Tungsten Information

The Differences Between Real and Fake Gold 2

Published on 22 October 2014

Sound

Another classic test is the "ring test". Drop the coin on a hard countertop to hear it's "ring". Gold and silver have very distinctive tones and qualities of sound, which are fairly easy to distinguish. The saying "it rings true" and the song Bing Crosby sang "Silver Bells" testify to this quality. Metals like lead have a dull thud. Even the sound of a tungsten slugged gold coin will sound different. It's best to have a known genuine coin around for comparison (and be sure to note the issue, date and mint mark to avoid confusion with the coin being tested).

Electronic Testing

Electronic testing runs a current through the coin to test the resistance and determine the purity of the metal. High quality testers like this can work and they are mainly used for buying jewelry, not coins.

Destructive Testing

The easiest destructive test is the scratch test, which does what the name suggests, scratches the surface of the coin to see if the color is the same underneath. This identifies those fakes that are stamped coins plated with gold. Gold plated coins also have a tendency for the details of the coin to fill in with the plating. Look carefully at the detail of coin with a 10x magnifier and compare it with a genuine coin, if you have one.

The touchstone is the other classic way to test gold. The edge of the coin is run along a stone so a very small amount of the gold leaves a "trail" on the stone. Acid of various strengths is dripped on this trail to determine the purity of the gold.

gold

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Tungsten Carbide Spiral Flute Tap Introduction

Category: Tungsten Information

Published on 21 October 2014

Tungsten carbide spiral flute tap, as a type of thread machning tool, is named according to its spiral-shaped flute. It can be classified into two categories according to different directions of turning: left-handed spiral flute tap and right-handed spiral flute tap. The left-handed spiral flute tap removes its chip downwards during tapping, thus is more suitable for through holes; the right-handed spiral flute tap removes its chip upwards during tapping, thus is more suitable for blind holes.

The characteristics of tungsten carbide spiral flute taps are as follows:

I. Ability to perform tapping down to the deepest part of blind holes.

II. Ability to go deep into the bottom holes more easily.

III. Good machinability.

Tungsten carbide spiral flute taps adopt different helical angles according to different working conditions. The most common ones adopted are right-handed 15°and 42°. Generally speaking, the larger the angle is, the better the chip removing is performed.

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Tungsten Carbide Extrusion Tap Introduction

Category: Tungsten Information

Published on 21 October 2014

The tungsten carbide extrusion tap is a type of threaded cutter used in inner thread machining according to the principle of metal plastic deformation, and its inner thread machining is chipless machining. It is suitable for the tapping towards copper alloy and aluminium alloy of low intensity and relatively high plasticity and also stainless steel and low-carbon steel with low hardness and high plasticity.

The threads processed by tungsten carbide extrusion taps is of good surface roughness and their metal fibers do not break and there is a chilling layer in their surface which can increase threads’ intensity and abrasion resistance. It has fundamentally solved the chip removal difficulty in tapping. Due to its chipless characteristic, it makes the thread fitting much easier, thus is widely applied in many industry areas such as electronics and plastics.

The tungsten carbide extrusion tap is more suitable for ferrous metal machining. It makes metals be out of shape through squeezing them, and thus produces inner threads. The inner threads formed by squeezing has continuous metal fibers and high tensile and shear strength and also relatively good surface roughness. However, there are higher requirements towards the bottom hole of extrusion tap: If the bottom hole is too too large, then base metals will be fewer and the minor diameter of inner threads will be oversize; if the bottom hole is too small, then the metal being closed and squeezed will have nowhere to go, causing the breaking off of the tap.

Tungsten Carbide Extrusion Tap

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Tungsten Carbide Straight Flute Tap Introduction

Category: Tungsten Information

Published on 21 October 2014

The tungsten carbide straight flute tap is typically used in the thread machining of engine lathes, drilling machines and tapping machines, with a relatively low cutting speed.It performs well in the machining of high hardness materials and materials easier to cause tool damage, and powdery materials cutting.

The tungsten carbide straight flute tap has widest universality. It can process both non-ferrous metal and ferrous metal. However, this characteristic is also companied by the downside of being able to doing many things, but being not particularly good at something. It may possess two, four, or six teeth in the cutting part. Short taps are used in blind holes, while long taps in through holes. As long as the bottom hole is deep enough, longer tap should be applied as far as possible, because if there are more teeth to share cutting load, there will be longer tool life.

Tungsten Carbide Straight Flute Tap

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Tungsten Carbide Spiral Pointed Tap Introduction

Category: Tungsten Information

Published on 21 October 2014

Tungsten carbide spiral pointed tap is also known as EX-POT, mainly used in borehole and deep thread machining, and is of high intensity and cutting speed, long service life, stable dimension and clear threads (especially fine pitch threads). Generally, it has the same straight groove as the straight flute tap, and is a kind of its deformation. In the front part of tungsten carbide spiral pointed taps, there is a helical groove specially designed which can squeeze chip out of the hole with the help of rotation and at the same time avoid tap demage caused by cutting conjection. That is why tungsten carbide spiral pointed taps have higher cutting speed than straight flute taps in high precision threads processing.

Tungsten carbide spiral tap has larger core and higher intensity and thus can withstand higher cutting force. It performs well in non-ferrous metal, stainless steel and ferrous metal processing. In the borehole processing, spiral pointed tap should be applied with priority.

Tungsten Carbide Spiral Pointed Tap

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Tungsten Carbide Tap Advantages

Category: Tungsten Information

Published on 21 October 2014

Tungsten carbide cutting tools have gradually replaced high-speed steel tools in turning machining, and so does the tungsten carbide tap. It has been used more and more often in threaded hole machining. Compared with the high-speed steel, the tungsten carbide is of higher hardness and but also higher brittleness, so when using tungsten carbide taps in tapping process, there exits a chip disposal problem. Despite all that, the tungsten carbide tap is still of high efficiency and long service life when used in processing cast iron and aluminium alloy materials. In car industry, the reducing of tap changing times is very competitive and crucial, which can be accomplished by using the tungsten carbide tap due to its long tool life. Using coated tungsten carbide taps with a samll helical angle to perform tapping machining on alumimium workpiece with a silicon content of about 1.5 % can obtain excellent machining effect. What is more, a tap made of submicron-grain tungsten carbide possesses higher toughness while maintains the same hardness, thus can work well in quenched steel, plastics and nickel base alloy cutting.

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The Differences Between Real and Fake Gold 1

Category: Tungsten Information

Published on 21 October 2014

It's All About the Physics

All the ways to determine the authenticity of a coin or bar of precious metal are based on differences between physical properties of the valuable metal and the lesser metals used to swindle the buyer. Each metal is an element, meaning it can't be further broken down into another element (without very heavy equipment like a particle accelerator, which is not practical). An element has its own unique density, conductivity, reaction to acids, melting point, conductivity of sound through the metal, etc. A fake gold coin will necessarily have an exterior of gold to help fool the buyer, regardless of the contents of the interior and whether the coin is created from an alloy (mix of metals) or a slug of base metal with a cladding or plating of gold on the outside.

Visual Inspection

The easiest place to start is the visual appearance of each metal. Does the coin look gold in color? Gold has a dull golden shine. Once you've spent time handling gold, this is the first give away. Keep in mind that some coins are 99.99 percent pure gold. Others are designed for circulation and have some copper and silver alloyed with the gold. These coins have a reddish tint. Jewelers use these properties to make many different shades of gold for jewelry.

The color difference is exaggerated in these photos, but it gives an idea of the difference between 99.99% pure gold coins (left) and 90% pure gold coins with an alloy of copper and silver that make the coin harder and able to circulate (right).

Density

The physical characteristics of metals are immutable and this is the counterfeiter's first decision; which metal(s) to use for the fake. Each metal has characteristics like density, malleability, the speed of sound in the metal and so on.

gold

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Choosing Brazed Tungsten Carbide Blade and Groove Shape

Category: Tungsten Information

Published on 20 October 2014

There are five main types of brazed tungsten carbide blade in China currently:

A-type blade is used in 90° bullnose tools, facing tools, etc.

B-type blade is used in straight bullnose tools, facing tools, hole boring cutters, etc.

C-type blade is used in straight and bend bullnose hole boring cutters, glaives, etc.

D-type blade is used in cut-off tools, grooving tools, etc.

E-type blade is used in threading turning tools.

Brazed tungsten carbide blades will differ according to different blade groove shapes:

Open slot: It is simple for manufacture, smaller in welding area, suitable for C-type blade and sometimes D-type blade as well.

Semi-closed slot: It is relatively difficult for manufacture, but firm in blade welded. It is suitable for E-type blade.

Closed slot: It is difficult for manufacture, but firm in blade welded. It can increase welding area and is often used in threading cutters and suitable for E-type blade.

Undercut groove: It is used in cut-off tools and grooving tools of relatively smaller base area, thus increasing welding area and bond strength. It is complicated for manufacture and suitable for D-type blade.

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Tungsten Carbide Keyway Milling Cutter and End Mill Differences

Category: Tungsten Information

Published on 20 October 2014

Tungsten carbide keyway milling cutter is a type of milling cutter and can be divided into two main types: straight shank keyway milling cutter and tapper shank keyway milling cutter.

The differences between tungsten carbide keyway milling cutter and end mill are as follows:

I. The tungsten carbide keyway milling cutter normally has two cutting teeth while end mill has over three.

II. The tungsten carbide keyway milling cutter is mainly used in machining key grooves and grooves, and is very useful in doing this. For example, end mill of 6mm, compared with tungsten carbide keyway milling cutter of 6mm, is more susceptible to being broken.

III. The cutting output of tungsten carbide keyway milling cutter is larger than that of end mill.

IV. The tungsten carbide keyway milling cutter cannot process flat while end mill can.

Tungsten Carbide Keyway Milling Cutter and End Mill

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Tungsten Carbide Indexable Turning Tool Advantages

Category: Tungsten Information

Published on 20 October 2014

Tungsten carbide indexable turning tool is made by clamping the indexable tungsten carbide blade on the shank through mechanical means. There are over three cutting edges in the blade for indexable use. When there is one of them being worn, the blade can be turned to anther cutting edge and thus continues to be in use. After all cutting edges are worn, they can be replaced by other blades of the same kind.

Tungsten carbide indexable turning tool, compared with brazed turning tool, is of advantages as follows:

I. Long service life due to the avoiding of high temperature caused by welding and sharpening.

II. High productivity due to the reducing of blade changing times.

III. Lower cost in cutting tools due to long service life of shanks and the simplification of cutting tool management.

Tungsten carbide indexable turning tool is all in all a type of advanced cutting tool which can greatly reduce sharpening cost of tools and improve cutting efficiency.