Tool wear is a problem in machining titanium alloy, so it is of great importance to find out the wear mechanism of cutting tools in order to improve the cutting tool life time. The mechanism controlling the wear of cemented carbide and influence of cutting parameters on different wear modes in machining Ti6Al4V has been investigated in this paper. Diffusion and chemical wear at high cutting speed and feed rate and attrition in low speed and feed rate is suggested to be the dominant wear mechanism in this case.
1. Introduction
Titanium shows a high strength-weight ratio and has exceptional corrosion resistance. Titanium alloys have received considerable interest recently due to their wide range of applications in the aerospace, automotive and medical industries. The most common titanium alloy is Ti6Al4V, which belongs to the α+ β alloy group. However titanium alloys are difficult to machine due to their low modules of elasticity. Titanium is a poor conductor of heat, its thermal conductivity is about 1/6 that of steel. Heat, generated by the cutting action, does not dissipate quickly; therefore, most of the heat is concentrated on the cutting edge and the tool face [1]. Titanium has a strong alloying tendency or chemical reactivity with materials in the cutting tools and also reacts with oxygen and nitrogen in air at tool operating temperatures. This causes galling, welding, and smearing along with rapid destruction of the cutting tool [1].
The element diffusion from the tool through the tool-chip interface leads to composition change of tool substrate, which may increase the possibility of mechanical damage of the cutting edge also the high strength of titanium at elevated temperature contributes to the high compressive stresses ...
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...ay crater and flank wear in combination with chipping and cracking along the cutting edge.
• At low cutting conditions attrition was found dominant wear mechanism of cemented carbide cutting tool.
• At severe cutting condition by increasing the temperature, mechanism of tool wear involve diffusion.
• The brittle failure is due to high contact stresses at the cutting edge due to a combination of critical cutting parameters. The weak cutting edge du to the crate also contributes to the brittle failure.
• Plastic deformation can also be a major contributor to wear mechanisms of cutting tool when machining titanium alloys
• High compressive stresses and the development of high temperature close to the cutting edge causes plastic deformation of cutting edge
• The tendency for chipping and micro fracture along the cutting edge increases with feed rate and cutting speed.
However, metals can be quite hard to cut or shape into a desirable piece, requiring application of extreme forces. Depending on the project,
The straight-edge blade will be useful for many purposes both in everyday occurrences and outdoor use, but the lack of a sawing ability makes it less useful ...
When examining textile damages, such information like the size of the knife blade and the types can be estimated. The more distinctive the weapon is, the more unique the features in any damaged apparel and therefore the stronger the association. In the blades of a weapon, the sharper ones will cut the fibres and yarns as it enters the fabric with little or no distortion; whereas the blunter ones maximises the distortion of the fabric and the disorder of the yarn and fibre ends. Scallops, imperfection and serration characteristics on the blade of a weapon increase fabric fraying and distortion. It has been reported that the dimensions on fabric when stabbed do not accurately reflect the dimensions of the knife blade.
For this scope of this assignment a study in the surface modification of a titanium alloy stem, used in a hip joint implant is going to be studied. A total hip joint implant consists of an articulating bearing basically the femoral head and cup and the stem. The stem is made from titanium alloy - Ti- 6Al- 4V where titanium is alloyed with aluminium and vanadium. When titanium is alloyed with these materials excellent properties are achieved such as high strength-to-weight ratio and exceptional corrosion resistance.2 However, this alloy gives poor tribological properties and tends to seize when it is subjected to sliding motion due to its low hardness of 36HRC.3 Several surface modification techniques are done on ti...
Fatigue failure can be divided in three parts i.e. Crack initiation, Crack propagation and Final rupture.
The machinability of copper and copper alloys is improved by lead, sulfur, tellurium, and zinc while it deteriorates when tin and iron are added. Lead in brass alloys with concentrations around 2 wt%, improves machinability by acting as a microscopic chip breaker, and tool lubricant, while they increase the brittleness of the alloy [17]. Lead additions are used to improve machinability. The lead is insoluble in the solid brass and segregates as small globules that help the swarf to break up in to small pieces and may also help to lubricate the cutting tool action. The addition of lead is however, affect cold ductility which may control both the way in which material is produced and the extent to which it can be post-formed after machining
The high temperature application of Austenitic Stainless Steel is somewhat limited because at higher temperatures it undergoes a phenomenon called Sensitization. According to Ghosh et al. [1], it refers to the precipitation of carbides and nitrides at the grain boundaries. Precipitation of Chromium rich carbides (Cr23C6) and nitrides at the grain boundaries result when the Austenitic stainless steel is heated and held in the temperature range of 500-8500C (773K-1123K). This precipitation of carbides taking place at the grain boundary is because of their insolubility at these temperature ranges. This leads to Chromium depreciated regions around the grain boundaries. So the change in microstructure is takes place and the regions with low Chromium contents become susceptible to Intergranular Corrosion (IGC) and Intergranular Stress Corrosion Cracking (Alvarez et al.) [1, 2]. Along with carbides and nitrides there is formation of chi phase. The chi phase, which is a stable intermetallic compound, consists of Fe, Cr, and Mo of type M18C. Some studies reveal that sensitization may lead to formation of Martensite. In addition to the altered microstructure, mechanical properties of the Austenitic Stain...
Comparing the joints welded with two different heat inputs, concluded that the ultimate tensile strength (UTS) and impact toughness of the welded joints decreases with increases the heat input.
If the blade did not hit the exact spot on the neck it would become as though it was an axe. It would hack away until the head came off. After all the chopping, the blade will often become dull. Throughout the revolution, the blade was changed, it became angled. The angling of the blade helps kill faster.
Emanating from the bulb of force will be ripple like compression rings that will be a visual representation of the force that traversed the material while on its way to remove the flake. Flake termination is another characteristic and is observed by the edge breaks. The most useful and planned one is the feather termination, this termination produces thin and sharp edges ready for use as blades or knives. The footprint on the core is positive and more flakes can be successfully removed in succession. While the most ideal termination there are others that will happen while producing flakes off of cores.
Flank – surface below the adjacent of the cutting edge is called flank of the tool.
...mpositional control needed and also the reactivity of the titanium. Fatigue failure has been known to occur with nitinol because of the extreme amounts of fatigue strain that it is necessarily exposed to. This is because it is still not completely defined how durable nitinol is, so it cannot be known what to use it for as it is the best of all metals known in this case. So it is used for the highest demanding applications but in some cases it can’t handle the pressure sustained. Another use for nitinol is a temperature control system, which would work by changing shape can activate a variable resistor or switch which would control the temperature, this is a situation where it is very significant for nitinol to be a smart material otherwise this system would simply just not work. There are many others but they are not really relevant to the engineering industry.
Chef’sChoice® Diamond Hone® EdgeSelect® Knife Sharpener Model 120. ($120.12 amazon). The EdgeSelect feature of this sharpener is designed in polishing edges of gourmet, sporting and butcher knife, as well as serrated 20 degrees knives. This professional sharpener has three stages of sharpening using 100% diamond abrasives. The Stage 1 has fine diamond coated disk that would create the microgrooves for angle bevel. In its stage 2, the more fine diamond defines the second bevel to produce the cut for sharp edge. The abrasive polish disk and strop in Stage 3 defines the boundary of this microgrooves for better finish and is designed to combat the wear and tear of the metal no matter how frequent the sharpening could be. But in order to protect the metals in the serration, only the Stage 3 slot is used for sharpening serrated
Abrasive Jet Machining (AJM) is the removal of material from a work piece by the application of a high speed stream of abrasive particles carried in gas medium from a nozzle. The AJM process is different from conventional sand blasting by the way that the abrasive is much finer and the process parameters and cutting action are both carefully regulated. The process is used chiefly to cut intricate shapes in hard and brittle materials which are sensitive to heat and have a tendency to chip easily. The process is also used for drilling, de-burring and cleaning operations. AJM is fundamentally free from chatter and vibration problems due to absence of physical tool. The cutting action is cool because the carrier gas itself serves as a coolant and takes away the heat.
Metals possess many unique fundamental properties that make them an ideal material for use in a diverse range of applications. Many common place things know today are made from metals; bridges, utensils, vehicles of all modes of transport, contain some form of metal or metallic compound. Properties such as high tensile strength, high fracture toughness, malleability and availability are just some of the many advantages associated with metals. Metals, accompanied by their many compounds and alloys, similar properties, high and low corrosion levels, and affects, whether negative or positive, are a grand force to be reckoned with.