Tungsten Dart News & Info

Extraction of Ferrotungsten from Ores with Low WO3 Content

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 17:06

Aluminothermic SHS reaction was explored as a possible route to manufacturing ferrotungsten alloy (FeW) from an ore concentrate. Changing green composition, i.e. the amount (x) of Al, it was possible to control the composition and microstructure of resultant alloys. Regardless of green composition, the final product always consisted of three phases: W, FeW, and Fe-Al-W. Compositions of the W and FeW phases were independent of x, while the Al content of the Fe-Al-W phase grew with increasing x. An alloy most closely fitting specification requirements was synthesized from green mixtures with a slightly lower amount of Al as compared to a stoichiometric one.

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Tungsten Carbide Tipped (TCT) Core Drills

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 17:04

TCT core drills are made from Tungsten carbide material on their tips. Tungsten carbide is a very hard man material and supposed to be one of the hardest material made by man. TCT core drills are more expensive then HSS core drills but are faster and easy to make bigger holes. There are also different types in TCT core drills. TCT core drills are cheaper for bigger diameter i.e. above 41 mm. They are very efficient for cutting hard material. The chances of tip breakage in TCT core drill is more compared to HSS Core drills. TCT core drills has a disadvantage that it can not be reground. Once the TCT core drill is damaged it has to be thrown away, it can not be re used like the HSS core drills. It is always recommended by manufacturers to use TCT core drills only for larger diameter and for very hard material, while giving priority to HSS core drills because of its price and re-sharpening advantages.

TCT Standard

A Standard TCT core drill is a with tungsten carbide tips. These types of core drills are now available in vast range of diameter, for up to 150 mm. These are popularly used core drills on magnetic core drilling machines. These core drills are popularly used to drill materials like railway tracks, structural steel,stainless steel, cast iron, etc.

TCT with hard coating

The TCT core drills with hard coating are core drills with a coating on it, generally TiN coating. This makes the core drills more resistant to heat, longer tool life and even removal of chips just like the advantage of HSS core drill. The biggest advantage of hard coated core drills is that these cutters are very good for cutting larger diameters on hard material. These core drills are popularly used to drill materials like corroded or weathered material, structural and stainless steel.

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Tungsten Carbide Annular Cutter(Core Drill) General Concept

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 16:55

An annular cutter (also called as core drill, core cutter, broach cutter, Trepanning drill or cup-type cutter) is a hollow, multiple cutting edges cutting tool used to make/drill holes in ferrous and non-ferrous metals. An annular cutter cuts only an annular groove at the periphery of the hole and leaves a solid core or slug at the hole center.[1] Annular cutter is a substitute for slower, more expensive and less efficient Twist drills and Hole saws. The function of Annular Cutters is more or less same as a hole saw but differs in geometry and material. Annular cutters are faster, easier and are more accurate than the conventional twist drills or drill bits.

An annular cutter or core drill removes the material from the metal to create cylindrical holes in a circular cross section. An annular cutter, unlike drill bits, cuts only on the periphery of the hole to be made. Annular cutters use almost the same method as concrete core drills, but are for metal drilling. An annular cutter is a multipoint cutting tool and is made from material like high speed steel and tungsten carbide tips.

Annular cutters are available in different sizes generally starting from diameter 12 mm (1/2’’) to 200 mm (7 7/8’’) and larger if required. The length of the annular cutter can be achieved depending upon the thickness of the material to be drilled. In the market the lengths 30 mm, 55 mm, 75 and 110 mm annular cutters are popularly available. These sizes though vary from manufacturer to manufacturer. The annular cutter’s material should be harder than the material to be drilled. Therefore there are various types of material used to manufacture annular cutters, for example different types HSS and TCT material. Annular cutters are also called as core drills because, after drilling hole, the drilled material is ejected from the cutter in the form of a cylindrical blank, this blank is called a core.

The first annular cutter was invented by Mr. Dough Hougen which he patented in 1973.[2] The High Speed Steel annular cutter was invented in 1983 by Michael Beharry [3] and the tungsten carbide tipped annular cutter was invented in 1985 by Mikiya Toshio and Shoji Michihiro.[4]

Though people use annular cutters on conventional drilling machines like radial drilling machines or pillar drilling machine, it is not recommended because these machines have very high RPM which creates high tool breakage risk for annular cutters as they are hollow unlike solid twist drills. It is always recommended to use an annular cutter or core drill with a magnetic core drilling machine (also called as magnetic drill, magnetic base drilling machine, etc.) as these machines are slower. A magnetic drilling machine is ideally made for using annular cutters.

Tungsten Carbide Nozzle Grain Growth

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 16:54

The grain growth problem, which is an inevitable problem during WC-Co cemented carbide nozzles liquid phase sintering process. While there are two main patterns of the grain growth, one is WC particles growing uniformly, approach the growth is constant. The other one is some WC grains is growing in advance. However, these two patterns of the grain growth is not independent, and they can be existing and occurring in the same time.

Generally, to control the constant growth of grains and avoid the regional growth, which is able to ensure the density of the material. During the sintering process, the regional WC grain growth and become thick, which is the source of tungsten carbide nozzle cracks appearing. Therefore, adds appropriate amount of the WC powder grain growth inhibitors, which can be beneficial for suppressing the growth of grain and improving the lifespan.

Tungsten Carbide Nozzle Plasma Activated Sintering Technology II

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 16:52

The four steps are applies an axial pressure to the powder, produces plasma for activation of the powder particles through pulse current discharge, with a direct current resistance of the sample is heated up to the required temperature and maintained for a certain time and the stress relief step. The most obvious difference between SPS and PAS is the third step, which SPS is heating by pulse current and it does not use DC as hot source during the whole sintering process.

Compared to common hot pressed sintering, conventional sintering and hot isostatic pressing (HIP), tungsten carbide nozzle plasma activated sintering technology has many advantages. First of all, it uses a DC to heat powder material and a graphite mold directly, and uses switching DC pulse voltage to generate high-temperature plasma among the powder particles or between voids. Therefore, the operation will be more convenient and more precise in sintering energy controlling. And the inside of material has been heated uniformly, the heat transfer efficiency improved, the material densification improved.
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Tungsten Carbide Nozzle Plasma Activated Sintering Technology

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 16:50

Plasma activated sintering (for short PAS), which takes advantage of switching DC pulse voltage generated high-temperature plasma among the powder particles or between voids. The plasma is a high-temperature, high reactive ionized gas conductance, and is capable of producing high-temperature about 4000-10000K.

So that the plasma can remove the impurities and gas adsorption of the powder grain surface quickly, which promote the substance spreading and moving, accelerating the sintering process and improving the efficiency. It is similar to self-propagation high-temperature synthesis (SHS) and microwave sintering, which is a kind of process that using the heat of inside powder for instant sintering. In general, tungsten carbide nozzle plasma activated sintering technology has four main steps.
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Tungsten Carbide Nozzle Spark Plasma Sintering Technology

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 16:48

During spark plasma sintering (SPS) process, the electrode through the DC pulse currents and generated discharge plasma, which makes individual particles uniformly distribute, generate Joule heat and particle surface activation. SPS process is similar to microwave sintering, which takes advantage of the self-heating effect inside for sintering. It can be considered as a process that combines the particle discharge, conductive heat and the pressure. Except heating and pressure two promoting factors, SPS technology can make partial melting of the surface and the surface of the material flaking through effective discharge produced local high temperature particles; And removing the impurities of powder grain surface or adsorption by the sputtering of high-temperature plasma and the impact of discharge.
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Tungsten Carbide Milling Cutter Nomenclature

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 16:13

A Tungsten carbide milling cutter usually have the following parts as you may also find mostly on common milling cutter, but a Tungsten carbide cutter has at least a special cutting part made of Tungsten carbide for even harder work.

• The pitch refers to the angular distance between like or adjacent teeth.

• The pitch is determined by the number of teeth. The tooth face is the forward facing surface of the tooth that forms the cutting edge.

• The cutting edge is the angle on each tooth that performs the cutting.

• The land is the narrow surface behind the cutting edge on each tooth.

• The rake angle is the angle formed between the face of the tooth and the centerline of the cutter. The rake angle defines the cutting edge and provides a path for chips that are cut from the workpiece.

• The primary clearance angle is the angle of the land of each tooth measured from a line tangent to the centerline of the cutter at the cutting edge. This angle prevents each tooth from rubbing against the workpiece after it makes its cut.

• This angle defines the land of each tooth and provides additional clearance for passage of cutting oil and chips.

• The hole diameter determines the size of the arbor necessary to mount the milling cutter.

• Plain milling cutters that are more than 3/4 inch in width are usually made with spiral or helical teeth. A plain spiral-tooth milling cutter produces a better and smoother finish and requires less power to operate. A plain helical-tooth milling cutter is especially desirable when milling an uneven surface or one with holes in it.

Tungsten Carbide Drill Bits Among Others- A Classification of Drills By Materials

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 11:39

Not all drill bits are the same. Because different projects have different needs, drill bits come in a variety of shapes and are made from different materials based on the task they are designed to perform. Choosing the wrong drill bit can lead to structural flaws in the project, broken bits, and even damaged drills. Selecting a bit that is made from the right material will help ensure the hole drilled has a smooth edge and that none of the equipment being used is damaged in the process. To a large degree, selecting the right drill bit material for a project depends on the material that will be drilled through and the hardness of the material used to form the drill bit.

The best way to determine what drill bit is right for the job is to have an understanding of all the available types and make an informed decision based on that understanding.

Drill Bit Materials

There are a number of metals used to make drill bits. Each material is best suited to drill through a particular type of surface. It is important to understand the strengths and weaknesses of each material type when selecting the bit for any project.

Low Carbon Steel

Low carbon steel drill bits are appropriate for drilling softwoods only. They are too soft for use with hardwoods and metals, and tend to dull frequently; they also need to be sharpened often to improve their lifespan. Despite these flaws, they have the distinct benefit of being extremely inexpensive.

High Carbon Steel

High carbon steel bits have a higher temperature tolerance than low carbon steel bits, so they hold up to wear better and require less frequent sharpening. They are suitable for drilling thin metal and hardwood surfaces. They cost about the same amount as low carbon steel bits and are a better option for basic drilling.

High-Speed Steel

High-speed steel bits, sometimes called HSS drill bits, are made of an extremely hard carbon steel that has a higher heat resistance than high carbon steel. This allows them to be used at higher drilling speeds, and insures that the bits maintain their structural integrity longer. HSS bits can be coated to improve certain features, and their porous surface holds coatings well.

Carbide

Carbide tipped drill bits are specialized tips on hardened steel bits. Carbide tipped drill bits have the ability to dissipate heat rapidly, and so will hold an edge longer and tolerate heat better than other drill bit options. Unfortunately, carbide tipped bits are very brittle and will chip if they are not handled with care. They are appropriate for drilling hardwood and thin metals.

Cobalt

Cobalt drill bits are extremely hard and are useful in boring into material too hard for standard high-speed drill bits like stainless steel and other thicker metal surfaces. Cobalt is less susceptible to heat damage than any other drill bit type, but it is also extremely brittle and prone to accidental damage.

Diamond Drill Bits

Polycrystalline diamond drill bits, sometimes simply referred to as PCDs, are made of the hardest drill bit material available on the market. The bits are made by coating a carbide bit in diamond particles. Diamond drill bits grind away the surface they are drilling into, rather than cutting into the surface. They are appropriate for cutting through a variety of extremely hard surfaces including granite, ceramic tile, marble, fiberglass, stone, glass, and heavy metals.

Drill Bit Coatings

Drill bit coatings make the drill bit harder, more lubricated, sharper, or more heat resistant than the metal bit is on its own. Coatings significantly improve the cutting quality, durability, and lifespan of drill bits.

Black Oxide

Black oxide is the most basic and inexpensive coating. It is commonly used on high-speed steel bits and provides a higher level of heat resistance and improved lubrication. It also protects the bit against water damage, rust, and corrosion.

Titanium Nitride

A titanium nitride, sometimes called TiN, coating reduces friction during drilling and increases heat resistance. Coating a drill bit with titanium nitride can increase the life of the bit up to 5 times. It also allows for faster drilling speeds.

Titanium Aluminum Nitride

Titanium aluminum nitride, sometimes referred to as TiAIN, is designed to increase the hardness and temperature resistance of the bit. Bits with a TiAIN coating are heat resistant up to 800 degrees Celsius, and cling well to a variety of base bit types.

Zirconium Nitride

Zirconium nitride strengthens brittle drill bit types and decreases friction. It is an excellent coating for drill bits that will be used for precision drilling. It is also effective at reducing the risk of accidental damage on brittle bit types caused by rough handling and basic wear and tear.

Specialty Bits

Specialty bits are made of rarer materials and often have a specifically designed shape that makes them perfect for a certain project. These bits are generally more expensive and harder to find than more traditional drill bits.

Tungsten Carbide

Tungsten carbide bits are extremely expensive and extremely brittle. This material is only used to make very fine drill bits. Typically tungsten carbide drill bits have a diameter of less than 1 mm. They are useful in small space drilling situations, and are hard enough to withstand the wear and tear of drilling through abrasive materials.

Diamond Core

Diamond core drill bits are used in stone cutting and masonry. Instead of the traditional point and auger style drill bit, these are hollow tip drill bits that cut or grind a circle using the outer edge of the bit. The core drill bit cuts a core or plug from the stone or glass it is used to cut, so that there are fewer shavings and potentially harmful shards of material when the drilling project is complete.

Masonry Bit

Masonry bits are made of hard carbon steel but have a specialized tip made of a harder metal. The tip is typically welded into the end of the drill bit. These bits are designed to cut through concrete, brick, and mortar during the masonry process.

PCB Drill Bit

PCB drill bits are a type of micro-drill bit that has a diameter of 1 mm or smaller. They are designed to bore holes in the electronic computer boards of most electronic objects. Because they are so fine, they are commonly made of carbide, which can hold up to the fiberglass board better than the alternatives.

Flexible Shaft Bit

Flexible shaft bits are made of spring steel and are designed to flex while drilling. They can be bent while in motion so that the hole drilled can curve inside of walls and create uniquely shaped holes. They are commonly used when running wiring in homes or doing construction work in areas with limited workspace.

Conclusion

Drill bits are used for boring holes through a number of surfaces including walls, wood, sheet metal, computer hardware, masonry projects, and more. Because drill bits are used on such a variety of surfaces, tool companies have developed drill bits in a growing number of materials and styles to accommodate the unique needs of every drilling project. Take the time to research what drill bit is right for a project before making a purchasing decision to ensure the bit selected is hard enough to bore through the material at hand and create a hole with smooth even edges.

API Standards For Rock Bits And PDC Bits

Details: Category: Tungsten Information; Published on Wednesday, 02 September 2015 11:35

API standards, as established by the American Petroleum Institute, enable drilling professionals the world over to communicate clearly.

American Petroleum Institute Standards for PDC and Rock Bit Tolerances

Bit Size (In.)	O.D. Tolerance (In.)	O.D. Tolerance (In.)
6 3/4" and smaller	-0.015 to +0.00 PDC	-0.0 to +1/32 Rock Bit
6 25/32" to 9"	-0.020 to +0.00 PDC	-0.0 to +1/32 Rock Bit
9 1/32" to 13 3/4"	-0.030 to +0.00 PDC	-0.0 to +1/32 Rock Bit
17 17/32" and larger	-0.063 to +0.00 PDC	-0.0 to +3/32 Rock Bit
9 1/32" to 13 3/4"	-0.030 to +0.00 PDC	-0.0 to +1/32 Rock Bit
13 25/32" to 17 1/2"	-0.045 to +0.00 PDC	-0.0 to +1/16 Rock Bit

PDC bits are gauged by either a "go" gauge or a "no go" gauge.

A "no go"gauge is used to ensure a bit is not smaller than allowed and, as the name implies, it should not go or slip down the entire length of the bit. A "go gauge ensures a bit is not larger than allowed and should slip down the entire bit.

Rock Bit Size and API Standard Connection

3 1/2" to 4 1/2" drill bits - 2 3/8" API Reg. pin
4 5/8" to 5 1/2" drill bits - 2 7/8" API Reg. pin
5 5/8" to 7 3/8" drill bits - 3 1/2" API Reg. pin

Number of Nozzles

Nozzle Size	1	2	3	4	5	6	7	8
7	.0376	.0752	.1127	.1503	.1877	.2255	.2631	.3007
8	.0491	.0982	.1473	.1963	.2454	.2945	.3435	.3927
9	.0621	.1242	.1864	.2485	.3106	.3728	.4249	.4970
10	.0767	.1534	.2301	.3060	.3835	.4602	.5369	.6136
11	.0928	.1856	.2784	.3712	.4640	.5568	.6496	.7424
12	.1104	.2209	.3313	.4418	.5522	.6627	.7731	.8836
13	.1296	.2592	.3889	.5185	.6481	.7777	.9073	1.0370
14	.1503	.3007	.4510	.6013	.7517	.9020	1.0523	1.2026
15	.1726	.3451	.5177	.6903	.8629	1.0354	1.2080	1.3806
16	.1963	.3927	.5890	.7854	.9817	1.1781	1.3744	1.5708
18	.2485	.4970	.7455	.9940	1.2425	1.4910	1.7395	1.9880
20	.3068	.6136	.9204	1.2272	1.5340	1.8408	2.1476	2.4544
	.3712	.7424	1.1137	1.4849	1.8561	2.2273	2.5986	2.9698

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