Surface Integrity of Magnesum-Calcium Orthopedic Biomaterial Procesed by Dry High-Speed Face Milling

Author(s):  
M. Salahshoor ◽  
Y. B. Guo

Biodegradable magnesium-calcium (Mg-Ca) implants have the ability to gradually dissolve and absorb into the human body after implantation. The critical issue that hinders the application of Mg-Ca implants is its poor corrosion resistance to human body fluids. A promising approach to tackle this issue is tailoring the surface integrity characteristics of the orthopedic implants to get an appropriate corrosion kinetic. High speed face milling of biodegradable Mg-Ca alloy is used in this study as a possible way to achieve that goal. Polycrystalline diamond inserts are used to avoid material adhesion and likely fire hazards. All the cutting tests are performed without using coolant to keep the manufacturing process ecological. High cutting speed of 40 m/s and 200 μm depth of cut are applied in a broad range of feed values to cover finish and rough cutting regimes. The effect of feed as a key machining parameter which defines the amount and duration of thermo-mechanical load and ultimately provides higher chances for surface integrity changes are investigated.

Author(s):  
Nhu-Tung Nguyen ◽  
Dung Hoang Tien ◽  
Nguyen Tien Tung ◽  
Nguyen Duc Luan

In this study, the influence of cutting parameters and machining time on the tool wear and surface roughness was investigated in high-speed milling process of Al6061 using face carbide inserts. Taguchi experimental matrix (L9) was chosen to design and conduct the experimental research with three input parameters (feed rate, cutting speed, and axial depth of cut). Tool wear (VB) and surface roughness (Ra) after different machining strokes (after 10, 30, and 50 machining strokes) were selected as the output parameters. In almost cases of high-speed face milling process, the most significant factor that influenced on the tool wear was cutting speed (84.94 % after 10 machining strokes, 52.13 % after 30 machining strokes, and 68.58 % after 50 machining strokes), and the most significant factors that influenced on the surface roughness were depth of cut and feed rate (70.54 % after 10 machining strokes, 43.28 % after 30 machining strokes, and 30.97 % after 50 machining strokes for depth of cut. And 22.01 % after 10 machining strokes, 44.39 % after 30 machining strokes, and 66.58 % after 50 machining strokes for feed rate). Linear regression was the most suitable regression of VB and Ra with the determination coefficients (R2) from 88.00 % to 91.99 % for VB, and from 90.24 % to 96.84 % for Ra. These regression models were successfully verified by comparison between predicted and measured results of VB and Ra. Besides, the relationship of VB, Ra, and different machining strokes was also investigated and evaluated. Tool wear, surface roughness models, and their relationship that were found in this study can be used to improve the surface quality and reduce the tool wear in the high-speed face milling of aluminum alloy Al6061


Author(s):  
M. Salahshoor ◽  
Y. B. Guo

Metallic degradable biomaterials have attracted a huge attention lately for orthopedic fixation applications. Binary magnesium and calcium (Mg-Ca) alloys have emerged as a promising choice in terms of biocompatibility to avoid stress shielding and provide sufficient mechanical strength. In this paper, efficient and ecologic machining of a lab-made Mg-Ca alloy with 0.8 wt% calcium, cutting speeds of up to 47 m/s, and without coolant are investigated. Polycrystalline diamond inserts are applied and the possibilities of flank built-up formation, chip ignition, and tool wear are sought during the cutting experiments with the aid of a developed on-line, optical monitoring system. Chip morphology characteristics produced by different combinations of cutting parameters, i.e. cutting speed, feed, and depth of cut are studied.


Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5677
Author(s):  
Elshaimaa Abdelnasser ◽  
Azza Barakat ◽  
Samar Elsanabary ◽  
Ahmed Nassef ◽  
Ahmed Elkaseer

This article presents the results of an experimental investigation into the machinability of Ti6Al4V alloy during hard turning, including both conventional and high-speed machining, using polycrystalline diamond (PCD) inserts. A central composite design of experiment procedure was followed to examine the effects of variable process parameters; feed rate, cutting speed and depth of cut (each at five levels) and their interaction effects on surface roughness and cutting temperature as process responses. The results revealed that cutting temperature increased with increasing cutting speed and decreasing feed rate in both conventional and high-speed machining. It was found that high-speed machining showed an average increase in cutting temperature of 65% compared with conventional machining. Nevertheless, high-speed machining showed better performance in terms of lower surface roughness despite using higher feed rates compared to conventional machining. High-speed machining of Ti6Al4V showed an improvement in surface roughness of 11% compared with conventional machining, with a 207% increase in metal removal rate (MRR) which offered the opportunity to increase productivity. Finally, an inverse relationship was verified between generated cutting temperature and surface roughness. This was attributed mainly to the high cutting temperature generated, softening, and decreasing strength of the material in the vicinity of the cutting zone which in turn enabled smoother machining and reduced surface roughness.


2015 ◽  
Vol 667 ◽  
pp. 35-40
Author(s):  
Xiao Bin Cui ◽  
Jing Xia Guo ◽  
Xiao Yang Wang

For the purpose of acquiring thorough understanding of the characteristics of cutting force in high and ultra-high-speed face milling of hardened steel, experimental investigations on face milling of AISI H13 steel (46-47 HRC) are conducted in the present study. The cutting speed of 1400 m/min, at which relatively low cutting force and relatively low surface roughness can be obtained at the same time, is considered as a critical value for both mechanical load and surface finish. The Taguchi method is applied to investigate the effects of cutting parameters on cutting force in different speed ranges (below and above 1400 m/min). In different speed ranges, the contribution order of the cutting parameters for the resultant cutting force is the same, namely axial depth of cut, cutting speed and feed per tooth. However, the contributions of cutting speed and feed per tooth increase substantially as the cutting speed surpasses 1400 m/min. Within the range of cutting parameters used in the present study, the optimum cutting conditions for the cutting force are cutting speed 200 m/min, feed per tooth 0.02 mm/tooth and axial depth of cut 0.1 mm.


Author(s):  
Balkrishna Rao ◽  
Yung C. Shin

This paper is concerned with the experimental and numerical study of the high speed face milling of Ti-6Al-4V titanium alloy. Machining is carried out by uncoated carbide and polycrystalline diamond cutters in the presence of an abundant supply of coolant. Experimental analysis is conducted in terms of cutting forces, chip morphology, surface integrity and tool wear. The experimental analysis is supplemented by simulations from the finite element analysis where needed. The highest cutting speed realized for both the cutting tool materials is 600 sfpm with the diamond cutter operating at feeds lower than that for carbide. Good surface integrity in terms of residual stress and surface finish is achieved under the machining conditions used with limited tool wear. Residual stresses imparted to the machined surface are compressive with the diamond tool yielding higher values and are the most sensitive to feed. Tool wear patterns are described in terms of various cutting conditions.


2011 ◽  
Author(s):  
M. Salahshoor ◽  
Y. B. Guo

Biodegradable magnesium-calcium (MgCa) alloys are capable of gradually dissolving and becoming absorbed in the human body after implantation. The critical issue that hinders the application of MgCa implants is their fast corrosion rate in human body fluids. A promising approach to tackle this issue is to tailor surface integrity of orthopedic implants for tuning the corrosion kinetic. The synergistic dry cutting and burnishing is used in this study to modify surface integrity of MgCa0.8 (wt%) implants for controlled corrosion performance. The effects of cutting speed and rolling force, as key parameters in the synergistic dry cutting-finish burnishing, on the electrochemical responses of the processed surfaces are investigated in the simulated body fluid (SBF). Potentiodynamic polarization curves are measured, and morphology and elemental composition of corroded surfaces are studied utilizing scan electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively.


2009 ◽  
Vol 407-408 ◽  
pp. 577-581
Author(s):  
Shi Chao Xiu ◽  
Zhi Jie Geng ◽  
Guang Qi Cai

During cylindrical grinding process, the geometric configuration and size of the edge contact area between the grinding wheel and workpiece have the heavy effects on the workpiece surface integrity. In consideration of the differences between the point grinding and the conventional high speed cylindrical grinding, the geometric and mathematic models of the edge contact area in point grinding were established. Based on the models, the numerical simulation for the edge contact area was performed. By means of the point grinding experiment, the effect mechanism of the edge contact area on the ground surface integrity was investigated. These will offer the applied theoretic foundations for optimizing the point grinding angles, depth of cut, wheel and workpiece speed, geometrical configuration and size of CBN wheel and some other grinding parameters in point grinding process.


2016 ◽  
Vol 836-837 ◽  
pp. 168-174 ◽  
Author(s):  
Ying Fei Ge ◽  
Hai Xiang Huan ◽  
Jiu Hua Xu

High-speed milling tests were performed on vol. (5%-8%) TiCp/TC4 composite in the speed range of 50-250 m/min using PCD tools to nvestigate the cutting temperature and the cutting forces. The results showed that radial depth of cut and cutting speed were the two significant influences that affected the cutting forces based on the Taguchi prediction. Increasing radial depth of cut and feed rate will increase the cutting force while increasing cutting speed will decrease the cutting force. Cutting force increased less than 5% when the reinforcement volume fraction in the composites increased from 0% to 8%. Radial depth of cut was the only significant influence factor on the cutting temperature. Cutting temperature increased with the increasing radial depth of cut, feed rate or cutting speed. The cutting temperature for the titanium composites was 40-90 °C higher than that for the TC4 matrix. However, the cutting temperature decreased by 4% when the reinforcement's volume fraction increased from 5% to 8%.


2012 ◽  
Vol 576 ◽  
pp. 60-63 ◽  
Author(s):  
N.A.H. Jasni ◽  
Mohd Amri Lajis

Hard milling of hardened steel has wide application in mould and die industries. However, milling induced surface finish has received little attention. An experimental investigation is conducted to comprehensively characterize the surface roughness of AISI D2 hardened steel (58-62 HRC) in end milling operation using TiAlN/AlCrN multilayer coated carbide. Surface roughness (Ra) was examined at different cutting speed (v) and radial depth of cut (dr) while the measurement was taken in feed speed, Vf and cutting speed, Vc directions. The experimental results show that the milled surface is anisotropic in nature. Surface roughness values in feed speed direction do not appear to correspond to any definite pattern in relation to cutting speed, while it increases with radial depth-of-cut within the range 0.13-0.24 µm. In cutting speed direction, surface roughness value decreases in the high speed range, while it increases in the high radial depth of cut. Radial depth of cut is the most influencing parameter in surface roughness followed by cutting speed.


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