Mitigation of Milling Chatter at High-Speed

2012 ◽  
Author(s):  
Meng-Kun Liu ◽  
C. Steve Suh
Keyword(s):  
High Speed ◽  
Stability Boundary ◽  
Adaptive Controller ◽  
Machining Process ◽  
Discrete Wavelet ◽  
Line System ◽  
Milling Stability ◽  
Tool Vibrations ◽  
The Time Domain ◽  
Milling Chatter

A highly interrupted machining process, milling at high speed can be dynamically unstable and chattering with aberrational tool vibrations. While its associated response is still bounded in the time domain, however, milling could become unstably broadband and chaotic in the frequency domain, inadvertently causing poor tolerance, substandard surface finish and tool damage. Instantaneous frequency along with marginal spectrum is employed to investigate the route-to-chaos process of a nonlinear, time-delayed milling model. It is shown that marginal spectra are the tool of choice over Fourier spectra in identifying milling stability boundary. A novel discrete-wavelet-based adaptive controller is explored to stabilize the nonlinear response of the milling tool in the time and frequency domains simultaneously. As a powerful feature, an adaptive controller along with an adaptive filter effective for on-line system identification is implemented in the wavelet domain. By exerting proper mitigation schemes to both the time and frequency responses, the controller is demonstrated to effectively deny milling chatter and restore milling stability as a limit cycle of extremely low tool vibrations.

Control of High Speed Milling Chatter in Simultaneous Time-Frequency Domain

2011 ◽  
Author(s):  
Meng-Kun Liu ◽  
C. Steve Suh
Keyword(s):  
Frequency Domain ◽  
Dynamic Stability ◽  
High Speed ◽  
Adaptive Controller ◽  
System Response ◽  
Discrete Wavelet ◽  
Line System ◽  
High Speed Milling ◽  
Time Frequency ◽  
Milling Chatter

The dynamics governing high speed milling has been extensively explored for decades, both numerically and experimentally. The process loses its dynamic stability and becomes chaotic through either Neimark-Sacker or period doubling bifurcation. While its associated response is still bounded in the time domain, however, it could become unstably broadband in the frequency domain, thus causing the uneven cutting surface on the workpiece and tool damage. A discrete-wavelet-based feedforward adaptive controller is developed to stabilize system response in the time and frequency domains simultaneously. An adaptive controller along with an adaptive filter effective for on-line system identification is implemented in the wavelet domain. By controlling both time and frequency responses, the presented controller design is demonstrated to effectively suppress milling chatter and restore the system back to dynamic stability.

scholarly journals Stability Analysis of Milling Process with Variable Spindle Speed and Pitch Angle considering Helix Angle and Process Phase Difference

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Gang Jin ◽  
Haotian Jiang ◽  
Jianxin Han ◽  
Zhanjie Li ◽  
Hua Li ◽  
...  
Keyword(s):  
Phase Difference ◽  
Pitch Angle ◽  
High Speed ◽  
Helix Angle ◽  
Stability Domain ◽  
Milling Process ◽  
Spindle Speed ◽  
The Stability ◽  
The Time Domain ◽  
Milling Chatter

Suppression of milling chatter by disrupting regenerative effect is a well-known method to obtain higher cutting stability domain. In this paper, a dynamic model of the milling process with variable spindle speed and pitch angle considering helix angle and process phase difference is presented. Then, an updated semidiscretization method is applied to obtain the stability chart. After the effectiveness of the proposed method is confirmed by comparisons with the previously published works and the time-domain simulations, lots of analyses are conducted to deeply evaluate the influence of the helix angle, the process phase difference, and feed per tooth on milling stability. Results show that the change of helix angle can result in significant stability discrepancies for both high-speed and low-speed regions. Though the process phase difference has the randomness and immeasurability in the practical application, it has an important influence on the stability and will result in a periodic evolution of the stability with a period π. Also, its recommended values are given for the practical milling process.

scholarly journals Thermographic Study of Chip Temperature in High-Speed Dry Milling Magnesium Alloys

2016 ◽  
Vol 7 (2) ◽  
pp. 86-92 ◽  
Author(s):  
Józef Kuczmaszewski ◽  
Ireneusz Zagórski ◽  
Piotr Zgórniak
Keyword(s):  
Temperature Measurement ◽  
Magnesium Alloys ◽  
High Speed ◽  
Machining Process ◽  
Dry Milling ◽  
Technological Parameters ◽  
Chip Temperature ◽  
Thermographic Study ◽  
On Chip ◽  
The Impact

Abstract This paper presents an overview of the state of knowledge on temperature measurement in the cutting area during magnesium alloy milling. Additionally, results of own research on chip temperature measurement during dry milling of magnesium alloys are included. Tested magnesium alloys are frequently used for manufacturing elements applied in the aerospace industry. The impact of technological parameters on the maximum chip temperature during milling is also analysed. This study is relevant due to the risk of chip ignition during the machining process.

Ultra-High Speed Grinding Using a CBN Wheel for a Mirror-Like Surface Finish

2005 ◽  
Vol 291-292 ◽  
pp. 67-72 ◽  
Author(s):  
M. Ota ◽  
T. Nakayama ◽  
K. Takashima ◽  
H. Watanabe
Keyword(s):  
Surface Finish ◽  
High Speed ◽  
High Efficiency ◽  
Ground Surface ◽  
Machining Process ◽  
Grinding Wheel ◽  
Cbn Wheel ◽  
Ultra High Speed ◽  
High Speed Grinding ◽  
Grinding Conditions

There are strong demands for a machining process capable of reducing the surface roughness of sliding parts, such as auto parts and other components, with high efficiency. In this work, we attempted to grind hardened steel to a mirror-like surface finish with high efficiency using an ultra-high speed grinding process. In the present study, we examined the effects of the work speed and the grinding wheel grain size in an effort to optimize the grinding conditions for accomplishing mirror-like surface grinding with high efficiency. The results showed that increasing the work speed, while keeping grinding efficiency constant, was effective in reducing the work affected layer and that the grinding force of a #200 CBN wheel was lower than that of a #80 CBN wheel. Based on these results, a high-efficiency grinding step with optimized grinding conditions was selected that achieved excellent ground surface quality with a mirror-like finish.

Numerical Simulation of Cutting Force in High Speed Machining of Inconel 718

2020 ◽  
Vol 856 ◽  
pp. 43-49
Author(s):  
Santosh Kumar Tamang ◽  
Nabam Teyi ◽  
Rinchin Tashi Tsumkhapa
Keyword(s):  
Cutting Force ◽  
Inconel 718 ◽  
High Speed ◽  
Experimental Results ◽  
Machining Process ◽  
Experimental Result ◽  
Work Piece ◽  
High Speed Machining ◽  
Numerical Result ◽  
3D Software

Machining is one of the major manufacturing processes that converts a raw work piece of arbitrary size into a finished product of definite shape of predetermined size by suitably controlling the relative motion between the tool and the work. Lately, machining process is shifting towards high speed machining (HSM) from conventional machining to improve and efficiently increase production, and towards dry machining from excessive coolant used wet machining to improve economy of production. And the tools used are mostly hardened alloys to facilitate HSM. The work piece materials are continually improving their properties by emergence and development of newer and high resistive super alloys (HRSA). In this paper an attempt has been made to validate an experimental result of cutting force obtained by performing HSM on an HRSA Inconel 718, by comparing it with the numerical result obtained by simulating the same setting using DEFORM 3D software. Based on the comparison it is found that the simulated results exhibit close proximity with the experimental results validating the experimental results and the effectiveness of the software.

scholarly journals Adaptive PD Sliding Mode Control For 4 DOF SCARA Variant

2021 ◽  
Author(s):  
Manjeet Tummalapalli
Keyword(s):  
Sliding Mode Control ◽  
Trajectory Tracking ◽  
High Speed ◽  
Sliding Mode ◽  
Adaptive Controller ◽  
Degree Of Freedom ◽  
Tracking Performance ◽  
Advantages And Disadvantages ◽  
Model Free ◽  
Adaptive Law

This project proposes a new SCARA variant with 4 degree of freedom. The proposed variant is achieved by swapping joint 2 and joint 3 of the standard SCARA robots. An adaptive controller is defined based on the advantages and disadvantages of PD, and SMC controllers.The purpose of the project is to understand the dynamics of the variant and to track the performance for trajectories. Simulations for tracking performance are carried under linear and circular trajectories. The variant is studied over the three controllers; PD, PD-SMC and A-PD-SMC. The variant under the adaptive controller is most efficient in terms of tracking performance and the control inputs to the system. The system is simulated under high speed and with the influence of friction at the joints. The control gains are held constant for both the trajectories and hence the controller is able to perform good under changing trajectories. Due to the use of the adaptive law, the system is at the ease of implementation and since no priori knowledge if the system is needed, it is model free. Therefore, the proposed adaptive PD-SMC has proven to provide good, robust trajectory tracking.

scholarly journals Impact of Cutting Environments on Sustainable Machining of H13 Tool Steel Alloy

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Vincent A Balogun ◽  
Isuamfon F Edem ◽  
Etimbuk B Bassey
Keyword(s):  
Tool Life ◽  
Tool Steel ◽  
High Speed ◽  
Machining Process ◽  
Steel Alloy ◽  
High Speed Machining ◽  
Sustainable Machining ◽  
H13 Tool Steel ◽  
Green Machining ◽  
The Impact

The use of electrical energy and coolants/lubricants has been widely reported in mechanical machining. However, increased research and process innovation in high speed machining has brought about optimised manufacturing cycle times. This has promoted dry machining and the use of minimum quantity lubrication (MQL). This work understudies the impact of different cutting environments in machining H13 tool steel alloys at transition speed regime with emphasis on sustainable machining of the alloy. To achieve this, end milling tests were performed on AISI H13 steel alloy (192 BHN) on a MIKRON HSM 400 high speed machining centre using milling inserts. After each cutting pass, the milling insert was removed for tool wear measurement on the digital microscope. The electrical power consumed was measured with the Fluke 435 power clamp meter mounted on the three phase cable at the back of the machine. It was discovered that MQL has a promising advantage in terms of tool life with 25 minutes of machining, net power requirement of 10% when compared to dry cutting, and environmental benefits when machining H13 tool steel alloy. This work is fundamentally important in assessing the environmental credentials and resource efficiency regime for green machining of H13 tool steel alloysKeywords— H13 tool steel, green machining, process optimization, tool life, cutting environments, energy consumption 

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.

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