Besides, according to the priority of the shortest distance, W grain will gather and come into being obturator when tungsten powder granularity is small. Due to the block and the unevenness of pores, the distance of electron is longer so that the conductivity decreases. On the contrary, the larger size of tungsten powder granularity distributes more uniformly, fewer pores left so that the distance of electron is straight and the conductivity is better.

In conclusion, firstly, the finer tungsten powder will cause much Cu gathering and have an effect on the uniformity of tungsten copper. Secondly, with tungsten powder granularity decreasing, the density and hardness of tungsten copper (W-Cu) will be remarkably improved. Finally, tungsten powder granularity has a huge effect on the porosity and micro-structure of tungsten copper.

More information about the effect of tungsten powder granularity on W-Cu electrode, click here:

http://news.chinatungsten.com/en/tungsten-information/79564-ti-10150 
http://news.chinatungsten.com/en/tungsten-information/79567-ti-10151 
http://news.chinatungsten.com/en/tungsten-information/79625-ti-10156

Tungsten Copper Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-copper.com/
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Take tungsten copper W-30Cu as an example, it has more Cu than W-20Cu so that it has better conductivity. With the increasing granularity of tungsten powder, the electric resistance is decreasing and the conductivity is enhancing. On the contrary, the smaller tungsten powder, the greater electric resistance. Except tungsten powder granularity, there are many factors affect the conductivity of tungsten copper electrode, such as chemical composition, porosity, impurities, micro-structure (grain size, grain boundary strength, the distribution of high thermal conductivity of copper phase and W-W connectivity) and so on.

Compared with other factors, tungsten copper granularity has an effect on the conductivity by the porosity and micro-structure of tungsten copper electrode. On the one hand, tungsten copper electrode still has some pores, which can not be neglected. On the other hand, the smaller size of tungsten powder will reduce the completeness of Cu grid, which causes the insufficiency of copper solution.













 

More information about the effect of tungsten powder granularity on W-Cu electrode, click here:

http://news.chinatungsten.com/en/tungsten-information/79564-ti-10150 
http://news.chinatungsten.com/en/tungsten-information/79567-ti-10151

Tungsten Copper Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-copper.com/
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Tungsten powder granularity has an effect on the density, the hardness and the electrical conductivity of tungsten copper electrode.

2. Effects on the Density and Hardness of Tungsten Copper Electrode

The experiment result shows that with the increasing powder granularity, the density of W70-Cu alloy is a trend of decreasing after infiltration. For instance, when tungsten powder granularity of W-30Cu is 2.65μm, the hardness is up to HB222. But the larger powder granularity, the lower hardness, and the lowest hardness is HB190 with 2.65 power granularity. The principle is that although tungsten has high density (19.3g/cm³), it belongs to fragile material. The finer power, the more active sintering, the more obviously shrinking of volume, which increases the content of W and improve the density and hardness of tungsten copper electrode.

More information about the effect of tungsten powder granularity on W-Cu electrode, click here:

http://news.chinatungsten.com/en/tungsten-information/79564-ti-10150

Tungsten Copper Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-copper.com/
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Compared with other electrode, tungsten copper electrode has many advantages, such as high quality, high efficiency, low wastage and high MRR (Material Removal Rate), etc. Therefore, tungsten copper electrode is suitable for rotating speed mold and finish of hard to processing material. At present, the most literatures are focused on the influence of processing, including W skeleton, density, hardness and uniformity on tungsten copper electrode, but this paper is inclined to discuss that tungsten powder granularity effects.

1. Effects on the Tissue of Tungsten Copper Electrode

The experiments result shows that the finer of tungsten powder, the more uniformly W powder distributes and the much more possibility of weakness and pores. On the contrary, the larger size of tungsten grain, the lower dispersion and the fewer pores left.












Tungsten Copper Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-copper.com/
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

In part 5 we know that straight reamers are used to enlarge a hole in small scale with a slight taper at one end and the length can be variable, and the reamed holes are typically used to any two locating parts where the locating accuracy is required within 0.02 mm. And here we explain hand reamer and machine reamer which are similar tungsten carbide reamers.

(To be continued. This article is divided into several parts and this is part 6, for part 5, please refer to http://news.chinatungsten.com/en/tungsten-information/79553-ti-10173)

Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

In part 4 we know that tungsten carbide reamers are used to enlarge or create a smooth surface finish to a hole already drilled since drilling followed by reaming generally produces hole geometry and finish that is as close to theoretical perfection as possible. And here we explain straight reamer.

Straight reamer

A tungsten carbide straight reamer is used to make only a minor enlargement to a hole. The entry end of the reamer will have a slight taper, the length of which will depend on its type. This produces a self centering action as it enters the raw hole. The larger proportion of the length will be of a constant diameter.

Reamed holes are used to create holes of precise circularity and size, for example with tolerances of -0/+0.02 mm(.0008") This will allow the force fitting of locating dowel pins, which need not be otherwise retained in the body holding them. Other holes, reamed slightly larger in other parts, will fit these pins accurately, but not so tightly as to make disassembly difficult. This type of alignment is common in the joining of split crankcase halves such as are used in motorcycle motors and boxer type engines. After joining the halves, the assembled case may then be line bored (using what is in effect a large diameter reamer), and then disassembled for placement of bearings and other parts. The use of reamed dowel holes is typical in any machine design, where any two locating parts have to be located and mated accurately to one another - typically as indicated above, to within 0.02 mm or less than .001".

Another use of reamed holes is to receive a specialized bolt that has an unthreaded shoulder - also called a shoulder bolt. This type of bolt is commonly used to replace hot peened rivets during the seismic retrofit of structures.

 (To be continued. This article is divided into several parts and this is part 5, for part 4 please refer to http://news.chinatungsten.com/en/tungsten-information/79531-ti-10169;for part 6 please refer to http://news.chinatungsten.com/en/tungsten-information/79554-ti-10174)

Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Tungsten powder re-sintering is can not be neglected when arcing. After Cu evaporating by pulsed arc, some W grains will be exposed in medium. This tungsten grains re-sintering and spheroidizing or transferring to the surface by surface effect at high temperature, which make the cracks expand inside skeleton inevitably. In general, tungsten copper will volatile and compound in high temperature arc, which the cracks is accelerating the erosion.

Those tiny pores left by Cu evaporating will become the source of the next cracks and the re-sintering accelerate cracks expanding. In addition, the oxides combine electrode contact with arc-blast medium and carbide is brittle so that they will be broken and spalling under mechanical impact until the electrode failed.

More infomation about tungsten copper electrode erosion mechanism, click here:

http://news.chinatungsten.com/en/tungsten-information/79477-ti-10142 
http://news.chinatungsten.com/en/tungsten-information/79543-ti-10144

Tungsten Copper Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-copper.com/
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

There are four kinds of tungsten copper processing, liquid phase sintering – repressing – re-sintering, solid phase sintering – repressing – re-sintering, infiltration – machining and pre-sintering tungsten (W) skeleton – melt dipping – machining. The last method is more popular currently, which make material has good mechanical properties. Because W grains is not longer individual in this process, which becomes firm tungsten skeleton after high temperature sintering. Therefore, this stable structure can endure the impact of machinery. Besides, the ability of resistance of cracks and expanding is much better in this way.

However, it is unavoidable that tungsten copper electrode also has weakness in structure. One is tungsten maybe has cracks, but it is unlikely. The other is more probable, which has pore in Cu when tungsten skeleton forming and condensation. Under high temperature and 10-times pressure, tungsten will emerge compressive stress, which will tear the cracks already exist. In addition, with the increasing of arc frequency, the stress of matrix enduring will enhance so that the cracks will expand and connected with cracks of surface outside.

More infomation about tungsten copper electrode erosion mechanism, click here:

http://news.chinatungsten.com/en/tungsten-information/79477-ti-10142

Tungsten Copper Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-copper.com/
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

In part 3 we know that tungsten carbide reamers are used to enlarge or create a smooth surface finish to a hole already drilled since drilling followed by reaming generally produces hole geometry and finish that is as close to theoretical perfection as possible. And here we will show you some reamer types and first comes adjustable hand reamer.

Adjustable hand reamer

An adjustable hand reamer can cover a small range of sizes. They are generally referenced by a letter which equates to a size range. The disposable blades slide along a tapered groove. The act of tightening and loosening the restraining nuts at each end varies the size that may be cut. The absence of any spiral in the flutes restricts them to light usage (minimal material removal per setting) as they have a tendency to chatter. They are also restricted to usage in unbroken holes. If a hole has an axial split along it, such as a split bush or a clamping hole, each straight tooth will in turn drop into the gap causing the other teeth to retract from their cutting position. This also gives rise to chatter marks and defeats the purpose of using the reamer to size a hole.

(To be continued. This article is divided into several parts and this is part 4, for part 3 please refer to http://news.chinatungsten.com/en/tungsten-information/79530-ti-10168)

Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

In part 2 we know that a tungsten carbide reamer usually consists of cutting edges with a slight undercut below each, a cylindrical body partly as the shank, and mostly preferred clockwise spiral, and the shanks have also different types for respective purpose.And here we reveal the different effect of reaming and drilling in making hole size.