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.

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.

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.

Machining Forces: Some Effects of Removing a Wavy Surface

1966 ◽  
Vol 8 (2) ◽  
pp. 129-140 ◽  
Author(s):  
P. W. Wallace ◽  
C. Andrew
Keyword(s):  
Chip Thickness ◽  
Shear Plane ◽  
Shear Angle ◽  
Surface Slope ◽  
Experimental Conditions ◽  
Undeformed Chip Thickness ◽  
Cutting Force Components ◽  
The Mean ◽  
Force Components ◽  
Made In

Previous work has shown that during the removal of a surface waveform oscillating cutting force components arise which may have a phase difference with respect to the oscillating component of undeformed chip thickness; it has also shown that the shear angle is affected by the slopes of the surface waveform. However, no attempt to predict the oscillating force behaviour from the geometry of cutting has been reported. The present work attempts to achieve such a prediction by means of an analysis of the phase and magnitude of the oscillating force components acting in two directions; in the directions of the mean shear plane and of the tool rake face. In the analysis it is assumed that the shear angle oscillates in phase with and proportionally to the surface slope, and that the curvature of the chip varies with the undeformed chip thickness. An experimental technique for cutting with variable undeformed chip thickness is described, together with a method for recording and measuring the oscillating components of force and undeformed chip thickness. Experimental results are presented which show the assumptions made in the analysis to be substantially valid; the predicted oscillating forces are shown to be in adequate agreement with experiment over a range of experimental conditions. It is shown that the oscillation of the shear angle is primarily dependent on the surface slope and that the frictional force behaviour is consistent with the characteristics of the two regions of friction, sticking and sliding, as found in work on cutting with constant undeformed chip thickness.

Electrochemical etching of micro-pores in medical grade cobalt–chromium alloy as reservoirs for drug eluting stents

2016 ◽  
Vol 27 (3) ◽  
Author(s):  
Kai Fuchsberger ◽  
Karoline Binder ◽  
Claus Burkhardt ◽  
Christian Freudigmann ◽  
Markus Herrmann ◽  
...  
Keyword(s):  
Electrochemical Etching ◽  
Drug Eluting Stents ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Drug Eluting ◽  
Cobalt Chromium Alloy ◽  
Medical Grade

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.

Experimental Investigations in Cutting Dynamics

1993 ◽  
Vol 115 (4) ◽  
pp. 508-511 ◽  
Author(s):  
K. Marchelek ◽  
J. Tomko´w
Keyword(s):  
Transfer Functions ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Cutting Process ◽  
Experimental Investigations ◽  
Process Dynamics ◽  
Cutting Force Components ◽  
Force Components ◽  
Additive Influence ◽  
Process Transfer

This paper presents the results of an investigation of cutting process transfer functions in orthogonal cutting. An empirical model of cutting process dynamics with respect to the inner modulation of the chip thickness has been developed. The hypothesis about the independent and additive influence of both inner and outer modulation on the cutting force components has been confirmed.

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