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Machinability Rating
Machinability is the ease with which a metal can be cut (machining, machined) permitting the removal of the material with a satisfactory surface finish, finish at low cost.Degarmo, p. 542. Materials with good machinability (free-machining materials) require little power to cut, can be cut quickly, easily obtain a good finish, and do not cause significant tool wear, wear on the cutting tool (machining), tooling. Factors that typically improve a material's performance often degrade its machinability, presenting a significant engineering challenge. Machinability can be difficult to predict due to the large number of variables involved in the machining process. Two sets of factors are the condition and physical properties of the work materials. The condition of the work material includes at least eight factors: microstructure, Crystallite, grain size, heat treatment, chemical composition, fabrication, hardness, yield strength, and tensile strength.Schneider, "Machinability." Physical p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Machining
Machining is a manufacturing process where a desired shape or part is created using the controlled removal of material, most often metal, from a larger piece of raw material by cutting. Machining is a form of subtractive manufacturing, which utilizes machine tools, in contrast to ''additive manufacturing'' (e.g. 3D printing processes, 3D printing), which uses controlled addition of material. Machining is a major process of the manufacture of many metal products, but it can also be used on other materials such as wood, plastic, ceramic, and composite material, composites. A person who specializes in machining is called a machinist. As a commercial venture, machining is generally performed in a machine shop, which consists of one or more workrooms containing primary machine tools. Although a machine shop can be a standalone operation, many businesses maintain internal machine shops or tool rooms that support their specialized needs. Much modern-day machining uses Numerical control, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alloy
An alloy is a mixture of chemical elements of which in most cases at least one is a metal, metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Metallic alloys often have properties that differ from those of the pure elements from which they are made. The vast majority of metals used for commercial purposes are alloyed to improve their properties or behavior, such as increased strength, hardness or corrosion resistance. Metals may also be alloyed to reduce their overall cost, for instance alloys of gold and Copper(II) sulfate, copper. A typical example of an alloy is SAE 304 stainless steel, 304 grade stainless steel which is commonly used for kitchen utensils, pans, knives and forks. Sometime also known as 18/8, it as an alloy consisting broadly of 74% iron, 18% chromium and 8% nickel. The chromium and nickel alloying elements add strength and hardness to the majority iron element, but their main function is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdenum
Molybdenum is a chemical element; it has Symbol (chemistry), symbol Mo (from Neo-Latin ''molybdaenum'') and atomic number 42. The name derived from Ancient Greek ', meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm. Molybdenum does not occur naturally as a Native metal, free metal on Earth; in its minerals, it is found only in oxidation state, oxidized states. The free element, a silvery metal with a grey cast, has the List of elements by melting point, sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of the world production of the element (about 80%) is used in steel alloys, including high-strength alloys and superalloys. Most molybdenum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tool Wear
In machining, tool wear is the gradual failure of cutting tools due to regular operation. Tools affected include tipped tools, tool bits, and drill bits that are used with machine tools. Types of wear include: * flank wear in which the portion of the tool in contact with the finished part erodes. Can be described using the Tool Life Expectancy equation. * crater wear in which contact with chips erodes the rake face. This is somewhat normal for tool wear, and does not seriously degrade the use of a tool until it becomes serious enough to cause a cutting edge failure. Can be caused by spindle speed that is too low or a feed rate that is too high. In orthogonal cutting this typically occurs where the tool temperature is highest. Crater wear occurs approximately at a height equalling the cutting depth of the material. Crater wear depth () = cutting depth * Notch wear which happens on both the insert rake and flank face along the depth of cut line causing localised damage to it prim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Feet Per Minute
Surface feet per minute (SFPM or SFM) is the combination of a physical quantity (''surface speed'') and an imperial and American customary unit (''feet per minute'' or ''FPM''). It is defined as the number of linear feet that a location on a rotating component travels in one minute. Its most common use is in the measurement of cutting speed (surface speed) in machining. It is a unit of velocity that describes how fast the cutting edge of the cutting tool travels. It correlates directly to the machinability of the workpiece material and the hardness of the cutting tool material. It relates to spindle speed via variables such as cutter diameter (for rotating cutters) or workpiece diameter (for lathe work). SFM is a combination of ''diameter'' and the ''velocity'' ( RPM) of the material measured in feet-per-minute as the spindle of a milling machine Milling is the process of machining using rotary cutters to remove material by advancing a cutter into a workpiece. This ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Iron And Steel Institute
The American Iron and Steel Institute (AISI) is a trade association of North American steel producers. Including its predecessor organizations, it is one of the oldest trade associations in the United States, dating back to 1855. It assumed its present form in 1908, with Judge Elbert H. Gary, chairman of the United States Steel Corporation, as its first president. Its development was in response to the need for a cooperative agency in the iron and steel industry for collecting and disseminating statistics and information, carrying on investigations, providing a forum for the discussion of problems and generally advancing the interests of the industry. Stainless steel numbering system The AISI maintained a numbering system for wrought stainless steel in which the three digits indicate the various compositions. The 200 and 300 series are generally austenitic stainless steels, whereas the 400 series are either ferritic or martensitic. Some of the grades have a one-letter or two-le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Normalization (statistics)
In statistics and applications of statistics, normalization can have a range of meanings. In the simplest cases, normalization of ratings means adjusting values measured on different scales to a notionally common scale, often prior to averaging. In more complicated cases, normalization may refer to more sophisticated adjustments where the intention is to bring the entire probability distributions of adjusted values into alignment. In the case of normalization of scores in educational assessment, there may be an intention to align distributions to a normal distribution. A different approach to normalization of probability distributions is quantile normalization, where the quantiles of the different measures are brought into alignment. In another usage in statistics, normalization refers to the creation of shifted and scaled versions of statistics, where the intention is that these normalized values allow the comparison of corresponding normalized values for different datasets in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Machining Steel
Free-machining steel is steel that forms small chips when machined. This increases the material's machinability by breaking the chips into small pieces, thus avoiding entanglement in the machinery. This enables automatic equipment to run without human interaction. Free-machining steel with lead also allows for higher machining rates. Free-machining steel costs 15 to 20% more than standard steel, but increased machining speeds, larger cuts, and longer tool life offset the higher cost.Degarmo, p. 117. The disadvantages of free-machining steel are: ductility is decreased, impact resistance is reduced, copper-based brazing, brazed joints suffer from embrittlement with bismuth free-machining grades, and shrink fits are not as strong.Degarmo, p. 118. Types There are four main types of free-machining steel: ''leaded'', ''resulfurized'', ''rephosphorized'', and ''super''. Super-free-machining steels are alloyed with tellurium, selenium, and bismuth. Mechanics Free-machining steels are c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strain Hardening
Work hardening, also known as strain hardening, is the process by which a material's load-bearing capacity (strength) increases during plastic (permanent) deformation. This characteristic is what sets ductile materials apart from brittle materials. Work hardening may be desirable, undesirable, or inconsequential, depending on the application. This strengthening occurs because of dislocation movements and dislocation generation within the crystal structure of the material. Many non-brittle metals with a reasonably high melting point as well as several polymers can be strengthened in this fashion. Alloys not amenable to heat treatment, including low-carbon steel, are often work-hardened. Some materials cannot be work-hardened at low temperatures, such as indium, however others can be strengthened only via work hardening, such as pure copper and aluminum. Undesirable work hardening An example of undesirable work hardening is during machining when early passes of a cutting tool (ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Built Up Edge
In machining, specifically cutting operations, a built-up edge (BUE) is an accumulation of material against the rake face that seizes the tool tip, separating it from the chip.The Open University (UK), 2001. T881 Manufacture Materials Design: Block 2: Cutting, page 14. Milton Keynes: The Open University. Formation Because shear is strongest at the initial contact surface with the cutting tool, the first layer of metal impacting and seizing on it work-hardens more than the rest of the volume of metal. As a consequence of this work hardening, this first layer of metal is stronger than the adjacent metal moving away from the workpiece. Effectively, said first layer becomes part of the tool. The process repeats itself and, after some time, a built-up edge (which could be several hundred micrometres thick) forms. The conditions necessary for a noticeable edge to build up are that: * The cutting speed is low.The Open University (UK), 2001. T881 Manufacture Materials Design: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specific Energy
Specific energy or massic energy is energy per unit mass. It is also sometimes called gravimetric energy density, which is not to be confused with energy density, which is defined as energy per unit volume. It is used to quantify, for example, stored heat and other thermodynamic properties of substances such as specific internal energy, specific enthalpy, specific Gibbs free energy, and specific Helmholtz free energy. It may also be used for the kinetic energy or potential energy of a body. Specific energy is an intensive property, whereas energy and mass are extensive properties. The SI unit for specific energy is the joule per kilogram (J/kg). Other units still in use worldwide in some contexts are the kilocalorie per gram (Cal/g or kcal/g), mostly in food-related topics, and watt-hours per kilogram (W⋅h/kg) in the field of batteries. In some countries the Imperial unit BTU per pound (Btu/lb) is used in some engineering and applied technical fields. Kenneth E. Hese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Speed Steel
High-speed steel (HSS or HS) is a subset of tool steels, commonly used as cutting tool material. Compared to high-carbon steel tools, high-speed steels can withstand higher temperatures without losing their temper (hardness), allowing use of faster cutting speeds. At room temperature, in their generally recommended heat treatment, HSS grades generally display high hardness (above 60 Rockwell C) and abrasion resistance compared with common carbon and tool steels. There are several different types of high speed steel, such as M42 and M2. History In 1868, English metallurgist Robert Forester Mushet developed Mushet steel, considered the forerunner of modern high-speed steels. It consisted of 2% carbon, 2.5% manganese, and 7% tungsten. The major advantage of this steel was that it hardened when air cooled from a temperature at which most steels had to be quenched for hardening. Over the next 30 years, the most significant change was the replacement of manganese with chromium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
