (PMMA) with respect to cutting point temperature, maximum machining temperature, and surface roughness. The machining parameters used in the analysis are spindle speed (rpm), depth of cut (mm), and feed rate (mm/min). The extreme ranges of the machining parameters for the material are obtained from trial experiments. From these experiments, four values of each parameter are adopted. This yields 12 experiments, which are divided into three sets. In the first set of experiments, the depth of cut and feed rate are held constant at 0.2 mm and 25 mm/min, while the spindle speed is varied from 1000 rpm to 4000 rpm. In the second set of experiments, the spindle speed and feed rate are held constant at 1000 rpm and 25 mm/min, respectively, while the depth of cut is varied from 0.2 mm to 1.1 mm. In the last set of experiments, the spindle speed and depth of cut are held constant at 1000 rpm and 0.2 mm, respectively, as the feed rate is varied from 25 mm/min to 100 mm/min. Thermal images are obtained during milling, where the cutting point and maximum machining temperatures are obtained. The milled surfaces are then investigated for surface roughness. The chips are also collected from each experiment and used in conducting chip morphology. From the results, it is observed that to obtain the least temperatures and best surface quality, the least machining parameters should be chosen. These parameters are identified as 1000 rpm, 0.2 mm, and 25 mm/min for the spindle speed, depth of cut, and feed rate, respectively. An increase in spindle speed seems to increase the milling temperatures and surface roughness, which is attributed to the reducing chip thickness. An increase in the depth of cut does not affect the generation of chips, and the thickness is relatively constant. However, an increase in milling feed increases the chip thickness, which increases the surface roughness.

Abstract: Inconel 718 is a nickel-based super alloy well suited for high-temperature applications encountered in space shuttles, aircraft black box and turbocharger due to their inherent properties. Taking into account of extreme working conditions, efficiency in the process of machining without affecting the nature of the surface integrity with utmost care assumes a lot of importance. In this current study, an attempt has been made to investigate the influence of cutting speed and feed rate on various machining aspects like cutting forces, chip morphology, surface roughness and tool wear during the orthogonal turning of Inconel 718. Also, the work has been focused on feed forces and thrust forces to understand the proper material deformation behaviour and surface integrity.

Abstract: In the present experimental study, the effect of turning tool overhang on the chip morphology and vibrations during orthogonal turning has been investigated. Orthogonal cutting (turning) setup was developed to ensure the cutting process happens in a 2-dimesional plane. Orthogonal cutting was realized by turning a circular tube with geometry of 33.88 mm external diameter and 3.5 mm wall thickness (7075-T6 Alloy). High speed steel (HSS) rod with a square cross-section (1⁄2 x 1⁄2 square inch) was used to fabricate the orthogonal turning tool with a geometry of 15 ̊ back rake angle and 9 ̊ clearance angle. The cutting experiments were conducted for different tool overhang lengths (2cm, 3cm, 4cm, 5cm & 6cm) by keeping constant cutting speed (25 m/min) and feed (0.15mm/rev). The vibrational characteristics were measured using accelerometer and Ni-DAQ card. The morphology and microstructure of the chips collected during cutting were studied under optical microscope using metallographic procedures. It was found that for increasing overhang length of cutting tool the chips serrations was found increasing. The frequency of cutting tool and amplitude of vibration was found increasing with increasing tool overhang length.

Abstract: Recently, titanium alloys have been widely used in industry owing to their excellent physical and mechanical properties. However, the severe cutting conditions such as abrasion, adhesion and high temperature accelerate the rate of chip formation and strongly affect the quality of machined surface. This paper investigates that the effect of the conventional coolant (CC) and graphene oxide suspended (GO) on the drilling process of titanium alloy Ti-6Al-4V using tungsten carbide tools. Here are two main chip formation could be found that zigzag chips and spiral chips. Through the analysis of chip morphology, it was found that under graphene oxide suspended fluid. It can be found that using conventional coolant would form the zigzag chips, while it formed spiral chips when graphene oxide suspended fluid applied. In addition, by analysing the chip free surfaces, the chip lamella stuck and chip flaw happened when conventional fluid used. While the back surfaces could be found that less chip stuck and crack occurred when graphene oxide suspended coolant applied. Finally, chip thickness were investigated that thinner chip thickness was found when graphene oxide suspended fluid used.

Abstract: Tool wear is an inevitable impediment in machining processes. It is the gradual failure of cutting tools due to regular use. Tool wear affects productivity, dimensional accuracy thereby indirectly representing a significant portion of the machining costs. In this paper, a novel technique has been proposed and adopted with an aim to reduce tool wear. External ultrasonic sound waves were applied in the turning process of mild steel in an attempt to reduce the cutting tool vibration thereby leading to improvements in tool life. In this unique technique ultrasonic sound has been applied from the both sides of the tool holder in the cutting process as waves to reduce tool vibrations and improvement of chip behavior at a certain optimized frequency. Experiments were carried out at 60 KHz ultrasonic frequency to determine the tool wear to the best degree possible. To investigate the cause of ultrasonic effects on tool wear, cutting tool vibration and chip morphology were also studied. The experimental results showed significant improvements in tool wear, vibration and chip behavior.

Abstract: Hardened AISI 1045 steel implemented in machine tool spindle was previously ground using grinding operation. This research aims to address the feasibility of hard turning AISI 1045 using PCBN tool with chip breaker under dry condition. Chip morphology, cutting force and temperature were measured, analyzed and correlated with machining parameters. Experimental results demonstrate that serrated chips are generated at high speeds, high feed rate is an assistant to promote serrated chips, and chip breaker can help break chip into acceptable lengths. Cutting forces were characterized with periodic fluctuation along three directions as chips are serrated. Temperature at machined zone can reach as high as 1200^°C, which indicates that adiabatic shear bands can be successfully achieved during the machining of hardened AISI 1045 steel without applying lubricants.

Abstract: Abrupt breakage of the taps is frequently encountered during tapping threads, especially when tapping on ‘difficult-to-cut’ material like titanium. This work therefore presents an extensive experimentation with the Taguchi approach to investigate maximum torque in tapping on titanium alloys while performing axial and, axial and torsional vibration-assisted tapping (AVAT and ATVAT). The experimentation shows that both AVAT and ATVAT reduce the tapping torqueduring tapping as compared to that of in conventional tapping process. However, ATVAT process had exhibited a higher degree of reduction in torque when compared to AVAT process.

Abstract: Tool wear is easy occurred in titanium alloy milling process which will affect the surface quality. Surface roughness and surface morphology as an important index to describe and evaluate the surface quality has a great influence on service performance. Therefore, the study on the effect of tool wear on surface qualities is important to improve the surface integrity of titanium alloy parts. Cutting radius of ball-end milling cutter is solved to analyze the effect of tool wear on the cutting radius. The tool wear and the surface qualities of TC4 are achieved through wear experiment. And then the influence law of tool wear on surface qualities and chip morphology are analyzed. The results show that surface roughness value decrease firstly and then increases and that chip morphology with flank wear increase from the unit chip to the serrated chip.