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- Oluşturulma: 07-09-21
- Son Giriş: 07-09-21
Açıklama: Understanding Auto Parts The basic idea of a car is pretty simple — turn wheels to pull you down the road. But, as illustrated by the hundreds of individual auto parts for sale at your local Pep Boys, AutoZone or Napa Auto Parts, it actually takes a lot of machinery to make cars work. If you're trying to figure out what all the parts in your car do, HowStuffWorks AutoStuff is the place for you. Here's a collection of our key car part articles. Engine System How Car Engines Work It's the reason you can put the pedal to the metal and go from zero to 60 in about 8 seconds. The car engine is a piece of engineering genius and one of the most amazing machines we use on a daily basis. Learn how the four-stroke internal combustion engine works. How Diesel Engines Work Ever wonder what the difference is between a gasoline engine and a diesel engine? Diesels are more efficient and cheaper to run than gasoline engines. Instead of using carburetion or port fuel injection, diesel engines use direct fuel injection. Find out what else makes diesel engines different! A turbocharger is actually an air compressor that compresses air to increase the air intake with turbocharger assy. It uses the inertial impulse of the exhaust gas from the engine to push the turbine inside the turbine chamber How Hemi Engines Work The HEMI engine has an awesome design and great performance, and it's pretty unique in operation. With the revitalization of the HEMI in the 2003 Dodge trucks, industry and consumer attention is once again on this interesting configuration. Check out how the HEMI works and see what makes it different from the typical engine design. How Rotary Engine blocks Work A rotary engine is an internal combustion engine, but it's not like the one in most cars. Also called a Wankel engine, this type of engine performs intake, compression, combustion and exhaust in a different part of the housing. Learn about the unique rotary setup and how it compares performance-wise to a piston engine. How Radial Engines Work Radial engines reached their zenith during WWII. But today they are not that common. One place where you can still see the radial engine's influence is in the two-cylinder engine of a Harley-Davidson motorcycle. This remarkable engine can be thought of, in a way, as two pistons from a radial engine. Find out about radial engines. How Quasiturbine Engines Work The quasiturbine engine takes the Wankel concept and improves on it: Instead of three combustion chambers, it has four, and the setup of a quasiturbine allows for continual combustion. That means greater efficiency than any other engine in its class. Learn about the quasiturbine and why it might be the most promising internal combustion engine yet. The automobile transmission system is composed of a series of crankshaft, flywheel, clutch, transmission, drive shaft, drive axle, etc. with elasticity and rotational inertia. The power is outputted by the engine and transmitted to the drive wheels through the clutch, transmission after the torque increase and change, drive shaft, main reducer, differential and half shaft. How Camshafts Work The camshaft has a huge effect on engine performance. It helps let the air/fuel mixture into the engine and get the exhaust out. Learn all about the camshaft and how a new one can radically change an engine's behavior. How Superchargers Work Overhal gaskets are parts used for sealing in automobiles, mainly made of elastomers Since the invention of the internal combustion engine, automotive engineers, speed junkies and race car designers have been searching for ways to boost its power. One way is by installing a supercharger, which forces more air into the combustion chamber. Learn how superchargers can make an engine more efficient. How Turbochargers Work When people talk about race cars, or high-performance sports cars, the topic of turbochargers almost always comes up. Turbochargers use some very cool technology to make an engine more powerful, but the concept is really quite simple. Find out how turbos increase the speed. The engine repair kit is very necessary. How Fuel Injection Systems Work The last carburetor-equipped car came off the assembly line in 1990. Since then, fuel injectors have been the primary means of getting gasoline into the engine cylinder so it can combust and you can drive. Find out how fuel-injection systems work. Power Train How Manual Transmissions Work The cylinder head is mounted on top of the cylinder block, sealing the cylinder from above and forming the combustion chamber. It is often in contact with high temperature and high pressure gas, so bear a large thermal and mechanical load. If you drive a stick-shift car, then you may have a few questions floating around in your head. Have you ever wondered, What would happen if I were to accidentally shift into reverse while I am speeding down the freeway? Would the entire transmission explode? Find out all about manual transmissions. How Automatic Transmissions Work Automatic transmissions take the work out of shifting. A truly amazing mechanical system, the automatic transmission in a car accomplishes everything a manual transmission does, but it does it with one set of gears. Learn how the whole setup works. How Clutches Work You probably know that any car with a manual transmission has a clutch -- it connects and disconnects the engine and transmission. But did you know that automatics have clutches, too? Learn how the clutch in your car works, and find out about some interesting and perhaps surprising places where clutches can be found. How CVTs Work In a regular transmission, the gears are literal gears -- interlocking, toothed wheels. Continuously variable transmissions, on the other hand, don't have interlocking gears. The most common type operates on a pulley system. Learn all about the smooth-operating, ultra-efficient CVT. How Differentials Work Without a differential, the driven wheels (front wheels on a front-wheel drive car or rear wheels on a rear-wheel drive car) would have to be locked together, forced to spin at the same speed. Find out how this essential component allows the wheels to rotate at different speeds. Braking System (including braking pads and braking shoe) In the cylinder block of the car engine, there are several waterways for cooling water circulation, and placed in the front of the car radiator (commonly known as the water tank) through the water pipe connected to form a large water circulation system, the upper outlet of the engine, equipped with a water pump, driven by the fan belt, the engine block waterway hot water pump out, the cold water pumped into. A car’s brakes are probably the most critical system on the vehicle -- if they go out, you have a major problem. Thanks to leverage, hydraulics and friction, braking systems provide incredible stopping power. Find out what happens after you push the brake pedal. How Disc Brakes Work Disc brakes are the most common brakes found on a car's front wheels, and they're often on all four. This is the part of the brake system that does the actual work of stopping the car. Find out all about disc brakes -- even when to replace the pads. How Anti-lock Brakes Work Stopping a car in a hurry on a slippery road can be challenging at best and at worst, very, very scary. Anti-lock braking systems (ABS) help alleviate the danger. Learn how anti-lock brakes prevent skidding, check out what that sputtering is and find out how effective they really are. How Power Brakes Work Power brakes are fairly ingenious machines -- they let you stop a car with a simple twitch of your foot. The concept at the heart of the power braking system is force multiplication -- a whole lot of force multiplication. Get inside the black cannister that provides the power. How Master Cylinders and Combination Valves Work We all know that pushing down on the brake pedal slows a car to a stop. We depend on that every day when we drive. But how does this happen? The master cylinder provides the pressure that engages your car brakes. Learn how the master cylinder works with the combination valve to make sure you can brake safely. Steering, Suspension and Tires How Steering Works When it comes to crucial automotive systems, steering is right up there with the engine and the brakes. Power steering systems make the job a whole lot easier, and the internal workings are pretty cool. What happens when you turn your car is not as simple as you might think. Find out all about car steering systems. How Car Suspensions Work All of the power generated by a car engine is useless if the driver can't control the car. The job of a car suspension is enormous: maximize the friction between the tires and the road surface, provide steering stability and ensure the comfort of the passengers. Learn how car suspensions work and where the design is headed in the future. How Tires Work In the market for new set of tires? All of the different tire specifications and confusing jargon the tire sales clerks or "experts" are shouting at you making your head feel like a tire spinning out of control? Find out all about car tires, including what those sidewall symbols mean! How Self-inflating Tires Work Self-inflating tires perform two crucial functions: They automatically maintain ideal tire pressure for safety and performance in standard conditions, and they allow the driver to alter psi on the fly to adjust to changing terrain. Learn how self-inflating systems like the Hummer's CTIS work. How Sequential Gearboxes Work Combine the ease of an automatic with the driver control of a manual, and what you've got is a sequential manual transmission. Instead of having to navigate an H pattern, a simple forward push advances the gear. It's the transmission used by race cars and an increasing number of high-performance street cars. Learn all about the sequential gearbox. How Torque Converters Work Cars with an automatic transmission have no clutch that disconnects the transmission from the engine. Instead, they use an amazing device called a torque converter. Find out all about the torque converter. Electrical System How Wires, Fuses and Connectors Work Wires, fuses and connectors - they may sound like the most mundane parts on your car, but they are essential. Yeah, they help keep the tunes going for a long ride, and they make reading that map at night a lot easier. But, they're also necessary for things like the cooling fan in the engine and your anti-lock brakes. Learn why wires, fuses and connectors are so important! How Ignition Systems Work A car's ignition system is the key component that helps the engine produce maximum power and minimum pollution. Find out how much is riding on a well-timed spark. How Car Computers Work Cars seem to get more complicated with each passing year. Today's cars might have as many as 50 microprocessors on them. Essentially, you're driving around in a giant computer. Learn all about the various computer systems that control your car. How Windshield Wipers Work Without windshield wipers, a rain storm would make cars pretty much useless. What began as a hand-cranked system is now automatic, and only getting more so: There are now some windshield wipers that can actually sense rain. Learn the mechanics behind this essential automotive tool. Exhaust System How Catalytic Converters Work A catalytic converter is one of the most important parts of a car's emissions control system. It treats the exhaust before it leaves the car and removes a lot of the pollution. Learn how catalytic converters reduce pollutants and help you pass the emissions test. How Mufflers Work Every car out there has a muffler -- it performs the crucial job of turning thousands of explosions per minute into a quiet purr. Mufflers use some pretty neat technology to dim the roar of an engine. Learn about the principles that make it work. Other Car Parts How Odometers Work Mechanical odometers have been counting the miles for centuries. Although they are a dying breed, they are incredibly cool inside. Learn how this simple device tracks distance and find out about digital odometers. How Cooling Systems Work A car engine produces so much heat that there is an entire system in your car designed to cool the engine down to its ideal temperature. In fact, the cooling system on a car driving down the freeway dissipates enough heat to heat two average-sized houses! Learn all about fluid-based cooling systems.
Yayınlanma Tarihi: 07-09-21
Açıklama: Understanding Compressors Compressors are mechanical devices used to increase pressure in a variety of compressible fluids, or gases, the most common of these being air. Compressors are used throughout industry to provide shop or instrument air; to power air tools, paint sprayers, and abrasive blast equipment; to phase shift refrigerants for air conditioning and refrigeration; to propel gas through pipelines; etc. As with pumps, compressors are divided into centrifugal (or dynamic or kinetic) and positive-displacement types; but where pumps are predominately represented by centrifugal varieties, compressors are more often of the positive- displacement type. They can range in size from the fits-in-a-glovebox unit that inflates tires to the giant reciprocating or turbocompressor machines found in pipeline service. Positive-displacement compressors can be further broken out into reciprocating types, where the piston style predominates, and rotary types such as the helical screw and rotary vane. In this guide, we will use both of the terms compressors and air compressors to refer mainly to air compressors, and in a few specialized cases will speak to more specific gases for which compressors are used. Types of Air Compressor Compressors may be characterized in several different ways, but are commonly divided into types based on the functional method used to generate the compressed air or gas. In the sections below, we outline and present the common compressor types. The types covered include: Piston Diaphragm Helical Screw Sliding vane Scroll Rotary Lobe Centrifugal Axial Due to the nature of the compressor designs, a market also exists for the rebuilding of air compressors, and reconditioned air compressors may be available as an option over a newly purchased compressor, including special process gas compressors. Piston Compressors Piston compressors, or reciprocating compressors, rely on the reciprocating action of one or more pistons to compress gas within a cylinder (or cylinders) and discharge it through valving into high pressure receiving tanks. In many instances, the tank and compressor are mounted in a common frame or skid as a so-called packaged unit. While the major application of piston compressors is providing compressed air as an energy source, piston compressors are also used by pipeline operators for natural gas transmission. Piston compressors are generally selected on the pressure required (psi) and the flow rate (scfm). A typical plant-air system provides compressed air in the 90-110 psi range, with volumes anywhere from 30 to 2500 cfm; these ranges are generally attainable through commercial, off-the-shelf units. Plant-air systems can be sized around a single unit or can be based on multiple smaller units which are spaced throughout the plant. To achieve higher air pressures than can be provided by a single stage compressor, two-stage units are available. Compressed air entering the second stage normally passes through an intercooler beforehand to eliminate some of the heat generated during the first-stage cycle. Speaking of heat, many piston compressors are designed to operate within a duty cycle, rather than continuously. Such cycles allow heat generated during the operation to dissipate, in many instances, through air-cooled fins. Piston compressors are available as both oil-lubricated and oil-free designs. For some applications which require oil-free air of the highest quality, other designs are better suited. Diaphragm Compressors A somewhat specialized reciprocating design, the diaphragm compressor uses a motor-mounted concentric that oscillates a flexible disc which alternately expands and contracts the volume of the compression chamber. Much like a diaphragm pump, the drive is sealed from the process fluid by the flexible disc, and thus there is no possibility of lubricant coming into contact with any gas. Diaphragm air compressors with spare parts are relatively low capacity machines that have applications where very clean air is required, as in many laboratory and medical settings. Helical Screw Compressors Helical-screw compressors are rotary compressor machines known for their capacity to operate on 100% duty cycle, making them good choices for trailerable applications such as construction or road building. Using geared, meshing male and female rotors, these units pull gas in at the drive end, compress it as the rotors form a cell and the gas travels their length axially, and discharge the compressed gas through a discharge port on the non-drive end of the compressor casing. The rotary screw compressor action makes it quieter than a reciprocating compressor owing to reduced vibration. Another advantage of the screw compressor over piston types is the discharge air is free of pulsations. These units can be oil- or water- lubricated, or they can be designed to make oil-free air. These designs can meet the demands of critical oil-free service. Sliding Vane Compressors A sliding-vane compressor relies on a series of vanes, mounted in a rotor, which sweep along the inside wall of an eccentric cavity. The vanes, as they rotate from the suction side to the discharge side of the eccentric cavity, reduce the volume of space they are sweeping past, compressing the gas trapped within the space. The vanes glide along on an oil film which forms on the wall of the eccentric cavity, providing a seal. Sliding-vane compressors cannot be made to provide oil-free air, but they are capable of providing compressed air that is free of pulsations. They are also forgiving of contaminants in their environments owing to the use of bushings rather than bearings and their relatively slow-speed operation compared to screw compressors. They are relatively quiet, reliable, and capable of operating at 100% duty cycles. Some sources claim that rotary vane compressors have been largely overtaken by screw compressors in air-compressor applications. They are used in many non-air applications in the oil and gas and other process industries. Scroll Compressors Scroll air compressors use stationary and orbiting spirals which decrease the volume of space between them as the orbiting spirals trace the path of the fixed spirals. Intake of gas occurs at the outer edge of the scrolls and discharge of the compressed gas takes place near the center. Because the scrolls do not contact, no lubricating oil is needed, making the compressor intrinsically oil-free. However, because no oil is used in removing the heat of compression as it is with other designs, capacities for scroll compressors are somewhat limited. They are often used in low-end air compressors and home air-conditioning compressors. Rotary Lobe Compressors Rotary-lobe compressors are high-volume, low-pressure devices more appropriately classified as blowers. To learn more about blowers, download the free Thomas Blowers Buying Guide. Centrifugal Compressors Centrifugal compressors rely on high-speed pump-like impellers to impart velocity to gases to produce an increase in pressure. They are seen mainly in high-volume applications such as commercial refrigeration units in the 100+ hp ranges and in large processing plants where they can get as large as 20,000 hp and deliver volumes in the 200,000 cfm range. Almost identical in construction to centrifugal pumps, centrifugal compressors increase the velocity of gas by throwing it outward by the action of a spinning impeller. The gas expands in a casing volute, where its velocity slows and its pressure rises. Centrifugal compressors have lower compression ratios than displacement compressors, but they handle vast volumes of gas. Many centrifugal compressors use multiple stages to improve the compression ratio. In these multi-stage compressors, the gas usually passes through intercoolers between stages. Axial Compressors The axial Low-Pressure Water Lubricating Oil-free Compressor achieves the highest volumes of delivered air, ranging from 8000 to 13 million cfm in industrial machines. Jet engines use compressors of this kind to produce volumes over an even wider range. To a greater extent than centrifugal compressors, axial compressors tend toward multi-stage designs, owing to their relatively low compression ratios. As with centrifugal units, axial compressors increase pressure by first increasing the velocity of the gas. Axial compressors then slow the gas down by passing it through curved, fixed blades, which increases its pressure. Power and Fuel Options Air compressors may be powered electrically, with common options being 12 volt DC air compressors or 24 volt DC air compressors. Compressors are also available that operate from standard AC voltage levels such as 120V, 220V, or 440V. Alternative fuel options include air compressors that operate from an engine that is driven off of a combustible fuel source such as gasoline or diesel fuel. Generally, electrically-powered compressors are desirable in cases where it is important to eliminate exhaust fumes or to provide for operation in settings where the use or presence of combustible fuels is not desired. Noise considerations also play a role in the choice of fuel option, as electrically driven air compressors typical exhibit lower acoustical noise levels over their engine-driven counterparts. Additionally, some air compressors may be powered hydraulically, which also avoids the use of combustible fuel sources and the resulting exhaust gas issues. Compressor Machine Selection in an Industrial Setting In selecting air compressors for general shop use, the choice will generally come down to a piston compressor or a helical-screw compressor. Piston compressors tend to be less expensive than screw compressors, require less sophisticated maintenance, and hold up well under dirty operating conditions. They are much noisier than screw compressors, however, and are more susceptible to passing oil into the compressed air supply, a phenomenon known as “carryover.” Because piston compressors generate a great deal of heat in operation, they have to be sized according to a duty cycle—a rule of thumb prescribes 25% rest and 75% run. Radial-screw Variable Frequency Water Lubricating Oil-Free Screw Compressor can run 100% of the time and almost prefer it. A potential problem with screw compressors, though, is that oversizing one with the idea of growing into its capacity can lead to trouble as they are not particularly suited to frequent starting and stopping. Close tolerance between rotors means that compressor needs to remain at operating temperature to achieve effective compression. Sizing one takes a little more attention to air usage; a piston compressor may be oversized without similar worries. An autobody shop which uses air constantly for painting might find a radial-screw compressor with its lower carryover rate and desire to run continuously an asset; a general auto-repair business with more infrequent air use and low concern for the cleanliness of the supplied air might be better served with a piston compressor. Regardless of the compressor type, compressed air is usually cooled, dried, and filtered before it is distributed through pipes. Specifiers of plant-air systems will need to select these components based on the size of the system they design. In addition, they will need to consider installing filter-regulator-lubricators at the supply drops. Larger job site compressors mounted on trailers are typically rotary-screw varieties with engine drives. They are intended to run continuously whether the air is used or dumped. Although dominant in lower-end refrigeration systems and air compressors, scroll compressors are beginning to make inroads into other markets. They are particularly suited to manufacturing processes that demand very clean air (class 0) such as pharmaceutical, food, electronics, etc. and to cleanroom, laboratory, and medical/dental settings. Manufactures offer units up to 40 hp that deliver nearly 100 cfm at up 145 psi. The larger capacity units generally incorporate multiple scroll compressors as the technology does not scale up well once beyond 3-5 hp. If the application involves compressing hazardous gases, specifiers often consider diaphragm or sliding-vane compressors, or, for very large volumes to compress, kinetic types.
Yayınlanma Tarihi: 07-09-21
Açıklama: Basics of acid dyes, disperse dyes, and reactive dyes. Acid dyes with improved light fastness have become important particularly in connection with the usage of acid dyes in information recording systems. The inferior light fastness may be due to several reasons. Auto oxidation reaction of dyes is generally considered to occur on exposure to ultraviolet (UV) radiation and prevented by the addition of UV absorbers or antioxidants such as hindered phenols or naphthylamines. In recent years as an approach to the photostabilisation of dyes attempts have been made to prepare dyes with built-in photostabilising moiety. Acid dyes, named for their application under acid conditions, are reasonably easy to apply, have a wide range of colours and, depending on dye selection, can have good colour fastness properties. The dyes are divided into three categories according to their levelling and fastness properties, namely levelling, milling and super milling dyes. Levelling, or equalising, acid dyes have good levelling properties and are applied from a bath containing sulphuric acid to achieve exhaustion. Because of the ease of migration of dye molecules into and out of the fibre, equalising acid dyes have poor fastness to washing, and are normally used for pale, bright shades where fastness is not paramount. Milling acid dyes have a greater substantivity for the fibre than levelling dyes, and therefore have poorer levelling properties. These dyes have better fastness properties than levelling acid dyes, and have reasonable wet fastness, particularly if alkaline milling is to take place in a subsequent process. Super milling acid, or neutral dyeing, dyes are applied in a similar way to milling acid dyes, except that greater control over the strike rate of the dye is exercised. Super milling dyes give very good fastness and, with an appropriate after-treatment, can satisfy requirements for shades of medium depth, especially where reasonable brightness is needed. Thus there are considerablef differences in the properties and application methods within the whole range of acid dyes. The dyer must take care to ensure that the dyes chosen in combination are from the same group and have very similar properties. Disperse dyes are characterised by the absence of solubilising groups and low molecular weight. From a chemical point of view more than 50% of disperse dyes are simple azo compounds, about 25% are anthraquinones and the rest are methine, nitro or naphthoquinone dyes. Disperse dyes are used mainly for polyester, but also for cellulose acetate and triacetate, polyamide and acrylic fibres. Disperse dyes are supplied as powder and liquid products. Powder dyes contain 40–60% of dispersing agents, while in liquid formulations the content of these substances is in the range of 10–30%. Formaldehyde condensation products and lignin sulphonates are widely used for this purpose. The following chemicals and auxiliaries are used for dyeing with disperse dyes; Dispersants: although all disperse dyes already have a high content of dispersants, they are further added to the dyeing liquor and in the final washing step. Carriers: for polyester fibre, dyeing with disperse dyes at temperatures up to 100°C requires the use of carriers. Because of environmental problems associated with the use of carriers, polyester is preferably dyed under pressure at temperature >100°C without carriers. However, carrier dyeing is still important for polyester-wool blends. Thickeners: polyacrylates or alginates are usually added to the dye liquor in padding processes. Reducing agents (mainly sodium hydrosulphite) are added in solution with alkali in the final washing step for the removal of unfixed surface dye. Owing to their low water solubility, disperse dyes are largely eliminated by adsorption on activated sludge in waste water treatment plants. Some disperse dyes contain organic halogen, but they are not expected to be found in the effluent after waste water treatment because of their adsorption on activated sludge. Reactive dye introduced on 1956 and for the first time dyeing became possible by direct chemical linkage between dye and fiber (Shenai, 1993). But all classes of reactive dye do not react in the same manner. So the group of dyes used for a ternary shade should have compatibility among themselves. Importantly, reactive dyes in a mixture should all exhaust and react with the fiber at about the same rate so that the shade builds up accurately. Dyes which are from different ranges, with different reactive groups, should not be used together because of their different dyeing character and reactivity. Compatible dyeing performance requires careful control of the dyeing parameters such as temperature, salt and alkali concentrations, the dyeing time and the liquor ratio. There is often a doubt about the particular reactive group presents in a reactive dye. For that reason in most of the cases selection of dyes depends on the maker’s recommendations (Broadbent, 2001). Shenai (1997) discussed in detail about the chemistry of vinyl sulphone dyes like Remazol class. Common salt and alkali plays the vital role in exhaustion and fixation of these dyes and addition of salt to the dye bath before adding the alkali is also essential. In reactive dyeing, though water is the competitor for reaction with the dye, cellulose fiber takes part in the reaction in majority. Because the substantivity of reactive dye to the fiber is greater than that to water (Chinta and Vijaykumar 2013). But factually all the reactive dyes do not have the same range of substantivity and reactivity, and intermediates are usually used. Reactivity is compulsory for these dyes but higher reactivity of a dye can spoil the dyeing due to hydrolysis. So the compatibility of the dyes used for ternary shades should be analyzed carefully to make the maximum utilization of each dyestuff especially when the reactive groups in them are different.
Yayınlanma Tarihi: 07-09-21
Açıklama: What is injection molding? Precision injection molding of high performance components requires primary error sources affected the molded component to be identified and isolated such that these errors can be reduced if needed. To systematically isolate and quantify the contribution of misalignment, thermal variation and component warpage to the accumulated error observed on the component, a methodology is presented and tested around an existing mold which produced parts with high dimensional variability. The mold featured two concentric guide pillars on opposite sides of the parting plane and rectangular centering block elements at three locations. Mold displacements at the parting plane were measured through the incorporation of three eddy-current linear displacement sensors. Thermal error sensitivity was investigated using FEM simulations such that the induced variability from thermal expansion and filling phase was identified and quantified. Finally, molded component warpage was isolated and quantified, again by the means of FEM simulation. The results were confirmed by using the mold on two injection molding machines to produce an array of parts whose key dimensions were measured. Micro/nanostructured components play an important role in micro-optics and optical engineering, tribology and surface engineering, and biological and biomedical engineering, among other fields. Precision glass molding technology is the most efficient method of manufacturing micro/nanostructured glass components, the premise of which is meld manufacturing with complementary micro/nanostructures. Numerous mold manufacturing methods have been developed to fabricate extremely small and high-quality micro/nanostructures to satisfy the demands of functional micro/nanostructured glass components for various applications. Moreover, the service performance of the mold should also be carefully considered. This paper reviews a variety of technologies for manufacturing micro/nanostructured molds. The authors begin with an introduction of the extreme requirements of mold materials. The following section provides a detailed survey of the existing micro/nanostructured automotive mold components manufacturing techniques and their corresponding mold materials, including fixtures and mechanical parts methods. This paper concludes with a detailed discussion of the authors recent research on nickel-phosphorus (Ni-P) mold manufacturing and its service performance. What is injection molding? Injection molding is a manufacturing process which is commonly used to create plastic components. Its ability to produce thousands of complex parts quickly makes it the perfect process for the mass production of plastic components. Essentially, the process involves the injection of plastic at high speed and pressure into a precision mechanical gear parts, which is clamped under pressure and cooled to form the final part. By melting thermoplastic and injecting it into an aluminium mold at high speed and pressure, manufacturers can create multiple complex parts at once. When the parameters of the process are controlled correctly, there’s also little need for finishing and processing the manufactured part, making it more cost effective and efficient. Although it’s one of the oldest manufacturing processes around, its speed and cost-efficiency is what continues to make it a popular choice with worldwide manufacturers. Today’s injection molding machines are fast, accurate and produce consistently high-quality components at scale. How does injection molding work? Although the process may seem simple, there are many elements involved which can alter and ruin the overall quality of the plastic component produced. In order to make a high-quality part, experienced manufacturers select the right thermoplastic (the material used to create the part), connector mold parts (which shapes the part), temperature and injection pressures to ensure the final part meets customer requirements. Before we talk about the specific parameters that need to be controlled within the process, how does injection molding actually work? Step 1: Feeding and heating the plastic To start, a thermoplastic or combination of thermoplastics are fed into an injection molding machine. The plastics, which turn to liquid when heated, are fed into the hopper at the top of the machine in solid pellet form. The pellets pass through the machine and into a temperature-controlled cylinder called the machine barrel. Here, the plastic pellets are heated until the thermoplastic is molten. The temperature of the barrel and the plastic needs to be carefully monitored to make sure the thermoplastic doesn’t overheat and burn or scorch the final part. Step 2: Pre-injection process Before the molten plastic is injected, the tool, which is usually made up of a fixed half called the cavity and a moving half called the core, closes. When closed, a clamp applies pressure to the tool, ready for the injection of the plastic. The screw within the barrel of the machine also screws back to its set point so the plastic can enter the barrel, ready to be injected. Step 3: Plastic injection Once the clamp pressure is at an optimum level, the plastic is injected by the screw at high speed and pressure into the cavity. A gate inside the tool helps to control the flow of the plastic. To make sure no damage is done to the final components, it’s important that the manufacturer monitors the injection pressure of the plastic and that they have the expertise to maintain and use the molds and tools correctly. This ensures they are creating high-quality and consistent parts from their injection molding process, like packaging mold components. Step 4: Forming the part When the tool cavity is mostly full of liquid, a holding phase begins. This is where the part in held under high pressure so it can start to take its final form. After a set holding time, the screw will screw back to its set point. This happens at the same time as the cooling phase of the cycle, which allows the thermoplastic to set in its final form. Once the set cooling time has passed, the mold opens and ejector pins or plates push the new part out of the tool, and there are also custom mold components. These fall on to a conveyor belt ready to be finished and packed. Step 5: Part finishing Depending on the final application of the part, the molded component may require some finishing, including dyeing, polishing, or removing of excess material. These processes are unique to each part and are completed before they’re packed and distributed to customers. By picking and checking products by hand, as well as performing regular quality checks, experienced manufacturers can make sure they’re producing consistent, high-quality parts for their customers.
Yayınlanma Tarihi: 07-09-21