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Interference Fit
An interference fit, also known as a pressed fit or friction fit is a form of fastening between two ''tight'' fitting mating parts that produces a joint which is held together by friction after the parts are pushed together. Depending on the amount of interference, parts may be joined using a tap from a hammer or ''pressed'' together using a hydraulic ram. Critical components that must not sustain damage during joining may also be cooled significantly below room temperature to shrink one of the components before fitting. This method allows the components to be joined without force and producing a shrink fit interference when the component returns to normal temperature. Interference fits are commonly used with aircraft fasteners to improve the fatigue life of a joint. Introducing interference between parts These fits, though applicable to shaft and hole assembly, are more often used for bearing-housing or bearing-shaft assembly. Tightness of fit The tightness of fit is con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fit (manufacturing)
In precision mechanics, fit refers to the degree of 'looseness' with which a shaft is inserted into a bored hole. This coupling is related to the tolerance or allowance of both parts' dimensions. The shaft and the orifice must be of a similar diameter, otherwise there will not be a correct adjustment. With this in mind, measurements have been internationally standardised according to ISO regulation to ensure the interchangeability of items and their mass production. Tolerance values are designated with a capital letter in the case of orifices and lower case letters in the case of shafts. The lower the value the higher the machining costs, as a greater precision is required. Maximum and minimum clearance The maximum clearance of a fit is the difference between the upper bound of the orifice diameter and the lower bound of the shaft diameter. : maximum clearance = maximum orifice diameter – minimum shaft diameter The minimum clearance meanwhile is the difference between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rack And Pinion
A rack and pinion is a type of linear actuator that comprises a circular gear (the '' pinion'') engaging a linear gear (the ''rack''). Together, they convert rotational motion into linear motion. Rotating the pinion causes the rack to be driven in a line. Conversely, moving the rack linearly will cause the pinion to rotate. A rack and pinion drive can use both straight and helical gears. Though some suggest helical gears are quieter in operation, no hard evidence supports this theory. Helical racks, while being more affordable, have proven to increase side torque on the datums, increasing operating temperature leading to premature wear. Straight racks require a lower driving force and offer increased torque and speed per percentage of gear ratio which allows lower operating temperature and lessens viscal friction and energy use. The maximum force that can be transmitted in a rack and pinion mechanism is determined by the tooth pitch and the size of the pinion as well as the gear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metalworking Terminology
This article is a list of terms commonly used in the practice of metalworking – the science, art, industry, and craft of shaping metal. Processes The following is a categorical list of metalworking processes: operations, procedures, techniques, and other actions performed that pertain to or consist of metalworking. Casting Casting is the process of creating objects by filling a mold with molten metal and allowing it to cool. *Centrifugal *Continuous *Die * Evaporative-pattern ** Full-mold ** Lost-foam * Investment ** in art: Lost-wax * Permanent mold * Plaster mold *Sand * Semi-solid metal * Shaw process * Shell molding * Spin ;Related terms *Foundry * Crucible *Molding sand *Refractory Forming Forming is the process of reshaping metal without adding or removing material. *Hot working ** Hot rolling ** Carburizing ** Drawing ** Forging ** Forge weld ** Oxidising ** Extruding *Cold working ** Coining ** Cutting **Electrohydraulic forming **Electromagnetic forming **Explosiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Engineering
Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, and maintain mechanical systems. It is one of the oldest and broadest of the engineering branches. Mechanical engineering requires an understanding of core areas including mechanics, dynamics, thermodynamics, materials science, structural analysis, and electricity. In addition to these core principles, mechanical engineers use tools such as computer-aided design (CAD), computer-aided manufacturing (CAM), and product lifecycle management to design and analyze manufacturing plants, industrial equipment and machinery, heating and cooling systems, transport systems, aircraft, watercraft, robotics, medical devices, weapons, and others. Mechanical engineering emerged as a field during the Industrial Revolution in Europe in the 18th ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tempering (metallurgy)
Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product. For instance, very hard tools are often tempered at low temperatures, while springs are tempered at much higher temperatures. Introduction Tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloy. The reduction in hardness is usually accompanied by an increase in ductility, thereby decreasing the brittleness of the metal. Tempering is usually performed after quen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Railway Tire
The steel wheel of a steam locomotive and other older types of rolling stock were usually fitted with a steel tire (American English) or tyre (in British English, Australian English and others) to provide a replaceable wearing element on a costly wheel. Installation Replacing a whole wheel because of a worn contact surface was expensive, so older types of railway wheels were fitted with a replaceable steel tire. The tire is a hoop of steel that is fitted around the steel wheel centre. The tire is machined with a shoulder on its outer face to locate it on the wheel centre, and a groove on the inside diameter of the flange face. The inside diameter of the tire is machined to be slightly less than the diameter of the wheel centre on which it is mounted, to give an interference fit. The tire is fitted by heating to a controlled temperature, avoiding overheating. This causes the tire to expand. The wheel centre, usually already mounted on the axle, is lowered into the tire whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shrink-fitting
Shrink-fitting is a technique in which an interference fit is achieved by a relative size change after assembly. This is usually achieved by heating or cooling one component before assembly and allowing it to return to the ambient temperature after assembly, employing the phenomenon of thermal expansion to make a joint. For example, the thermal expansion of a piece of a metallic drainpipe allows a builder to fit the cooler piece to it. As the adjoined pieces reach the same temperature, the joint becomes strained and stronger. Other examples are the fitting of a wrought iron tyre around the rim of a wooden cart wheel by a wheelwright, or of a steel tyre to the wheel of a railway engine or rolling stock. In both cases the tyre will be heated and expands to slightly greater than the wheel's diameter, and is fitted around it. After cooling, the tyre contracts, binding tightly in place. A common method used in industry is the use of induction shrink fitting which refers to the use of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat
In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is also often used to refer to the thermal energy contained in a system as a component of its internal energy and that is reflected in the temperature of the system. For both uses of the term, heat is a form of energy. An example of formal vs. informal usage may be obtained from the right-hand photo, in which the metal bar is "conducting heat" from its hot end to its cold end, but if the metal bar is considered a thermodynamic system, then the energy flowing within the metal bar is called internal energy, not heat. The hot metal bar is also transferring heat to its surroundings, a correct statement for both the strict and loose meanings of ''heat''. Another example of informal usage is the term '' heat content'', used despite the fact that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axle
An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type axle is referred to as a '' spindle''. Terminology On cars and trucks, several senses of the word ''axle'' occur in casual usage, referring to the shaft itself, its housing, or simply any transverse pair of wheels. Strictly speaking, a shaft which rotates with the wheel, being either bolted or splined in fixed relation to it, is called an ''axle'' or ''axle shaft''. However, in looser usage, an entire assembly including the surrounding axle housing (typically a casting) is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Train Wheel
A train wheel or rail wheel is a type of wheel specially designed for use on railway tracks. The wheel acts as a rolling component, typically press fitted onto an axle and mounted directly on a railway carriage or locomotive, or indirectly on a bogie (in the UK), also called a ''truck'' (in North America). The powered wheels under the locomotive are called driving wheels. Wheels are initially cast or forged and then heat-treated to have a specific hardness. New wheels are machined using a lathe to a standardized shape, called a profile, before being installed onto an axle. All wheel profiles are regularly checked to ensure proper interaction between the wheel and the rail. Incorrectly profiled wheels and worn wheels can increase rolling resistance, reduce energy efficiency and may even cause a derailment. The International Union of Railways has defined a standard wheel diameter of , although smaller sizes are used in some rapid transit railway systems and on ro-ro carriages. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wheelset (rail Transport)
A wheelset is a pair of railroad vehicle wheels mounted rigidly on an axle such that both wheels rotate in unison. Wheelsets are often mounted in a bogie ("truck" in North America) – a pivoted frame assembly holding at least two wheelsets – at each end of the vehicle. Most modern freight cars and passenger cars have bogies each with two wheelsets, but three wheelsets (or more) are used in bogies of freight cars that carry heavy loads, and three-wheelset bogies are under some passenger cars. Four-wheeled goods wagons that were once near-universal in Europe and Great Britain and their colonies have only two wheelsets; in recent decades such vehicles have become less common as trainloads have become heavier. Conical wheel-tread Most train wheels have a conical taper of about 1 in 20 to enable the wheelset to follow curves with less chance of the wheel flanges coming in contact with the rail sides, and to reduce curve resistance. The rails gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chamfer
A chamfer or is a transitional edge between two faces of an object. Sometimes defined as a form of bevel, it is often created at a 45° angle between two adjoining right-angled faces. Chamfers are frequently used in machining, carpentry, furniture, concrete formwork, mirrors, and to facilitate assembly of many mechanical engineering designs. Terminology In machining the word ''bevel'' is not used to refer to a chamfer. Machinists use chamfers to "ease" otherwise sharp edges, both for safety and to prevent damage to the edges. A ''chamfer'' may sometimes be regarded as a type of bevel, and the terms are often used interchangeably. In furniture-making, a lark's tongue is a chamfer which ends short of a piece in a gradual outward curve, leaving the remainder of the edge as a right angle. Chamfers may be formed in either inside or outside adjoining faces of an object or room. By comparison, a '' fillet'' is the rounding-off of an interior corner, and a ''round'' (or ''ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
