High Speed Non-Linear Micro-Milling Dynamics

2012 ◽  
Author(s):  
Eric B. Halfmann ◽  
C. Steve Suh
Keyword(s):  
Slip Line ◽  
Chip Thickness ◽  
Rake Angle ◽  
Micro Milling ◽  
Work Piece ◽  
Formation Mechanisms ◽  
Effective Rake Angle ◽  
Non Linear ◽  
Force Mechanism ◽  
Milling Dynamics

The efficiency of the milling process is limited due to excessive vibrations that negatively impact the tool and work-piece quality. This becomes even more of a concern in micro-milling where sudden tool breakage occurs before the operator can adjust cutting parameters. Due to different chip formation mechanisms in micro-milling, an increased tool-radius to feed-rate ratio, and higher spindle speeds, micro-milling is a highly non-linear process which can produce multiple and broadband frequencies which increase the probability of tool failure. This paper investigates micro-milling through the development and analysis of a 3-D nonlinear micro-milling dynamic model. A lumped mass, spring, damper system is assumed for modeling the dynamic properties of the tool. The force mechanism utilized is a slip-line field model that provides the advantages of being highly dynamic by accounting for the constantly changing effective rake angle and slip-line variables. Accurate prediction of the chip thickness is important in correctly predicting the dynamics of the system since the force mechanism and its variables are a function of the chip thickness. A novel approach for calculating the instantaneous chip thickness which accounts for the tool jumping out of the cut and elastic recovery of the work-piece is presented. The derivation for the effective rake angle is given and the helical angle is accounted for resulting in a 3-D micro-milling model. The results of simulating the model demonstrate its capability of producing the high frequency force components that are seen in experimental data available in literature. The advantages of using this approach over the constant empirical force coefficient approach when studying micro-milling dynamics is discussed and the instability of the system is investigated utilizing instantaneous frequency.

Impact of Spindle Speed on Micro-Milling Stability

2012 ◽  
Author(s):  
Eric B. Halfmann ◽  
C. Steve Suh
Keyword(s):  
Slip Line ◽  
Chip Thickness ◽  
Rake Angle ◽  
Micro Milling ◽  
Work Piece ◽  
Formation Mechanisms ◽  
Lumped Mass ◽  
Effective Rake Angle ◽  
Helical Angle ◽  
Force Mechanism

Milling efficiency is hampered by excessive tool vibrations that negatively impact the work-piece quality. This is more of a concern in micro-milling where sudden tool breakage occurs before the operator can adjust cutting parameters. Due to different chip formation mechanisms in micro-milling, an increased tool-radius to feed-rate ratio, and higher spindle speeds, micro-milling is a highly non-linear process which can produce multiple and broadband frequencies which increase the probability of tool failure. Micro-milling is studied through the development and analysis of a 3-D nonlinear micro-milling dynamic model. A lumped mass, spring, damper system is assumed for modeling the dynamic properties of the tool. The force mechanism utilized is a slip-line field model that provides the advantages of being highly dynamic by accounting for the constantly changing effective rake angle and slip-line variables. Accurate prediction of the chip thickness is important in correctly predicting the dynamics of the system since the force mechanism and its variables are a function of the chip thickness. A novel approach for calculating the instantaneous chip thickness which accounts for the tool jumping out of the cut and elastic recovery of the work-piece is presented. The effective rake angle and helical angle is accounted for resulting in a 3-D micro-milling model. The model is shown to resolve the high frequency force components that are seen in experimental data available in literature. Also, exciting the system at various spindle speeds results in dynamic states of motion that negatively impact the process through increased vibration amplitude and a broad frequency bandwidth.

Mathematical Modeling of Cutting Forces in Microdrilling

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Kumar Sambhav ◽  
Puneet Tandon ◽  
Shiv G. Kapoor ◽  
Sanjay G. Dhande
Keyword(s):  
Mathematical Modeling ◽  
Slip Line ◽  
Cutting Forces ◽  
Chip Thickness ◽  
Rake Angle ◽  
Cutting Mechanism ◽  
Line Field ◽  
Slip Line Field ◽  
Effective Rake Angle ◽  
Secondary Cutting

In drilling, the primary and secondary cutting lips of the drill shear the material while the central portion of the chisel edge indents the workpiece, making the cutting process complex to understand. As we go for microdrilling, it exhibits an added complexity to the cutting mechanism as the edge radius gets comparable to chip thickness at low feeds. The presented work models the forces by the primary cutting lip of a microdrill analytically using slip-line field that includes the changes in the effective rake angle and dead metal cap during cutting for cases of shearing as well as ploughing. To study the variation of forces experimentally, the primary cutting lip and chisel edge forces are separated out by drilling through pilot holes of diameter slightly above the drill-web thickness. Finally, the analytical and experimental results are compared and the model is calibrated.

scholarly journals Experimental Study on the Minimum Undeformed Chip Thickness Based on Effective Rake Angle in Micro Milling

Micromachines ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 924
Author(s):  
Xian Wu ◽  
Li Liu ◽  
Mingyang Du ◽  
Jianyun Shen ◽  
Feng Jiang ◽  
...  
Keyword(s):  
Averaging Method ◽  
Chip Thickness ◽  
Rake Angle ◽  
Cutting Process ◽  
Micro Milling ◽  
Undeformed Chip Thickness ◽  
Effective Rake Angle ◽  
Force Signal ◽  
Micro Parts ◽  
Tool Cutting

Micro milling is widely used to manufacture micro parts due to its obvious advantages. The minimum undeformed chip thickness, the effective rake angle, and size effect are the typical characteristics and closely related to each other in micro milling. In this paper, the averaging method is proposed to quantitatively estimate the effective rake angle in the cutting process. The minimum undeformed chip thickness is explained based on the effective rake angle and determined to be 0.17 rn (tool cutting edge radius). Then, micro milling experiment was conducted to study the effect of the minimum undeformed chip thickness. It is found that the minimum undeformed chip thickness results in the unstable cutting process, the uneven peaks on cutting force signal, and the dense characteristic frequency distribution on frequency domain signal. The dominant ploughing effect induces the great specific cutting energy and the deteriorated surface roughness due to the minimum undeformed chip thickness.

Experimental investigation of a slip-line field model for a worn cutting tool

2013 ◽  
Vol 228 (8) ◽  
pp. 1398-1404 ◽  
Author(s):  
Alper Uysal ◽  
Erhan Altan
Keyword(s):  
Wear Rate ◽  
Slip Line ◽  
Field Model ◽  
Cutting Tool ◽  
Flank Wear ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
Uncut Chip Thickness ◽  
Line Field

In this study, the slip-line field model developed for orthogonal machining with a worn cutting tool was experimentally investigated. Minimum and maximum values of five slip-line angles ( θ1, θ2, δ2, η and ψ) were calculated. The friction forces that were caused by flank wear land, chip up-curl radii and chip thicknesses were calculated by solving the model. It was specified that the friction force increased with increase in flank wear rate and uncut chip thickness and it decreased a little with increase in cutting speed and rake angle. The chip up-curl radius increased with increase in flank wear rate and it decreased with increase in uncut chip thickness. The chip thickness increased with increase in flank wear rate and uncut chip thickness. Besides, the chip thickness increased with increase in rake angle and it decreased with increase in cutting speed.

Influence of Depth of Cut on Contact Phenomenon in Micromachining

2014 ◽  
Vol 660 ◽  
pp. 8-12
Author(s):  
J.B. Saedon ◽  
Noor Aniza Norrdin ◽  
Mohd Azman Yahaya ◽  
N.H. Mohamad Nor ◽  
Mohd Zulhafiz Md Salih
Keyword(s):  
Cutting Tool ◽  
Chip Thickness ◽  
Rake Angle ◽  
Depth Of Cut ◽  
Work Piece ◽  
Arbitrary Lagrangian Eulerian ◽  
Contact Phenomenon ◽  
Aisi D2 ◽  
Material Separation ◽  
Contact Distribution

Chip formation is a dynamic process that is often nonlinear in nature. A chip may not form when the depth of cut is less than a minimum chip thickness. It is aimed to investigate influence of depth of cut on contact phenomenon in micromachining. This paper presents a series of simulation works by finite element method on depth of cut effect on micromachining. A model is developed with consideration of the Johnson-Cook material and Arbitrary Lagrangian–Eulerian (ALE) method. In this work investigate the effect of depth of cut on the contact phenomenon during micromachining AISI D2. The results of the analysis are showed in aspects of interrelationship between material separation and frictional shear contact, distribution of stick-slide regions and contact stress on the work piece and cutting tool. It is found that the sticking and sliding was occurred on three zones as primary, secondary and tertiary shear zone. The contact phenomena can be showed around the tool edge radius where material flows around it and piles in front of the cutting tool through material separation. The investigation of contact phenomena inclusive under three criteria such as a/r < 1, a/r > 1 and a/r = 1 on positive rake angle.

scholarly journals Microstructure-Based 3D FE Modeling for Micro Cutting Ferritic-Pearlitic Carbon Steels

2014 ◽  
Author(s):  
M. Abouridouane ◽  
F. Klocke ◽  
D. Lung
Keyword(s):  
Size Effects ◽  
Chip Thickness ◽  
Rake Angle ◽  
Carbon Steels ◽  
Micro Milling ◽  
Fe Model ◽  
Two Phase ◽  
Workpiece Material ◽  
Micro Cutting ◽  
Feed Force

The mechanics of the cutting process on the microscopic level differ fundamentally from the conventional macro cutting. For example, the tool edge radius influences the cutting mechanism in micro machining significantly with regard to the effective rake angle, the minimum chip thickness, the dominance of ploughing, and the related elasto-plastic deformation of the workpiece material. These phenomena, known as size effects, have a profound impact on the cutting force, process stability, and resulting surface finish in micro cutting. Therefore, microstructural effects in microscale cutting require quite different assumptions to be made concerning underlying material behaviour during micro cutting and have led to the need for new modeling approaches to account for such effects. This paper presents a three-dimensional finite element approach to incorporate microstructure into micro cutting simulation based on the concept of a representative volume element (RVE) and constitutive material modeling as well as using the Lagrangian formulation proposed in the implicit FE code Deform 3D™. Micro drilling and micro milling tests using solid carbide tools with different diameters (d = 50 μm − 1 mm) were performed on ferrite-pearlite two-phase steel AISI 1045 for the verification of the developed 3D multiphase FE computation model regarding chip formation, feed force, and torque. The developed 3D multiphase FE model was successfully used to predict size effects in micro cutting.

Experimental Study on the Chip Geometry and Shear Angle in Micro-Cutting Aluminum 7050-T7451

2010 ◽  
Vol 443 ◽  
pp. 657-662
Author(s):  
Jun Zhou ◽  
Jian Feng Li ◽  
Jie Sun
Keyword(s):  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
Shear Angle ◽  
Micro Scale ◽  
Effective Rake Angle ◽  
Al 7075 ◽  
Chip Geometry ◽  
Cutting Experiments ◽  
Machining Characteristics

In this paper, the micro-scale machining characteristics of a non-ferrous structural alloy, aluminum 7050-T7451 is investigated through a series of cutting experiments. The effects of cutting speed and undeformed chip thickness on the chip geometry, cutting ratio, effective rake angle and shear angle in orthogonal micro-scale cutting of Al 7075-T7451 are presented. Explanations for the observed trends are also given.

scholarly journals Prediction of Surface Quality Based on the Non-Linear Vibrations in Orthogonal Cutting Process: Time Domain Modeling

2019 ◽  
Vol 3 (3) ◽  
pp. 53
Author(s):  
Kibbou ◽  
Dellagi ◽  
Majdouline ◽  
Moufki
Keyword(s):  
Surface Quality ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
Cutting Conditions ◽  
Process Time ◽  
Mean Deviation ◽  
Non Linear ◽  
Linear Vibrations

This work presents an analysis of relationships between the non-linear vibrations in machining and the machined surface quality from an analytical model based on a predictive machining theory. In order to examine the influences of tool oscillations, several non-linear mechanisms were considered. Additionally, to solve the non-linear problem, a new computational strategy was developed. The resolution algorithm significantly reduces the computational times and makes the iterative approach more stable. In the present approach, the coupling between the tool oscillations and (i) the regenerative effect due to the variation of the uncut chip thickness between two successive passes and/or when the tool leaves the work (i.e., the tool disengagement from the cut), (ii) the friction conditions at the tool–chip interface, and (iii) the tool rake angle was considered. A parametric study was presented. The correlation between the surface quality, the cutting speed, the tool rake angle, and the friction coefficient was analyzed. The results show that, during tool vibrations, the arithmetic mean deviation of the waviness profile is highly non-linear with respect to the cutting conditions, and the model can be useful for selecting optimal cutting conditions.

Effect of side edge angle and effective rake angle on top burrs in micro-milling

2012 ◽  
Vol 36 (3) ◽  
pp. 444-450 ◽  
Author(s):  
Kushendarsyah Saptaji ◽  
Sathyan Subbiah ◽  
Jaspreet Singh Dhupia
Keyword(s):  
Rake Angle ◽  
Micro Milling ◽  
Edge Angle ◽  
Side Edge ◽  
Effective Rake Angle

Mathematical Modeling of Cutting Forces in Micro-Drilling

2012 ◽  
Author(s):  
Kumar Sambhav ◽  
Puneet Tandon ◽  
Shiv G. Kapoor ◽  
Sanjay G. Dhande
Keyword(s):  
Mathematical Modeling ◽  
Chip Thickness ◽  
Rake Angle ◽  
Cutting Mechanism ◽  
Line Field ◽  
Slip Line Field ◽  
Effective Rake Angle ◽  
Micro Drilling ◽  
Micro Drill ◽  
Secondary Cutting

In drilling, the primary cutting lips and the secondary cutting lips of the drill shear the material while the central portion of the chisel edge indents the workpiece, making the cutting process complex to understand. As we go for micro-drilling, it exhibits an added complexity to the cutting mechanism when the edge radius gets comparable to chip thickness at low feeds. The presented work models the forces by the primary cutting lip of a micro-drill analytically using slip-line field that includes the changes in the effective rake angle and dead metal cap during cutting for cases of shearing as well as ploughing. To study the variation of forces experimentally, the primary cutting lip and chisel edge forces are separated out by drilling through pilot holes of diameter slightly above the drill-web thickness. Finally, the analytical and experimental results have been compared and the model has been calibrated.

Sign in / Sign up

Export Citation Format

Share Document