Cemented Carbide Coated Tool Coated Substrate Gradient

The bonding strength of the coating and cemented carbide coated tools alloy matrix is key carbide tool life, the coating must be suitable substrates therewith can combine to achieve the desired performance. Not the same material as each of the thermal expansion coefficients are different, probably because of the thermal stress cracks in the coating during cooling. Due to the brittle cemented carbide coated tool coating material, usually easier to crack the coating to the substrate surface extension. Gradient of substrate processing, the surface area of the coated substrate forming ductile region cubic carbides and carbonitrides, the binder content in this region is higher than the nominal binder content of the coating substrate; when the coating formed when the crack growth to the region, because of their toughness, crack propagation can absorb the energy, it is possible to effectively prevent the crack to the inside of the alloy expansion, improve the performance of cemented carbide cutting tools.

Tungsten Carbide Coated Tool Flexibility of The Coating Process

Single tungsten coated carbide coated tools can not meet the increasingly complex machining requirements, therefore, it appears coating technology portfolio diversification. "Nitriding / PVD" composite coating technology is one of them. As early as 1983 it was suggested that the plasma nitriding and ion plating process together. To improve the performance of the hard protective coating substrates by thermal chemical pretreatment technology more and more attention. The matrix nitriding and ion plating TiN composite processing, it can form a reasonable hardness gradient distribution, and also because of the role of TiN and N and further spread to internal nitrided layer deposition process, so that the transition layer hardness than a single nitrided layer is higher around 100HV0.1, so that the composite coatings have been strengthened.

Cemented Carbide Coating Tool Coating Composition Diversification

With the continuous development of technology, cell coated cemented carbide coated tools can not meet the needs of the market, does not match the substrate and the hardness, elastic modulus and thermal expansion coefficient of the coating material coated tools unit, the lattice type are not the same, resulting in residual stress between the substrate and coating, adhesion is not strong. Adding new elements in a single coating (such as adding Al, Cr and Y increase antioxidant activity, adding Zr, V, B and Hf improve wear resistance, hardness and resistance to adding Si improve chemical diffusion) prepare a diverse tool coating layer material, greatly improving the overall performance of carbide-coated tools. In the multi-carbide coated tool, the most commonly used is the TiCN, (Ti, Al) N coatings.

Preparation Cemented Carbide Coated Tool

Preparation cemented carbide coated tool varied, its methods are vapor deposition, thermal spraying, chemical treatment, thermal reaction diffusion deposition, sol-gel. Is a method commonly used in the preparation of vapor deposition, because the preparation of the coating quality is good, has gradually become the dominant tool coating preparation methods, vapor deposition, chemical vapor deposition technology is divided into (chemicalvapordeposition, CVD) and physical vapor deposition (physicalvapordeposition, PVD). Chemical vapor deposition (CVD) deposition category belonging atom, a pioneer in the use of gaseous reactants through the atom generated solid coating, intermolecular chemical reaction pathway techniques.

Cemented Carbide Coated Tool Heat Treatment

Heat quantity cemented carbide coated tool because it is in an arc ion plating process, the substrate temperature between 200 ~ 400 ℃, due to the lower temperature, the coating material is deposited on the substrate surface is quenched, the coating material due to the thermal expansion coefficient differences have different heat shrinkage tendency, between the coating of each grain thus generating a thermal stress. The existence of thermal stress accelerates cemented carbide coated tool failure in mechanical cutting process. The heat can absorb part of the strain energy, easing the stress relaxation, coordination of the corresponding state change. Heat-treated steel base CVD-TiN coating, the coating after 1030 ℃ 250 ℃ after quenching and tempering, TiN coating microhardness increase, the crystal structure of the coating tends to be more complete, its lattice spacing and more TiN crystal plane close to the standard value of the pitch, while the density of the coating increased, and a good combination of strength of the matrix.

Cemented Carbide Coated Tool Cold Treatment

Cemented carbide coated tool, the composition and nature of the binder phase matrix Co tool for strength and deformation characteristics of cemented carbide coated tool plays a vital role. If you want to change the characteristics of this ingredient and alloys, has two ways, one is the heat treatment, another is the tool cold treatment. Cold treatment cemented carbide coated tool creates a ultra-low temperature environment, the degree of supercooling is increased, so that the cobalt alloy free energy difference of the phase change increases, increasing the driving force of phase transition, thereby reducing the tool in the cutting process abrasive wear and diffusion wear. Because of the higher surface hardness and wear resistance coating material, cemented coated carbide allows a higher cutting speed, thereby improving the processing efficiency; or can greatly improve tool life at the same cutting speed.

Introduction of Cemented Carbide Coated Tool

Cemented carbide coating on the carbide cutting tool is coated substrate layer or layers of high hardness, good wear resistance of metal or non-metallic compound thin film coated tools, combined with a matrix of high strength, high toughness and Tu storey hardness, high wear resistance advantages, reduces the friction coefficient between the tool and the workpiece, to improve the wear resistance without lowering the toughness of the tool substrate. Thus, coated cemented carbide having high hardness and excellent wear resistance, extended tool life. Processing technology on tool performance coated tool after a certain influence, after cemented carbide coated tool processing techniques include heat treatment, magnetic treatment, cryogenic treatment, as technology advances, more updated type of post-processing techniques will bring Tu layer another tool change.

ZrN Coating Tungsten Carbide Coated Tools Introduction

Tungsten carbide coated tools in addition to ZrN coatings resistant to corrosion, high temperature, wear resistance, but also has good mechanical properties and electrical conductivity, beautiful golden appearance and so on. ZrN coating has been widely used in electronic circuit electrical contact layers, the jewelry industry and mechanical friction decorative layer of anti-friction layer, but not a common tool coating applications. With advances in machinery manufacturing technology continues to high-precision, high-speed direction, so the cutting tool in strength, high temperature, wear resistance and service life and other aspects of the performance requirements is also rising. The tool coating treatment is one of the important means to improve the performance of the tool. Because coating can improve the processing efficiency and accuracy, longer tool life, reduce processing costs, and therefore, the coating of metal cutting tools used in more and more widely.

Relationship Tungsten Carbide Coated Tool Coating Hardness and Thickness of The Tool Wear

Tungsten carbide coated tool hardness and thickness of the coating of the tool wear plays a great influence, the higher the hardness, wear resistance is also relatively higher. However, the high hardness, crack sensitivity of the coating is also increased. The coating is too thin, can not protect the base material, the wear resistance relatively badly; thick coating, the residual stress due to the difference in thermal expansion coefficient between the coating and the substrate material is produced on a large, excessive residual stress will cause cracks produced, thereby reducing the strength of the material. Therefore, the coating thickness should be appropriate. Coating interfacial bonding force matching coat and showed good tool materials, combined with strength, long service life of the tool. Tool material and the coating material matching the better, the closer the coefficient of thermal expansion, the tool will have a high thermal conductivity and heat resistance.

Mechanical Properties of ZrN Coated Tungsten Carbide Coated Tool

ZrN, ZrN / Zr and ZrN / TiN / Zr coated tungsten carbide coated tool microhardness than the matrix YT15 tungsten carbide inserts (16.5GPa) is even higher, up to no transition layer coating hardness, 28.0 GPa, composite coating hardness is slightly lower. Under the same conditions of base material, zirconium transition layer of ZrN coating thickness maximum, minimum buffer layer of zirconium ZrN / TiN composite coating thickness. This is because during the deposition process, the titanium ions and zirconium ions collide with each other, resulting in the deposition speed is reduced, so that, in the same deposition time, the minimum coating thickness. No transition layer coating interfacial bonding force lower than that of the buffer layer coating, ZrN / TiN / Zr highest adhesion of the coating, no transition layer of ZrN coating adhesion to a minimum. This is due to take place between the transition layer of zirconium and composite coatings TiN and ZrN coatings YT15 matrix and ion diffusion, reducing the residual thermal stress between the coating and the substrate, thereby increasing the binding force of the coating.

How to Prevent Tungsten Carbide Broach Without Failure When Broaching?

Tungsten carbide broach not prevent failure when broaching, you can take the following measures:

1, requires pre-hole precision IT8 ~ IT10, the surface roughness of the Ra≤5μm, prefabricated holes and positioning the end face of the vertical deviation of not more than 0.05mm.

2, strict inspection Carbide broach manufacturing precision. For outsourcing can broach teeth liter volume chip space and broaches strength check.

3, broaching performance and difficult to machine materials, you can select the appropriate heat treatment to improve the workability of the material, often using carbide high-performance materials or coatings broach broach.

4, storage, transportation Carbide when broaches, broach prevent bending and damage the teeth.

Tungsten Carbide Broach Broaching Faults and Solutions

There may tungsten carbide broach the production process will be a variety of failures, thus affecting Carbide broaches broaches broaching the quality and longevity, and even damage the tool. Carbide broach damage was due mainly to the teeth when broaching the pressure too much, not enough strength to pull a knife. Carbide Broach caused by excessive force teeth for many reasons, such as: pulling teeth liter excessive bending Carbide broaches, broaching the cutting edge of each point margin uneven, cutter radial runout large, prefabricated hole too rough, hard spots inside the material, workpiece strength too seriously sticky crumbs and chip flutes such as congestion and the workpiece clamping skew.

How to Use Tungsten Carbide Reamers

Tungsten carbide reamer to use, according to the assembly precision, feed part of the cutting edge notch checks oiling method, the guide sleeve and the workpiece clamping five aspects are introduced. First talk about the assembly precision in the use of carbide reamer to note that at the time it is loaded onto the machine, shake carbide reamer feed the front part to control the 0.02mm or less. In cutting, in order to always maintain this accuracy, you can use the guide sleeve. Then to feed part of the cutting edge gap check: Even reamer jitter can be limited within a desired range, but in fact often due to chipping of the cutting edge itself, gap, or lack of good surface roughness and precision of the hole. Therefore, before using, not only to check tungsten carbide reamer jitter, but also to check whether the chipping of the cutting edge itself, and the gap.

Tungsten Carbide Broach Eliminate Surface Defects When Broaching Method

1. To improve the quality tungsten carbide broach sharpening teeth and prevent edge chipping produce and maintain sharp edge, each tooth rake and the same width.

2. To maintain the stability of broaching process, while working to increase the number of teeth, reduce fine incisor teeth and tooth pitch calibration, broaching process systems to improve rigidity.

3. The rational use of broaching speed, resulting in the production of reptiles often encountered in practice due to the low speed broaching broaching, broaching speed is too high there will be vibration. In addition, the impact speed broaching broaching surface quality, wear and pull broaching rate important factor knife.

4. The use of tungsten carbide broaches, broach coating, laser hardening high-speed steel broaches, etc., which have a good surface quality broaching role in improving the speed of broaching, broach reduce wear and increase life expectancy and improve broach.

5. The rational use of cutting fluids and the full cast. For example, when broaching carbon and alloy steel, if the choice of extreme pressure emulsion, curing and processing oil extreme pressure additives to improve broach cutting oil life, significantly reducing the surface roughness effects.

Tungsten Carbide Broach Broaching of Surface Defects

Tungsten carbide broach in broaching process, factors broaching surface defects are mainly crowded highlights, scales thorns, scratches, burnishing, circular ripples and bite knives. Factors that cause surface defects when tungsten carbide broach broaching have slight edge passivation or chipping, edge sticky crumbs, cutter blade with too much or uneven width, rake angle is too large or too small, broaching produced during vibration. If the surface roughness qualified, but when you scratch defects generated, you can check if there are bumps cutter blade gap; if there has not been cleaned chips attached to the cutter; Broach tolerance after repeated sharpening shavings whether or not caused by the shape of the groove smooth stepped to cause the chip curling is not smooth and squeeze bad. Teeth and scratch the machined surface and the like. In addition, if the pre-processing of oxide on the surface of the hole may also cause localized bumps and scratches tooth defects.

After Sintering of Tungsten Carbide Inserts Molding Method

Tungsten carbide insert after molding to sintering, the sintering method is:

1, which has been finely divided tungsten carbide powder and cobalt powder according to the desired shape of the pressure, the metal particles are connected to each other, because only the first step, so the combination is not very strong.

2, the powder particles of the already formed block with increasing temperature, gradually strengthening the degree of the connection, in conjunction 700-800 ℃ when the particles still fragile, more voids between the particles, the voids called pores.

3, the heating temperature is increased to 900 ~ 1000 ℃, the voids between the particles decrease, linearly black part almost disappeared, leaving only the black portion chunks.

4, the temperature was slowly approaching 1100 ~ 1300 ℃ (i.e., normal sintering temperature), to further reduce the gap, binding between the particles become more robust.

5, when the sintering process is completed, the tungsten carbide inserts in the form of small particles of polygonal, in which can be seen around the white substance, that is cobalt. Blade organization based sintered cobalt finished basement, covered with tungsten carbide particles. Particle size, shape and the cobalt layer thickness is different, the nature of the cemented carbide inserts are also different.

Tungsten Carbide Blade Manufacturing Process

Tungsten carbide blade manufacturing powder metallurgy method is generally used, will reach 2870 ℃ melting tungsten carbide powder is heated to more than one thousand degrees Celsius to make sintering. In order to make a more solid tungsten carbide powder combination, to use cobalt powder as a binding agent. Under high temperature, high pressure, and affinity tungsten carbide powder and cobalt powder each other will increase, thereby forming, a phenomenon called sintering. Carbide blade production processes: particle size of several micrometers fine material - with a ball mill powder mixing W powders and C - W mixed powder and C powder powder made of the WC powder carbonization - WC powder has been carbonized - adding a lubricant in the WC powder and Co powder - carbide inserts molded.

Damage Rule Tungsten Carbide Inserts

Tungsten carbide inserts damage can be divided into crater, thermal cracking, chipping, chipping, or gap, wear three cases. Produced crater, thermal cutting is because the temperature is too high; produce chipping, chipping or notch toughness of tungsten carbide body because of inadequate or unstable lead the rotary machine with the gap exists between the various parts; wear generation is small because the cutting edge of the scraper loss nibs caused by the contact of the tool and the workpiece caused. For the crater and thermal cracking solution is to use high-temperature performance is good and contains a lot of titanium carbide or tantalum carbide materials; for chipping, chipping or gap solution is to strengthen the material holding force particles with cobalt content and more material; for the cutting edge loss solution is to increase the content of tungsten.

Tungsten Carbide Milling Problems and Solutions

When tungsten carbide milling cutter, the inevitable always a wide variety of problems. These problems generally include tool breakage, wear, short tool life (edge passivation), blade gap, chip stacking, edges, no vertical edge, size is not enough precision, noisy and rough surface fine milling and other phenomena. Carbide tool breakage occurs reasons generally feed too fast, chip volume is too high, the total length of the blade length is too long or too long, such as excessive wear, the solution is to reduce the feed rate, lower feed per tooth to the rate fixed shank deep; use shorter end mill, early grinding. Reason for the occurrence of a short life of tungsten carbide cutting tools (knife edge passivation) is generally too high friction when cutting the workpiece and tough or incorrect cutting angle, its grinding solutions for the early use of advanced tool steel (metal polymer molecules ) or switch to the correct cutting angle and clearance angle.

Damage Tungsten Carbide Tools and Solutions

Tungsten carbide tool abrasion damage usually wear, crater, chipping, thermal cracking, gap, abnormal debris, BUE peel, peel into a piece of plastic deformation and a total of nine kinds of situations. Tungsten carbide cutting tool wear abrasion occurs, when the strip behind severe wear occurs, you should use the tool fine particulate material, and to enhance its hardness and strength at high temperature quenching. Rigid; material containing a trace amount may be used tantalum carbide; crater occurs when tungsten carbide tools, the current severe concave surface wear occurs, it should be noted diffusion and strength at high temperature, can be used titanium carbide, tantalum carbide content of high material alloy tool chipping occurred, when the tiny slivers falling behind, then carefully polished tip of the cutting edges should be ground, can reduce debris.

Quality Tungsten Carbide Tool Sharpening

After sharpening tungsten carbide tools, surface prone to burns and cracks, which seriously affected the performance of tungsten carbide cutting tools and tool life. But the choice of how much size, how much line speed wheel, use what's grinding parameters, in order to make the sharpening of knives get smaller surface roughness, in order to effectively avoid the tool surface cracks and burns, ensure better quality sharpening issues such as interpretation. Carbide tool sharpening depends on the combined effect of the level of quality parameters wheel, grinding parameters, tool material and grinding methods and other factors; improved cutting tool surface roughness smaller.

Tungsten Carbide Cutting Tool Wear Mechanism

In the initial stage of tungsten carbide tool wear, plastic deformation of Co binder phase in the surface layer is extruded Co WC grains. Due to the small Co hardness, good ductility, under certain conditions, may be in surface friction micron film formation, while a hard WC particles are slowly protruding from the friction surface, to avoid the rapid wear of the surface and further, the procedure proceeds to friction relatively stable phase. With the loss of binder phase of Co, WC skeleton material destruction, a significant increase in the dislocation density WC particles, when the dislocation density is accumulated to a certain amount, it will form a micro-cracks in the WC particles, and thus make WC carbide particles begin to pull out from the matrix. Shedding of WC particles remain in the wear area into abrasive, under load extrusion occurs and the substrate, resulting in plastic deformation and breakage of new grains.