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http://www.wisegeek.com/how-do-i-begin-a-career-in-quality-assurance.htmQuality Assurance (QA) is a process-centered approach to ensuring that a company or organization is providing the best possible products or services. It is related to quality control, which focuses on the end result, such as testing a sample of items from a batch after production. Although these terms are sometimes used interchangeably, quality assurance focuses on enhancing and improving the process that is used to create the end result, rather than focusing on the result itself. Among the parts of the process that are considered in QA are planning, design, development, production and service.
The Shewhart Cycle
There are many QA tools that organizations can use and that will help guide them through the steps that are needed to ensure that their processes are as efficient and productive as possible. One of the most popular tools is called the Shewhart cycle, which was developed by Dr. W. Edwards Deming, a 20th-century American management consultant who named the tool after his associate, Walter A. Shewhart. This cycle for quality assurance consists of four steps: Plan, Do, Check and Act (PDCA). At the end of Shewhart cycle, which also is called the Deming cycle or PDCA cycle, the steps are repeated to ensure that the process is being evaluated and improved on a constant basis.
During the first step of the PDCA cycle, Plan, the organization should establish its objectives and determine the processes or changes in the processes that are required to deliver the desired results. The second step, Do, is when the processes or changes are developed and tested. In the third step, Check, the processes or changes are monitored and evaluated to determine whether the results are meeting the predetermined objectives. The final step, Act, is when actions that are necessary to achieve the desired improvements are fully implemented into the process. The cycle can then be repeated, beginning with new objectives being planned.
Excellence in Every Component
The Shewhart Cycle can be an effective method for achieving quality assurance because it analyzes the existing conditions and methods that are used to provide the product or service to customers. The goal is to ensure that excellence is inherent in every component of the process. Quality assurance also helps determine whether the steps that are used to provide the product or service are appropriate for the time and conditions. In addition, if the cycle is repeated throughout the lifetime of the product or service, it helps improve the company's efficiency by ensuring that the process is always being refined and improved.
Attention to Detail
Quality Assurance demands a degree of detail in order to be fully implemented at every step. Planning, for example, could include determining specific levels of quality or measurable results that the organization wants to achieve. Checking could involve testing and other objective measurements to determine whether the goals were met, rather than mere subjective evaluation of quality. Acting could mean a total revision in the manufacturing process to correct a technical or cosmetic flaw or very small changes to improve efficiency or accuracy.
Competition to provide specialized products and services often results in breakthroughs as well as long-term growth and change. Quality assurance verifies that any customer offering, regardless whether it is new or evolved is produced and offered with the best possible materials, in the most comprehensive way and with the highest standards. The goal to exceed
http://www.wisegeek.com/how-do-i-manage-customer-expectations.htmcustomer expectations in a measurable and accountable process is provided by quality assurance.
Computer-aided design (
http://www.wisegeek.com/what-is-cad.htmCAD) is a process that allows computer users to design a variety of products and geometric shapes on-screen, rather than building them by hand. Using
http://www.wisegeek.com/what-is-cad-software.htmCAD software, one can create and modify an object to determine how it will appear and function after it is built. CAD drawings often include a computer-generated image of the design, as well as its dimensions, processes, and materials. These drawings may be either two dimensional (2D) or three-dimensional (3D). When an object is drawn in 3D using CAD, the process is often referred to as (rendering प्रतिपादन) or modeling, while 2D design is often called “drafting.”
CAD drawings are used in a large number number of industrial and manufacturing applications. This technology is widely utilized in art and
http://www.wisegeek.com/what-is-graphic-design.htmgraphic design, and gives these artists a greater level of design flexibility than that of other mediums. These drawings are also used in automotive and aerospace design, as well as in the development of industrial products and equipment. Many special effects used in films and television (rely on पर भरोसा)
http://www.wisegeek.com/what-is-computer-animation.htmcomputer animation generated with CAD software. Finally, CAD drawings are a critical component of the construction and engineering trades.
Before the invention of CAD, products and
http://www.wisegeek.com/what-are-building-plans.htmbuilding plans were drawn by hand. This was a laborious and time-intensive process that required a high number of draftsmen, as well as frequent revisions. With the introduction of CAD software, engineers and designers were able to quickly and easily generate and modify drawings. Design firms could hire fewer staff, and both design and product development cycles were greatly reduced. CAD software also allowed engineers and designers to generate their own drawings, rather than to attempt to explain them to a draftsman, resulting in more accurate design.
Though CAD drawings have been in use since the 1960s, it wasn't until the late 1980s and early 1990s that CAD software became a cost-effective option for many industries. Early versions of the software relied on 2D vector design, while modern CAD drawings include
http://www.wisegeek.com/what-is-3d-modeling.htm3D modeling capabilities. Today's modeling software allows designers to not only draw an object, but to rotate it on an axis, and to see through the object's walls from the inside. This modeling capability is particularly useful in construction and engineering, allowing designers to virtually “walk-through” (a tour or demo of an area or task) a structure and explores different angles.
Most CAD software is designed only for Windows or Linux operating systems. Complex CAD drawings may require advanced graphics cards and high levels of random access memory (RAM), but simpler drawings can be done on almost any basic computer. CAD software is operated using a traditional mouse, though some professional designers may supplement this operation using a digital pen or drawing tablet.
A dial gauge is a precision measurement commonly used to measure machined parts for production tolerances or wear. Dial gauges are capable of producing extremely fine measurement values; increments of 0.00005 inch (0.001mm) may be possible with some gauges. Measurement inputs are transferred to the gauge via a
http://www.wisegeek.com/what-is-a-plunger.htmplunger (a device consisting of a rubber cup on a long handle, used to clear blocked pipes by means of water pressure)., hinged lever, or the jaws of a vernier. Plunger instruments are generally used in conjunction with a clamp or stand which holds the gauge in a fixed position in relation to the work piece. The work piece is then rotated or moved to take the measurements. Dial gauges are available with analog needle and
http://www.wisegeek.com/what-are-dial-indicators.htmdial indicators or digital liquid crystal displays (LCDs).
The dial gauge has long been a standard with engineers, artisans, and do-it-yourself enthusiasts for taking very fine measurements on precision parts. High levels of accuracy are possible in extremely small increments with typical measurement ranges running from [0.015 inches to 12 inches (0.25 – 300 mm)] in increments as small as 500 thousands of an inch (0.001 mm). There are two basic dial gauge formats; the first is the plunger or lever type gauge. In this case, a spring loaded plunger or lever at the bottom of the gauge transfers workpiece surface height deviations to the gauge. The second type is the vernier dial gauge which receives its measurement input from the movement of the jaws of a conventional vernier.
Plunger type dial gauges are typically held in a fixed position while taking measurements. Specially designed weighted or magnetic clamps or stands are used to support the instrument while the work piece is rotated or moved. This process generally involves zeroing the gauge, adjusting its position until the plunger or lever rests on the work piece, and then rotating or moving the work piece to check for anomalies (defects). The contact tip of a lever type gauge is generally relatively small and measures narrow grooves where the plunger would not fit.
A vernier type dial gauge utilizes the movement of the verniers jaws as a measurement input. These gauges indicate measurements both on the dial and on the conventional
http://www.wisegeek.com/what-is-a-vernier-scale.htmvernier scale. The vernier type gauge is capable of producing very accurate measurements across the vernier's standard inside and outside diameter and depth measuring ranges. The analog dial gauge may be capable of allowing the needle to travel around the dial several times if the measurement input is large enough. These gauges then have a second, smaller dial, much like a wristwatch lap timer, on their face which indicates the number of full revolutions of the needle.
Digital indication dial gauges function in exactly the same way as their analog siblings but display their measurements digitally on a LCD display. Many users find this gauge quicker and easier to read than the needle and dial type. As with all precision instruments, care should be taken to keep the dial gauge clean and not subject it to excessive impact to preserve its accuracy.
A cap screw is a type of fastener used for making mechanical connections between mating objects, to ensure that they are held together securely. These screws are commonly used to fasten machine parts and many other types of objects, such as those inside home appliances or consumer electronic devices. It is important to select the right size and type of cap screw for each individual application.
A cap screw is directly tightened into a threaded or tapped hole, and is normally used without a nut. It has a large head on one end and a cylindrical shaft with an external thread — a helical structure that allows the screw to be advanced when rotated. The tapped hole has an internal thread that matches the external thread of the screw. When this screw is inserted and rotated into a tapped hole, it advances. The screw is tightened and loosened by applying torque to the head of the screw using a tool.
A variety of cap screw heads are available to allow different tools to be used for tightening or loosening the screw. The head has a larger diameter than the threaded portion to provide a positive mechanical stop when tightening the screw, and to allow the head to be shaped to accept a specific type of tool. Examples of commonly used cap screw heads are the hex head, which has a hexagonal shape for use with a spanner wrench; the socket head, which has recessed hexagonal hole for use with an
http://www.wisegeek.com/what-is-an-allen-wrench.htmAllen wrench; and the button head, which has a lower profile, dome-shaped head and recessed hexagonal hole for use in counter bored holes.
A cap screw can generate a high amount of clamping force when tightened. The mating surfaces between the screw and nut resist the force being applied by the screw, and help to prevent the mechanical connection from loosening over time. The type and size of cap screw selected for a particular application depends primarily on the forces required to adequately secure the mechanical connection.
Cap screws are available in both English and metric sizes, and with a wide variety of coarse and fine threads. They can be manufactured using carbon steel, stainless steel, or brass for
http://www.wisegeek.com/what-is-corrosion.htmcorrosion resistance; metal alloys for high-strength applications; and even plastic materials. When selecting a cap screw, it is important to understand the environment and stresses that the mechanical connections will be exposed to, so that the proper size and material are used.
A heat number is a unique identifying code a technician stamps on a piece of metal to provide information about its origins. Metal plate and pipes are most likely to bear this number, and in some cases, the law requires its use on metal products. The heat number provides a method for tracing materials and is an important part of quality assurance and control. People can usually find it near the edge or end of a finished metal piece, and other information may be on the stamp as well.
There are three segments in a heat number. The first digit indicates which furnace a technician used to prepare a batch of molten metal. The next digits indicate the year of the casting, and the last two or three digits describe the number of the casting. A number like 222121 indicates that the metal came from furnace two in the year 2022, and it was the 121st melt for that furnace that year. This information corresponds to a record the manufacturer keeps for future reference.
In quality control, people subject a sample piece of metal from a given batch to some testing to make sure it meets the required tolerances. People will test for contaminants, weak spots, and other issues. If there is a problem with the metal, people can recall other pieces with that heat number to check them and see if they share the issue. The number also corresponds to records about the shift that handled the metal, what time of day it was cast, and so forth. This information can be useful when people want to determine why the same quality control problem keeps recurring.
With the heat number, people can trace all the materials from a particular factory. Along with the heat number, the stamp includes a disclosure of the manufacturer and the facility, if the manufacturer has more than one metalworking shop. The stamp may also discuss the mold number, referring to the mold the company used to make the product. This can be useful for matching replacement parts, as people can use the mold number to get an exact replacement.
Manufacturers may apply the heat number even if the law does not require it because it can be a useful tool for monitoring materials. As long as the company maintains current records, it should be able to look up any piece of metal by its heat number and provide insight into its origins. This can be useful for activities like accident forensics, where investigators may want to find out more about a particular metal product to see if a problem with the metal contributed to the accident. Heat numbers are also useful for recalls, allowing people to identify a bad batch of metal and issue a warning to the public.
Butt-welding is the process of joining two pieces of material together along a single edge in a single plane. This process can be used on many types of materials, though metal and thermoplastics are the most common. When two sheets of steel are laid side-by-side and joined together along a single joint, this is an example of butt-welding.
Welding can be done using a large machine or a simple portable
http://www.wisegeek.com/what-is-a-welder.htmwelder. The machine applies heat to the two materials that are being joined, which causes them to melt slightly to form a liquid. A filler material made from tungsten or a metal alloy is often added in between the two objects and melted into the pool of liquid. When the heat from the welding machine is turned off, the liquefied metal and filler will quickly solidify to form a single unit. When this process is done correctly, the edges of each object are not distinguishable beneath the filler material.
There are three basic types of butt-welding, and each is chosen based on the thickness of the objects being joined. For thin sheets of metal or plastic, a square
http://www.wisegeek.com/what-are-the-different-types-of-weld-joint.htmweld joint can be used. In this instance, the edges of the objects form 90-degree angles to one another, and can be butted together like two building blocks. This is the simplest and most economical type of butt-welding joint.
When thicker materials are welded, the edges must be beveled to form a single or double V-groove. A single V-groove is used on items of moderate thickness, including many pipes. Filler is placed into the wider part of the V-shape to help firmly secure the objects to one another. On a double V-groove, both the top and bottom of each object is beveled. Filler must be placed on both sides and heated in alternating patterns to form the most secure bond possible. This double V-shape is generally used on very thick or large objects.
Butt-welding is used to produce machines, tools, and equipment in a wide variety of industries. It may be performed in manufacturing plants, on construction sites, or in specialty welding shops. Most cities require welders to be trained and certified to operate welding machines, and may also require the use of personal protective equipment and fire-prevention measures.
One of the primary benefits to butt-welding is that it is the only type of welded joint that can be continuously performed by a machine. Series of objects can be passed under a welder automatically in an assembly-line fashion, making this the most efficient and affordable welding technique in use today. While butt welds are considered very strong and secure, they are generally not recommended for use on objects that will be subject to heavy loads or extreme levels of force.
Butt welding steel is laid end to end. Fillet welding one piece is laid overlapping the other creating a 90 degree corner to which the filler is applied.
One type of butt welding is called flash butt welding. With flash butt welding, the two pieces of metal are laid end to end, then "flashed" with welding current, causing them to weld together. It requires a special flash butt welding machine, and is usually used to join rods, chains, bars, etc. together.
Flash butt welding is popular because of the strong bond it creates between pieces -- in some cases, as strong as strong as parent metal
For butt welding, you put two pieces of metal flush up against each other; in fillet welding you leave a small gap which is then filled with welding rod. Also, fillet welding usually uses lower voltage and speed than butt welding of a similar nature.
The biggest difference between a sprocket and a gear is how each works on a functional level. Both tend to be grooved wheels used in machinery, and their basic appearance is often really similar — but how they operate and what, exactly, it is they do tends to be really different. In general, a gear is a toothed wheel designed to mesh with other gears and transmit movement to them, which in turn can cause movement elsewhere. A sprocket, conversely, is a toothed wheel designed to engage and directly move a flexible indented or perforated item, like a chain or belt. The applications of each are different as a result. Sprockets are most common when there’s a moving belt or chain that is contained, as is commonly the case in bicycles,
http://www.wisegeek.com/what-is-a-conveyor.htmconveyor belts, and film projection reels. Gears are typically preferable in all other scenarios, cars and heavy machinery included. Not only are gears more universally useful, but they also aren’t as likely to need repairs or re-fittings.
Sprockets and gears are both used to transmit power within machines or to move items by interlocking with them. A sprocket usually interacts directly with some part of the machinery at issue, however, whereas gears can and often does push against each other first, then use that collective movement to influence some larger mechanical process. Another way of expressing this is that sprockets have to work independently, but gears can use networks to build strength and precision. The difference is usually most noticeable when looking closely at the grooves or teeth of each.
In the case of a sprocket, the teeth are constructed to fit precisely into the perforations or slots of the items that the tool is designed to move. The possibilities for design variations tend to be somewhat limited as a consequence. Gears, on the other hand, mesh directly with each other, and thus lend themselves to a wide variety of applications. For instance, a gear’s teeth might be on the outside of the wheel or on the inside circumference; another type, called a worm gear, isn’t a wheel at all but a threaded rod.
Impact of Damage
Another important difference between a sprocket and a gear is what happens if either is damaged. The two sprockets that carry a bicycle chain, for example, also guide the chain in a straight line, and if a single tooth on one of the sprockets breaks, the chance of the chain’s being thrown off increases. A broken chain will generally incapacitate the entire bicycle. If a tooth breaks off a gear, on the other hand, assuming the broken tooth falls out of the machine’s works, there’s little likelihood that the machine itself will fail as a result, although it may experience reduced efficiency. In most cases, the damaged gear’s load can shift to another without causing much strain.
Common Uses for Sprockets
Aside from bicycles, sprockets are also commonly found on tracked vehicles like tanks and bulldozers and in film cameras and film projectors. In each, rotation of the sprocket moves a flexible device, like a chain, a belt, or a strip of photographic film. In those cases where the flexible device is a continual loop, as in bicycles and tracked vehicles, the many segments that make up the loop make it more vulnerable to wear and tear. In some cases this necessitates more maintenance, and also means that sprockets are typically placed on the outside of appliances, or at least behind panels that are relatively easy to access.
Situations Where Gears Are Best
Gears are found in the inner workings of many if not most machines. They're an integral component of automobile engines, for example, where they work transmitting power from the engine to the drive wheels. Some gear arrangements, like worm drives, can limit the transmission of power to a single direction without any additional devices like brakes. Precision-made gears also operate many clocks and watches.
The functional differences between a sprocket and a gear combined with the gear’s general superiority over the sprocket usually lead designers to choose gears when they can. A commonly-cited example is cars and trucks with rear-wheel drives, which employ a rigid
http://www.wisegeek.com/what-is-a-drive-shaft.htmdrive shaft to transmit power from the engine to the drive wheels. Bicycle-type chain drives were popular with some of the first automotive vehicles, but their popularity waned with time; the last chain-driven car was manufactured in the 1960s.
Tungsten Inert Gas (TIG) welding is the process of blending together reactive metals, such as
http://www.wisegeek.com/what-is-magnesium.htmmagnesium and aluminum. During the welding process, an arc is formed between a pointed tungsten electrode and the area to be welded. A
http://www.wisegeek.com/what-is-a-shielding-gas.htmshielding gas is used to help create a clean weld, as it prevents oxidization from occurring. The welding method became popular and useful in the early 1940s and, as a result, has greatly propelled the use of aluminum for welding and structural processes. It is commonly used for both high quality and manual welding. The type of gas shielding typically used for TIG welding is argon, helium, or a combination of both. When combined, these two gases can ensure a higher welding speed and welding penetration. Argon is usually preferred by most welders simply because it is heavier than air and provides better coverage when welding.
Using the TIG welding process, a person can perform a variety of weld types on a number of different metals, although steel and aluminum are the most widely used. A filler rod, usually made from the same material as the base metal, is used for reinforcing joints and welding heavy metals.
There are several different types of joints designed for use with this method of welding, including the butt joint, lap joint, corner joint, and t-joint. The butt joint, which can be welded without the assistance of a filler rod, involves two pieces of metal being joined together along the seams. With a lap joint, the top edge is welded to the bottom piece in an area between the two overlapping metals. A corner joint involves welding one piece of metal at a right angle to the edge of a second piece of metal in order to form a corner. The t-joint is created by placing one piece of metal perpendicular to another piece of metal to form a T shape, and it does require a filler rod. This type of welding is done along either side of the perpendicular seam.
Computer-aided manufacturing has come to be used as a general term to describe a variety of industrial automation technologies. Some common types of computer-aided manufacturing, also known as CAM, include numerical control (NC) machines; industrial robots; flexible manufacturing systems (FMS); and complete facility systems that incorporate CAM with computer-aided design (
http://www.wisegeek.com/what-is-cad.htmCAD) software, product life cycle software, and overall facilities management. Modern manufacturing facilities use CAM technologies to machine products, convert two-dimensional plans into three-dimensional schematics, monitor equipment, and even track and order raw material
In the early years of computer-aided manufacturing, CAM simply implied automation through
http://www.wisegeek.com/what-is-computer-software.htmcomputer software. Software helped design and tool aircraft and automotive parts or helped operate robotic arms during assembly. Machinists were still needed in most CAM facilities to reset machines and reason through problems associated with tool misalignment and machine maintenance. Modern computer-aided manufacturing, however, is much more advanced that early CAM technology.
Numeric control (NC) machines, one of the oldest and most common types of computer-aided manufacturing, applies specific formulas to processing raw materials. For example, if a circle must be cut from a sheet of metal, an NC machine can determine, using mathematical calculations and numeric input, exactly where and how to cut to get a perfect circle. Additionally, using the same algorithms, the computer can determine the exact placement of cuts to produce the largest number of circles per sheet, as well as exactly how to position the metal for optimal cutting.
Industrial robots are another example of computer-aided manufacturing. Robots perform many of the repetitive tasks once performed by human hands. Computers control the robots, sending and receiving data such as the number of pieces to produce per minute, placement of robotic arms, and timing between task stations. Programmers and other computer experts thus replace human workers, who now run the computer system rather than performing the manufacturing tasks.
Flexible manufacturing systems, CAM/CAD integrated systems, and setups that integrate with various data exchange systems provide unlimited possibilities for computer-aided manufacturing. As technology continues to evolve and broaden, flexible systems can easily produce several similar products with the same equipment, assisted by CAM software. Specific changes needed for various products can be performed within the CAM software, allowing the entire production process to become automated.
Nearly every aspect of the manufacturing process, with the exception of skilled computer programmers and operators, could be controlled by CAM technologies. Rather than simply controlling the manufacturing or fabrication process, computer-aided manufacturing software can monitor supplies, track performance, order replacement parts for machines, and even notify maintenance personnel of needed upkeep or repairs. Customization of various systems and available technologies makes the different types of CAM software virtually unlimited.
What is Holistic Design?
Holistic design is an approach to design which considers the system being designed as an interconnected whole which is also part of something larger. Holistic concepts can be applied to architecture as well as the design of mechanical devices, the layout of spaces, and so forth. This approach to design often incorporates concerns about the environment, with holistic designers considering how their design will impact the environment and attempting to reduce environmental impact in their designs.
Aesthetics can also be an important consideration in holistic design. Designers may consider how the design will look as a whole, thinking about different ways in which people will view the design. For example, when designing a structure, the designer reflects on the environment the structure will be built in, thinking about how it will integrate into the existing environment, and also about how views of the structure may change depending on angle, time of day, and other factors. In addition, the designer considers how the space will feel from the inside, and what kind of messages should be sent with the space.
The integration of a consistent look and feel is an important aspect of holistic design. Jarring design elements can throw off the aesthetics of the entire design. Holistic designers try to design spaces with future needs in mind so that additions which change the nature of the space will not need to be made. Designers try to make spaces flexible and easy to maintain to reduce the need to make major changes in response to changing needs.
This approach to design can also consider how other things in the same design family will fit. A designer of computer peripherals, for example, would want to design them in a way which meshes well aesthetically as well as functionally with the computers they are designed for. Some companies are especially famous for the beauty and harmony of their designs, with users appreciating that any product from the product line will look and work well with other products.
Holistic design also heavily incorporates sustainability, as discussed above. Designers may try to work with materials which are sustainable, and to design efficiency and environmental friendliness into whichever system is being built, whether it is a computer or a high rise. Sometimes making small changes during the design phase can have a big environmental impact, and this is an important consideration in holistic design. The designer may consider everything from passive systems to reduce energy use to active systems which are designed to make a structure's carbon footprint smaller.
What are the Common Kinds of Quality Control Measures?
Quality Control (QC) measures vary widely by industry, and the concerns or standards of those industries. For example, in
http://www.wisegeekhealth.com/what-is-food-processing.htmfood processing and water management, quality control checks may include tests for contaminants, annual inspections, and certifications. In manufacturing, quality control measures may include certification by a particular group and random product testing to make sure the items are functioning as they are intended. Various professional occupations may have their own quality control standards to ensure that those practicing in the profession have met certain standards as well.
For food and water service, there are many different types of quality control measures put into place. An initial inspection of a restaurant will determine whether it is able to open, and then annual inspections usually happen from that point forward. The inspectors will look at food preparation, making sure the food surfaces are clean and that it is cooked to, and maintained at, the proper temperature. Food handling issues include making sure there is no chance of cross contamination. In public water systems, testing may take place more frequently to ensure contaminants are within acceptable levels.
Manufacturing often has many different types of QC measures, depending on the product being produced. For example, industrial equipment may be tested for strength and durability, and some products may be tested for consistency and conformity. Depending on the industry involved, there could be a variety of certifications or standards that must be met. A few of these include ASTM International, the American National Standards Institute, and the International Organization for Standardization. Each of these groups has certain benchmarks that manufacturers must meet in order to achieve certification.
Depending on the situation, quality control measures may also apply to various professional occupations. For example, teachers, attorneys and medical doctors are just a few of the professions that require a license in order to practice. If there are issues that come regarding professionalism or malpractice, then review boards will look at the issues and perhaps approve sanctions for the professional, up to possibly losing the license to practice. In addition to those oversight responsibilities, quality control policies may also require continuing education in certain areas for a professional to maintain an active license.
While quality control measures may help to ensure that consumers are protected to a certain degree, they do not always ensure a quality service or product. Therefore, consumers still must do some research in order to determine if their needs or wants are likely to be met in choosing a particular product or service provider. Quality control may help provide some direction, but is not the only consideration.
What are the Different Types of Conveyor Belts?
There are three different types of
http://www.wisegeek.com/what-is-a-conveyor.htmconveyor belts: the basic belt, snake sandwich belt and long belt. A basic belt conveyor consists of two or more pulleys that hold one continuous length of material. These types of belts can be motorized or require manual effort. As the belt moves forward, all the items on the belt are carried forward.
A common installation sites for conveyor belts include packaging or parcel delivery services. This industry often requires a method of relocating materials from one place to another, quickly and with minimal human intervention. The belt is typically installed at waist height to improve the ergonomics for the staff that are interacting with the materials.
The conveyor structure consists of a metal frame with rollers installed at various intervals along the length of the conveyor belt. The belt is typically a smooth, rubberized material that covers the rollers. As the belt moves over the rollers, the items placed on the belt are transferred with a reduced amount of friction, due to the use of multiple rollers. Basic belt conveyors also have curved sections to allow the belt to move product around corners.
The snake sandwich conveyor consists of two separate conveyor belts that are set up parallel to each other and hold the product in place while moving along the belt. This type of belt is used to move items up steep inclines, up to 90 degrees. Created in 1979, the snake sandwich conveyor was designed as a simple, efficient method of moving rocks and other material out of a mine.
The system was designed to make use of widely available hardware and used simple principles to ensure that it was easy to repair. Any type of mechanical system intended for deployment to mining operations must recognize the limited access to parts in remote areas. This system offers the ability to move a high volume of material at a consistent rate. Smooth surfaced belts allow the conveyor belts to be cleaned automatically with the use of belt scrapers and plows. The design is flexible enough to allow the materials redirected off the conveyor belt at any point through simple redirection.
The long belt conveyor is a system of three drive units used to move materials over a long distance. The most important feature of this system is the ability of the rollers to handle both horizontal and vertical curves. The long belt
http://www.wisegeek.com/what-is-a-conveyor-system.htmconveyor system can reach up to 13.8 km (8.57 miles) in length. This type of conveyor belt is often used in mining operations to transport materials to remote construction or building site locations, such as the bottom of a mining pit.
What Are the Different Uses of Brass?
There are many uses for
http://www.wisegeek.com/what-is-brass.htmbrass, from hammers and tools to musical instruments. Brass has been used for thousands of years to make weapons, sculptures and even armor for warriors. In manufacturing areas that contain explosive fumes, materials or liquids, brass is commonly used to make fasteners that will not spark and potentially create an explosion.
Many machinists use a brass hammer to allow hammering on a delicate steel
http://www.wisegeek.com/what-is-machining.htmmachining without leaving a damaging mark. The softer material will not mar the much harder surface of the steel, thereby allowing the machinist to pound on the delicate steel component without fear. In some applications, the use of a brass hammer is also intended to avoid making a spark. Unlike a steel hammer that can send a spark into explosive gas or materials and cause an explosion, the softer metal will not spark when struck against a steel object. Refineries, oil fields and many mining companies use the softer hammers when needed.
Musical instruments are manufactured from the shiny metal for several reasons. The tonal quality of the metal makes a brass instrument pleasing to the ear. Also, the metal is softer than most other metals, which allows the tubing to be twisted into complex windings, such as those of the trumpet and French horn. This soft metal is also lighter than steel, making it possible for the instruments to be carried for long periods by
http://www.wisegeek.com/what-is-a-marching-band.htmmarching band members. The high luster of the metal also makes the instruments as visually appealing to the eye as they are musically appealing to the ear.
It is the ability of the soft metal to conduct electricity that makes brass a good choice for electronic devices. Used as contacts for speaker wires, the metal is very good at conducting a wide range of signals, which are transferred into a full, rich sound by the speaker. Being easily manipulated and fashioned, brass is a good medium for sculptors and trophy makers alike. The soft metal can be shaped and molded into an artist's impression of many different types of objects.
Rivets of the metal have been used in blue jeans and other types of clothes, boots and other garments for centuries. Some famous makers of denim products use the rivets as a trademark sign on product lines. In high-
http://www.wisegeek.com/what-is-corrosion.htmcorrosion areas, nuts, bolts and even tools are manufactured from this soft metal due to the anti-corrosive tendencies of the material. It is also common to use a wrench made of the same soft metal as the fasteners when working in a dangerously explosive environment.
What is a Hoistway?
Also known as an elevator hoist way or elevator shaft, a hoistway is the shaft constructed to allow elevators to efficiently move between the floors of a building. The shafts are typically constructed so that an elevator may move smoothly from one floor to the next, while also allowing room for the use of ancillary equipment to manage the opening and closing of doors as the elevator reaches a given floor. It is not uncommon for an elevator shaft to be constructed so that access to strategic points along the shaft is possible in the event of a mechanical failure.
In many public buildings equipped with elevators, each hoistway provides easy access to each floor in the structure. There is also what is known as a blind hoistway. In this design, the shaft is not equipped with access to every floor in the building. This is sometimes a practical approach in buildings where security clearance is necessary to limit access by unauthorized personnel. With this design, the public elevators allow access to all floors considered open, while private elevators use a hoistway design that allows access to every floor in the building, including those that are security restricted.
The construction of a hoistway usually includes ventilation equipment, making it possible for maintenance workers to comfortably correct any issues with the hydraulic system or other equipment used to operate the elevators. Another common feature of the hoistway is a set of sliding doors that are found at each floor where the elevators stop. Sensors that are mounted in the shaft signal those doors to open just as the elevator arrives at the floor, making it possible for people to enter or leave the elevator at will. A hoistway is also sometimes equipped with emergency ladders along one wall of the shaft, making it possible for workers to enter the shaft and use the ladder to reach an elevator that has stopped between floors due to some type of mechanical failure.
While the basic design of the hoistway has remained constant for decades, advances in technology have aided in making it easier to monitor the condition and status of equipment that is contained in the shaft. The end result is that maintenance tasks for elevator systems, including conducting safety checks, is easier to accomplish than in decades past. Today, the use of robotic technology has minimized the need for workers to physically enter the shaftway to perform some maintenance tasks, which in turn has helped to reduce the potential for physical harm during the repair or replacement of key components housed in the shaft.
What is Smelting?
Smelting is a process for extracting usable ore from mixed deposits where people find ore bound with other metals, rock, and extraneous material. It is very unusual to find deposits of pure ore and this method allows people to separate out useful metals. The invention of this process was an important step in the development of human societies, allowing people to make more complex metal products and alloys.
In the smelting process, people heat the material with an agent to trigger a chemical reaction. Although people often refer to smelting as another form of melting, simply melting material is not enough. The chemical reaction is necessary to force the desired ore to precipitate out, and it may be helpful to add a flux to bind with particulate materials, forming slag, a mass of unwanted material that will settle to the bottom of the furnace where people do their smelting.
As the ore precipitates out and gathers together, density changes in the composition of the material will cause it to form layers, allowing the operator to skim off the desirable ore. After the smelting is complete, people can take out the byproducts and discard them, although sometimes there are uses for them, such as combining them in aggregate concrete mixtures. The yield from a given smelting run varies, depending on the quality of the base product and what kind of ore people are attempting to extract.
People need to control the conditions carefully while smelting. The heat must be appropriate to the ore and the furnace requires good air circulation to fully heat all of the material, avoiding situations where it forms masses and does not have a chance to react chemically while in the furnace. People also need a nonreactive
http://www.wisegeek.com/what-is-furnace-lining.htmfurnace lining and must be careful with certain substances because they can produce toxic fumes and may make people sick.
Industrial metals production relies on a number of processes to get usable ore out of deposits. It can be a painstaking procedure. Companies weigh the value of the ore they are extracting against the costs of extraction to determine if smelting is an efficient and appropriate processing method. In some cases, ore may be left alone because it would cost too much money to extract, even if it is valuable. People in the area around a metal mine may notice discarded waste material with traces of the metal that would be too expensive to recover inside.
What is a Thermal Relief Valve?
As a substance increases in temperature, it also increases in size, which causes a subsequent increase in pressure when contained. This process, called
http://www.wisegeek.com/what-is-thermal-expansion.htmthermal expansion, could easily destroy equipment based on hot steam or water. In order to counteract thermal expansion, people use thermal relief valves. These valves allow excess pressure to bleed out of a system rather than cause an explosion. A thermal
http://www.wisegeek.com/what-is-a-relief-valve.htmrelief valve is common on many home and commercial devices, as the law requires their use as a basic safety precaution.
Though it is called a thermal relief valve, it operates based on pressure. As temperature increases, so does internal pressure—it is this pressure that cases the valve to trigger. The thermal relief valve entered common usage with the
http://www.wisegeek.com/what-is-a-steam-boiler.htmsteam boiler, a machine that uses heat to turn water into steam, which creates a positive pressure inside the boiler. This pressure forces the steam out and past a wheel, which turns from the force of the passing steam. The turning generates power, and the steam is contained, allowed to cool and put back into the boiler.
These machines were prone to overheating and explosion if not monitored very carefully. The earliest thermal relief valves allowed the water to come out when the pressure become too high inside the boiler. The early valves were very simple, usually relying on a plug that would be forced up and out when the pressure became too high. Even though it was very rudimentary, this is still the basis for many modern thermal relief valves.
A thermal relief valve varies in size based on whether it releases water or vapor. A water relief valve is usually much smaller than a steam release valve. This is because pressure is based on quantity. In a steam-based system, much of the volume is taken up by air, while a water system is just water. This means to get rid of the same volume of material, a lot more air needs to be removed.
Most of the time, a person will find a thermal relief valve on the portion of a system that relies on hot water. While portions of systems that run on hot steam will also generate excess heat and pressure, they are less likely to have full valve systems. When air is under enough pressure, it reverts to a liquid; in liquid form, it takes up less space, which removes pressure. It takes a significant amount of pressure to cause water to revert to a solid, a pressure far in excess of most equipment. This generally makes water-based pressure more dangerous than steam-based.
1off the desirable ore. After the smelting is complete, people can take out the byproducts and discard them, although sometimes there are uses for them, such as combining them in aggregate concrete mixtures. The yield from a given smelting run varies, depending on the quality of the base product and what kind of ore people are attempting to extract.
Industrial metals production relies on a number of processes to get usable ore out of deposits. It can be a painstaking procedure. Companies weigh the value of the ore they are extracting against the costs of extraction to determine if smelting is an efficient and appropriate processing method. In some cases, ore may be left alone because it would cost too much money to extract,