Chatter When Machining Aluminium Alloy: An Investigation Using a Structural Model

1968 ◽  
Vol 183 (1) ◽  
pp. 17-29 ◽  
Author(s):  
B. M. Johnson ◽  
C. Andrew
Keyword(s):  
Machine Tool ◽  
Aluminium Alloy ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Regenerative Chatter ◽  
Tool Vibration ◽  
Undeformed Chip Thickness ◽  
Machining Force ◽  
Conventional Tool

This paper describes an experimental investigation of machine tool chatter, in which the machine tool structure was replaced by a model, two-degrees-of-freedom structure with adjustable and consistent vibration characteristics. Primarily non-regenerative chatter, and secondarily regenerative chatter, were investigated for orthogonal cutting of an aluminium alloy with both conventional and restricted-contact cutting tools. The results are presented in the form of stability charts; these show the limiting widths of cut which can be machined without chatter, for given sets of machining and structural conditions. For non-regenerative chatter, it was found that the limiting width of cut: increases with a decrease in the structure's cross-receptance between the directions normal and tangential to the cut surface; increases with a decrease in cutting speed, but in a manner depending on the structural characteristics; is substantially independent of the mean undeformed chip thickness; increases by at least 25 per cent if contact is restricted to a length approximately equal to the undeformed chip thickness. For regenerative chatter it was found that the limiting width of cut: was approximately one half of the limiting width for non-regenerative chatter, for the otherwise similar machining and structural conditions investigated; increases with a decrease in cutting speed; increases by at least 25 per cent if contact is restricted to a length approximately equal to the undeformed chip thickness. Theoretical predictions of non-regenerative chatter with a conventional tool, based on independent measurements of machining force oscillations during tool vibration, agree well with experimental results. For regenerative chatter with a conventional tool, the theory was based on the superposition of machining force oscillations arising from tool vibration and from removing a wavy surface. The predictions were in error at low cutting speeds, indicating that the force oscillations are not superposable at this condition.

Finite Element Modeling of Chip Formation in the Domain of Negative Rake Angle Cutting

2003 ◽  
Vol 125 (3) ◽  
pp. 324-332 ◽  
Author(s):  
Y. Ohbuchi ◽  
T. Obikawa
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
Undeformed Chip Thickness ◽  
Element Modeling ◽  
Single Grain ◽  
Serrated Chips

A thermo-elastic-plastic finite element modeling of orthogonal cutting with a large negative rake angle has been developed to understand the mechanism and thermal aspects of grinding. A stagnant chip material ahead of the tool tip, which is always observed with large negative rake angles, is assumed to act like a stable built-up edge. Serrated chips, one of typical shapes of chips observed in single grain grinding experiment, form when analyzing the machining of 0.93%C carbon steel SK-5 with a rake angle of minus forty five or minus sixty degrees. There appear high and low temperature zones alternately according to severe and mild shear in the primary shear zone respectively. The shapes of chips depend strongly on the cutting speed and undeformed chip thickness; as the cutting speed or the undeformed chip thickness decreases, chip shape changes from a serrated type to a bulging one to a wavy or flow type. Therefore, there exists the critical cutting speed over which a chip can form and flow along a rake face for a given large negative rake angle and undeformed chip thickness.

scholarly journals An investigation of force components in orthogonal cutting of medical grade cobalt–chromium alloy (ASTM F1537)

2017 ◽  
Vol 231 (4) ◽  
pp. 269-275 ◽  
Author(s):  
Szymon Baron ◽  
Eamonn Ahearne
Keyword(s):  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Lifestyle Changes ◽  
Ageing Population ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Undeformed Chip Thickness ◽  
Force Components ◽  
Medical Grade

An ageing population, increased physical activity and obesity are identified as lifestyle changes that are contributing to the ongoing growth in the use of in-vivo prosthetics for total hip and knee arthroplasty. Cobalt–chromium–molybdenum (Co-Cr-Mo) alloys, due to their mechanical properties and excellent biocompatibility, qualify as a class of materials that meet the stringent functional requirements of these devices. To cost effectively assure the required dimensional and geometric tolerances, manufacturers rely on high-precision machining. However, a comprehensive literature review has shown that there has been limited research into the fundamental mechanisms in mechanical cutting of these alloys. This article reports on the determination of the basic cutting-force coefficients in orthogonal cutting of medical grade Co-Cr-Mo alloy ASTM F1537 over an extended range of cutting speeds ([Formula: see text]) and levels of undeformed chip thickness ([Formula: see text]). A detailed characterisation of the segmented chip morphology over this range is also reported, allowing for an estimation of the shear plane angle and, overall, providing a basis for macro-mechanic modelling of more complex cutting processes. The results are compared with a baseline medical grade titanium alloy, Ti-6Al-4V ASTM F136, and it is shown that the tangential and thrust-force components generated were, respectively, ≈35% and ≈84% higher, depending primarily on undeformed chip thickness but with some influence of the cutting speed.

Study on the Influence of Anisotropy on Cutting Performance of Aviation Aluminium Alloy 7050-T7451

2020 ◽  
Vol 990 ◽  
pp. 29-35
Author(s):  
Hui Wang ◽  
Ying Meng ◽  
Duo Duo Li ◽  
Xiu Li Fu ◽  
Qi Hang Shi
Keyword(s):  
Aluminium Alloy ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Cutting Performance ◽  
Rolled Sheet ◽  
Feed Speed ◽  
Aluminium Alloy 7050 ◽  
Degree Of Anisotropy ◽  
Forming Angle

Based on the hypocycloid theory, a highspeed orthogonal cutting simulation model was established. The cutting parameters (cutting speed, feed rate) and plane forming angle of the workpiece of aeronautical aluminium alloy 7050-T7451 pre-stretched rolled sheet were simulated and validated. The mapping relationship between cutting parameters, anisotropy and cutting performance was analyzed. The results show that the degree of anisotropy and the difficulty of material cutting are proportional to the forming angle, and the anisotropy decreases with the increase of cutting speed and the decrease of feed speed. Finally, the optimal cutting process range of aluminum alloy 7050-T7451 was obtained, which provides data support for highspeed cutting of anisotropic materials.

Dimensional Deviation Affected by Cutting Parameters and Machine Tool Rigidity in Dry Turning of S45C Steel

2013 ◽  
Vol 315 ◽  
pp. 749-754 ◽  
Author(s):  
M.A. Rahman ◽  
A.B. Baharudin ◽  
S. Adi ◽  
Nur Izan Syahriah Hussein ◽  
H. Isa ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Machine Tool ◽  
Regression Model ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Numerical Control ◽  
Depth Of Cut ◽  
Dry Turning ◽  
Tool Vibration ◽  
Dimensional Deviation

Performance of machining processes is assessed by dimensional and geometrical accuracy which is mentioned in this paper as dimensional deviation. A part quality does not depend solely on the depth of cut, feed rate and cutting speed. Other variable such as excessive machine tool vibration due to insufficient dynamic rigidity can be deleterious to the desired results. The focus of the present study is to find a correlation between dimensional deviation against cutting parameters and machine tool vibration in dry turning. Hence cutting parameters and vibration-based regression model can be established for predicting the part dimensional deviation. Experiments are conducted using a Computerized Numerical Control (CNC) lathe with carbide insert cutting tool. Vibration data are collected through a data acquisition system, then tested and analyzed through statistical analysis. The analysis revealed that machine tool vibration has significant effect on dimensional deviation where statistical analysis of individual regression coefficients showed p<0.05. The developed regression model has been validated through experimental tests and found to be reliable to predict dimensional deviation.

scholarly journals Neural Network Modeling of Cutting Force and Chip Thickness Ratio for Turning Aluminum Alloy 7075-T6

2018 ◽  
Vol 14 (1) ◽  
pp. 67-76
Author(s):  
Mohanned Mohammed H. AL-Khafaji
Keyword(s):  
Cutting Force ◽  
Feed Rate ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Cutting Parameters ◽  
Thickness Ratio ◽  
Depth Of Cut ◽  
Feed Force ◽  
Machining Force ◽  
Force Components

The turning process has various factors, which affecting machinability and should be investigated. These are surface roughness, tool life, power consumption, cutting temperature, machining force components, tool wear, and chip thickness ratio. These factors made the process nonlinear and complicated. This work aims to build neural network models to correlate the cutting parameters, namely cutting speed, depth of cut and feed rate, to the machining force and chip thickness ratio. The turning process was performed on high strength aluminum alloy 7075-T6. Three radial basis neural networks are constructed for cutting force, passive force, and feed force. In addition, a radial basis network is constructed to model the chip thickness ratio. The inputs to all networks are cutting speed, depth of cut, and feed rate. All networks performances (outputs) for all machining force components (cutting force, passive force and feed force) showed perfect match with the experimental data and the calculated correlation coefficients were equal to one. The built network for the chip thickness ratio is giving correlation coefficient equal one too, when its output compared with the experimental results. These networks (models) are used to optimize the cutting parameters that produce the lowest machining force and chip thickness ratio. The models showed that the optimum machining force was (240.46 N) which can be produced when the cutting speed (683 m/min), depth of cut (3.18 mm) and feed rate (0.27 mm/rev). The proposed network for the chip thickness ratio showed that the minimum chip thickness is (1.21), which is at cutting speed (683 m/min), depth of cut (3.18 mm) and feed rate (0.17 mm/rev).

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.

The Measurement of Dynamic Cutting Force Data and its Application to the Prediction of Chatter

1982 ◽  
Vol 24 (3) ◽  
pp. 139-145
Author(s):  
M. Burdekin ◽  
S. E. Kilic
Keyword(s):  
Machine Tool ◽  
Cutting Force ◽  
Orthogonal Cutting ◽  
Cutting Conditions ◽  
Cutting Force Coefficients ◽  
Regenerative Chatter ◽  
Dynamic Cutting Force ◽  
Force Data ◽  
Cut Surface ◽  
Tangential Directions

A method and the related equipment to obtain dynamic cutting force coefficients under simulated regenerative chatter conditions are described. The coefficients in both thrust (normal to the cut surface) and the main cutting (tangential) directions for orthogonal cutting are presented for various cutting conditions. An algorithm which is developed to predict chatter instability by combining the receptance of a machine tool with the dynamic cutting data is also presented. Comparison of experimentally-determined stability charts of a centre lathe with the predicted ones is made to evaluate the reliability of the method.

Investigation of Cutting Parameter and Machine Tool Vibration Effects Using Regression Analysis to Enhance Part Dimensional Accuracy

2015 ◽  
Vol 761 ◽  
pp. 93-97
Author(s):  
M.A. Rahman ◽  
Nur Atiqah Md Sadan ◽  
Mohammad Minhat ◽  
Halim Isa ◽  
Abu Bakar Baharudin
Keyword(s):  
Machine Tool ◽  
Cutting Speed ◽  
Dimensional Accuracy ◽  
Numerical Control ◽  
Manufacturing Cost ◽  
Machining Parameters ◽  
Turning Process ◽  
High Quality ◽  
Tool Vibration ◽  
Machined Parts

Dimensional accuracy plays important criteria in producing high quality machined parts. This is a big challenge to manufacturers of precision components to produce good quality parts with minimum manufacturing error. The focus of this paper is to study the influence of the machine tool rigidity and cutting parameters on dimensional accuracy in turning operation. A method was prepared for identifying the factors effecting dimensional accuracy in a turning process. Experimental setup involved computerized numerical control (CNC) lathe machine, with VBMT 160404 carbide insert and mild steel, as cutting tool and workpiece respectively. The statistical analysis was used for analyzing and determining the accuracy of experimental data through Minitab statistical software. The regressions model was developed. The developed regression model could be used to predict the dimensional precision of the parts based on machine tool vibration and machining parameters during turning process. This is the aspect to be seriously considered and be applied in attaining sustainable machine tool development during design and development stage and its usage. This finding provides useful guidelines for manufacturers to produce high quality machined parts at minimum manufacturing cost. It was found that the cutting speed, feed rate, final part length, vibration x and vibration z have significant effects on dimensional accuracy of the machined parts.

A Graphical Analysis of Regenerative Machine Tool Instability

1962 ◽  
Vol 84 (1) ◽  
pp. 103-111 ◽  
Author(s):  
J. P. Gurney ◽  
S. A. Tobias
Keyword(s):  
Machine Tool ◽  
Penetration Rate ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Graphical Analysis ◽  
Mode Interaction ◽  
Thickness Variation ◽  
Machine Tool Structure ◽  
The Stability ◽  
Radial Drilling

A graphical method for the investigation of regenerative machine tool chatter is presented. The method is based on the harmonic response locus of the machine tool structure and allows the determination of the stable and unstable cutting speed ranges. The chip thickness variation effect as well as the penetration rate effect are taken into consideration. The method is illustrated by a number of examples relating to drilling or spot facing chatter arising on a radial drilling machine. The effects of mode interaction and of the penetration rate on the stability and on the variation of the chatter frequency are discussed. A critical assessment of the method is presented, in comparison with other methods available.

Research on Relationship between Cutting Conditions and Chip Formation during End Milling of Aluminium Alloy 6061

2017 ◽  
Vol 909 ◽  
pp. 56-60
Author(s):  
Mohd Rasidi Ibrahim ◽  
Najah Mahadi ◽  
Afiff Latif ◽  
Zulafif Rahim ◽  
Zazuli Mohid ◽  
...  
Keyword(s):  
Aluminium Alloy ◽  
Feed Rate ◽  
End Milling ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Chip Morphology ◽  
Depth Of Cut ◽  
Slot Milling ◽  
Milling Operation ◽  
Alloy 6061

This paper studied chip morphology in end milling of aluminium alloy 6061 by various cutting parameter such as feed rate, cutting speed and depth of cut. Slot milling operation were conducted. The analysis consists of chip morphology, chip weight, chip thickness and chip length. Scanning Electron Microscope (SEM) were used to obtain and examine the chips. Result shows that, end milling with higher cutting speed, feed rate and depth of cut generated short, small and light weigh of chips.

Sign in / Sign up

Export Citation Format

Share Document