March 31, 2017

How to drive up cutting level for carbide insert

As more and more advanced industrial automation control equipment and the computer go into the cemented carbide manufacturing enterprises, the production of cemented carbide control technology is more and more stable, controllable and reliable mechanical properties. The result is produced by the blade becomes more and more consistent, the processing result of predictable and not because of different blade batch processing different results; new technology also makes the size tolerance of sintering blade band is narrower, higher precision,the performance for carbide insert has been greatly improved.

 

However, after the ordinary blade wheel or diamond wheel grinding after the micro gap existed in different degree, in the cutting process of micro gap expand easily, quicken blade wear and damage. The coated carbide blade must be passivated in front of the coating to ensure the coating durability and service life.

 

Cemented carbide insert passivation geometry has a great influence on the service life of the blade, there are mainly two kinds of edge passivation shape:a circular arc edge, form a symmetrical arc in the corner of the blade, blade passivation for more than 80% of the use, applicable to coarse and fine processing; the other is the waterfall edge in the mouth, the corner edge of the top surface and the side forming ratio of asymmetrical arc 2:1, suitable for the impact of bad processing.

Method of carbide cutting edge passivation is also in constant development, the earliest use of manual and mechanical passivation, passivation passivation to improve efficiency and quality, with the continuous development of technology, there are special CNC edge passivation machine.

The cemented carbide blade passivation technology is one of the effective measures to improve the service life of the blade. It is feasible and effective in the two aspects of economy and technology

It must be noted that,circulating for cutting temperature in the cutting process,the maximum and minimum temperature remained unchanged, and has no effect on the gasket type. Therefore, the compression of the thermal stress can be controlled by the volume of the temperature for carbide insert in the cutting process in cutting. Before the start of cemented carbide preheating can reduce high initial stress, which helps to improve the performance of the tool.

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March 30, 2017

Study on coating method of carbide cutting tools

 

It is an important technology in the production and processing of the coatedcarbide cutting tools that it has important influence on the cutting performance, service life, surface quality, machining efficiency and machining precision. At present, the main process is to retreat back coating of TiN coated single component coating and (Ti, Al, Zr, Cr) N multi-component composite coating back coating, with the continuous development of coating technology, appearance and application of diamond coating,diamond coatings, nano coating and other new coating technology. Back coating technology needs continuous development to meet the new demand of industrial production. In this paper, the characteristics and research progress of the coating process are briefly introduced from two aspects of physical and chemical coating.

 

Back coating process: coating materials include nitrides, carbides, nitrides, oxides, boride, silicide, diamond and composite coating of eight categories of dozens of varieties. The most commonly used is single layer TiN coating, TiCN coating, TiAlN coating, CrN coating, DLC (DLC) coating and diamond coating, etc.. For different coating materials and structures, the coating process is not the same.

 

However, in practical application, there are two main types of physical and chemical coating.

Physical back coating: physical back coating refers to the use of mechanical methods to remove the film from the body, the physical back of the main methods of sand blasting, machining grinding, etc.. The utility model is suitable for the substrate which is not suitable to be immersed in the chemical solution, and has the advantages of low requirement for surface finish, low requirement on the dimensional precision, simple surface shape and easy grinding and polishing.

Chemical back coating: chemical coating refers to the dissolution of the carbide tool coating in the acidic or alkaline chemical solution, the solution of the coating and the alloy coating on the surface of thecarbidecutting tool. The solution needs to have contact and effect on compound membrane peeling off, the coating from the body relax time after the complex was separated from the matrix tool or workpiece, not attached in the tool body mixture of residue, recovery tool without coating before the original matrix. This method is commonly used in the coating of the coating method.

 

There are two kinds of chemical coating technology, chemical back coating and electrolytic coating. These two kinds of coating processes are based on the principle of chemical reaction.

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March 29, 2017

China cemented carbide inserts market is divided into five major areas

Tool companies generally focus on the maintenance of the brand, they are at the beginning of the establishment, not demanding the number of sales profits, but the focus of enterprise development, the brand building. They promote the quality of products to customers, how to improve the production efficiency of products, as well as to reduce the cost of production for the customer, the beginning of the development of enterprises laid a good foundation.

The following are the main market segments of Chinese brand cemented carbide cutting round inserts.

Automotive Industry: automotive industry processing characteristics of a large quantity, assembly line production, two processing conditions are relatively fixed.In order to optimize the production and improve the quality and efficiency of constant force machinery, the automotive industry on the cutting tool processing efficiency and service life put forward very harsh requirements. At the same time, as a result of the use of assembly line operations, in order to avoid the replacement of the blade leading to the entire production line downtime, resulting in huge economic losses, it is usually the use of a mandatory unified tool change.The stability of the quality of cemented carbide blade also raised a unique high demand.

Aerospace Industry: Aerospace processing characteristics of the industry is one of the high processing accuracy requirements,these two is difficult to process materials. The processing of the parts of the material is mostly toughness and strength are very high temperature alloy and nickel titanium alloy (such as INCONEL718, etc.), make carbide circular blade is a great advantage.

Machine manufacturing enterprises of large turbines, steam turbines, diesel generators and these enterprises to the processing of parts are bulky, expensive, in the process, ensure the precision machining parts and less waste is crucial,so in these industries are often made of cemented carbide insert.

The use of CNC machine tools more enterprises as the saying goes, "a good horse with a good saddle, in order to improve the processing efficiency and product quality, give full play to the efficiency in the use of CNC machine tools, often made of hard alloy circular blade is more likely to achieve the desired effect.

In these enterprises, foreign enterprises tend to pay more attention to production efficiency and quality assurance. As many of the equipment of foreign enterprises is the introduction of foreign machine tools and equipment, the use of imported carbide insertis also a matter of course. In addition, there are many other industries, such as mold industry, military enterprises, such as the use of cemented carbide round blades are also very common.

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March 28, 2017

The difference in prices between tungsten carbide powder market is reduced

This week because the tungsten tungsten enterprises sell limited production, the overall stabilization, many mines have raised the price, but acceptance is not too high, the scarcity of transactions, are the basic orders after the procurement of raw materials will have to buy some, so you want to continue to rebound to the downstream demand. The APT is now less than eighty thousand of the transaction, basically in the more than 8.2, more than 83 thousand yuan / ton, but also because the price of tungsten concentrate had to adjust the price, while smelting manufacturers also have a willingness to price. Thetungsten carbide powdermarket because of the limited downstream order not much demand, but still want the price to upgrade, so now the price temporarily stabilized, or to maintain the original level, did not increase to 140 yuan / kg. But it is no longer difficult to continue to decline in the past few weeks the price can remain stable, has been compared to the previous decline in the situation began to improve, as the follow-up depends on the specific supply and demand.

 

On Monday, the dollar index rose 0.3% to $99.82, less than a mere $12 from its March high of just over $1%. Now it seems that the Fed's interest rate hike in December FOMC meeting, the market seems to have reached a consensus. However, the pace of follow-up will be much faster, the market is still controversial. Fed officials have repeatedly said that the magnitude and pace of interest rate will depend on the data. The United States chief economist Jan Hatzius and his team Goldman announced at the weekend report, the United States will be described as experiencing "turtle speed recovery" (tortoise recovery), but they expect the Fed will raise interest rates next year a total of 100 basis points, or "every quarter of an interest rate increase".

 

The continued strengthening of the dollar, exacerbated by the oversupply of metal market concerns, coupled with the impact of weak demand in China, metal prices fell to multi-year lows. LME copper fell 2% to $4462 a tonne, close to its lowest level in more than six years. Aluminum prices also fell 1.3% to $1447 per ton. Nickel prices fell 4.9% to $8340 per ton, after hitting a record low for the past 12 years. COMEX traded gold fell $8 to $1067 an ounce, hovering at its lowest level since February 2010.

 

This year is the tungsten industry preferential policy, launched the cancellation of export duties, clearing fees fund, reduce electricity policy, it can be said now for national enterprises preferential policies is gradually increased, so although the tungsten industry in the winter period, but with the national policy support, the economic environment of the industry to pick up, the future must be bright.

 

For more details visit our website at www.wococarbide.com

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March 24, 2017

What plays a key role on cemented carbide insert coating

There are few other materials, such as cemented carbides, that have had such a significant impact on the global economy and industrial civilization.This hard and wear-resistant materials are widely used in the manufacture of a variety of different products, such as pen nib, rod guide ring, wear parts, dental drill,and its most important use is the manufacture of cutting tool. In fact, coated carbide tools are the most widely used cutting tools in the market. Such tools significantly improve the productivity of the metal cutting process, thereby greatly reducing the cost of the production of many daily necessities.

However, at present, a variety of advanced coating technology and coating materials emerge in endlessly, it is not always easy to select the best coated blade grade for a specific processing task. Select the best blade from thematerial, because the type of material to be processed to determine whether the need for hard alloy coating plays a key role.

Coated cemented carbide inserts are essential for the machining of ferrous materials such as iron, cast iron, steel or stainless steel. In most cases, the use of coated inserts is also the best choice for cutting high temperature alloys, especially when they are capable of cutting to the middle / high level. Processing of titanium alloys can also benefit from the coating, especially in the absence of high pressure coolant.

Uncoated cemented carbide inserts suitable for processing non-ferrous metals (e.g. aluminium). In fact, due to the aluminum is relatively soft, and easy to produce a built-up edge, it is best to use extremely sharp uncoated cutting edge processing. Other materials that do not require the use of coated inserts include brass, bronze, a variety of composite materials and wood. However, the use of appropriate diamond coating can greatly improve the machining efficiency and tool life.

Choosing the appropriate coating type is the most difficult part of the coating blade. After all, the various processing tasks vary widely, so careful consideration should be given to the coating process and coating materials. In addition, there is no simple answer to the question of how to choose the right blade coating. Understanding some of the basic knowledge of coating processes and coating materials will help to eliminate some of the uncertainties in the selection of cemented carbide inserts.

Chemical vapor deposition (CVD) and physical vapor deposition (PVD) are two main cemented carbide blade coating processes, each with its own characteristics and advantages. CVD coating is thick (usually 10 - 20 m), and has good wear resistance, especially suitable for cutting steel and cast iron, and widely used in turning.

However, unfortunately, this thick coating may have an adverse effect on the toughness of the cutting edge. The PVD coating is thin (typically 2 - 3 m), and has a better toughness and smoother surface than the CVD coating. Therefore, this kind of coating is very suitable for the processing of high temperature alloy, titanium alloy and stainless steel, which are difficult to be machined.

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March 23, 2017

How to select the excellent quality of tungsten carbide rod

Tungsten carbide rod iscalled tungsten rod, tungsten steel rod or simply carbide rods. Cemented carbide is a kind of composite material which is made of refractory metal compound (hard phase) and bonded metal. Hard alloy is also known as tungsten steel, is relatively different local name. So what are the attention to the selection of tungstencarbide rod?

Tensile strength, elongation,chemical composition of the standard or commitment to the indicators.

The appearance of the cemented carbide rod should be rounded, without any defects such as flying edge, skin, hemp pit, abrasion and so on. If the hard alloy rod product suppliers to provide the appearance of rules of the circle, the surface is very smooth, only that the rod is type two molding extrusion products, many cable companies are confused by the appearance of smooth round pole, that the quality of the pole must be good.

Continuous casting and rolling production oftungsten carbiderodcommon specifications for the 9.5MM diameter, it is impossible to three roll rolling, is a circle shape, the appearance will mark the pole slightly.

The quality of the hard alloy wire rod breakage rate must be less than or equal to 3 times. If the broken line rate is greater than 3 times, to analyze its disconnection.

The wire is broken in inside or outside the box, if it is broken in the box, see the first few modes, to break down the interception mouth clean, check the broken mouth, some are caused by the breaking of impurities is obviously different from the color of the conductor, some are pouring hydrogen absorbing too much gas bubble caused by the formation of hollow bolt. In short, the broken line rate is too high or simply pull a broken and can not pull, there are four reasons:

First, the hard alloy conductor material, the front has been said.

Secondly, the problem of equipment, many enterprises are used to draw pure hard rod of the hard wire drawing machine, the popular vertical die drawing machine ten overall power is generally only 75KW, can not draw hard alloy wire. Type 11 or 13 die die drawing machine also depends on the motor power, if the power is 75KW, is certainly not pull hard alloy wire. Our company has had at least 6 such incidents.

Thirdly, the problem with mold. Some enterprises into the line compression ratio is not well controlled, and some did not grasp the law, once the number of silk

Need to adjust the number and position of the mold, often mistaken.

Fourthly, mold material problem. The angle of the die material and the entrance area of the die is hard. If the die material is not appropriate, it is possible to draw out the surface of thetungsten carbide rodhas a lot of burrs, skin and scratches.

Above all,High qualitytungsten carbiderod drawing out must be bright silver, precisely, hard alloy wire should be very smooth, bright silver shiny, translucent, pure color effect is significantly more than the pure hard to. Therefore, with the appearance of carbide rods can not judge the quality of drawn out of the silk, the key depends on the actual drawing of the silk surface effect.

Tungsten carbidewire surface color is darker, faint or obvious gray spots, indicating that the hard alloy rod production process in addition to impurity control. Such a wire is likely to be a good pull.

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March 22, 2017

The market situation and the basic characteristics of tungsten carbide powder

In addition to tungsten powder has certain requirements on impurity content, oxygen content should be controlled in a certain range. Commonly used tungsten powder size is generally average particle size 2 ~ 10 mu m.polygonal tungsten powder particle shape.In addition,the tungsten powder surface, bulk density, tap density also changes in a certain range.. has a direct impact on the quality and properties oftungsten powderon the production of tungsten materials and tungsten powder metallurgy products, especially the influence of purity and granularity of tungsten powder is more obvious. And according to the classification of purity and granularity and different purposes.The earliest production of tungsten powder Huachang company is according to the chemical purity of hydrogen the reduction of tungsten powder is divided into three levels; Japan has formulated the "tungsten powder and tungsten carbide powder according to the industry standard (JISH2116-1979); Britain, France and the former Soviet Union and other countries have a unified national standard of tungsten powder tungsten powder.Chinese industrial production in 1982 developed a technology of hydrogen reduction of tungsten powder. A > (GB3458-82). The standard specifies the properties of tungsten powder and classification number. And the test method, inspection rules, packaging, transportation and storage projects are made clear. For special purposes and military special tungsten powder production plant, according to the production requirements of the users.

 

 

The use of tungsten powder

 

Tungsten powder is the main raw material processing powder metallurgy of tungsten alloy products and the pure tungsten powder can be made into silk, rod, tube, plate shape and material processing products. Tungsten powder and other metal powder, can be made into all kinds of tungsten alloy, such as tungsten alloy, tungsten rhenium alloy, tungsten copper alloy and high density tungsten alloy.Another important application of tungsten powder is made of tungsten carbide powder, and preparation of cemented carbide tools, such as turning, milling, drilling and other molds.

 

The market situation of tungsten powder

 

At present, affected by the whole market of tungsten powder, the market is still light, but relatively speaking, the market price range slowly toward the low price, volatility is not too large, due to the continued weak demand from downstream enterprises, so the purchase is unlikely, according to production orders, fewer new orders and new customers,with the increase of production and production. The upstream and downstream businesses operating enthusiasm is low, wait-and-see attitude intensifies, some manufacturers of tungsten powder due to the current market price is slightly lower, the funds can flow under the condition of not only a few sellers, or sell the goods, do not rush shipping, hope prices can be stabilized to improve.Because of the powder size and structure is different,the actual turnover the price may be slightly different, and different applications have different structure of powder,the corresponding product structure and profit are different, like tungsten bars, tungsten plate and other primary products, the profit is relatively low for airlines The empty space and special features in the field of alloy products, has a relatively good development prospect. At present, enterprises can according to their own characteristics, to seek new product development, and constantly improve the proportion of these high-end products for enterprise products, feedback to the enterprise benefit,enhance the market share, to occupy the advantage in the market competition.

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March 20, 2017

Annotate developing situation of cemented carbide industry of China

According to our understanding of the situation, the existing recycling technology mainly has several types, one is the so-called high temperature treatment method, including: saltpeter melting, air oxidation sintering, oxygen calcination method; two is the mechanical crushing method, including: cold crushing grinding, grinding, crushing heat zinc melting method; three is a chemical treatment method, including metal multivalent salt treatment, chlorination, phosphoric acid, hydrochloric acid leaching treatment method; the four is the electrochemical method, have different routes with alkali as the dielectric, with hydrochloric acid or sulfuric acid and nitric acid as the dielectric; also useful through hyperbaric oxygen, ammonia or amine solution leaching method; light based compound method and steam distillation were decomposition method and so on.

Since the advent of cemented carbide,recycling issues have been of concern to the industry. Tungsten carbide is the main raw material of tungsten carbide and rare metal, and its economic value and manufacturing cost is relatively high. In the recent years, because of the increasingly strict requirements of environmental protection, some recycling processes will be stopped due to pollution. At present, it is widely used in the field of mechanical crushing, zinc melting and selective electrochemical dissolution. For the evaluation of these processes, it is very difficult to choose a more reasonable, more economical and more worthy of popularization and application, because the quality of process route of the first and the basic principle is recycled products to be high, the process should be simple, have two times of no pollution to the environment, labor conditions should be clean and safe. This paper briefly introduces several commonly used recycling processes.

Crushing method

For hard alloy containing drilling is not high, because the hardness is relatively low, can use manual or mechanical means broken to a certain fineness in wet grinding mill for a period of time, to reach a certain size for reproduction of hard alloy. This force is a method has the advantages of simple process, short process, low energy consumption, no pollution to the environment, but often in the manual crushing hard alloy, metallic materials due to debris into the tools have broken material pollution, in addition, due to the hard alloy drill containing high amount of easily broken, mechanical crushing method is very limited; cemented carbide complex material by this method is also very difficult to ensure the quality of recycled products.

Process method: artificial crushing is broken, crushed into powder 200 mesh or using bulk of hard alloy ball mill for crushing strikes the ball, then add in the bjm alcohol in wet grinding, and then enter the remanufacturing process of hard alloy. Some companies use cooling method: first crushing waste hard alloy in a muffle furnace heated to 80 above this immediately into the water quench, resulting in hard alloy cracking, and then enter the mechanical crushing process.

At present, there is still some room for the development of crushing method, the use of more advanced cleaning equipment or the use of high efficiency does not destroy the hard alloy microstructure of the force of a method to deal with cemented carbide, crushing method still needs to be improved.

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March 16, 2017

Market demand for carbide cutting tools show the trend of falling down

The development in the modern manufacturing industry, improve the processing quality and efficiency is the eternal pursuit of a modern and efficient tool. The demand for such services is the "high precision, high efficiency, high reliability and special tool". China the tool of enterprise, to the development of modern and efficient tool as a strategic direction in modern high.carbide cutting tool is the main force, including high-speed steel cutting tool is the development of super hard cutting tools and specific areas.China there was a continuous development of a growing manufacturing sector,such as automobile manufacturing,power generation equipment, aerospace, rail transportation,large precision molds,universal heavy machinery,shipbuilding, weapon industry,so in the strong momentum of development, provides a broad market for domestic tool industry.

Although China manufacturing will be because of the impact of the financial crisis led to the recent growth rate has slowed down.In 2008 As the second half of carbide cutting tool market there have been signs of a drop in demand, but the decline is mainly the larger export enterprises export blocked, the domestic market is a large decline in the low-end products,the demand of the high efficiency tool did not change significantly. Although the influence by external difficulties, in a period of time will lead to the development of our growth slowed down. But the tool if the enterprise can use this period of time, pay close attention to structural adjustment, survive, in the long term, domestic demand prospect. For example, in the Chinese adjustment of energy structure, wind power the unit to accelerate the development of 2008 has doubled, the increase of installed capacity of nearly 3 million kilowatts, and 2015 will maintain this speed even faster. After the development of the current domestic wind turbine mainstream production From the development trend, the developed countries have generally adopted more than 1000 kilowatts of units, 2000 ~ 5000 kW units have been put into commercial operation.

 

So the wind power industry is facing a sharp increase in demand Chinese challenges facing large unit complex manufacturing technology challenges. The remarkable needs of the high efficiency tool. So, I think that the development of the modern high-efficiency carbide tool, must be firm in strategic direction, can not be irresolute and hesitant bungled fighters.there have been a number of advance tool of enterprise, in this regard has developed many useful experiences. The approach is to start from the import substitution, combining imitation and creation, and gradually expand the results,go on the road of independent innovation,in the process of continuous solid foundation, rolling forward. 

Needs to be emphasized is that the core value of modern cemented carbide cutting tools, is to help improve the quality and efficiency of manufacturing industry, so as to enhance the competitive ability. Pull off to the manufacturing industry to improve the service level of the core, modern and efficient tool mistakenly understood as the tool material for hard alloy or better material on the line. Not in a special "efforts, continue to produce the monotony of things,which  is sure to fail.

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March 13, 2017

Development of precision cemented carbide saw blades for automobile parts

Cemented carbide saw blades,is short for carbidesaw blade,whichis currently Aluminum Alloy, copper, organic glass, acrylic, plastic, wood, sheet metal and other soft materials, the material most commonly used, the most economical, the most efficient cutting tool, is the most important tool of this material cutting.

Now that cemented carbide saw bladesare so widely usedin many areas , it means so understanding and operating methods of every user of hard alloy saw nature is also different, it is helpful to improve the cutting effect or contribute to prolong the service life of saw blade, are good method for practical verification.

The tool material can not, especially for precision cutting of commutator commutator, copper materials, precision cemented carbidesaw cutting life showed more durable and more consistent cutting performance.

Direct reflection of the automobile industrial production technology and automation requirements of auto parts production technology is intelligent,to maximize production efficiency. This requires to do good work,this must first sharpen his tools, this tool for high performance products, put forward higher requirements for endurance life especially for automobile copper commutator parts precision machining operations, cutting operation lasting life and consistency of machining products, direct request of carbide saw blade quality requirements.

Application of cemented carbidematerial is the foundation, the precision and consistency of cemented carbide saw bladesmilling cutter finished batch production is required,with the direct embodiment of the mechanical operation of the production efficiency. Simply, high speed milling operation of cemented carbide saw precision consistency is very high, the precision requirements of each dimension are in order to ensure the stability of machining and using life. Any deviation from a size of high speed machining will affect directly the life and cutting performance of hard alloy saw blade, auto parts copper commutator, the whole flow is reflected on the processing quality of precision alloy blades.

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March 10, 2017

Tungsten carbide makes diamond become harder

As a major challenge for diamond cutting tool is very brittle. The diamond is a form of carbon atoms arranged very closely. In face centered cubic structure, each atom and the other four adjacent atoms connected by bonds, thus forming a very strong crystal structure. Not only the intensity is very high. This structure also makes the chemical properties of diamond is very stable, has very high thermal conductivity, low thermal expansion, the plane is very smooth, and a high refractive index. These properties are very useful. For example, surface smoothness and chemical inertness means non viscous. As a result of this, the wettability of diamond poor, can not work well with adhesive. When considering the diamonds for drilling tools,it becomes a problem.To do this, the only effective way is the particles in the metal matrix, relying on the mechanical strength of the metal, which is fixed. 

Heat is another problem, making it very easy to oxidation or reduction of graphite. Despite all that "diamonds are forever", but the fact is that when the temperature is above 400 DEG C, the diamond will quickly become soft graphite, graphite - especially in the presence of metal. In the end, although the lattice structure diamond anisotropy is very strong, but it does exist along the fracture surface, the crystal plane will smash.

The solution for the last question,is diamond, which is very much a small diamond crystal combination. Because of these small diamonds are very random, so it is not easy to form a continuous fracture surface, which makes the unfavorable fracture.

There are two types of diamond, diamond composite and thermodynamic stable diamond composite. The surface hardening tool, TSP type is obviously a better choice, but it is also facing new challenges. Especially the use of nickel coating to help sintering diamond matrix will lead to the many problems of nickel. Will form a weak chemical bond and diamond, when material expansion, the bond breaks. In addition, Ni also can promote diamond to graphite transformation.

By chemical vapor deposition method to form tungsten carbide coating on the surface of diamond crystal, tungsten carbide in the process from the condensed gas can be formed on the diamond surface atoms, which will form a strong bond, and does not have the formation porosity. The wettability of diamond coating has been greatly improved,the diamond can be better embedded cutting tool. Laboratory tests confirmed the fracture analysis. Tests show that even under the condition of fracture, the coating still bonding with diamond.

When the global search for oil and gas reserves to move to more remote areas, are more obvious. So the importance of drill engineering and manufacturing pressure is bigger. This new technology can get the world's most hard materials, plays an important role in many key aspects.

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March 08, 2017

Analysis of the price trend of tungsten powder

Tungsten powder with tungsten oxide as raw materials, in four or more tube muffle furnace tube furnace with hydrogen reduction, grain size from 0.6 to 30 microns.Coarse, medium and fine granularity of several main points, silver powder, impurity content based on the national standard.

By hydrogen reduction of tungsten trioxide or secondary ammonium tungstate method. By hydrogen reduction of tungsten powder process generally divided into two stages: the first stage in temperatures of 500 ~ 700 oc, tungsten trioxide reduction of tungsten oxide; The second phase in temperatures of 700 ~ 900 oc, tungsten oxide reduction of tungsten powder. Reduction reaction in tubular furnace or rotary furnace.

Reduction of tungsten powder properties (such as purity, particle size, particle size composition, etc.) mainly depends on the reduction process. Reduction in the tube furnace tungsten powder, the main process parameters affecting the reduction rate is the tungsten oxide reduction temperature, burning the boat loading capacity, burning speed boat, hydrogen flow rate and moisture content in the hydrogen. With the increase of reduction temperature, the granularity of tungsten powder.

Tungsten powder for making except hydrogen reduction method, and early use of tungsten oxide carbon reduction method,the reduction temperature higher than 1050 oc. Use this method to get the low purity of tungsten powder. In addition, the metal aluminum, calcium, zinc and so on reduction of tungsten oxide process research work is in progress. For special applications requiring high purity and ultrafine particle size oftungsten powder, the development of the tungsten hydrogen chloride reduction method, the granularity of tungsten powder can be less than 0.05 microns.

 

Tungsten powder in the near future price trend analysis

 

Since the early stage of the downstream customers receive a degree is not high, so powder metallurgy factory pricing suspended, tungsten concentration, APT now has a rapid speed rises and, under cost powder manufacturer also need pricing, with a firm itself pretty price will stronger, so every day now prices are up slightly, export prices have to rise.

Powder market there is no obvious change. On-demand procurement market inquiry, powder enterprises, manufacturing-according-to-sale patterns remain low, as for the price of the holiday expectations, powder to the back-end enterprise market confidence is insufficient, relatively cautious. Powder enterprises are greatly influenced by the cost, the late rise in raw material market, powder market price can also follow up, but to rose by a big breakthrough.

 

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March 06, 2017

Cemented carbide milling cutter in the machining of the unique advantages

Regardless of the carbide end milling cutter in the cutter body structure, processing capacity, processing efficiency, processing quality or economy, compared with the previous knife type have a breakthrough.

Mills in the overall structure, divided into the overall end mill and carbide milling cutters. Two types of end mill to meet the processing needs, the company design and manufacture of the cutter head, different sizes of structure shape, helix angle and number of teeth and other products. The whole cutter material is mainly used for high speed steel. In order to improve the machining efficiency and quality, the higher hardness, better wear resistance, better rigidity and whole hard alloy and higher machining precision milling cutter is more and more widely. Because of the whole hard alloy, so the price is more expensive, especially for large diameter and thick. So it's like turning tool, milling cutter, milling cutter also fitted with inserts, to conform to the requirements of the processing, inserts can be made into a variety of different functions of milling cutters.

The surface of the mold cavity forming small and small and complex parts,which is mainly used in several different vertical milling cutter. Overall processing of large molds and large parts for economic reasons, the rough machining used with carbide milling cutter machining precision machining, with its high vertical milling cutter are expensive and small diameter at present the whole solid carbide end mill by the diameter of 0.1~ with a diameter of about 25 (high speed steel can be made thicker, even with more than 60). With milling cutter can according to need to do with 160 or even more. But it's smallest size will be limited, because of the use of the knife should be small screw, fixed blade will be more fine, and the strength is less restricted. The general minimum diameter with 10 individual cases, such as a simple function,only the cutter can do more, even do Phi 4.

With cemented carbide with coarse,in order to save the knife rod,many companies developed a replaceable cutter heads with inserts.The knife head injury, the replacement of a knife head can continue to use.The connection mode and size, can also change the other processing functions of the cutter head a variety of shapes, surface processing parts, so as to realize the centralized process,a card to complete or mostly complete all processing, greatly improving the efficiency and the mutual position of the surface accuracy.

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March 03, 2017

Preventive Measures and wear of cemented carbide Milling Cutter

Because of the small shape tolerance, the forming cemented carbidemilling cutter is widely used, because it can not replace the blade directly, and most of the milling cutters are used for scrap treatment, which greatly improves the processing cost

Processing of materials properties. In the process of cutting titanium alloy, due to the poor thermal conductivity of titanium alloy, cutting easy bonding formed in the tip edge or near the built-up edge, in the vicinity of the tool tip, the formation of high temperature on the tool flank, red hardness loss, increased wear. Under the condition of high temperature continuous cutting bonding material and weld materials, by the impact of the subsequent processing, after being forced off the process will take away part of the tool material, tool and defect caused by damage. In addition, when the cutting temperature reaches 600 degrees above, parts of the surface will form a hardening layer, tool produced strong wear elastic titanium alloy. Low modulus, elastic deformation, close to the flank at the surface of the springback, so the machined surface and the flank of the contact area is large, serious wear.

According to normal wear. In the normal production process, when the margin of continuous milling titanium alloy parts at 15mm-20mm will appear serious abrasion of the cemented carbidemilling cutter. The milling efficiency to very low, and the surface finish is poor, can not meet the production and quality requirements.

Improper operation. The production and processing of titanium alloy castings, a box body and a box cover in the process of clamping is not reasonable, not suitable for cutting depth, spindle speed too fast, inadequate cooling improper operation will cause tool tipping, breakage, broken and so on. This kind of defect in milling cutter can not effectively milling, but also in the milling process for "eating knife" caused by concave surface defects such as surface processing, not only affects the processing quality of the milling surface, even cause parts scrapped.

The improved method. The cutting edge chipping (i.e. mild damage) the most common case, only through the cutting edge grinder grinding out the damaged part, reuse can be realized. The cemented carbidecutter grinding cemented carbidecutter should use silicon carbide grinding wheel, and can not be dipped in water or by grinding, cemented carbidequench cracking and completely scrapped.

After grinding grinder, effective length after grinding tool than the new tool without the use of short, but this process indirectly enhance the rigidity of the cutting tool, the processed surface quality better, improve the milling efficiency. Because titanium alloy casting molding will be formed after the uneven skin is hard and brittle, easily cause chipping phenomenon the crust has become one of the most difficult, removal of the titanium alloy processing in the process. Recommend appropriate to increase the depth of rough machining first took the knife when the (2mm-4mm), to control the tip in the surface crust is appropriate, to prevent direct contact of the tip or tipping phenomenon.

Posted by: hannahgwendolyn at 09:34 AM | No Comments | Add Comment
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March 02, 2017

Grinding and quality control of tungsten carbide coating on ultra high strength steel

Supersonic flame spraying WC - 10 co4cr coating with low porosity, high bonding strength and excellent wear resistance, etc, have wear-resisting request in aircraft landing gear shaft parts on the size and precision of the repair has been widely used. But, subject to the limit of the process and coating properties, raw coating surface roughness and uniformity of generally cannot meet the requirements of design, must be guaranteed by grinding. In actual production, because of the improper operation or parameters selection is not reasonable to control such links is bad, often leading to parts deformation, thermal stress in coating spalling, crack, or micro cracks and other defects, seriously affect the quality of tungsten carbide coating, restricted the products of normal delivery. By strengthening the materials, equipment and maintenance, manufacturing process and personnel control, put an end to the a type ultra-high strength steel shaft parts coating grinding quality problem happen, and after a long-term practice test, it has reference significance to guide production.

 

Preparation by supersonic flame spraying process of WC - 10 co4cr coating on the tungsten carbide coating density, porosity < 1%; The combination of coating and substrate in machinery and metallurgy, high bonding strength, can > 70 mpa; Can reach 1100 ~ 1100 hv hardness, high wear resistance can be obtained. The aircraft landing gear shaft parts with wear-resisting requirements, size and precision has been widely used to repair, but subject to the limit of the process and coating properties, original supersonic flame spraying coating surface roughness generally > Ra3.2 mu m, can't meet the design requirements (< Ra0.2 microns).Ultimately, coating thickness and surface roughness must be guaranteed by grinding.

 

Grinding is the use of high speed rotating diamond grinding wheel,through the coarse grinding and fine grinding to be processed parts surface roughness Ra0.4 ~ Ra0.6 microns, the surface roughness after polishing can achieve Ra0.1 ~ Ra0.2 microns. In actual production, because of the improper operation or parameters selection is not reasonable to control such links is bad, often leading to thermal stress parts deformation, micro cracks appear, the serious influence the quality of coating and restricted the products of normal delivery. In order to ensure the quality of coating grinding, coating process quality control, namely on the material and personnel, equipment and maintenance as well as manufacturing process control, etc.

 

For grinding tungsten carbide coatingsteel substrates, reasonable control of grinding parameters can effectively prevent the parts surface burns and the thermal stress deformation, put an end to the generation of surface crack defects such as cracks, coating. In the process of grinding, due to the effect of grinding stress, crack in the substrate attaches first, after coating is pulled open, then extend grinding stress perpendicular to the main direction.To reduce the probability of crack, the grinding parameters should be optimized to reduce the stress of grinding, the surface roughness matrix materials at the same time, increase the adhesion strength of the coating and interface.


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March 01, 2017

Research on the wear resistance of coated carbide inserts

There are few other materials like carbide, for the global economy and industrial civilization produced such a significant impact.The high hard wear-resistant material is widely used in the manufacture of a variety of different products, such as ball-point pen nib, rod guide ring, wear parts, dental drill bits, armor-piercing core and so on, and it is the most important purpose is manufacturing cutting tools. In fact,the coated cemented carbide cutting tools are the most widely used cutting tools on the market. Such tools greatly increase the productivity level of the metal cutting process, thereby significantly reducing the costs of many everyday products manufacturing.

However, currently on the market all kinds of advanced coating technology and coating material emerge in endlessly, for specific processing tasks to choose the best coated carbideinsert brand isn't always easy. Choose the insert brand is best, from the perspective of the workpiece material, because of the type of processed materials to determine whether you need carbide insert coating plays a key role.

Coated carbide insert for iron group materials (such as iron, cast iron, steel or stainless steel) machining is necessary. Cutting high temperature alloy (especially its machinability alloy material of medium/high level), in most cases, the coating insert is the best choice. Machining titanium alloy can also benefit from the coating, especially in the case of without the use of high pressure coolant.

Uncoated cemented carbide insertis suitable for processing non-ferrous metal materials (such as aluminium). In fact, because aluminum is soft, is easy to produce the devolop tumor, had better use extremely sharp uncoated cutting edge to processing. Other do not need to use the insert coating workpiece materials include brass, bronze, a variety of composite materials and wood. However, using suitable diamond coating can greatly improve the machining efficiency and tool life.

Choose the appropriate coating types are choosing coated carbide insert is the most difficult part. After all, all kinds of processing tasks differ in thousands ways, so you must carefully consider coating technology and coating should be adopted. In addition, for "should be how to choose the appropriate insert coating", is not a simple answer. Learn some basic knowledge of the coating technology and coating material, will help to eliminate the insert selected some uncertainty.

Chemical vapor deposition (CVD) and physical vapor deposition (PVD) are two main types of carbide insert coating process, and each has its own characteristics and advantages. CVD coating thicker (usually 10-20 microns), and have good wear resistance, especially suitable for cutting steel and cast iron, and is widely used in turning processing.

Unfortunately, however, the coating thickness may be harmful to the toughness of the cutting edge. PVD coating thin (usually for 2-3 microns), compared with CVD coating has better toughness, and the surface is usually more smooth. Therefore, this kind of coating is very suitable for high temperature alloy, titanium alloy, and difficult to machining of stainless steel, workpiece materials which tend to cause a cutting edge curve insert wear or crack.

Posted by: hannahgwendolyn at 09:29 AM | No Comments | Add Comment
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