Method for assessing the thermophysical properties of the contact pair ‘tool – steel workpiece’

To The analysis of methods for evaluating the properties of contact pairs “hard -alloy coated tool-steel billet” is carried out in order to use them to increase the reliability of the choice of turning modes in the generations of CNC systems equipped with technological intelligence. It is proposed to use the value of the thermo-emf of the test pass as an indirect indicator of the properties of contact pairs composed of a coated carbide tool and a processed steel billet. Models for calculating the cutting speed based on a given tool durability period of a coated carbide tool and predicting the actual cutting tool durability period for given processing conditions are proposed by introducing into their structure an additional informative value about the properties of each contact pair - the thermo-EMF of the test pass. The conducted resistance tests of various carbide plates during the processing of P-group steels showed sufficient reliability of the proposed dependences.

Optimization of the Cutting Tool for Internal Flash Removing Operations in the Production of Electric-Welded Tubes

The article considers the structural optimization results for the process of mechanic removing inside flash during the production of longitudinal electric-welded pipes with a diameter of 60.3 ... 89.0 mm. Mechanical processing was performed with a pipe electric welding unit, designed for the manufacture of pipes with a diameter of 60.0 ... 178.0 mm, using various cutting tools and grades of hard alloys. The influence of the parameters of chip formation and cutting forces on the quality of inside flash removing in a longitudinal electric-welded pipe is found. The experiments were carried out using both the basic and experimental geometry of the cutting tool. The dependence of the tool durability at the operation of flash removing on the hardness of the alloy and the wear resistance of the coating has been studied. The analysis of the results of the study of annular inserts made of a three-carbide hard alloy with a multilayer wear-resistant coating showed the possibility of reducing the consumption of cutting tools and emergency stops of the mill, improving the quality of processing and the rate of yield.

Tool Materials for Turning Specialized Stainless Steels

The article considers the issues of increasing the tool durability when turning specialized hard-to-work corrosion-resistant stainless steels 09Kh17N7Yu, 12Kh18N10T and 13Kh15N5AM3 with standard replaceable carbide tip. To develop recommendations for reducing tool consumption, a number of experimental and simulation studies was performed. The simulation was performed in the Deform software for three parameters: temperature, stress, and strain. The simulation results are compared with the operational parameters (wear of the tool material). Simulation was performed for ten different coatings on a hard-alloy substrate of the VK8 brand. The tool hard alloy VK8 is used as the base tool material, the other tool materials differ in the architecture (design, composition, structure and coating method) of the coatings applied to the VK8 substrate. The techniques of selecting the most rational tool materials are developed. The results obtained by simulation are verified experimentally. A good agreement between the results of simulation and experimental research has been achieved.

Characteristic of the wear of a tool coating based on amorphous carbon during chipboard milling

Characteristic of the wear of a tool coating based on amorphous carbon during chipboard milling. The study verified the durability and the course of wear during the durability tests of the TiAlN / a-C:N double tool coating. The aforementioned coating consisted of a bottom layer of TiAlN and a top layer based on nitrogenenriched amorphous carbon. Standard replaceable cutters for milling heads made of WC-Co sintered carbide were subjected to the modification process. The coating was applied using plasma by RF Magnetron Sputtering. During the tests, the blade wear was measured using a workshop microscope. The VB max indicator measured on the clearance face was adopted as the blunting criterion and its maximum value was set on 0,2 mm. The results show that the additional coating of amorphous carbon contributed to the increase of the tool durability determined with cutting distance. The use of only a single layer based on TiAlN shortened the durability by about 3%. On the other hand, applying both the bottom and top layers TiAlN /a-C:N) extended the cutting distance by about 24%. The research showed a clear advantage in terms of the durability of the blades modified with a multi-layer coating in relation to a single-layer. Moreover, the positive effect of the top layer containing amorphous carbon on tool durability has been demonstrated.

CRITERIA FOR ASSESSING THE COST OF MANUFACTURING PROCESSES AND YOU EFFECTIVITY

The aim of this paper is to theoretically evaluate the process of machining metallic materials and at the same time evaluate the cost reduction defined by the evaluation criteria. When cutting conditions and tool durability optimizing, it is necessary to apply certain optimizing criterion within certain restraining conditions. [12] The restrictions are given by technical parameters of a machine, tool, machined material, required quality of machined surface etc. The essential economic criterion is the amount of production cost. The notion of “machinability of materials” is a complex of characteristics of the machined material which is monitored in the view of its fitness for the production in a certain way of machining.

Experimental Study on Wear of Indexable Coated Blades as Applied to Cutting of PCrNi3MoVA Gun Steel Workpieces

In this paper, based on the theoretical study of tool wear and the systematic analysis of the main factors affecting the tool durability, four types of PVD and CVD-coated blades from three manufacturers were subjected to cutting tests using PCrNi3MoVA gun steel workpieces. The wear morphology, fatigue curves, and chip patterns of the tested blades were comparatively analyzed. The influence of the coating type on the tool durability was investigated using a scanning electron microscopy and energy dispersive spectroscopy. The results obtained strongly indicate that TiAlN coating deposited by the PVD technology has the best thermal stability, temperature oxidation resistance, and tool durability when cutting PCrNi3MoVA gun steel workpieces under semi-finishing conditions. The wear resistance of the other three types of blades was relatively lower due to less favorable coating compositions and structures. The study findings are instrumental in the substantiated selection of cutters for practical applications and provide a reference for the design optimization of indexable coated inserts.

Influence of machining parameters on the polymer concrete milling process

The paper examines the wear of end mill cutters, the parameters of a workpiece’s surface layer and the values of cutting forces during the machining of polymer concrete, which is one of the most difficult-to-cut materials. Increased abrasive wear of the active cutting edges is a result of the heterogeneous structure of this material, and it has a negative effect on the cutting process, the durability of the cutting tools as well as the roughness of the workpiece. It is very important to determine the machining parameters for this material from a tool durability and quality of machining point of view. The research was divided into two stages. In the first stage, the appropriate machining parameters were determined based on the measurement of the components of the cutting force. In the second stage, durability tests of four end mill cutters were carried out. During the tests, the component cutting forces, tool wear and surface roughness were measured. The highest tool durability was recorded for the monolithic cemented carbide cutter with coating NC Mill G9F42120N 4F. Tools made of high-speed steel should not be used for machining polymer concrete, as they exhibited the highest intensity of tool wear. The rapid loss of machinability of these tools leads to a rapid increase in cutting force and the roughness of the machined surface. From an economic point of view, cemented carbide end mill cutters with coatings seem to be the appropriate choice for machining polymer concrete.