scholarly journals General Cutting Dynamics Model for Five-Axis Ball-End Milling Operations

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Jianhui Li ◽  
Z. Murat Kilic ◽  
Yusuf Altintas
Keyword(s):  
Tool Path ◽  
End Milling ◽  
Forced Vibrations ◽  
Numerical Control ◽  
Chatter Stability ◽  
Dynamics Model ◽  
Control Machine Tool ◽  
Axis Orientation ◽  
Ball End Milling ◽  
Five Axis

Abstract Five-axis ball-end milling is used extensively to machine parts with sculptured surfaces. This paper presents the general cutting dynamics model of the ball-end milling process for machine tools with different five-axis configurations. The structural dynamics of both the tool and workpiece are considered for the prediction of chatter stability at each tool location along the tool path. The effects of tool–workpiece engagement and tool axis orientation are included in the model. By sweeping the spindle speeds, the chatter-free spindle speeds are selected followed by the prediction of forced vibrations in five-axis milling of thin-walled, flexible parts. The proposed model has been experimentally illustrated to predict the chatter stability and forced vibrations on a table-tilting five-axis computer numerical control machine tool.

Tool Orientation Planning in Milling With Process Dynamic Constraints: A Minimax Optimization Approach

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Tao Huang ◽  
Xiao-Ming Zhang ◽  
Jürgen Leopold ◽  
Han Ding
Keyword(s):  
Tool Path ◽  
End Milling ◽  
Tool Path Generation ◽  
Optimization Approach ◽  
Path Generation ◽  
Tool Orientation ◽  
Minimax Optimization ◽  
Ball End Milling ◽  
Dynamic Constraints ◽  
Five Axis

In five-axis milling process, the tool path generated by a commercial software seldom takes the dynamics of the machining process into account. The neglect of process dynamics may lead to milling chatter, which causes overcut, quick tool wear, etc., and thus damages workpiece surface and shortens tool life. This motivates us to consider dynamic constraints in the tool path generation. Tool orientation variations in five-axis ball-end milling influence chatter stability and surface location error (SLE) due to the varying tool-workpiece immersion area and cutting force, which inversely provides us a feasible and flexible way to suppress chatter and SLE. However, tool orientations adjustment for suppression of chatter and SLE may cause drastic changes of the tool orientations and affects surface quality. The challenge is to strike a balance between the smooth tool orientations and suppression of chatter and SLE. To overcome the challenge, this paper presents a minimax optimization approach for planning tool orientations. The optimization objective is to obtain smooth tool orientations, by minimizing the maximum variation of the rotational angles between adjacent cutter locations, with constraints of chatter-free and SLE threshold. A dedicated designed ball-end milling experiment is conducted to validate the proposed approach. The work provides new insight into the tool path generation for ball-end milling of sculpture surface; also it would be helpful to decision-making for process parameters optimization in practical complex parts milling operations at shop floor.

An Approach to Modeling Cutting Forces in Five-Axis Ball-End Milling of Curved Geometries Based on Tool Motion Analysis

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Guo Dongming ◽  
Ren Fei ◽  
Sun Yuwen
Keyword(s):  
Motion Analysis ◽  
Cutting Forces ◽  
End Milling ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Axis Orientation ◽  
Undeformed Chip Thickness ◽  
Ball End Milling ◽  
Tool Motion ◽  
Five Axis

The prediction of five-axis ball-end milling forces is quite a challenge due to difficulties of determining the underformed chip thickness and engaged cutting edge. To solve these concerns, this paper presents a new mechanistic model of cutting forces based on tool motion analysis. In the model, for undeformed chip thickness determination, an analytical model is first established to describe the sweep surface of cutting edge during the five-axis ball-end milling process of curved geometries. The undeformed chip thickness is then calculated according to the real kinematic trajectory of cutting edges under continuous change of the cutter axis orientation. A Z-map method is used to verify the engaged cutting edge and cutting coefficients are subsequently calibrated. The mechanistic method is applied to predict the cutting force. Validation tests are conducted under different cutter postures and cutting conditions. The comparison between predicted and measured values demonstrates the applicability of the proposed prediction model of cutting forces.

scholarly journals Minimizing Flute Engagement to Adjust Tool Orientation for Reducing Surface Errors in Five-Axis Ball End Milling Operations

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
M. Habibi ◽  
Z. M. Kilic ◽  
Y. Altintas
Keyword(s):  
Optimization Problem ◽  
Tool Path ◽  
End Milling ◽  
Contact Point ◽  
Geometrical Approach ◽  
Tool Orientation ◽  
Ball End Milling ◽  
Surface Errors ◽  
Five Axis ◽  
Path Modification

Abstract Surface errors due to force-induced tool and workpiece deflections are one of the major errors in multi-axis machining of parts especially with thin-walled structures. Dominant approaches to reduce these surface errors are re-machining the part, feed scheduling, and tool path modification. These methods are time consuming and computationally costly, and they rely on experimental data which is used in cutting force and deflection predictions. The present paper introduces a pure geometrical approach to reduce surface errors drastically by minimizing the engagement lengths of flutes’ cutting edges when a point on the flute’s cutting edge is in contact with the design surface. The total engagement length of the flutes’ cutting edges when one of them generates a contact point on the workpiece surface is formulated and considered as the minimization objective function of an optimization problem. Tilt and lead angles, which define the tool orientation, are the design variables of the optimization problem subjected to constraints based on the geometrical requirements of the ball end milling process. The optimization problem uses the nominal tool path to generate an optimal tool path with adjusted tool orientations. The presented method is computationally inexpensive and does not need any experimentally calibrated coefficients to predict cutting forces because of the pure geometrical nature of the approach. The method is experimentally validated through five-axis ball end milling experiments in which more than 90% surface error reduction is achieved.

Parameter Optimization of Ball End Milling Process on Inconel 718 Using RSM and TLBO Algorithm

2015 ◽  
Vol 15 (3) ◽  
pp. 293-300 ◽  
Author(s):  
Nandkumar N. Bhopale ◽  
Nilesh Nikam ◽  
Raju S. Pawade
Keyword(s):  
Surface Roughness ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Surface Integrity ◽  
Inconel 718 ◽  
Tool Path ◽  
End Milling ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Ball End Milling

AbstractThis paper presents the application of Response Surface Methodology (RSM) coupled with Teaching Learning Based Optimization Technique (TLBO) for optimizing surface integrity of thin cantilever type Inconel 718 workpiece in ball end milling. The machining and tool related parameters like spindle speed, milling feed, axial depth of cut and tool path orientation are optimized with considerations of multiple response like deflection, surface roughness, and micro hardness of plate. Mathematical relationship between process parameters and deflection, surface roughness and microhardness are found out by using response surface methodology. It is observed that after optimizing the process that at the spindle speed of 2,000 rpm, feed 0.05 mm/tooth/rev, plate thickness of 5.5 mm and 15° workpiece inclination with horizontal tool path gives favorable surface integrity.

scholarly journals Optimisation of Planning Parameters for Machining Blade Electrode Micro-Fillet with Scallop Height Modelling

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 237
Author(s):  
Yue Liu ◽  
Zhanqiang Liu ◽  
Wentong Cai ◽  
Yukui Cai ◽  
Bing Wang ◽  
...  
Keyword(s):  
Path Planning ◽  
Tilt Angle ◽  
Tool Path ◽  
End Milling ◽  
Tool Path Planning ◽  
Scallop Height ◽  
Aero Engine ◽  
Tool Tilt Angle ◽  
Five Axis ◽  
Height Model

Aero-engine blades are manufactured by electroforming process with electrodes. The blade electrode is usually machined with five-axis micromilling to get required profile roughness. Tool path planning parameters, such as cutting step and tool tilt angle, have a significant effect on the profile roughness of the micro-fillet of blade electrode. In this paper, the scallop height model of blade electrode micro-fillet processed by ball-end milling cutter was proposed. Effects of cutting step and tool tilt angle the machined micro-fillet profile roughness were predicted with the proposed scallop height model. The cutting step and tool tilt angle were then optimised to ensure the contour precision of the micro-fillet shape requirement. Finally, the tool path planning was generated and the machining strategy was validated through milling experiments. It was also found that the profile roughness was deteriorated due to size effect when the cutting step decreased to a certain value.

Surface Integrity Studies in Ball End Milling of Thin Shaped Cantilever Inconel 718

2014 ◽  
Author(s):  
Nandkumar N. Bhopale ◽  
Raju S. Pawade
Keyword(s):  
Surface Integrity ◽  
Inconel 718 ◽  
Tool Path ◽  
Surface Defects ◽  
End Milling ◽  
Surface Region ◽  
Lower Surface ◽  
Machined Surface ◽  
Ball End Milling ◽  
Integrity Analysis

The paper presents the surface integrity analysis in ball end milling of thin shaped cantilever plate of Inconel 718. It is noticed that the workpiece deflection has significantly contributed to machined surface integrity in terms of surface topography and subsurface microhardness. The ball end milling performed with 15° workpiece inclination with horizontal tool path produced higher surface integrity which varies with the location of machined surface region. In general, the mid portion of the machined plate shows lower surface roughness and microhardness with less surface defects.

scholarly journals Experimental Verification of Chatter-Free Ball End Milling Strategy

2013 ◽  
Vol 7 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Lin Lu ◽  
◽  
Masahiko Sato ◽  
Hisataka Tanaka ◽  
Keyword(s):  
Cutting Tool ◽  
End Milling ◽  
Cutting Parameters ◽  
Cutting Condition ◽  
Chatter Stability ◽  
Chatter Vibration ◽  
Ball End Milling ◽  
Machining Center ◽  
Avoidance Control ◽  
Avoidance Strategy

Chatter vibration frequently occurs in ball end milling. If the characteristics of the cutting tool system and cutting process are known, chatter stability in ball end milling can be evaluated. Hence, in this paper, a chatter-avoidance strategy based on a regenerative chatter theory is proposed to prevent the occurrence of chatter. This consists of a simulation of chatter stability and cutting condition control. When the characteristics of a vibration system change, this chatter-avoidance strategy cannot cope with it. Therefore, another chatter-avoidance control algorism that changes cutting parameters on a machining center is proposed. This can adapt to the change in the characteristics of the vibration systemduring cutting. The effectiveness of the two chatter-avoidance methods proposed is examined through experiments.

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