Tungsten Information

Tungsten Carbide Cutting Tool Coating Technology Introduction

Details: Category: Tungsten Information; Published on Wednesday, 29 October 2014 18:16; Hits: 329

During machining, the cutting tool property has decisive impact on the cutting efficiency, precision, and surface quality. Two essential dictators of tungsten carbide tool property are hardness and intensity, which, however, are always contradictory to each other. Materials with high hardness are often at the expense of their intensity, while increased intensity always results in decreased hardness. In order to settle this kind of contradiction and improve cutting tool property, one effective solution is by taking coating technology. Coatings are materials put on the surface of tungsten carbide cutting tools through coating technology and they are of high hardness and high abrasion resistance. The tungsten carbide cutting tool coating, like a chemical and thermal barrier, can reduce crater wear of the tools and thus significantly improve machining efficiency and precision, extend tool life and reduce cost.

Tungsten carbide cutting tool coatings help improve tool's abrasion resistance but at the same time maintain tool intensity and reduce friction between tools and work pieces, so the tool life is thus extended. In addition, because the coefficient of heat conduction of coatings is much lower than that of tools and materials being processed, it can contribute to reducing heat caused by friction. It forms a thermal barrier and change the ways of heat lost, and thus reducing the thermal and force impact from the friction and effectively improve the tool property.

Main functions of tungsten carbide cutting tool coatings are as follows:

I. To form a isolated layer between tools and materials being processed.

II. To reduce thermal impact through inhibiting heat conduction from cutting area to blades.

III. To effectively reduce friction and heat caused by friction.

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Counterfeit Gold-Plated Tungsten Bar-1

Details: Category: Tungsten Information; Published on Wednesday, 29 October 2014 08:50; Hits: 314

The following article is talking about the story of counterfeit gold-plated tungsten bar, written by unknow person.

In his March 2 column, he told about the news story where an employee at the world’s largest private refinery had discovered a gold-plated 500 gram gold bar received from an unidentified bank. His column included an internet link where readers could themselves view the German television station report.

As is common for his columns, this particular one was picked up by several other websites. This particular column inspired a relatively harsh response from Robert Bradshaw. In an essay Robert wrote that was posted yesterday at http://www.marketoracle.co.uk/Article17820.html, Robert took me to task for repeating the story that China’s central bank last year had received at least four counterfeit gold-plated 400 ounce tungsten bars. Robert seemed concerned that he was perpetuating a myth about a massive number of counterfeit gold-plated 400 ounce tungsten bars that were supposedly manufactured during the 1990′s at the behest of the US government. Allegedly, about half of them were shipped to Fort Knox.

Until today’s column, he have never referred to the rumor of large numbers of counterfeit gold bars supposedly stored at Fort Knox. he is well aware of the details of this rumor but, like Bradshaw, the possibility of the whole story being true is pretty far-fetched. He would need to dig up more hard confirmation of its veracity before discussing it. If such verification were available, I’m sure that this story would be headline news in the mainstream financial press.

The precious metals markets are not transparent. To get the best idea of what is really happening means listening to sources that often cannot be independently double-checked. In his writings, he tries to be careful to listen only to those sources that have developed a track record of reliability. In this manner, he can often discern the truth long before it is publicly disclosed.

gold-plated-tungsten-bar

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Tungsten Carbide Keyway Broach Introduction

Details: Category: Tungsten Information; Published on Tuesday, 28 October 2014 18:01; Hits: 310

Tungsten carbide keyway broach, as its name implies, is a kind of cutter using for splining.

Types of keyway:

Woodruff keyway has the same keyway size and limit deviation with flat key keyway. Therefore, the tungsten carbide keyway broach can be used in both of them.

Taper key keyway is 0.5~1.3mm shallower than flat key keyway. The groove depth of guide sleeve should be increased if the standard keyway broach is used in splining taper key keyway at one time. But if it is doing for many times (b≥14mm), then the gasket thickness should be calculated again.

Thin flat key keyway is 0.9~3.5mm shallower than flat key keyway, and the groove depth of guide sleeve during splining at one time should be chosen based on the guide sleeve size a. But if it is doing for many times, proper gasket thickness should be selected.

The characteristics of tungsten carbide keyway broach:

I. It has large broaching allowance and teeth number, therefore if the groove is quite deep, then the splining should be done by two times.

II. The broaching surface roughness is relatively high (Ra 2.5~1.25 μm or even higher). When low surface roughness is required, keyway broach with lateral wiper should be adopted.

III. When the guide sleeve is not long enough, the broach may bend upwards and even break during operation.

IV. Edge-line of teeth with enough width should be guaranteed in order to increase broaching stability.

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Tungsten Carbide Gear Shaving Cutter Introduction

Details: Category: Tungsten Information; Published on Tuesday, 28 October 2014 17:59; Hits: 367

Tungsten carbide gear shaving cutter is a kind of finish machining cutter used in the involute cylindrical gear machining. When doing gear shaving, the cutting edge of gear shaving cutters shaves a thin layer of metal along the workpiece surface, which can effectively improve the precision and gear surface quality of the gears being shaved. It has high machining efficiency and long tool life and thus is the most widely used tool in the mass production of cylindrical gears with medium precision.

In the teeth surface of tungsten carbide gear shaving cutters, there are many narrow grooves. The cutter cuts beard-shaped thin chip from the gear surface during machining, which is the origin of its name. Generally, it is applied to do finish machining towards gear teeth after gear hobbing and shaping.

Tungsten carbide gear shaving cutters, used to machine inner and outer cylindrical gears with straight teeth and helical teeth, can achieve a high productivity and good surface finish of workpieces. There are also turbine gear shaving cutters for machining sophisticated turbines, whose basic worm types and parameters should be the same as that of the working worms matching with the turbine. Just like the gear shaving cutter, it also has many narrow grooves on the helicoid to form the cutting edge and hold chip. Turbine gear shaving cutters are difficult to manufacture, and thus they are used only when machining of turbines with high precision requirements is needed.

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Tungsten Carbide Slotting Cutter Introduction

Details: Category: Tungsten Information; Published on Tuesday, 28 October 2014 17:58; Hits: 324

Tungsten carbide slotting cutter, a type of gear machining tool, is gear-shaped or rack-shaped. It can be used in machining inner gearing and outer gearing spur gears and helical gears through generating method.

The precision of standard tungsten carbide slotting cutters can be divided into class AA, class A and class B according to the international standard. Normally, they are used to machine gears with precision of class 6, class 7 and class 8 respectively. Gears that need shaving or grinding again for the needs of machining should adopt pre-shaving or pre-grinding slotting cutters respectively to ensure there is a certain amount of machining allowance on the gear surface. Therefore, the teeth shape of these slotting cutters needs special design.

Tungsten carbide slotting cutters can be classified into four types according to its shape: disk, bowl-shaped, cylindrical, taper-shank. Disk slotting cutters are mainly used in machining inner gearing and outer gearing spur gears, helical gears and herringbone gears. Bowl-shaped gears are generally used to machine inner gearing spur gears with circular bead, which are different from disk slotting cutter in that when they work, nuts can be placed inside the slotting cutter and thus will not hamper machining. Cylindrical slotting cutters are used in machining inner gears and outer gears with small modules. Taper-shank are mainly used in machining inner gearing spur gears and helical gears.

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Tungsten Gold Plated Bar Story -- Aliens hunting for gold on Earth? 2

Details: Category: Tungsten Information; Published on Tuesday, 28 October 2014 08:43; Hits: 291

“We are at the heart of this global control because of our mineral resources,” he said.

On the first day of the conference, all the speakers agreed that like humans who had the potential to be both good and bad, so too was the population of galactical beings.

Extra-terrestrials were also not dissimilar to politicians, who pushed their own agenda for material gain.

“They came to Earth looking for gold. We are all still obsessed with gold,” he said.

The research, according to Tellinger, showed that the extra-terrestrial “Annunaki” came to Earth around 300,000 years ago to look for gold, and that they were also responsible for cloning their own genetic structures and creating mankind.

tungsten-gold-plated-bar

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Tungsten Carbide Reamer Reaming

Details: Category: Tungsten Information; Published on Monday, 27 October 2014 18:52; Hits: 309

Tungsten carbide reamer is the most widely used tungsten carbide cutting tools in hole machining, which mainly consists of cutter diameter, shank diameter, cutting cone length, cutting cone angle, cutting length, total length, and so on.

Tungsten carbide reamer reaming refers to the semi-finish and finish machining towards the existing holes to achieve precise hole size, good surface roughness, etc. During reaming by tungsten carbide reamer, in order to get hole precision needed, the reamer diameter should correctly selected, and thus the expansion margin decided by workpiece material and machining condition should be taken into consideration. In order to obtain good finish machining surface, in addition to the adopting of high precision reamer, the correct cutting condition should also be provided.

Tungsten carbide reamer precision mainly depends on its diameter and radial run-out. As for cutting condition, it is better to adopt tungsten carbide blade low-speed cutting, but at the same time the upper limit value should be taken in the consideration of machining efficiency.

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Tungsten Carbide Gear Hob’s Basic Worm Introduction

Details: Category: Tungsten Information; Published on Monday, 27 October 2014 18:51; Hits: 302

Tungsten carbide gear hob’s bilateral blades is the intersection between the rake face and the lateral shovel surface, and it is located on the spiral surface of the worm, which is also called the basic worm of hobs. The basic worms of tungsten carbide gear hobs include three types as follows:

I. Involute worm

The tungsten carbide gear hob made by using involute worm has no teeth shape error and the gear being cut has higher precision. However, the hob manufacturing is more difficult with it.

II. Archimedes worm

It is more simple and convenient to manufacture a tungsten carbide gear hob with a Archimedes worm, as well as to test the hob teeth shape. However, there exists small teeth shape error. Fortunately, this kind of error is within the permitted range. Therefore, most of the basic worms of finish tungsten carbide hob in production are Archimedes worms instead of involute worms.

III. Straight sided normal worm

There is larger teeth shape error in tungsten carbide gear hob with straight sided normal worms instead of involute worms. Therefore, straight sided normal worms are often used in multithread hobs and roughing hobs.

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Tungsten Carbide Spline Hob Spline Joint

Details: Category: Tungsten Information; Published on Monday, 27 October 2014 18:49; Hits: 314

Tungsten carbide spline hob spline joint consists of internal spline and external spline, which are both multitooth parts. The spline on the internal cylinder surface is called internal spline, while that on the external cylinder surface is called external spline.

Due to the differences in structure and manufacturing technique, tungsten carbide spline hob spline joint, compared to flat key joint, has characteristics in intensity, technique, and usage as follows:

I. Its joint force is more uniform due to its larger number of teeth and grooves produced directly and uniformly on the shaft and hub bore.

II. It has good guidance quality, which is very important to movable connection.

III. It has larger number of teeth and larger total contact area, and thus can withstand larger load.

IV. It has good coaxiality between shaft parts and the shaft, which is essential to high-speed and sophisticated machines.

V. It has shallow grooves, so the stress concentration is smaller in the teeth root and the intensity of shaft and hub is less reduced.

VI. The machining precision and joint quality can be improved through grinding.

VII. Its manufacturing technique is more complicated and sometimes special equipment will be needed, so that the cost is relatively higher.

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Tungsten Carbide End Mill Vibration

Details: Category: Tungsten Information; Published on Monday, 27 October 2014 18:47; Hits: 318

Between the tungsten carbide end mill and the tool-holder, there exists small gap, which may result in vibration during machining. This phenomenon may cause uneven engagement of the circular blade of end mills, and increasing of cutting expansion to a value that is higher than the one set originally, and therefore the machining precision and service life of tungsten carbide end mills will be affected. However, when the groove width is too small, tool vibration can be achieved on purpose to increase cutting expansion, through which the groove width needed can be obtained. However, maximum amplitude should be restricted under 0.02mm, or it will not achieve stable cutting performance. Of course, during normal machining, it is better to have smaller end mill vibration.

When tungsten carbide end mill vibration occurs, operators should consider lowering the cutting speed and feeding speed. If there is still great vibration after both of them being lowered, then the reducing of cutting expansion should be considered.

If there is sympathetic vibration in machining system, it may be because that the cutting speed is too high, or the feeding speed is too low, or the cutter system lacks rigidity, or the clamping force is inefficient, etc. Therefore, when this happens, the countermeasures like cutting parameters adjustment, increasing cutter system rigidity and increasing feeding speed should be adopted.