Surface Integrity of Biodegradable Magnesium-Calcium (Mg-Ca) Alloy by Low Plasticity Burnishing

2010 ◽  
Author(s):  
M. Salahshoor ◽  
Y. B. Guo
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Bulk Material ◽  
Large Diameter ◽  
Biological Response ◽  
The Body ◽  
Low Plasticity Burnishing ◽  
Sever Plastic Deformation ◽  
Biodegradable Magnesium

When a device is implanted into the body, into either hard or soft tissue, the body will respond. While the bulk material of the device is often important for integrity and mechanical success, the device surface is at the interface with biology. Major effort has been spent modifying a biomaterial surface in order to elicit or inhibit a biological response. Metallic biodegradable Magnesium-Calcium (Mg-Ca) alloys have attracted an increased attention for orthopedic fixation applications. This research focuses on low plasticity burnishing (LPB) as a novel surface modification technique that is added to the surface to control biodegradation as a biological response. The effects of burnishing pressure as an important process parameter on surface integrity characteristics such as surface roughness, surface topography, and residual stresses are investigated. Burnished surface roughness is smaller than the machined ones. However, some amount of waviness is observed which might be due to large diameter of the burnishing ball and sever plastic deformation. High compressive residual stresses are measured on the burnished surface.

Effects of Burnishing Pattern on Surface Integrity in Microforming of Biodegradable Bone Implants

2011 ◽  
Author(s):  
M. Salahshoor ◽  
Y. B. Guo
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
Structural Integrity ◽  
Bulk Material ◽  
Biological Response ◽  
The Body ◽  
Important Process ◽  
Micro Forming ◽  
Implant Surface ◽  
Biodegradable Magnesium

When a medical device is implanted into the human body, either hard or soft tissue, the body will respond to the device surface. While the bulk material of the device is often important for structural integrity, the device surface is at the interface with biology function. Major effort has been spent modifying an implant surface in order to control a biological response. Metallic biodegradable Magnesium-Calcium (MgCa) alloys have attracted an increased attention for orthopedic fixation applications. This research focuses on plastic burnishing as a novel micro forming technique that is tune surface integrity to control biodegradation as a biological response. The effects of burnishing pattern as an important process parameter on surface integrity characteristics such as surface roughness, surface topography, microstracture, microhardness, and residual stresses are investigated.

Analysis and Prediction of Surface Integrity in Machining: A Review

2014 ◽  
Vol 610 ◽  
pp. 1002-1020 ◽  
Author(s):  
Yuan Gao ◽  
Xin Huang ◽  
Ming Jie Lin ◽  
Zheng Guo Wang ◽  
Rong Lei Sun
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Material Properties ◽  
Cutting Parameters ◽  
Mechanical Parameters ◽  
Factors Affecting ◽  
Grain Size And Shape

Surface integrity is widely used for evaluating the quality of machined components. It has a set of various parameters which can be grouped as: (a) topography parameters such as surface roughness, textures and waviness (b) mechanical parameters such as residual stresses and hardness, and (c) metallurgical state such as microstructure, phase transformation, grain size and shape, inclusions etc. Surface roughness and residual stresses are among the most significant parameters of surface integrity, so that it is worth investigating them particularly. Many factors affect the surface integrity of machined components, including cutting parameters, tool parameters, material properties and vibrations. We can make prediction and optimization for surface integrity by taking advantage of these factors. This paper reviews previous studies and gives a comprehensive summary of surface integrity in the following order: introduction of surface integrity, main parameters of surface integrity, factors affecting surface integrity, prediction and optimization for surface integrity.

A Study of Surface Integrity when Machining Refractory Titanium Alloys

2009 ◽  
Vol 83-86 ◽  
pp. 1059-1068 ◽  
Author(s):  
Armansyah Ginting ◽  
Mohammed Nouari ◽  
Nadhir Lebaal
Keyword(s):  
Surface Roughness ◽  
Titanium Alloys ◽  
Surface Integrity ◽  
Bulk Material ◽  
Cutting Speed ◽  
Cutting Condition ◽  
Feed Speed ◽  
Machined Surface ◽  
Feed Mark ◽  
Coated Carbide

In this paper, the surface integrity is studied when machining the aeronautical titanium alloys. Surface roughness, lay, defects, microhardness and microstructure alterations are studied. The result of surface roughness judges that the CVD-coated carbide fails to produce better Ra value than the uncoated. Lay is characterized by cutting speed and feed speed directions. Feed mark, tearing surface, chip layer formation as built up layer (BUL), and deposited microchip are the defects. Microhardness is altered down to 350 microns beneath the machined surface. The first 50 microns is the soft sub-surface caused by thermal softening in ageing process. Microstructure alteration is observed in this sub-surface. Down to 200 microns is the hard sub-surface caused by the cyclic internal work hardening and then it is gradually decreasing to the bulk material hardness. It is concluded that dry machining titanium alloy is possible using uncoated carbide with cutting condition limited to finish or semi-finish for minimizing surface integrity alteration.

Surface Integrity of End Milled Ti-6Al-4V Using the TiAlN Coated Tool

2008 ◽  
Author(s):  
Y. B. Guo ◽  
Jie Sun
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
End Milling ◽  
Bulk Material ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Near Surface ◽  
Β Phase ◽  
Radial Depth ◽  
Milled Surface

End milling titanium Ti-6Al-4V has wide applications in aerospace, biomedical, and chemical industries. However, milling induced surface integrity has received little attention. In this study, a series of end milling experiment were conducted to comprehensively characterize surface integrity at various milling conditions. The experimental results have shown that the milled surface shows the anisotropic nature with a surface roughness range in 0.6 μm–1.2 μm. Surface roughness increases with feed and radial depth-of-cut (DoC), but varies with the cutting speed range. Compressive residual normal stress occurs in both cutting and feed directions, while the influences of cutting speed and feed on residual stress trend are quit different. The microstructure analysis shows that β phase becomes much smaller and severely deformed in the very near surface with the cutting speed. The milled surfaces are at least 60% harder than the bulk material in the subsurface.

Analysis of Reversible Fine Machining Sequence Effect on Surface Integrity

2006 ◽  
Vol 315-316 ◽  
pp. 391-395
Author(s):  
Wen Ge Wu ◽  
Si Qin Pang ◽  
Zhan Qiang Liu
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Machining Process ◽  
Processing Route ◽  
Machining Accuracy ◽  
Machining Efficiency ◽  
Micro Hardness ◽  
Rough Machining ◽  
Machined Surface

Reversible cutting method is a new research thesis proposed to shorten processing route, decrease tool number and handling time, increase machining efficiency. The aim of the presented work was to analysis the effects of reversible fine machining sequence on surface integrity in machined layer. Nonlinear hardening during reverse loading and the change of the Bauschinger effect factor with plastic strain were properly taken into account. In experiments, the residual stresses have been measured using the X-ray diffraction technique (at the surface of the workpiece and in depth). Moreover, micro-hardness and surface roughness of machined surface are presented. Experimental data for the range of cutting parameters tested showed that the reversible fine machining produce the tensile residual stresses at the surface, which are critical in the performance of the machined components. The experimental results of micro-hardness of reversible fine machining technique are smaller than that of general fine machining show that decreased plastic deformation of the surface layer and work-hardening. Surface roughness of machined surface with reversible finishing is discussed. Research results indicted that it can be adopted such planning which rough machining during advance stroke and fine machining or semi-finishing during return stroke in machining process. In this way, it has such advantages that increase machining efficiency and machining accuracy, decrease bending deformation.

Finite Element Modeling of Burnishing and the Effects of Process Parameters on Surface Integrity of Orthopedic Implants

2011 ◽  
Author(s):  
M. Salahshoor ◽  
Y. B. Guo
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Process Parameters ◽  
Surface Integrity ◽  
Internal State ◽  
Material Model ◽  
Orthopedic Implants ◽  
Fe Model ◽  
Dynamic Mechanical Behavior ◽  
Layer I

Hydrostatic burnishing is mainly a ceramic ball supported by a pressurized cushion of hydraulic oil and pushed against the workpiece surface. As the ball rolls along the surface it produces a unique combination of three physical effects in the surface layer: i) work hardening and increased hardness, ii) burnishing and decreased roughness, and iii) increased compressive residual stresses. This process has gained an increasingly great attention in automotive, aerospace, and especially medical device manufacturing industries. However, most of the research in hydrostatic burnishing has been performed experimentally and there is still lack of numerical studies providing fundamental understanding of the mechanics and the way process parameters interact with surface integrity characteristics particularly surface roughness and residual stresses. Understanding the correlation between process parameters and surface integrity is critical in efficiently adjusting the surface integrity in order to achieve proper biodegradation rate in human body after implantation. In this study, the dynamic mechanical behavior of the material is simulated using internal state variable (ISV) plasticity model. A semi-infinite, two-dimensional, plane strain FE model is developed and the ISV material model is incorporated into it using a user defined material subroutine. The effects of burnishing pressure and feed on surface roughness and residual stresses are investigated. The simulation results are validated with experimental measurements of residual stresses and surface roughness.

Effect of Machining Parameters on Surface Integrity in Dry Turning of Inconel 718

2013 ◽  
Vol 634-638 ◽  
pp. 2831-2834
Author(s):  
Xiao Li Zhu ◽  
Jin Fa Zhang ◽  
Wu Jun Chen ◽  
Ji Wen Deng
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Feed Rate ◽  
Inconel 718 ◽  
Cutting Speed ◽  
Diffraction Method ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Machining Parameters

Surface quality including residual stresses and surface roughness due to turning operations in Inconel 718 were studied as a function of cutting speed, feed rate and depth of cut. By means of X-ray radiation diffraction method, the influence of cutting parameters on residual stress was investigated. The results show that dry cutting of Inconel 718 resulted in predominantly tensile residual stresses at the machined surface and the surface roughness increased with the increase of cutting parameters.The effects of the cutting parameters on surface integrity are investigated while employing the range analysis. From these results it was possible to select a combination of cutting speed, feed rate and depth of cut that generate favorable surface characteristics.

Low Plasticity Burnishing: An Innovative Manufacturing Method for Biomedical Applications

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
C. Y. Seemikeri ◽  
P. K. Brahmankar ◽  
S. B. Mahagaonkar
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Surface Integrity ◽  
Biomedical Applications ◽  
Hip Prosthesis ◽  
Surface Hardness ◽  
Surface Characteristics ◽  
Manufacturing Method ◽  
Work Material ◽  
Low Plasticity Burnishing

Biomedical manufacturing technologies are assuming highly visible position at the frontiers of manufacturing. A new field, “engineered surfaces,” is emerging as a more effective and economic route to successful manufacture. Low plasticity burnishing (LPB) is relatively a new method of surface enhancement, which raises the burnishing to the next level of sophistication. LPB can provide deep and stable surface compression for improved surface integrity characteristics. This technology could be applied to diversified biomedical applications, since it has the potential to improve many surface characteristics, such as low- and high-cycle fatigue strengths, surface finish, surface hardness, corrosion resistance, wear resistance, etc. The present study focuses on the surface roughness, microhardness, surface integrity, and fatigue life aspects of AISI 316L work material, which is most commonly used in prosthesis, using full factorial design of experiments. Favorable and optimum conditions could be predicted and tailored for different biomedical requirements and applications. The assessment of the surface integrity aspects on work material was done, in terms of identifying the predominant factors, their order of significance, evaluating the interaction effects of parameters, and setting the levels of the factors for minimizing surface roughness and∕or maximizing surface hardness and fatigue life. Regression models were developed for surface characteristics of importance as response variables. Subsurface microhardness studies were also done to assess the depth of compression, altered material zone, and correlate fatigue life with surface roughness and surface hardness. The process can be applied to critical components used in biomedical field, such as total hip prosthesis, invasive surgeries, or medical implants effectively, as the LPB process today has significant process cycle time advantages, lower capital cost, and adaptability to conventional machine shop environment.

Some Aspects of Improving Integrity of Machined Surfaces on Al/SiCp Metal Matrix Composites

2010 ◽  
Vol 443 ◽  
pp. 596-601 ◽  
Author(s):  
Uday A. Dabade ◽  
Suhas S. Joshi
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Experimental Work ◽  
Metal Matrix ◽  
Cutting Tool ◽  
Matrix Composites ◽  
Machined Surface ◽  
Machined Surface Roughness ◽  
Machined Surfaces

This paper presents findings of an experimental work which involved use of wiping edge on the cutting tool and a priory heating of the work surfaces to improve the integrity of machined surfaces. The wiper edge cleans the machined surface and a priory heating induces necessary local ductility into the machined surface to promote improvement in the surface integrity. The result shows that the wiper inserts reduce surface roughness (by about 38%); cutting forces (by about 8%) and induce compressive (or lower tensile) residual stresses in the machined surfaces, hence help to improve the surface integrity. Similarly, a priory heating of work surfaces at 70°C was also found to improve machined surface roughness considerably.

Surface Integrity in Notches Machining

2011 ◽  
Vol 496 ◽  
pp. 176-181 ◽  
Author(s):  
Jan Madl ◽  
Vitezslav Razek ◽  
Vaclav Koutny ◽  
Jindrich Kafka
Keyword(s):  
Surface Roughness ◽  
Surface Layer ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Fatigue Cracks ◽  
Precision Machining ◽  
Material Structure ◽  
Machining Processes ◽  
High Interest ◽  
Machined Parts

Precision machining of soft and hardened materials is a topic of high interest to substitute some traditional operations. This paper deals with some aspects of the precision machining of notches. All machining processes result in changes of surface layer properties. There are changes in residual stresses, in harness, changes in material structure etc. and also in surface accuracy and surface roughness. All these characteristics may affect fatigue cracks in machined parts.

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