scholarly journals Experimental investigation on burr formation in vibration-assisted micro-milling of Ti-6Al-4V

2018 ◽  
Vol 233 (12) ◽  
pp. 4112-4119 ◽  
Author(s):  
Lu Zheng ◽  
Wanqun Chen ◽  
Dehong Huo
Keyword(s):  
High Strength ◽  
Resonant Mode ◽  
Micro Milling ◽  
Burr Formation ◽  
Machining Accuracy ◽  
Tool Wear Rate ◽  
Slot Milling ◽  
System A ◽  
Mode Vibration ◽  
Vibration Parameters

Titanium alloys have been widely used in aerospace, marine and medical industries, due to their high strength, good corrosion resistance and excellent heat resistance. High tool wear rate and low machining accuracy limits conventional micro-milling to meet increasing stringent demand. In this paper, a prototype of two-directional vibration stage and its control system are developed for non-resonant mode vibration-assisted micro-milling system. A series of slot milling experiments are carried out to investigate the effects of vibration parameters on burr generation. The results show that vibration-assisted micro-milling is an effective way to reduce burr size when choosing appropriate vibration parameters and directions.

Study on the Burr Formation Process in Micro Milling of High Aspect Ratio Structures

2021 ◽  
Author(s):  
Xinlei Zhang ◽  
Ni Chen ◽  
Jinming Wu ◽  
Jiawei Wei ◽  
Bo Yan ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Formation Mechanism ◽  
High Aspect Ratio ◽  
Formation Process ◽  
Element Model ◽  
Micro Milling ◽  
Burr Formation ◽  
Machining Accuracy ◽  
Machined Surface ◽  
Micro Structures

Abstract High-aspect-ratio (HAR) micro-structures of harden steel (SKD11) are widely used in the national defense and electronic fields. Micro-milling is a suitable method for machining HAR micro structures, however the inevitable generation of burrs deteriorates the machined surface. Previous studies have mostly focused on the burr formation process of shallow grooves, but have ignored HAR grooves. This paper investigated the burr formation mechanism in HAR (2:1) grooves on harden steel (SKD11). Due to the fact that the burr formation process was difficult to be observed in the actual micro-milling process, a finite element model was established. A corresponding experimental research was conducted, which revealed a good consistency between simulation and experimental results. Moreover, a new burr type was formed on the sidewall of the HAR groove, which was transformed from top burrs and was named as side burr. The results demonstrated that the chip flow on the rake face of the micro-mill was hindered by the sidewall, which caused chip crumbling, chip accumulation, and surface scraping, seriously affecting the burr formation mechanism. This paper revealed the burr formation mechanism for HAR grooves, and provided research direction for improving the machining accuracy of HAR grooves.

Simultaneous Time-Frequency Control of Multi-Dimensional Micro-Milling Instability

2012 ◽  
Author(s):  
Meng-Kun Liu ◽  
Eric B. Halfmann ◽  
C. Steve Suh
Keyword(s):  
Frequency Response ◽  
High Speed ◽  
Frequency Control ◽  
External Perturbation ◽  
Micro Milling ◽  
Time Frequency ◽  
System A ◽  
Control Concept ◽  
The Time Domain ◽  
Tool Damage

A novel control concept is presented for the online control of a high-speed micro-milling model system in the time and frequency domains concurrently. Micro-milling response at high-speed is highly sensitive to machining condition and external perturbation, easily deteriorating from bifurcation to chaos. When losing stability, milling time response is no longer periodic and the frequency response becomes broadband, rendering aberrational tool chatter and probable tool damage. The controller effectively mitigates the nonlinear vibration of the tool in the time domain and at the same time confines the frequency response from expanding and becoming chaotically broadband. The simultaneous time-frequency control is achieved through manipulating wavelet coefficients, thus not limited by the increasing bandwidth of the chaotic system — a fundamental restraint that deprives contemporary controller designs of validity and effectiveness. The feedforward feature of the control concept prevents errors from re-entering the control loop and inadvertently perturbing the sensitive micro-milling system. Because neither closed-form nor linearization is required, the innate, genuine features of the micro-milling response are faithfully retained.

Experimental research on the top burr formation in micro milling

2021 ◽  
Author(s):  
Xian Wu ◽  
Mingyang Du ◽  
Jianyun Shen ◽  
Feng Jiang ◽  
Yuan Li ◽  
...  
Keyword(s):  
Experimental Research ◽  
Micro Milling ◽  
Burr Formation

Mikrofräswerkzeuge mit Schneiden aus cBN*/Micro-cutting tools with cBN cutters

2018 ◽  
Vol 108 (11-12) ◽  
pp. 773-777
Author(s):  
E. Uhlmann ◽  
J. Polte ◽  
M. Polte ◽  
Y. Kuche ◽  
H. Wiesner
Keyword(s):  
Surface Roughness ◽  
Cubic Boron Nitride ◽  
Cutting Tools ◽  
High Strength ◽  
Hardened Steel ◽  
Micro Milling ◽  
Geometric Accuracy ◽  
Micro Cutting ◽  
Core Technology ◽  
Milling Tools

Die Mikrozerspanung ist eine Kerntechnologie bei der Fertigung von Mikrospritzgussformen. Die hohen Ansprüche an die geometrische Genauigkeit und Oberflächenrauheit erfordern den Einsatz hochfester Werkstoffe. Jedoch unterliegen aktuelle Fräswerkzeuge bei der Mikrozerspanung einem hohen Verschleiß. Einen Lösungsansatz bietet der erfolgreich in der Makrozerspanung eingesetzte Schneidstoff kubisch-kristallines Bornitrid (cBN). Ziel der Untersuchungen war es daher, detaillierte Informationen zur Bearbeitung von gehärtetem Stahl mit cBN-Mikrofräswerkzeugen bereitstellen zu können.   Micro-cutting is a core technology for producing micro-injection moulds. High demands on geometric accuracy and surface roughness require high-strength materials. However, current milling tools for micro-cutting suffer from excessiv tool wear. A solution is offered by cutting materials based on cubic Boron Nitride (cBN), which have been used successfully in macro-machining. This article contains detailed information on the machining of hardened steel with micro-milling tools and cutting edges made of cBN.

A Magnetic Bearing Suspension System for High Temperature Gas Turbine Applications: Part III — Magnetic Actuator Development

1997 ◽  
Author(s):  
William P. Kelleher ◽  
Anthony S. Kondoleon
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Copper Wire ◽  
High Vacuum ◽  
High Strength ◽  
Magnetic Bearing ◽  
Suspension System ◽  
Control Power ◽  
System A ◽  
Turbine Shaft

Magnetic bearings, unlike traditional mechanical bearings, consist of a series of components when mated together, form a stabilized system. A series of four papers will summaries the results carried out at Draper in the development of a high temperature magnetic bearing suspension system for a gas turbine application. Part I [1] will document our approach for rotordynamics modeling of the turbine shaft and the development of models for use in our simulation programs. Part II [2] documents the simulation efforts and the control system which resulted from this effort. Parts III and IV [3] document the design and fabrication of the magnetic bearing actuators and the auxiliary touchdown bearings. This paper, part III, deals with the design of the high temperature magnetic bearing actuators. Two radial and one axial magnetic bearing actuator were designed to meet the requirements for the turbine application. No bias coils are included in these design. The biasing flux is provided by current from the control power amplifiers. All the coils are made from ceramic coated copper wire and are terminated to high temperature connectors designed into the actuators. The new high strength Hiperco 50 HS material was chosen for the rotor lamination material for the radial bearings. A customized heat treatment process for this material in a high vacuum environment was developed to insure the maximum strength was obtained with the maximum magnetic properties. High temperature ceramic coated copper wire and bonding and potting material used for the coil assembly were tested up to 650 degrees C without failures.

Design of Special Fixture for Micro High Speed Motorized Spindle

2011 ◽  
Vol 228-229 ◽  
pp. 66-71
Author(s):  
Xiao Hong Lu ◽  
Zhen Yuan Jia ◽  
Zhi Cong Zhang ◽  
Xv Jia
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Speed ◽  
Micro Milling ◽  
Machining Accuracy ◽  
Milling Machine ◽  
Cnc Milling ◽  
Analysis Method ◽  
Motorized Spindle ◽  
Element Analysis

The fixture of motorized spindle significantly affect the vibration of micro high speed CNC milling machine, its performance can directly affect the machining accuracy of the entire micro milling machine. A special fixture of high-speed motorized spindle is designed in the paper and its static characteristics are checked by utilizing ANSYS finite element analysis software. To guarantee the sufficient strength of bolts and the safety of motorized spindle when the motorized spindle runs at high speed, theory analysis method and ANSYS finite element analysis method are used to make the strength check of the fixture. The designed special fixture for high speed motorized spindle plays an important part in the design of high-speed motorized spindle.

Burr formation and correlation with cutting force and acoustic emission signals

2016 ◽  
Vol 231 (3) ◽  
pp. 399-414 ◽  
Author(s):  
Seyed Ali Niknam ◽  
Victor Songmene
Keyword(s):  
Acoustic Emission ◽  
Cutting Force ◽  
Formation Mechanism ◽  
Acoustic Emission Signal ◽  
Cutting Forces ◽  
Burr Formation ◽  
Slot Milling ◽  
Emission Signal ◽  
Burr Size ◽  
Milling Operation

The principle objective of this work is to present a methodology to evaluate the correlation between burr size attributes (thickness and height) and information computed from acoustic emission and cutting forces signals. In the proposed methodology, cutting force and acoustic emission signals were recorded in each cutting test, and each recorded original acoustic emission signal was segmented into two sections that correspond to steady-state cutting process (cutting signal) and cutting tool exit from the work part (exit signal). The dominant acoustic emission signal parameters including AEmax and AErms were computed from each segmented acoustic emission signal. The maximum values of directional cutting forces (FX, FY and FZ) were also measured in each trial. The experimental verification was conducted on slot milling operation which has relatively more complicated burr formation mechanism than that in many other traditional machining operations. Among slot milling burrs, the top-up milling side burrs and exit burrs along up milling side were largest and thickest burrs which were studied in this work. To evaluate the correlation between signal information and burr size, the computed signal information (5 parameters) and their interaction effects (10 parameters) were used to construct the input parameters of the multiple regression fitted models. Statistical methods were then used to assess the adequacy of individual input parameters and signal information. Using the acoustic emission and cutting force signals information in the input layer of multiple regression models, a high correlation was observed between the predicted and observed values of burr size. It was exhibited that due to complex burr formation mechanism in milling operation and strong interaction effects between cutting process parameters, no systematic relationship can be formulated between the milling burrs.

Comparison between EBM and DMLS Ti6Al4V Machinability Characteristics under Dry Micro-Milling Conditions

2016 ◽  
Vol 836-837 ◽  
pp. 177-184 ◽  
Author(s):  
Zdenka Rysava ◽  
Stefania Bruschi
Keyword(s):  
Titanium Alloys ◽  
Surface Defects ◽  
Removal Rate ◽  
Cutting Speed ◽  
Micro Milling ◽  
Burr Formation ◽  
Tool Geometry ◽  
Work Piece ◽  
Dry Cutting ◽  
High Flexibility

This paper is aimed at evaluating the micro-machinability of the Ti-6Al-4V titanium alloy made by the means of two different Additive Manufacturing (AM) technologies. AM comprises promising technologies, widely used especially to produce parts made of difficult-to-cut materials, such as the titanium alloys. Titanium alloys represent one of the most widely used materials in the biomedical field, thanks to the high biocompatibility and excellent mechanical characteristics. Even if near-net-shape parts can be produced through AM, semi-finishing and/or finishing machining operations may be necessary to obtain the required surface finish and geometrical tolerances. Micro-milling technique is a soliciting solution for this kind of application due to its high flexibility, elevated material removal rate and direct contact between the tool geometry and work piece. Nevertheless, there are deficiencies in the literature regarding the study of micro-machinability of materials produced by means of AM technologies. In this paper, the micro-machinability of the Ti-6Al-4V alloy obtained by two different AM technologies, namely Electron Beam Melting (EBM) and Direct Metal Laser Sintering (DMLS), was studied and compared in order to assess the influence of the material as-delivered condition. Micro-milling tests were conducted on a high-precision 5-axis Kugler™ micro-milling centre under dry cutting conditions, by using uncoated, two fluted, flat-end-square, tungsten carbide tools with a diameter of 300 microns. The full immersion slotting strategy was chosen under full factorial design of experiments with two factors (cutting speed and feed per tooth). The micro-machinability was evaluated in terms of burr formation, surface integrity (surface topography and surface defects), tool damage and microstructure alterations.

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