Underwater Laser Turning of Commercially-Pure Titanium

2020 ◽  
Vol 861 ◽  
pp. 23-27
Author(s):  
Wisan Charee ◽  
Viboon Tangwarodomnukun

Underwater laser machining process is a material removal technique that can minimize thermal damage and offer a higher machining rate than the laser ablation in ambient air. This study applied the underwater method associated with a nanosecond pulse laser for turning a commercially pure titanium rod. The effects of laser power, surface speed and number of laser passes on machined depth and surface roughness were investigated in this work. The results revealed that a deeper cut depth and smoother machined surface than those obtained from the laser ablation in ambient air were achievable when the underwater laser turning process was applied. The machined depth and surface roughness were found to significantly increase with the laser power and number of laser passes. The findings of this study can disclose the insight as well as potential of the underwater laser turning process for titanium and other similar metals.

Author(s):  
Karibeeran Shanmuga Sundaram ◽  
Gurusami Kiliyappan ◽  
Senthil Kumaran Selvadurai

Laser shock peening (LSP) is one of the innovative technique that produces a compressive residual stress on the surface of metallic materials, thereby significantly increasing its fatigue life in applications where failure is caused by surface-initiated cracks. The specimens were treated with laser shock waves with different processing parameters, and characterization studies were made on treated specimens. The purpose of the present study was to investigate the influence of Nd:YAG laser on commercially pure titanium (CP-Ti) used in prosthetic dental restorations. The treatment influenced change in microstructure, micro hardness, surface roughness, and wear resistance characteristics. Though CP-Ti is considered as an excellent material for dental applications due to its outstanding biocompatibility, it is not suitable when high mastication forces are applied. In the present study, pulsed Nd:YAG laser surface treatment technique was adopted to improve the wear resistance of CP-Ti. The wear test pin specimens of CP-Ti were investment cast with centrifugal titanium casting machine. The wear properties of specimens were evaluated after LSP on a “pin-on-disc” wear testing tribometer, as per ASTM G99-05 standards. The results of the wear experiment showed that the treated laser surface has higher wear resistance, micro hardness, and surface roughness compared to as-cast samples. The improvement of wear resistance may be attributed due to grain refinement imparted by LSP processes. The microstructure, wear surfaces, wear debris, and morphology of the specimen were analyzed by using optical electron microscope, scanning electron microscope, and X-ray diffraction (XRD). The data were compared using ANOVA and post-hoc Tukey tests. The characteristic change resulted in increase in wear resistance and decrease in wear rate. Hence, it is evident that the more reliable and removable partial denture metal frameworks for dental prostheses may find its applications.


Author(s):  
Kurian Antony ◽  
T Reghunathan Rakeshnath

Laser additive manufacturing processes melt the powder particles using laser beam energy to form solid three-dimensional objects. This article mainly focuses on numerical analysis and experimentation of laser melting of commercially pure titanium powder. Numerical solutions to moving heat source problems were developed, and their influences on process parameters were validated. The energy density has a significant role in laser melting process. The numerical investigation demonstrates the significant effect of laser energy density on laser tracks. The laser power, distribution of powder particles, the absorptivity, density, and chemical constitution of powder materials are the main factors which influence the laser energy penetration. The absorptivity plays a vital role in consolidation phenomena of the powder layer which helps to get a denser part or layer. The experimental result clearly indicates that at lower laser speed the powder compaction is better. Temperature distribution, depth, and width of laser track were compared in this article. By investigating the observations from optical microscopic images and scanning electron microscopic images, the surface characteristics of laser-melted tracks were studied. The study on numerical and experimental results shows that the optimum condition for better laser track is laser power 45 W, laser speed 20 mm/s, and laser diameter 2.5 mm. This study provides important insights into laser parameters in the melting of commercially pure titanium powder.


2020 ◽  
Vol 10 (3) ◽  
pp. 293-310 ◽  
Author(s):  
Akhtar Khan ◽  
Kalipada Maity

PurposeTo explore a hybrid approach in order to attain optimal cutting conditions proficient of generating adequate dimensional accuracy in combination with virtuous surface finish during turning of commercially pure titanium (CP-Ti) grade 2.Design/methodology/approachIn the present paper, an application of the hybrid fuzzy–VIKOR method has been proposed to estimate an optimal combination of process variables during turning of commercially pure titanium (CP-Ti) grade 2. Three distinct input factors, namely, cutting speed, feed rate and depth of cut, were selected, each varied at three levels. Thus, a series of experiments were performed based on Taguchi's 3-factor-3-level (L27) orthogonal array. The major attention was given to acquire minimum cutting force and flank wear along with good surface finish. The adequacy of the proposed methodology was verified with the help of ANOVA test.FindingsThe results of the investigation revealed that the suggested hybrid technique is quite effective, easily understandable and time-saving approach, which can be successfully implemented to solve various problems either of similar or of different kinds.Originality/valueIncreasing demand of qualitative as well as low cost products is identified as the main challenging task in the current competitive market. Therefore, estimation and selection of the most suitable machining environment are of paramount importance in a real-time manufacturing system. Machining process involves both qualitative and quantitative factors, may be conflicting in nature, all to be considered together. Consequently, an appropriate combination of the machining variables is evidently desirable to meet the aforesaid challenges effectively.


2012 ◽  
Vol 159 ◽  
pp. 56-68 ◽  
Author(s):  
Anish Kumar ◽  
Vinod Kumar ◽  
Jatinder Kumar

Titanium is present in the earth’s crust at a level about 0.6% and is therefore the fourth most abundant structural metal after aluminum, iron, and magnesium. High strength, low density, and excellent corrosion resistance are the main properties that make titanium attractive for a variety of applications. The major application of the material is in the aerospace industry, both in airframes,engine components,steam turbine blades, superconductors, missiles etc. or corrosion resistance, for example marine services, chemical, petrochemical, electronics industry, biomedical instruments etc.In this study, wire electrical discharge machining (WEDM) is adopted in machining of commercially pure titanium (Grade-2). During experiments, parameters such as Pulse on time, Pulse off time, Peak current, Spark Gap set Voltage, Wire Feed and Wire Tension were changed to explore their effect on the cutting rate, gap current and surface roughness of the machined specimens. The ranges of process parameters for the experiments were decided on the basis of literature survey and the pilot experiments conducted using one factor at a time approach(OFTA). It is found that the intensity of the process energy does affect the cutting rate, gap current and surface roughness as well as, the wire speed, wire tension and dielectric fluid pressure not seeming to have much of an influence.


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