An Improved Method for Cutting Force and Surface Error Prediction in Flexible End Milling Systems

1986 ◽  
Vol 108 (4) ◽  
pp. 269-279 ◽  
Author(s):  
J. W. Sutherland ◽  
R. E. DeVor
Keyword(s):  
Cutting Force ◽  
End Milling ◽  
System Model ◽  
Machining Processes ◽  
Force System ◽  
Surface Error ◽  
Rigid System ◽  
Load Model ◽  
Flexible System ◽  
Chip Load

As more emphasis is placed on quality and productivity in manufacturing, it becomes necessary to develop models that more accurately describe the performance of machining processes. An improved model for the prediction of the cutting force system and surface error in end milling has been developed and has been implemented on the computer. This enhanced model takes into account the effect of system deflections on the chip load, and solves for the chip load that balances the cutting forces and the resulting system deflections. Such a model allows for the evaluation of cuts in which deflections significantly effect the chip load. The flexible system model predictions of forces and surface error are compared against both measured and rigid system model-predicted values associated with the machining conditions for experiments performed on the 390 casting aluminum alloy. It is shown that the enhanced chip load model gives predictions of both cutting force signatures and surface error profiles that are significantly better than the rigid system chip load model developed previously. The fact that system deflections temper the effects of runout, and reduce both peak cutting force and maximum surface error is demonstrated and discussed.

A Flexible Ball-End Milling System Model for Cutting Force and Machining Error Prediction

1996 ◽  
Vol 118 (4) ◽  
pp. 461-469 ◽  
Author(s):  
Hsi-Yung Feng ◽  
Chia-Hsiang Menq
Keyword(s):  
Cutting Forces ◽  
Present Model ◽  
End Milling ◽  
System Model ◽  
Rigid System ◽  
Ball End Milling ◽  
Flexible System ◽  
Machining Errors ◽  
Chip Geometry ◽  
Cutting System

This paper presents a flexible system model for the prediction of cutting forces and the resulting machining errors in the ball-end milling process. Unlike the previously developed rigid system model, the present model takes into account the instantaneous and regenerative feedback of cutting system deflections to establish the chip geometry in the cutting force calculation algorithm. The deflection-dependent chip geometry is identified by using an iterative procedure to balance the cutting forces and the associated cutting system deflections. A series of steady state 3D cross-feed ball-end milling cuts were performed to validate the capability of the present model in predicting the cutting forces and the resulting machining errors. It is shown that the flexible system model gives significantly better predictions of the cutting forces than the rigid system model. Good agreement between the predicted and measured machining errors is demonstrated for the simple surfaces generated by horizontal cuts.

scholarly journals Modified Mechanistic Model Based on Gaussian Process Adjusting Technique for Cutting Force Prediction in Micro-End Milling

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Xiaoping Liao ◽  
Zhenkun Zhang ◽  
Kai Chen ◽  
Kang Li ◽  
Junyan Ma ◽  
...  
Keyword(s):  
Gaussian Process ◽  
Cutting Force ◽  
Cutting Forces ◽  
End Milling ◽  
Mechanistic Model ◽  
Machining Process ◽  
Mechanistic Models ◽  
Machining Processes ◽  
Model Based ◽  
Micro End Milling

Micro-end milling is in common use of machining micro- and mesoscale products and is superior to other micro-machining processes in the manufacture of complex structures. Cutting force is the most direct factor reflecting the processing state, the change of which is related to the workpiece surface quality, tool wear and machine vibration, and so on, which indicates that it is important to analyze and predict cutting forces during machining process. In such problems, mechanistic models are frequently used for predicting machining forces and studying the effects of various process variables. However, these mechanistic models are derived based on various engineering assumptions and approximations (such as the slip-line field theory). As a result, the mechanistic models are generally less accurate. To accurately predict cutting forces, the paper proposes two modified mechanistic models, modified mechanistic models I and II. The modified mechanistic models are the integration of mathematical model based on Gaussian process (GP) adjustment model and mechanical model. Two different models have been validated on micro-end-milling experimental measurement. The mean absolute percentage errors of models I and II are 7.76% and 6.73%, respectively, while the original mechanistic model’s is 15.14%. It is obvious that the modified models are in better agreement with experiment. And model II performs better between the two modified mechanistic models.

An Adaptive Fuzzy Controller for Constant Cutting Force in End-Milling Processes

2006 ◽  
Author(s):  
Chengying Xu ◽  
Yung C. Shin
Keyword(s):  
Cutting Force ◽  
Fuzzy Logic Controller ◽  
Fuzzy Controller ◽  
Metal Removal ◽  
End Milling ◽  
Open Architecture ◽  
Real Time Control ◽  
Machining Processes ◽  
Adaptation Mechanism ◽  
Machining Productivity

A novel multi-level fuzzy control (MLFC) system is introduced and implemented for online force control of end-milling processes to increase machining productivity and improve workpiece quality, where the cutting force is maintained at its maximum allowable level in the presence of different variations inherent in milling processes, such as tool wear, workpiece geometry and material properties. In the controller design, the fuzzy rules are generated heuristically without any mathematical model of the milling processes. An adaptation mechanism is embedded in to tune the control parameters on-line and the resultant closed-loop system is guaranteed to be stable based on the input-output passivity analysis. In the experiment, the control algorithm is implemented using a National Instrument real-time control computer in an open architecture control environment, where high metal removal rates (MRR) are achieved and the cycle time is reduced by up to 34% over the case without any force controller, and by 22% compared with the regular fuzzy logic controller (FLC), thereby indicating its effectiveness in improving the productivity for actual machining processes.

scholarly journals Precise Machining Based on Ritz Non-uniform Allowances for Titanium Blade Fabricated by Selective Laser Melting

2021 ◽  
Author(s):  
Bo Zhang ◽  
Juntang Yuan ◽  
zhenhua wang ◽  
Xi Li
Keyword(s):  
Selective Laser Melting ◽  
End Milling ◽  
Deformation Model ◽  
Thin Wall ◽  
Laser Melting ◽  
Machining Processes ◽  
Element Analysis ◽  
Surface Error ◽  
Wall Stiffness ◽  
Finishing Machining

Abstract Selective Laser Melting (SLM) is an increasingly concerned trend in Ti-6Al-4V blade manufacturing, while the SLMed Ti-6Al-4V blade cannot be used directly because of poor surface integrity and high residual stresses. Precise machining after SLM is a feasible solution but also a challenge. The low rigidity of the blade will lead to deformation when machining. The deformation can lead to surface error and may make defect parts. Two-steps machining processes to address the problems were proposed in this paper. First, a non-uniform allowance distribution was allocated and optimized in semi-finishing based on Ritz solution to elastic deformation. The blade was simplified as a cantilever thin plate with various thickness, and the thickness of finishing allowance was designed and optimized on the premise of ensuring the thin-wall stiffness of the blade, so as to realize the design of Ritz non-uniform allowance. Then, finishing machining was conducted to achieve precise parts. A blade deformation model was established to evaluate surface error with cutting force moving and changing. Finite element analysis and experimental validation in ball-end milling of a blade were conducted. FEA results and experimental results showed dimensional errors have been reduced up to 50%. Further surface tests demonstrated that the mean surface roughness reduced from 7.88 μm to 0.815 μm. And the residual surface stresses of the SLM samples changed after semi-finishing machining due to the residual stress relaxation and redistribution. The results demonstrated that the proposed method enhanced the surface quality of blade fabricated by SLM.

Study of Effect of Teeth Number on Cutting Force for Cutter Selection in the End Milling of TC4

2019 ◽  
Author(s):  
Kaining Shi ◽  
Ning Liu ◽  
Sibao Wang ◽  
Chi Ma ◽  
Bo Yang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
End Milling ◽  
Chip Thickness ◽  
Machining Efficiency ◽  
Machining Processes ◽  
Cutting Force Coefficients ◽  
Side Milling ◽  
Force Coefficients ◽  
Comparison Results

Abstract Cutting force is a very important factor in machining processes for predicting chatter, surface roughness and machining efficiency. For a given cutter, cutting force is determined by cutting force coefficients and uncut chip thickness. Once a new cutter is adopted, repeated experiments are carried out to calibrate its cutting force coefficients. To reduce the high cost and longtime experiments, theoretical analysis of the effect of cutter parameters on cutting force is required. In current literatures, some cutter parameters, such as helix angle and pitch angle, have been studied to explore their effects on cutting force. However, there is little research about the effect of teeth number on the cutting force. To fill up this gap, the effect of teeth number on cutting force is studied in the paper. Firstly, it is derived and experimentally verified that the cutting force coefficients are unchanged for cutters with different teeth number but the same teeth parameters, e.g., rake angle, shear angle, etc. Secondly, by matching the measured cutting force point with the cutter rotation angle, the cutting force coefficients can be calibrated by only one experiment when we assume that the material of the cutter is the same. Therefore, the cutting forces generated by cutters with different teeth numbers can be predicted based on only one experiment. Thirdly, from the various comparisons, it is concluded that cutter with 2 teeth number is suggested for side milling and cutter with 3 teeth number is suggested for slotting when surface roughness is considered. The cutter with 5 teeth number is suggested when only the machining efficiency is concerned. Finally, various experiments are carried out to verify the proposed study in milling of titanium alloy Ti6Al4V (TC4), and the comparison results show a good agreement.

An Adaptive Fuzzy Controller for Constant Cutting Force in End-Milling Processes

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Chengying Xu ◽  
Yung C. Shin
Keyword(s):  
Cutting Force ◽  
Fuzzy Logic Controller ◽  
Fuzzy Controller ◽  
Metal Removal ◽  
End Milling ◽  
Open Architecture ◽  
Real Time Control ◽  
Machining Processes ◽  
Adaptation Mechanism ◽  
Machining Productivity

A novel multilevel fuzzy control system is introduced and implemented for online force control of end-milling processes to increase machining productivity and improve workpiece quality, where the cutting force is maintained at its maximum allowable level in the presence of different variations inherent in milling processes, such as tool wear, workpiece geometry, and material properties. In the controller design, the fuzzy rules are generated heuristically without any mathematical model of the milling processes. An adaptation mechanism is embedded to tune the control parameters online, and the resultant closed-loop system is guaranteed to be stable based on the input-output passivity analysis. In the experiment, the control algorithm is implemented using a National Instrument real-time control computer in an open architecture control environment, where high metal removal rates are achieved and the cycle time is reduced by up to 34% over the case without any force controller and by 22% compared with the regular fuzzy logic controller, thereby indicating its effectiveness in improving productivity for actual machining processes.

In-Process Compensation for Milling Cutter Runout via Chip Load Manipulation

1994 ◽  
Vol 116 (2) ◽  
pp. 153-160 ◽  
Author(s):  
S. Y. Liang ◽  
S. A. Perry
Keyword(s):  
Cutting Force ◽  
Control Strategy ◽  
End Milling ◽  
Learning Control ◽  
Cutter Runout ◽  
Machined Surface ◽  
Integral Control ◽  
Proportional Integral ◽  
Proportional Integral Control ◽  
Chip Load

This paper discusses a real-time chip load compensation methodology for the elimination of cutting force oscillation and machined surface scalloping due to cutter runout so as to gain better utilization of machine tools. The concept and implementation of the methodology is illustrated using end milling as a process of example. In this work a force feedback system was discussed in the angle domain based upon a proportional-integral control strategy and a repetitive learning control strategy to actively manipulate the chip load during end milling. Numerical simulations based on experimentally identified machining dynamics were presented to compare the performance of the two control schemes. Experimental investigation under various cutting conditions was performed to assess the viability of the feedback compensation system in the context of cutting force response as well as machined surface finish. It has been shown that a proportional-integral control has limited effectiveness in eliminating the runout-induced cutting force oscillation due to the constraints of system stability and dynamic performance. On the other hand, the learning control system based on the internal model principal successfully yields a cutting force free of oscillatory components at the spindle frequency and significantly improves the quality of machined surfaces by cancelling the nonasymptotically stable dynamics of cutter runout.

The Prediction of Surface Accuracy in End Milling

1982 ◽  
Vol 104 (3) ◽  
pp. 272-278 ◽  
Author(s):  
W. A. Kline ◽  
R. E. DeVor ◽  
I. A. Shareef
Keyword(s):  
Optimization Problems ◽  
End Milling ◽  
Milling Process ◽  
Force System ◽  
Surface Error ◽  
Design And Optimization ◽  
Surface Errors ◽  
Cutter Deflection ◽  
The Difference ◽  
End Milling Process

In the end milling process, the cutting forces during machining produce deflection of the cutter and workpiece which result in dimensional inaccuracies or surface error on the finished component. A previously developed mathematical model for the cutting force system in end milling is combined with models for cutter deflection and workpiece deflection so that the surface error profile may be predicted from the machining conditions and geometry and material properties of the cutter and workpiece. Machining experiments are performed on rigid and flexible workpieces of 7075 aluminum to verify the ability of the models to predict surface error. The model predicted surface error profiles are accurate both in magnitude and shape with the difference between measured and predicted surface errors ranging from 5 to 15 percent. This approach for the prediction of surface errors provides a useful aid for the analysis of a variety of end milling process design and optimization problems.

Sign in / Sign up

Export Citation Format

Share Document