Prediction of Minimum Chip Thickness in Tool Based Micro End Milling

This paper presents the analysis and modelling of minimum chip thickness by tool based micro end milling with control parameter of cutting speed, feed rate, and depth of cut. The formed chip thickness was measured using scanning electron microscope The data were analyzed and an empirical model is developed. The optimum value for the minimum chip thickness was 375 nm with cutting speed of 2275 rpm, feed rate of 2.6 mm/min, and depth of cut 0.6 μm using Ø 0.8 mm tool. The analysis revealed that the depth of cut is the most influential parameter on the minimum chip thickness. The investigation was performed on poly methyl methacrylate (PMMA) using integrated multi-process micro machine tools DT 110. The minimum chip thickness is found to be important to avoid tool breakage, deterioration of surface finish and to increase the tool life

Minimum chip thickness in machining MEMS structure using Tool Based Micromilling

Tool based micromilling is a promising micromanufacturing technology to produce miniaturized features of about 25μm in size frMEMS and Bio-MEMS applications.It is the most flexible and the fastest way to produce complex three dimensional microcomponents including sharp edges with surface finish at a reasonble cost.Moreover,it is capable of machining a broader range of materials such as engineering plastics, aluminium, titanium, etc. However,the issue in tool based micromilling is the minimum chip thickness which is often between5-30% of the tool edge radius. No chip will form if the depth of cut cannot achieve the minimum chip thickness value.The lack of control on minimum chip thickness often leads to the coarse machined surface, poor machining accuracy and difficult in chip removal from the machining zone which leads to burrformation.Hence, the chip formation mechanism should be studied deeply to avoid these problems.In this research WC was elected for tool material and Aluminium Alloy 1100 for work material for the investigation of minimum chip thickness.The experiment is being conducted on a miniature machine known as Microtools Integrated Multi-purpose machine modelled DT-110.The value of chip thickness produced by tool 4.8μmwith3mm/min feedrate,3000rpm cutting speed and 5μm depth of cut.The minimum chip thickness is useful for machining Micro electromechanical System(MEMS) and Bio-MEMSstructures

Material microstructure effects in micro-endmilling of Cu99.9E

This article presents an investigation of the machining response of metallurgically and mechanically modified materials at the micro-scale. Tests were conducted that involved micro-milling slots in coarse-grained Cu99.9E with an average grain size of 30 µm and ultrafine-grained Cu99.9E with an average grain size of 200 nm, produced by equal channel angular pressing. A new method based on atomic force microscope measurements is proposed for assessing the effects of material homogeneity changes on the minimum chip thickness required for a robust micro-cutting process with a minimum surface roughness. The investigation has shown that by refining the material microstructure the minimum chip thickness can be reduced and a high surface finish can be obtained. Also, it was concluded that material homogeneity improvements lead to a reduction in surface roughness and surface defects in micro-cutting

MICRO MILLING OF METALLIC MATERIALS - A BRIEF OVERVIEW

Micro milling is an important process of mechanical micromachining, with practical application in aerospace, automotive, mould and die, biomedical, military and microelectronics packaging industries. This article will give a brief overview of the effects and conditions of micro milling with an emphasis on minimum chip thickness, size effect, cutting forces, cutting temperature, tool wear and tool failure, burr formation and surface quality. The case study presented in the present paper refers to the micro milling of an aluminium alloy

Chip Production Rate and Tool Wear Estimation in Micro-EndMilling

abstract: In this research, a new cutting edge wear estimator for micro-endmilling is developed and the reliabillity of the estimator is evaluated. The main concept of this estimator is the minimum chip thickness effect. This estimator predicts the cutting edge radius by detecting the drop in the chip production rate as the cutting edge of a micro- endmill slips over the workpiece when the minimum chip thickness becomes larger than the uncut chip thickness, thus transitioning from the shearing to the ploughing dominant regime. The chip production rate is investigated through simulation and experiment. The simulation and the experiment show that the chip production rate decreases when the minimum chip thickness becomes larger than the uncut chip thickness. Also, the reliability of this estimator is evaluated. The probability of correct estimation of the cutting edge radius is more than 80%. This cutting edge wear estimator could be applied to an online tool wear estimation system. Then, a large number of cutting edge wear data could be obtained. From the data, a cutting edge wear model could be developed in terms of the machine control parameters so that the optimum control parameters could be applied to increase the tool life and the machining quality as well by minimizing the cutting edge wear rate. In addition, in order to find the stable condition of the machining, the stabillity lobe of the system is created by measuring the dynamic parameters. This process is needed prior to the cutting edge wear estimation since the chatter would affect the cutting edge wear and the chip production rate. In this research, a new experimental set-up for measuring the dynamic parameters is developed by using a high speed camera with microscope lens and a loadcell. The loadcell is used to measure the stiffness of the tool-holder assembly of the machine and the high speed camera is used to measure the natural frequency and the damping ratio. From the measured data, a stability lobe is created. Even though this new method needs further research, it could be more cost-effective than the conventional methods in the future.Dissertation/ThesisDoctoral Dissertation Mechanical Engineering 201

Experimental investigation on micromilling of oxygen-free, high-conductivity copper using tungsten carbide, chemistry vapour deposition and single-crystal diamond micro tools

Insufficient experimental data from various micro tools limit industrial application of the micromilling process. This paper presents an experimental comparative investigation into micromilling of oxygen-free, high-conductivity copper using tungsten carbide (WC), chemistry vapour deposition (CVD) diamond, and single-crystal diamond micromilling tools at a uniform 0.4mm diameter. The experiments were carried out on an ultra-precision micromilling machine that features high dynamic accurate performance, so that the dynamic effect of the machine tool itself on the cutting process can be reduced to a minimum. Micromachined surface roughness and burr height were characterized using white light interferometry, a scanning electron microscope (SEM), and a precision surface profiler. The influence of variation of cutting parameters, including cutting speeds, feedrate, and axial depth of cut, on surface roughness and burr formation were analysed. The experimental results show that there exists an optimum feedrate at which best surface roughness can be achieved. Optical quality surface roughness can be achieved with CVD and natural diamond tools by carefully selecting machining conditions, and surface roughness, Ra, of the order of 10nm can also be obtained when using micromilling using WC tools on the precision micromilling machine.EU FP6 MASMICRO projec

Parametric optimization of turning operation on stainless steel using a carbide tool

The term microturning is used to refer to operation processes occurring at dimensions of 1 to 999 micrometres. Stainless steel is a widely used material in day to day applications. In this case, a carbide tool has been used to machine stainless steel. The machining parameters are cutting speed, feed and depth of cut. The main aim is to understand the optimum settings of these parameters to reduce the machining forces, namely the feed force, the thrust force and the cutting force. To better understand these effects, experiments were carried out on a lathe and the machining forces measured with a dynamometer. The mode of machining was chosen as wet machining. The Taguchi method and ANOVA were used to analyse the obtained results. The statistical software MINITAB was then used to confirm the results obtained from statistical analysis

Size effect analysis during cutting and its importance for evaluation of minimum chip thickness

Při obrábění sehrávají rozměry součásti rozhodující úlohu z hlediska jejich chování. To je důsledkem „rozměrového účinku“, který mění obecné charakteristiky procesu řezání. Cílem diplomové práce bylo přispět k ověření poznatků o tomto účinku a možnostech dalšího využití při obrábění. Hlavní pozornost je zaměřena na vztah mezi poloměrem zaoblení ostří a hloubkou třísky.During machining play the size off component deciding role from the viewpoint of their behaviour. This is result of „size effect”, which turns common characteristic cutting process. The aim of diploma thesis was contribute piece of knowledge verification of this effect and the further exploit during machining. The main interest is directed to the relation between the cutting edge and depth of cut.

Modeling of three-dimensional cutting forces in micro-end-milling

A new nominal uncut chip thickness algorithm for micro-scale end-milling is proposed by considering the combination of an exact trochoidal trajectory of the tool tip and tool run-out, and then the actual uncut chip thickness may be obtained from a comparison between the current accumulative uncut chip thickness and the minimum chip thickness. Due to the intermittency of the chip formation, the milling process is divided into an elastic-plastic deformation regime and a chip formation regime dominated by ploughing forces and shearing forces, respectively, and three-dimensional cutting forces are modeled according to different regimes. Based on the modeling and simulation technologies introduced, a simulation system for the prediction of three-dimensional cutting forces of a micro-scale end-milling process is developed. The simulation results show a very satisfactory agreement with those data from milling experiments.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58144/2/jmm7_4_001.pd