At present, almost all the famous cemented carbide cutting tools and knife auxiliary tools companies and their products have entered China. Many companies have also invested in factories in China to provide carbide cutting tools and technical support services to domestic automobile manufacturers. Domestic cemented carbide tool manufacturing enterprises are also trying to improve the design, manufacturing, grinding and coating of cemented carbide tool technology level, in order to adapt to the domestic automobile manufacturing industry using a large number of CNC processing equipment, constantly to high-speed, high-precision processing development requirements. All these provide good external conditions for the automobile manufacturing industry to further improve the application and management level of cemented carbide cutting tools.

Whether it is the centralized and unified management of cemented carbide tools carried out by automobile manufacturing enterprises themselves, or the management of cemented carbide tools outsourced, or the management ofcarbide cutting toolscombined with the two, they will make full use of social resources. This is the inevitable result of economic globalization and industrial informationization, as well as the inevitable trend of development of cemented carbide tool management.

Automobile manufacturing enterprises with the carbide cutting tools manufacturing and service enterprises to establish long-term cooperative partnership, established in computer and information technology on the basis of cemented carbide tool information database management software and carbide cutting tools production and demand will further develop communication, between customers and suppliers, problems and solutions.

With the establishment of some professional cemented carbide tool research and development, cemented carbide tool manufacturing, cemented carbide tool grinding and cemented carbide tool coating companies and their extensive service outlets in China, the management of cemented carbide tool in the automobile manufacturing industry will get more powerful support. Other auxiliary tools such as various new tool handle systems, carbide tool adjustment, testing equipment, carbide tool dynamic balance system and their suppliers will also be developed in China along with the rapid development of automobile manufacturing industry and the demand of carbide tool management, and provide effective services and support to automobile manufacturing industry.

The materials used for making carbide cutting tools must have high hardness and wear resistance at high temperature, necessary bending strength, impact toughness and chemical inertness, good technicality (cutting, forging and heat treatment, etc.), and not easy to deform.

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Electrostatic powder spraying is the use of high voltage electrostatic corona electric field principle. The metal guide ring on the head of the spray gun is connected with the high pressure negative electrode and is grounded to the positive electrode by the coated workpiece. A strong electrostatic field is formed between the spray gun and the workpiece. When shipping carrier (compressed air) to pass through the duct powder for powder coating from the unit to the spray gun guide ring, due to the guide ring connected to high voltage anode produce corona discharge, the surrounding to produce dense and make the powder with negative charge, charge in electrostatic force and compressed air under the joint action of the two force, powder spray gun from the mouth to fly to the workpiece, and adsorb evenly on the workpiece surface, and dissolved by heating the powder a flat to a uniform, continuous, smooth, glossy coating.

The first stage: under the action of electrostatic electric field force, the powder evenly adsorbs on the surface of the workpiece, forming a thin continuous covering layer. In this stage, the powder is basically adsorbed by the workpiece.

The second stage: powder under the action of static electric field, continue to fly to the workpiece surface, because of has been covered with powder and powder in the same electric charge and produce new repulsion, but static electric field strength is stronger than the repelling force, powder will continue to adsorption, thickening of coating will continue, but there are some powder adsorbed on the surface and not drop down.

The third stage: with the continuous increase of coating thickness, the repulsive force increases. When it reaches the same with the electrostatic field force, the powder will no longer be adsorbed. At this time, the coating thickness will no longer increase, and the ejected powder will not be adsorbed completely.

Of course, powder coating in the current process also has some shortcomings, such as powder xu material can not be as liquid coating can be quickly changed color; Uneven powder on the edges and corners of the powder coating; Powder coatings can not be as easily obtained as solvent based coatings. High curing temperature required for powder coating; When the dust concentration of powder coating construction site is too high, there may be danger of dust fire and explosion.

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The working principle of thermal spraying determines that the coating pores are inevitable. When the coating is used to prevent corrosion, the corrosive medium will reach the surface of the substrate through the pores, resulting in failure of protection. Therefore, sealing is an important way to improve the corrosion resistance of coating. In this paper, the methods of coating sealing hole are summarized, the prospect of coating sealing hole technology in the future is prospected, and a new coating sealing agent, glaze, is put forward.

At present, the commonly used methods to reduce the porosity of coating are thermal diffusion remelting, self-sealing coating, improvement and improvement of spraying process, hole sealing agent and so on.

Thermal diffusion remelting

Remelting is a process of reheating and melting the formed coating to make the coating more compact in order to eliminate the pores generated by spraying and improve the corrosion resistance and bonding strength of the coating. During remelting, the components in the coating that are easy to melt are melted, and the liquid phase is generated to help strengthen the diffusion process, permeate the components and slag formation of oxides, so that the coating has a certain shrinkage. The melting results make the bonding zone between the thermal spray coating and the substrate change from the original stacked layer-like structure to the dense and more uniform structure, and the pores decrease or even disappear. The heating methods of coating melting include gas combustion heating, atmosphere control furnace heating and high-frequency induction heating, etc. In recent years, we have developed laser, electron beam, plasma beam, solar energy and other heating methods.

The use of spray material itself to reduce porosity

Improve spraying method and process

When spraying, select appropriate spraying distance, main gas flow and powder feeder flow, gun speed, electrical power, powder particle size and other parameters to reduce the coating porosity and improve the bonding strength is very helpful.

Hole sealing agent for hole sealing treatment

Other ways to reduce porosity

Impregnation of low temperature solder for tungsten carbide coating improves strength and wear resistance. The process is carried out in vacuum at 1000 degrees or hydrogen at 800 degrees. At these temperatures the filler flows into the gap to fill the unmelted carbide and capillary action occurs rapidly, allowing for 12min. It has been confirmed that most lead, tin, silver and copper solders provide satisfactory results.

Mechanical treatment somethermal spray coatingscan be mechanically treated to close pores connected to the surface and improve smoothness. Shot hardening is used on some aeronautical parts. Active metal coatings can be improved by shot hardening and rolling to improve cavitation resistance.

Related link:

http://www.wococarbide.com/Transaction/en_information.html

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In the traditional cutting process, in order to improve the machining quality and extend the tool life, a large amount of cutting fluid is usually used. In the 21st century, people began to advocate "green manufacturing" dry cutting technology without cutting fluid is favored, especially the development of tool coating technology makes the application of dry cutting is expanding. But practice has proved that in the difficult processing materials (such as heat resistant steel, stainless steel titanium alloy, etc.) and difficult processing processes (such as drilling, tapping, cutting groove, especially deep hole processing, etc.) in the cutting process, even if the use of coating tool for dry cutting still have some difficulties, therefore, it is necessary to develop a new cooling lubrication way. This topic about carbide cutting tools and small Quantity Lubrication (Minimum Quantity Lubrication, MQL) and air cooling cutting technology, combining of austenitic stainless steel cutting experiment research has important practical significance. The study on austenitic stainless steel ICr8Ni9Ti material, before using the blade and knife surface coated respectively after TiCN + Al_2O_3 and Al_2O_3 TiCN + + TiN coating cemented carbide blade, through the cutting experiment was carried out, analysis in dry cutting, different bearing fluid for MQL, low temperature cold wind, and the change rule of cutting force under the condition of low temperature MQL, on this basis, to choose the right condition, cooling and lubrication for tool wear test, emphatically analyzes the characteristics of tool wear and wear mechanism of chip morphology after test observation, analysis the mechanism of chip breaker.

Through the experiment of cutting austenitic stainless steel 1Cr18Ni9Ti by four kinds of coated carbide cutters, the influence of cutting parameters on cutting force was studied, and the cutting force of four kinds of cutters was compared and analyzed. The test results show that the back force is larger than the main cutting force when cutting with small feed and small back feed. With the increase of cutting speed, cutting force of YBC251 and GC2025 cutting tools decreases first and then increases. Compared with CVD coated carbide cutting tools, pvd-coated carbide cutting tools of the same type have significantly less cutting force than cvd-coated carbide cutting tools.

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Coating material aspect. Such as cast iron, cast aluminum pieces have sand holes, or hot rolled steel plate surface rough, have fine holes, etc., these conditions will make the coating prone to appear sand (particles) or volcanic pits. This is because when baking curing powder coating, powder coating melt flow makes the coated surfaces closed at ordinary times, as the coated temperature increases, the coated sand holes or pores of air pressure, melt flow flat coating to hog, if internal pressure is not broken drum coating to form sand (particles), when drum coating and coating cannot heal when formation volcanic crater.

The most fundamental measure to solve this problem is to ensure that there is no sand hole in cast iron and cast aluminum. The surface of hot milk steel plate is flat without oxide skin and pores. If the material selection can not be solved, from the aspect of coating process, will be preheated, the use of thermal spraying process can solve this problem; In addition, the process of spraying twice can also solve this problem, but these two methods are more troublesome, and also increase the cost of coating.

If it is difficult to solve from the powder spray coating factory, you can also ask the powder coating factory to cooperate to solve. When the material quality of the coating can not be solved, it is the most effective method to solve from the powder coating production formula.

From the point of view of the powder coating factory, you can add defoamer and other additives in the formula to reduce the surface tension of powder coating in the melt flow at ordinary times, so that the air is easy to escape from the coated material sand holes or pores, at the same time, the air gap (hole) after the escape from the air can quickly smooth without leaving traces. In some cases, it is also necessary to adjust the reactivity of the powder coating to slow down the curing rate of the powder coating, so that the pores after escaping from the air have enough time to fuse and level out, without leaving behind the coated sand (particles) or volcanic crater.

The surface treatment of the coating is not good, the phosphating residue and other impurities in the surface treatment liquid are still attached to the surface of the coating, and it is easy to produce particles or particles of the coating film during powder spraying. This problem can be solved as long as the residue in the phosphating solution is cleaned in time and the coating is cleaned in the washing process.

In electrostatic powder coating, the production environment around the powder spraying room is not clean, especially some dust and particles in the air are brought into the powder coating or powder spraying room, or because of electrostatic induction effect, charged impurities are adsorbed to be coated above, in powder coating melting flow usually, become the particles or particles in the coating film. This problem can be solved by separating the powder spraying room from the production workshop to prevent the dust and dirt from entering the powder spraying room, and at the same time, the air entering the powder spraying room can be seriously purified. If the friction charge electrostatic powder spray gun is used, the dust in the environment will not be electrostatic, in contrast, the coating is less likely to produce particles (particles) caused by dust and other impurities in the air.

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