Protect and enhance the durability of your dart flights using flight protectors. Darts is a game of skill and is played by men and women of all ages. For serious players, a flight protector can help eliminate damage with a regular dart use as well as strengthening your flight so that is able to be used over and over again.

Instructions

1
Purchase flight protectors. Flight protectors can be purchased for a small price from retailers such as sporting good stores and online specialty stores. Typically, for a few dollars you can get several flight protectors in a package.

2
Attach the flight protector to the dart. Flight protectors are small clips that are usually made out of plastic or metal. Clip the flight protectors onto the dart by placing them on the top of each flight making sure to cover all four edges. The flight protectors will fit any shape of flight whether it is a soft tip or steel tip darts.

3
Test out your darts using your flight protectors. The flight protectors may alter the way the darts are thrown since they are also used to help with aerodynamics by keeping the dart flight in good shape. This translates into a more accurate hit when the dart is thrown at the target.

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When you buy an incandescent light bulb, you never know how long it will burn. Its service life is limited mainly by microscopic cracks in the tungsten filament. A simulation model for materials reveals crack formation before and after the drawing process.

Ideally, light bulbs last for 42 days in continuous operation – or so the manufacturers would have us believe. But the reality is not quite so lustrous: Some light bulbs do not burn out for years, but others last only a few days. Fine cracks in the tungsten filament, which eventually cause it to break, preclude a more uniform product quality. This is a problem also faced by Osram and Philips, the world’s biggest light bulb manufacturers. The industry has so far relied on trial and error to improve the drawing process for the filament. Production processes can be enhanced more strategically by simulating the material behavior. Supported by researchers from the Fraunhofer Institute for Mechanics of Materials IWM, the manufacturers are investigating the cracks and the resultant difficulties when spiraling the wire. Osram project manager Bernd Eberhard is confident that “Once we have more insight into the composition and behavior of the filament, we will be able to optimize and standardize our production processes.”

With an average diameter of 40 micrometers depending on the type of lamp, the tungsten filament is only about half as thick as a human hair. To reach this diameter, the wire has to be pulled repeatedly through a wire-drawing die that stretches it lengthwise and makes it progressively thinner. Depending how often the process is repeated, it may acquire a varying number of longitudinal cracks. Splits of this kind form primarily during the first stages of the drawing process, when the wire is thinned from almost four millimeters to only 0.3. The fine cracks grow longer when the wire is stretched further to a diameter of as little as five micrometers. This fact can be attributed to the tension that remains in the wire after drawing out, as IWM project manager Holger Brehm and his predecessor Sabine Weygand have discovered. “We have already succeeded in mathematically describing the behavior of the wire and the cracks that form during and after the drawing-out process. For the first time ever, the tungsten filament can be monitored on the screen during the entire thinning-out process.”

Crack formation is being further investigated and other decisive factors are integrated in the model. One such factor is the friction between the wire and the wire-drawing die. High friction makes the metal hotter. The researchers are therefore currently integrating the temperature change during and after drawing into their simulation. “The drawn wire cools faster on its surface than on the inside,” Brehm summarizes the latest experimental findings. “Unfortunately, splits can occur during this process as well.”

source from www.azom.com

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Introduction
High-speed steels are tool steels that find applications in machine tools that have high rates of material removal. Tungsten high-speed steels (group T) and molybdenum high-speed steels (group M) are two types of high-speed steels. These two groups of high-speed steels have similar hardening abilities and other characteristics.

High-speed tool steels are capable of being hardened to 62 - 67 HRC and their hardness can be maintained at service temperatures up to 540°C (1004°F). This makes them suitable for use in high-speed machinery.

The tungsten series include the T1 to T15 class alloys. Tungsten is a good carbide former that prevents grain growth, enhances toughness and increases red hardness and high temperature strength. Tungsten is used in hot forming tool steels and high-speed steels.

Overview
White and Taylor developed the type T1 series of tungsten high-speed steels. In the early 1900s, they discovered that certain steels exhibited red hardness and such steels comprised more than 14% W, about 0.3% V and about 4% Cr. T1 in its earliest form contained about 18% W, 0.68% C, 0.3% V and 4% Cr. An increase in the quantity of vanadium was seen by 1920. The carbon content of most steels also increased to approximately 0.75% over the years.

The most significant alloying elements found in tungsten high-speed steels include carbon, tungsten, cobalt, chromium and vanadium. Tungsten high-speed steels contain 4% chromium. T4 and T15 are the cobalt-base tungsten varieties that contain different amounts of cobalt. The T1 type of tungsten high-speed steels is free of cobalt or molybdenum.

Classification
The American Iron and Steel Institute (AISI) has classified high-speed tool steels into about 40 individual categories. This classification system uses a T for referring to steels in which tungsten the primary alloying element. The letter T is followed by a number which distinguishes each of the tungsten tool steels ranging between T1 and T15.

Hardness
Tungsten high-speed steels have good wear resistance and high red hardness. The maximum hardness of group T steels differs according to the carbon content and also the alloy content. A minimum hardness of 64.5 HRC can be imparted to all types of high-speed steels. Types such as T15 can be hardened to 67 HRC as they have high carbide and carbon content (1.55%). Hence T15 is considered as the most wear-resistant steel of the tungsten high-speed steel series. Tungsten high-speed steels comprising more than 1.0% C and 1.5% V produce a high number of wear-resistant hard carbides in the microstructure due to the presence of high carbon and alloy content. Tungsten high-speed steels are deep hardening when they are quenched from their hardening temperature of 1205 to 1300°C (2200 to 2375°F). Solid tools such as cold extrusion punches and broaches with large diameters are made from tungsten high-speed steels. Full hardness is provided for tools with large diameters using an accelerated oil quench.

Applications
The major applications of tungsten high-speed steels are the following:

•Interrupted-cut applications and delicate tools
•Cutting tools including hobs, milling cutters, bits, reamers, drills, broaches and taps
•Production of dies and punches
•Making high-temperature and high load structural components, e.g., pump parts and aircraft bearings.

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Introduction
Hot work tool steels are steels capable of withstanding high abrasion, heat and pressure conditions that prevail in manufacturing units that perform processes such as forming, shearing and punching of metals at high temperatures of 480 to 760°C (900 to 1400°F). These steels have wear resistance up to 540°C (1000°F).

Hot work tool steels are designated as group H steels and they have 0.35% to 0.45% carbon, 6% to 25% chromium, with vanadium, molybdenum, and tungsten as the other alloying elements. Tungsten is primarily used in hot forming tool steels due to its high temperature strength, toughness and resistance to grain growth.

Overview
Tungsten hot-work steels constitute the H21 to H26 types of hot work steels. These steels have similar characteristics as those of other of high-speed steels. The hot work steel type H26 has low carbon content when compared to that of T1 high speed steel. The primary alloying elements of tungsten hot-work steels include tungsten, carbon, chromium and vanadium.

Properties
Tungsten hot work steels have high alloy content, which enhances their heat resistance. The high alloy content also makes the tungsten steels brittle and unsuitable for the water-cooling process. Breakage of tungsten hot work steels can be reduced if they are preheated to operating temperatures prior to use. Tungsten steels have normal working hardness of 45 to 55 HRC. Thermal shock resistance and toughness of these steels can be improved by reducing the carbon content. In such cases, it is necessary to adjust the tungsten and vanadium content also as these two reduce the hardenability of steel by trapping large amount of carbon in the form of carbides.

Scaling can be reduced by quenching tungsten hot-work steels in oil or hot salt. Tungsten hot-work steels are resistant to distortion when they are air- hardened, and have higher hardening temperature when compared to chromium hot-work steels.

Applications
Tungsten hot work steels find applications in the following areas:

•Manufacturing mandrels and extrusion dies for high temperature applications, such as extrusion of brass, nickel alloys, and steel
•Hot-forging dies of rugged design.

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