Hard-alloy Cutters Research Articles

Modeling of Surface Roughness and Tool Wear when Finishing Milling Process of the Circular Bevel Gear

1. THINH H.X., 2021, Study the Effect of Cutting Parameters on Tooth Surface Roughness and Tool Wear During Finishing Cutting Process of Spiral Bevel Gears Using Hard Alloy Cutter, PhD thesis, Hanoi University of Industry. Google Scholar

Chatter prediction of milling process for titanium alloy thin-walled workpiece based on EMD-SVM

Easy cutting vibration of Titanium alloy thin-walled structural components in processing process directly influences the quality of part machining surface. So, the chatter prediction has become a research hotspot. The milling process of Ti-6Al-4V framework parts for hard alloy cutter is researched and chatter prediction methods are proposed to solve the chatter problem generated in milling process. The signals in milling process are comprehensively considered to work out the stability boundary and the chatter prediction model based on Empirical Mode Decomposition (EMD) and Support Vector Machine (SVM). The stability lobe diagram is utilized to select experiment parameter for experiment, in which the 1/3-2/3 position of framework parts chatters easily in processing. The model training in experiment aims to monitor the time of chatter, with the recognition precision of 97.50%.

Evaluation of the stressed state of cutting elements of coated end-milling hard-alloy combined cutters

This paper compares stresses arising in the tool material of combined end-milling cutters and their admissible values with the purpose of preventing cutter destruction. The limit stress values of tool materials for the developed endmilling hard-alloy combined cutters having an interfaced cutting part and tailpiece were investigated. The cutting part was made of a tool-grade hard alloy, and the tailpiece was made of structural steel. To determine stresses, simulation modelling was carried out in the ANSYS and Deform software. The cutting force components were found experimentally. It was assumed that lower cutting force components lead to lower stresses in the tool material. This results in a lower probability of tool material destruction. The process of cutting the hard-to-cut stainless steel 12Kh18N10T was considered at the following parameters: a cutting speed of 70 m/min, a cutting depth of 1 mm, and a feeding of 0.1 mm/tooth. The tool material VK8 with no coating and with various coatings promoting the reduction of cutting force components was studied. It was confirmed that a combined end-milling cutter 16 mm in diameter and 92 mm long can be used to cut parts with the same accuracy as using a solid end-milling hard-alloy cutter. An increase in the length of combined cutters decreases the cutting accuracy; however, for lengths 123 and 180 mm, these cutters can be used to manufacture parts applied in general machine building. Therefore, combined end-milling cutters can compete with solid cutters in terms of the manufacturing accuracy and resilience period, which limits the existing applicability of solid cutters. The cost of combined cutters is 10–60% lower than that of solid cutters.

Finish boring process of hard alloy cutter based on electrostatic cooling-aided machining

A boring process based on electrostatic cooling is proposed, and the effectiveness of the cooling process is verified by simulation and experiment. First, the action mode of active gas in the cutting area is analyzed on the basis of the electrostatic cooling mechanism and metal cutting law. Second, a corona discharge device with an external gas path is designed, and the attenuation law of the length and bending degree of the external gas path on the concentration of active gas in the transmission process is analyzed as well. Third, the precision boring cutter is modified into an internal cooling precision boring cutter with an external gas path. The gas concentration attenuation value at the outlet of the boring head is also obtained. Finally, finite element simulation and experimental analyses are conducted. Results show that the error of main cutting force between simulated and theoretical calculation is less than 2.65%, which verifies the correctness of the simulation. Electrostatic cooling can obviously reduce the feed force and cutting temperature, improve the wear life of tools, and achieve the effect of wet boring compared with dry cutting. The results of this study can be applied to the cooling process modification of cylindrical holes, V-shaped grooves, end faces, and threads during boring. In addition, it can also provide theoretical support for the cooling effect of gear hobbing experiments, welding, and other processes.

Повышение эффективности плоского шлифования за счет применения рациональных рабочих циклов

A possibility for machinery billet machining effectiveness increase at the expense of the use of high-speed grinding machines operated in an automated cycle of machining mode changes is considered. It allows performing operations of roughing and then finishing ensuring the required accuracy and quality of surfaces worked. The application of high-speed force grinding allows rejecting rough and finish preliminary milling and, in such a way, decreasing the number of machine equipment, hard-alloy cutters, production areas and increasing labor productivity.

The effect of electro-erosion treatment of the surface of hard alloy plates on their phase composition and soldering of nitride ceramics cutting elements

The effect of electroerosive treatment of the surface of carbide plates from superhard nitride ceramics on their phase composition and vacuum soldering of cutting elements is studied. Studies of the surface quality and elemental composition have been carried out. The surface of the plates for soldering is processed by the method of electroerosive cutting with brass wire in water, as well as by the method of electroerosive direct burn-through using copper and graphite electrodes in kerosene. The microstructure and elemental composition of the surfaces of hard-alloy plates were investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy before and after their processing. The analysis of the obtained data indicates that the best results at electro-erosion treatment of the hard-alloyed plate and the strongest bonding of brazed materials are achieved using a copper electrode and brass wire, since this ensures maximum wetting of the plate surface with solder based on Cu–Ti–Sn and the absence of pores. The hard-alloy cutter plate and ceramic cutting element were joined by high-temperature brazing in vacuum. Tests of hard-alloy plates with brazed cutting elements showed that the roughness of the machined surface of workpieces made of ХВГ steel with hardness of HRC 47–62 and ШХ15 steel with hardness of HRC 57–58 corresponded to 6–8 purity class at cutting speed of 155–170 m/min. The wear of the cutter along the trailing edge of 0.4 mm served as a criterion for evaluation of the cutting properties of superhard materials according to the results of durability tests.

Surface Quality after High-Speed Grinding

In producing machine parts from the hard materials used today in the military–industrial complex, attainment of the required precision is difficult and sometimes unfeasible unless finishing operations are employed. In general, finishing operations are expensive and slow and they require highly skilled workers and specialized equipment. That considerably increases the production costs. Finishing operations can only be eliminated if the cutters used in the prior machining processes ensure satisfactory surface quality. However, that is not always the case, on account of bluntness of the tool. In the present work, attention focuses on the precision that may be attained in machining key components made of hard materials when using high-quality hard-alloy cutters produced by ultrahigh-speed grinding.

Frictional Coefficients between Aluminum–Silicon Alloy and Cutting Inserts with MPCVD Diamond Coatings

The frictional coefficients at the front and rear surfaces of a VK6 hard-alloy cutter with experimental nano- and microcrystalline CVD diamond coatings applied in microwave plasma are determined by extrapolation to zero cut-layer thickness. It is found that, for diamond coatings with a single microcrystalline layer and those with both a microcrystalline layer and a nanocrystalline layer, the frictional coefficients are less than for an uncoated hard-alloy cutter and also for a cutter with a Sandvik diamond coating.

Determination of maximum working capacity of retrofittable cutters on the basis of physical-mechanical features of tool hard alloys

This research is dedicated to the determination of maximum working capacity temperature of tool hard alloy cutters during a processing of parts by means of cutting made of hard-to-cut materials including assessment of possibility of using of tools made in Russian Federation without loss of the processing efficiency.

Effect of microrelief on the contact shakedown of fixed joints

Under the conditions of cyclic loading at fixed joints, the repeated mutual slip of the contacting surfaces is observed in the contact zone, fretting appears, and the wear and destruction of the assembly elements occurs. The existing methods for overcoming fretting are aimed at reducing its intensity. The finite element analysis of fixed joints of smooth contact surfaces and surfaces with relief under the conditions of cyclic loading of junctions makes it possible to reveal the regions of mutual slip and, to determine the parameters of the microrelief, which contribute the most to the onset of contact shakedown. The method for improving the resistance to fretting in friction units based on achieving the conditions for the onset of contact shakedown using microrelief is implemented for fixed joints of a hard-alloy cutter pick and a drilling bit rolling cutter, as well as for an abutting joint of the rotor impeller shrouds of a universal gas distributor.

Study on the Tribological Properties of Porous Titanium Sliding against Tungsten Carbide YG6

In the metal cutting process, the friction and wear behavior between the cutting tool and machined surface is the most important factor that affects the surface quality and the service life of the cutter. The irregular pore structure of porous titanium alloy has changed its mechanical properties and the processing technology. The friction and wear mechanism of the cutting tool and the machined surface is greatly different from the traditional dense metal processing because of the crumbling at the edges, tearing phenomenon and the pore agglomeration effect of chips. In this paper, the tribological characteristics and the wear mechanism of friction pair which was formed by porous titanium alloy material and hard alloy cutter were studied from cutting force, cutting speed and temperature in micro-cutting condition, and the influence of porosity on the wear rate and friction coefficient was analyzed. Results show that the main factor which influences the friction coefficient and wear rate is the porosity. The wear mechanisms of porous titanium materials were abrasive and oxidation wear while the wear mechanism of tungsten carbide YG6 was abrasive wear. The friction coefficient and wear rate of the relatively stable state are beneficial to improve the surface quality and tool life. As a result, in the micro-cutting process of porous titanium alloys, the best choice of machining parameters for different porosity materials are as follows: the load is about 8 N, the sliding speed is about 400 r/min and the temperature is about 300 °C.

Analysis of structure and bonding strength of AlTiN coatings by cathodic ion plating

AlTiN coating was prepared on the surface of YT14 hard alloy cutter by cathodic arc ion plating, and the surface-interface morphologies, line scans of the interface elements and valence state of chemical elements were analyzed with field emission scanning electron microscopy, energy dispersive spectrometer and X-ray photoelectron spectroscopy, respectively, and bonding strength of the coating was measured with scratching tester. The results show that the elements of Al and N mainly exist in the AlTiN coating with an AlN and AlTiN hard phase, and (the) Ti element mainly exists in the coating with a TiN hard phase, which improve wear resistance of AlTiN coating. The elements of Al, Ti and N are diffused at the coating interface, in which part of Ti atoms are replaced by Al atoms at the TiN lattice, still keep face-centered cubic structure of TiN coating to form metallurgical bonding, and bonding strength of the coating interface measured by scratching tester is 78.75 N, which is beneficial to improving service life of AlTiN coating prepared on the surface of carbide tool cutter.

Selecting the cutting geometry of reground hard-alloy plates for roughing

To extend tool utility, we may regard worn hard� alloy cutters as blanks for further machining. We must take into account here that the cost of new highqual� ity hard alloy is as much as $10 per kg, while experi� ence in regrinding shows that plates with normal wear (without catastrophic wear) are free of internal defects.

Study on Technology Parameters for Coated Carbide Cutting Tools

Metal cutting processing is the most fundamental, most widely and the most important processing in industrial production. Because the development of mechanical manufacturing level plays a very important role in the coating technology material machining process. A coated carbide cutting tool with its high hardness and high wear resistance, good chemical stability and extensive compatibility characteristics, is widely applied in the metal cutting processing field. The author mainly studies the cutting force contrast between coated carbide cutting tools and not coated ones. Cutting tests have testified that if PVD technology applied on cutting, the cutting force of hard alloy cutter will alter with the change of feeds (f), depth of cutting (ap) and cutting velocity (v). The experiment suggests that the size of three-way cutting force of either the brand ZP25 hard alloy cutter or the carbide cutter by employing matrix ZP25 hard alloy cutter to respectively using PVD technology coat TiN or TiCN coating is successively FZP25>FTiCN>FTiN. The main reason for this is that the difference of frictional factor of the three kinds of cutter material and the workpiece material.

Experiment Study on Cutter Disrepair Principle and Optimization for Machining Heat-Resistant Steel

In order to find out the cutter disrepair principle and provide a valuable reference for the design, production and use of the heavy-duty hard alloy cutter, have experiment study on machining the heat-resistant steel-the 3Cr-1Mo-1/4Vsteel. First, have impact disrepair experiments with several types of different grooves milling inserts, and find out the difference of the impact disrepair invalidation types among them, and build the impact disrepair life cumulating distribution function mathematic model. Second, based on the adhering disrepair experiments, find out the difference of the adhering disrepair invalidation types, build the quantitative mathematic relation between milling temperature and maximal adhering disrepair depth on rake face of the cutter, and analyze the rule that the milling temperature affects the adhering disrepair. And then, on the basis of the scene machining, have analysis on cutter disrepair phenomenon and mechanism under the joint action of force and heat, so to provide a theoretical basis on how to avoid premature failure of the tool for the actual production process.

Influence of relative oscillation of the cutting tool and blank on the tool wear

370 Automated equipment with numerical control systems is used in modern production, where rapid changes are required. However, even high-quality control programs cannot always meet the requirements imposed on machine tools. Problems may arise on account of the changing machining conditions for any specified parameter. Important production parameters include the specified productivity and the specified machining quality of the part. The actual productivity and machining quality will depend primarily on the state of the cutting edges of the tool employed. To ensure specified tool life and, hence, to rule out malfunctioning, ongoing control of the machining process is required, on the basis of current information and adequate models. In other words, mechatronic systems must be used. In a technological system, the cutting (machining) process will always be accompanied by other processes that occur at various speeds: high-speed, mediumspeed, and low-speed processes. Wear of the cutting tool is a medium-speed process and is usually related only to the static loads at the front and rear surfaces of the cutting blade. The influence of oscillations of the elastic system is ignored, since these constitute a highspeed process. However, some phenomena that sometimes arise in tool operation even in continuous cutting (for example, the appearance of cracks and subsequent rapid failure of hard-alloy cutters) call for further analysis of the wear model.

Soldering of hard-alloy cutters on units with a mechanical generator

Soldering of hard-alloy cutters on units with a mechanical generator

Effect of selenium on the structure and properties of structural steel

1. Small selenium additions (0.04–0.08%) have a substantial effect on the nature, morphology, and dispersity of nonmetallic inclusions and thus the mechanical, technological, and operating properties of structural steel. 2. Selenium additions, leading to globularization of nonmetallic inclusions, reduce the anisotropy of the ductility and fracture toughness and also susceptibility to brittle fracture (tested with transverse samples). 3. Microalloying with selenium reduces the loss of metal (scrap and rejects) due to metallurgical defects and also the tendency to form quench cracks. 4. In terms of improved machinability with high-speed machining with use of hard-alloy cutters the addition of selenium is much superior to microalloying with lead, especially in machining with use of high-speed steels.

Durability of cutters when cutting porous cermet materials

1. For cutting iron-base porous materials it is better to use cutters with VK-type hard alloys if the pearlitic structural component is absent in the structure of the machined material. 2. When machining these materials with a pearlitic structure it is better to use cutters with TK-type hard alloys if the cutting speeds are within the 20–30 min durability limits. Cutters of VK hard alloys should be used at lower cutting speeds or at higher durabilities. 3. The wear resistance of hard-alloy cutters when turning porous cermet iron-base materials is mainly determined by the thermophysical properties of the tool and machined materials and by the lubricating action of graphite and the difference of wearability of the structural components of the machined material.