Regrinding and recoating of the hottest coated too

Regrinding and recoating of coated tools due to the high surface hardness, the grinding ratio is small when grinding with ordinary grinding wheel, and regrinding is difficult. Many operators discard it as a tool without regrinding, resulting in great waste. This paper introduces the regrinding and recoating methods of coated tools

coated cutting tools are hard to melt metal or non-metallic compounds with good wear resistance, such as tic, tin, TiCN, TiAlN, Al2O3, C3N4, MoS2, DLC and diamond, which are coated on the surface of cemented carbide or high speed steel (HSS) matrix with good strength and toughness by vapor deposition method. It can be coated with a single coating, as well as composite and multi-component coatings. A high-speed and powerful drill bit launched by Sumitomo Electric Co., Ltd. of Japan is interactively coated with 1000 layers of tin and AlN nano ultra thin films on the tungsten cobalt cemented carbide matrix, with a total coating thickness of about 2.5 μ m。 The ZX coated end milling cutter developed by the company has up to 2000 thin layers of ultra thin film, and the thickness of each layer is about 1 nm, which solves the contradiction between the higher the hardness and wear resistance of the tool material and the lower the strength and toughness

as a chemical barrier and thermal barrier, the coating reduces the diffusion and chemical reaction between the tool and the workpiece, thus reducing the crescent wear. Coated tools have the characteristics of high surface hardness, good wear resistance, stable chemical properties, heat and oxidation resistance, small friction coefficient and low thermal conductivity. When cutting, they can increase the service life by more than times compared with uncoated tools, increase the cutting speed by 20%-70%, and improve the machining accuracy by 0.5% Level, reduce the tool consumption cost by 20%-50%. Therefore, coated cutting tools have become the symbol of modern cutting tools. In industrial developed countries, the proportion of coated tools has exceeded 70%, and 80% - 85% of the tools used in numerical control machine tools (NC) and machining centers (MC) in the United States are coated tools. At present, all kinds of cutting tools used in cutting, including turning tools, boring tools, drill bits, reamers, broaches, taps, thread combs, rolling heads, milling cutters, forming tools, gear hobs, gear shapers and shaving cutters, can adopt coating technology to improve their performance

coated blades and their cutters

now, Hunan Zhuzhou Cemented Carbide group company in Chinese Mainland has and can continuously test products that can provide Yb series, CN series and Ca series of coated cutters. Sichuan Zigong Cemented Carbide factory, Shanghai Tool Factory Co., Ltd., ionbond (Suzhou) and shengpeier super coating (Suzhou) Co., Ltd. and other enterprises can provide users with products of various coated cutters or coated blades

it must be pointed out that there is a misunderstanding in the use of coated tools at present. Due to its high surface hardness, when the tool is worn or the coating is peeled off, due to the small grinding ratio when grinding with ordinary grinding wheel, it is difficult to Regrind, so many operators discard it as a tool without regrinding, resulting in a great waste. The coated tool must be reground after wear. When regrinding the coated tool, it is necessary to grind off all the worn parts on the tool. For tools that only need to regrind the front face (such as broach, formed turning tool, formed milling cutter, gear hob and gear shaper cutter) or tools that only need to regrind the rear face (such as drill bit and reamer), if the coating on the other face adjacent to the cutting edge (such as the spiral chip groove of drill bit) is not damaged, the wear resistance of the tool can be improved. After regrinding, the service life of coated tools can reach about 50% or more of that of the original coated tools, which is still higher than that of uncoated tools

diamond grinding wheel can be used for grinding coated carbide tools. However, when grinding coated high-speed steel tools, cubic boron nitride wheel grinding has a better effect. The worn parts of the tool should be completely removed, and the coating should not peel off, but the tool should not be annealed

an important problem of using coated tools is the recovery of cutting performance of tools after regrinding, that is, whether the tools can be coated (recoated) again after each grinding (opening). Table 1 lists the wear resistance test results of coated high-speed steel gear hobs and gear shapers after regrinding the rake face and then recoating. Table 1 number of gears processed by gear hobs and gear shapers without coating, coating and repeated coating

it can be seen from the above table that the service life of gear hobs and gear shapers after coating and repeated coating has been significantly improved. The actual test shows that the film thickness does not increase significantly on the repeated coating layer of the above gear hob and gear shaper cutter, but the gear processed with the tool after multiple recoating can still meet the accuracy requirements specified in the drawing. After 17 times of repeated coating, the cumulative total thickness of the coating film on the flank of the gear hob is still only μ m. Moreover, the coating film is uniform on the tool surface, and the newly coated film forms a metallurgical combination with the original coating. There is no discernible boundary layer and no obvious holes between the two. Repeated coating is also effective for other tools such as fried dough twist drills, reamers and end mills

when recoating coated tools, new coating materials can be used in addition to the original coating materials. The actual application shows that if TiAlN new coating material is used when recoating tin coated tools, both the cutting speed and the service life of the tools will be significantly improved. In addition, the service life of coated tools also has a certain relationship with the film thickness. If the tool surface wear is taken as the benchmark in the future, the tool life will increase with the increase of film thickness, but the film thickness is 5 μ M, that is, the service life is no longer significantly increased. If the crater depth of the previous tool surface is the benchmark of the tool life, the tool life is proportional to the film thickness, and no saturation is found. However, when the film layer is too thick, it is easy to cause peeling, so the coating thickness of tools now generally does not exceed μ m。

for regrinding forming tools, only recoating can ensure that the total service life of the tools is increased by more than times. All recoated tools must first be ground according to the process requirements, and the polished part is not allowed to have various quality defects, such as grinding paste, burr, etc. During recoating, local shielding technology can be used to coat only the grinding surface. For recoating without shielding technology, after recoating times, the coating thickness of one side of the tool, which is an effective tool for human beings to fight against disease, will be too large, which will affect the accuracy of the tool and produce local peeling phenomenon. At this time, the tool should be recoated after film removal treatment. The cutting performance of the tool after recoating is generally not lower than that of the tool newly coated for the first time. The tool can be recoated many times until it is scrapped

it can be seen from the above that recoating has great potential to improve tool wear resistance and productivity. Generally, cemented carbide manufacturers can recoat. At present, there are special coating companies in Chinese Mainland to carry out this business, such as Shanghai nano coating Co., Ltd., a Sino Swiss joint venture, which is a large coating service center, which specializes in coating, regrinding and recoating services for cutting tools. The company has introduced four sets of coating equipment, which can be coated with s-altin (super aluminum nitride), s-tin (super titanium nitride), TiCN, DLC, CrN and other coatings. However, whether the coated tool needs to be recoated after regrinding depends on whether the tool can be recoated technically and economically

enterprises talk about coatings and tools

as for tools, major breakthroughs have been made in coating technology, superhard materials, cad/cam software, etc., especially the rapid development of coating technology. So, what efforts have tool enterprises and coating enterprises made in this regard

iska: direct to "rapid metal cutting"

improve tool performance, and the most basic research and development direction is to improve tool materials. This involves two aspects: substrate and coating

cemented carbide matrix has a basic characteristic, that is, the higher the toughness, the lower the wear resistance; vice versa. Therefore, when intermittent cutting, such as milling and discontinuous turning, the matrix with high toughness can be selected; When continuous finish turning is carried out, the matrix with high wear resistance shall be selected

the development of ultra-fine grain grades breaks the conventional law of the matrix. Ultra fine grain brand, with high wear resistance and high toughness. This opens a channel for the versatility of blades and cutters. Ic07 and ic08 ultra-fine grain cemented carbide matrix introduced by iska is a model of general-purpose cemented carbide matrix, with high wear resistance and high toughness. In particular, ic908 after coating treatment, with the perfect combination of substrate and coating, can be used for drilling, grooving, cutting and milling of steel, hardened steel, stainless steel, superalloy and cast iron. Ic908 has been on the market for many years, and has won the trust of many users because of its excellent performance in processing

in recent years, iska has also made great progress in coating technology, mainly in the following aspects:

1, medium temperature chemical vapor coating (mt-cvd). Compared with Ti (C, n) prepared by high temperature chemical vapor coating (ht-cvd, deposition temperature, 100 ℃), Ti (C, n) prepared by medium temperature chemical vapor coating (mt-cvd, deposition temperature, 100 ℃) has a dense structure and a thickness of 10 μ M above, and it is columnar crystal, and the stress of tool surface damage is smaller after coating. This cemented carbide coating treatment has higher wear resistance, thermal shock resistance and higher toughness. When applied to high-speed heavy cutting and dry cutting under harsh conditions, the tool life is significantly improved. Iska adopts medium temperature chemical vapor coating technology in class P brands such as ic8150-ic8350 and ic9150-ic9350, and class k brands such as ic5005, ic5010 and ic5100

2. Cemented carbide α- Al2O3 coating technology. When depositing Al2O3 coating, Al2O3 will show different crystalline phases with different deposition temperature, such as: γ、δ、α、κ- Al2O3, etc. Among them, only α- Al2O3 is a thermodynamically stable structure. Due to the change of process conditions, the α Phase κ Phase Al2O3 mixture, which reduces the performance of the coating. When the product standard is not specified, iska can now obtain pure through strict control of process parameters α- Al2O3, and control its crystal growth direction, showing a columnar structure; And name this technology α- TEC。 Iska will also α- Tec technology has been applied to class P brands such as ic8150-ic8350 and ic5400, and class k brands such as ic5005, ic5100 and ic5010

3. Adopt composite coating (do-tec). This technology is based on medium temperature chemical vapor coating (mtcvd) surface for PVD coating. Iska's dt7150 brand adopts this technology. TiCN is the bottom layer, Al2O3 is the middle layer, and tin is the transition layer, all of which adopt medium temperature chemical vapor coating technology; TiAlN is the top layer and adopts PVD coating technology. This brand performs well in medium high speed milling of gray cast iron and nodular cast iron

4. TiAlN (PVD) coating or AlTiN (PVD) coating is used. TiAlN is purple black, with a hardness of 35gpa and a friction coefficient of 0 6. The maximum service temperature is 800 ℃, which can be used for processing difficult to machine materials, dry cutting and hard cutting. This coating is applied to ic908, ic907, ic808, ic830, ic928 and ic950 of iska

and AlTiN is black, with a hardness of 38gpa and a friction coefficient of 0 7. The maximum service temperature is 900 ℃, and the performance is better than TiAlN coating. This coating is applied to IC900, ic903, ic810 and ic910 of iska

5. Beam magic coating technology (sumo-tec) is adopted. When the beam magic technology is applied to the chemical coating, through special process control, the stress on the CVD coating surface is effectively reduced and the thermal cracking is reduced