Powder Wire Research Articles

Development of a Model of Transition Element Factor of Alloying Elements of Self-Shielding Flux-Cored Powder Wire and Optimization of its Core Filler Composition

Development of a Model of Transition Element Factor of Alloying Elements of Self-Shielding Flux-Cored Powder Wire and Optimization of its Core Filler Composition

ВОССТАНОВИТЕЛЬНАЯ НАПЛАВКА И ЭЛЕКТРОМЕХАНИЧЕСКАЯ ПОВЕРХНОСТНАЯ ЗАКАЛКА ЗАМКОВ БУРИЛЬНЫХ ТРУБ

The main reason for the wear of the drill pipe locks when rotating in an open borehole is the presence of a solid layer in aggressive geological formations. (Research purpose) The research purpose is increasing the physical and mechanical properties of the surface layer by researching and developing a technology for hardening the outer surfaces of drill pipe locks restored by electromechanical surface hardening. (Materials and methods) Surfacing was performed on the coupling parts of drill pipes with thread Z-147 in the strength group G105. They were fused with a powder wire of various chemical composition back-to-back with three belts on each sample. Wear tests of surfacing were carried out on a test bench using a special technique (resistance to abrasive wear). The chemical composition of the surfacing indicates a carbon content in the surface layer of 0.28 to 0.40 percent. Methods of restoration of locks by surfacing were examined and the physical and mechanical properties of the surface layer of the restored drill pipes were evaluated, the microstructural state of the base and deposited metal was analyzed. (Results and discussion) It was noted that despite the large number of technologies for surfacing drill pipe locks, the special equipment used, the high labor intensity and cost of surfacing processes and subsequent turning on pipe-cutting machines, it is not possible to increase their wear resistance. This is due to the insufficient hardness of the surface layer of the deposited locks (no more than 28-32 on the Rockwell scale), which does not exceed the surface hardness of the new drill pipe. An experimental increase in the hardness of the surface layer of the deposited samples after electromechanical surface hardening was confirmed. (Conclusions) The results of wear tests of deposited materials indicate the effectiveness of electromechanical surface hardening of reducing surfacing.

Дослідження відновлення корпусних деталей автомобільних двигунів методом електродугової металізації

Road transport ensures a rational organization of production and transportation of products. The cylinder block is a basic part, mechanisms and engine parts are attached to it. Engine blocks are operated with high loads. Defects arise and develop, which can be eliminated during major repairs. Improving the methods of restoring worn cylinder blocks of automobile engines is an urgent task. The possibility of restoring parts with such defects by gas-thermal methods was considered. The total level of defects that can be eliminated by applying a restorative coating by the method of electric arc metallization is 37%. The analysis of literary sources shows that surfacing and welding methods do not ensure the quality of the restored part. Gas-thermal methods are often used in the process of repairing parts. The most technological and effective is electric arc metallization. Productivity of electric arc metallization can be very high. Operating costs of using electrometallization are small. The equipment is relatively simple. Restoration of parts by electric arc metallization increases wear resistance and durability of the engine. To assess the repeatability of block defects, we analyzed a sample of 20 truck cylinder blocks from different manufacturers. It was established that the resource of the block depends on: wear of the main bearing beds, holes, cracks, damage to the thread and breakage of pins and holes. Laboratory experiments on the application of electroplating coating were carried out on samples of high-strength cast iron. Preparatory processing of samples - shot blasting. Experiments on sputtering of samples were carried out with known powder wires PG-SR4 and PG-SR4+3% Al with a diameter of 2.0 mm. Spraying was carried out with an EM-17 electric arc metallizer. Tests on the adhesion strength of the coating to the base metal were carried out using the adhesive method. From the research results, we can see that the coating applied with PG-SR4+3%A1 wire is destroyed at the joint under a higher load than the corrosion formed by PG-SR4 wire. At the same time, the adhesion strength also exceeds, and is 22.9 MPa. The microhardness of the coating built up with powder wire PG-SR4+3%A1 exceeds the level of microhardness of the surface built up with wire PG-SR4. Microhardness in both cases. decreases with distance from the surface of the deposited layer. Conclusions. From the conducted research, it follows that the electric arc restoration does not have a thermal effect on the part, provides high adhesion strength of the applied layer, which prevails over the majority of traditional methods of restoration of parts. In addition, the method of electric arc metallization is characterized by low energy consumption, small-sized and mobile technological equipment. Therefore, there is a need to continue the research of electric arc metallization in the restoration of worn surfaces of car parts.

Fusion of dies with economy-layed secondaryhard-ducted steel

Problem. The purpose of the work is to increase the wear resistance and heat resistance of secondary hardening surfacing steels by improving the composition of alloying powder wires due to the optimization of the content of titanium, molybdenum and chromium. It was found that increasing the heat resistance of iron-based Cr-Mn-Ti alloys contributes to an increase in the content of the carbide phase [TiC]; the introduction of [Mo] stabilizes the value of hardness at elevated temperatures, increases heat resistance and hardness during dispersion hardening. High indicators of heat resistance and wear resistance of steel 18X4G10M5T3S are achieved due to additional diffusion formation of the carbide phase during aging, increased contact strength, a significant amount and uniform distribution in the volume of the deposited metal of the carbide phase. Goal. Іncreasing the wear resistance and heat resistance of secondary hardening surfacing steels by improving the composition of alloying powder wires due to the optimization of the content of titanium, molybdenum and chromium. Methodology. For automatic arc surfacing under the flux, attachment devices were designed and manufactured for feeding the de-energized flux-cored wire into the welding bath. The use of these devices on the A-1401 and TS-17M welding machines made it possible to study the influence of the de-sintering additive on the deposition parameters, chemical and phase composition of the deposited metal. The surfacing was carried out on samples made of steel 20 and 50 KhNM according to the "slide" scheme. The powder wire was produced at the laboratory facility of the Department of Welding Production of UIPA. The crack resistance of the alloys was studied at the LTP 1-6 installation. Results. On the basis of experimental studies, it was established that automatic surfacing with a de-energized additive increases the technical and economic indicators of melting - the surfacing coefficient is up to 30 g/Ag, the share of the base metal in the surfacing decreases to 11...14%, reduces the specific fuel costs and energy costs - increases the specific energy for the formation of a seam above the conventional limit of fusion and thermal efficiency. by 60...70% and 40...50%, reduces the coefficients of the relative mass of slag by 24...28%, increases the absorption coefficients of alloying elements by 70...80% in contrast to single-electrode melting. Originality It was found that increasing the heat resistance of iron-based Cr-Mn-Ti alloys contributes to an increase in the content of the carbide phase [TiC]; the introduction of [Mo] stabilizes the value of hardness at elevated temperatures, increases heat resistance and hardness during dispersion hardening. Practical value. On the basis of the conducted research, economically alloyed wear-resistant alloys and the technology of their application were developed to restore the grooves of the matrices of hot metal stamping dies. The use of these alloys and the technology of their application ensures a reduction in energy and resource costs and an increase in the durability of the stamping tool.

Influence of tempering on structure of deposited high speed steel coatings

The technology of plasma surfacing in a protective-alloying nitrogen medium with an additive powder wire is characterized by high productivity and the possibility of alloying the deposited metal. Durability of metal products depends on microstructure, chemical composition, production technology, modes of thermal and surface treatments. The article presents the results of a study of structure and microhardness of the high speed alloy R18Yu deposited in nitrogen medium on medium-carbon steel 30KhGSA. There were no differences in structure of the surfacing layer up to 4 mm in depth, but after four times high-temperature tempering at 580 °C, structural and phase changes were revealed. The values of microhardness after surfacing and tempering are consistent with the literature data.

Nitrogenous Porosity and Ways to Prevent it Under Conditions of Arc Surfacing in a Nitrogen-containing Atmosphere

Pores coming to the surface can cause a violation of the tightness of the valve when the valve is closed, as well as be a focus of erosive destruction, especially in conditions of high-speed flows of the medium. Pores also contribute to the corrosive destruction of metals, since under the influence of certain aggressive media, they increase in size and cause a breach of the tightness of the gate. In the presence of carbon dioxide, nitrogen absorption by the weld pool metal increases and the tendency of the deposited metal to form pores decreases. The introduction of carbon dioxide of at least 30% to nitrogen makes it possible to obtain a dense deposited metal due to its better absorption of nitrogen. A significant factor reducing the formation of pores from nitrogen in the deposited metal 10X17H8X5G2T is the content of ferrotitane in the charge of the PP-AN 133 powder wire. The titanium content in the deposited metal should be within 0.2...0.4%. A further increase in the concentration of titanium leads to a deterioration in the formation of the deposited metal and to an increase in the amount of slag on the surface of the deposited layer

Влияние режимов дуговой автоматической сварки на геометрические параметры шва стыковых соединений из низкоуглеродистой стали, выполненных с применением экспериментального флюса

Introduction. The metallurgical industry in the territory of the Russian Federation has accumulated a significant amount of slags obtained during the smelting of steels and cast iron. The presence of slag dumps adversely affects the ecology of regions with metallurgical enterprises. When reducing iron from slags, the by-product becomes an oxide agglomerate, which can be considered as a flux composition for arc welding/surfacing under a layer of flux, fillers of powder wires, coatings of welding stick electrodes. The purpose of the work is to establish the possibility of arc welding using the flux obtained by the authors and to determine the optimal welding modes with the condition of achieving the geometric parameters of the seam according to GOST 8713-79 and the quality of the welded joint (absence of internal defects). In this paper, butt welded joints of sheet steel VSt3sp with a thickness of 5 mm obtained by automatic welding under a layer of flux at direct current with forced formation of a root roller on ceramic linings using flux from recycled metallurgical slag of an electric steelmaking enterprise are investigated. Automatic welding of flat specimens was carried out on a tractor-type ADF-1250 machine with a wire with a diameter of 3 mm, at a constant welding speed of 54 cm/min with varying current and arc voltage within 400–600 A and 27–37 V. The methods of investigation: Visual measuring and radiographic control, determination of deformation of specimens by laser scanning and computer processing of 3D models were used to evaluate the quality of welded joints. Statistical modeling in the form of a two-factor experiment was also used in the work, with obtaining adequate regression equations of the influence of welding modes on the geometric parameters of the seam: the height of reinforcement and the width of the seam on the front and back of the joint. Results and discussion. The possibility of obtaining welding fluxes from metallurgical slags of an electric steelmaking enterprise and its use for creating welded joints is shown. Optimal modes of arc welding of thin-walled sheet parts made of low-carbon steel with forced formation of a root roller on ceramic linings is established, ensuring the absence of internal defects in the form of pores, cracks and lacks of penetration, a minimum of residual deformations and compliance of the weld size with the requirements of the existing standard. The nominal values of the geometric parameters of the seam according to GOST 8713-79-C4 correspond to welding mode: welding speed 54 cm/min, welding current 550 A, arc voltage 30 V. The results of the work can be applied in metallurgical electric steelmaking enterprises producing low-carbon steel in the development of technologies for the use of welding materials from slag.

Microstructure and properties of HEA fabricated through metal powder wire arc additive manufacturing

This study underscores the successful attainment of a homogeneous chemical composition within the billet, demonstrating its aptness for uniform material properties. Nevertheless, microstructural variations, encompassing texture, grain size, dislocation density, and microhardness, were discernible along the height of the billet. These variations are attributed to the presence of intricate oxides, which originate from the purity of the initial metal powder. Importantly, despite these microstructural disparities, the mechanical properties of the high-entropy alloy (HEA) billet exhibited consistent distribution. These observations emphasize the pivotal role of microstructural control in customizing HEA properties for specific applications.

Characteristic Features of Structure and Analysis of Friction Behavior of Electric-Spark Coatings from Powder Wires

Characteristic Features of Structure and Analysis of Friction Behavior of Electric-Spark Coatings from Powder Wires

AN EXAMPLE OF DIAGNOSTICS OF A TECHNOLOGICAL CUTTING SYSTEM WHEN MILLING MATERIALS OF HIGH HARDNESS

There is a growing demand for materials that have a layer of high hardness applied on a soft base. Technologies for obtaining such materials have been developed. One of the technologies is based on the use of surfacing from specialized powder wire. The hardness of such a surfacing is HRC 65. Accordingly, there are difficulties in processing such surfacing. The paper considers the features of milling such surfacings with a face mill with mechanical fastening of replaceable carbide plates. The purpose of the work is to improve the efficiency of the milling cutters and to identify a method by which it is convenient and reliable to diagnose the condition of the cutting plates of the milling cutter. The paper shows that the goal is achieved by using the acoustic emission method, in particular by using the parameter "total count of the number of acoustically active events".

Analysis of Microstructural Parameters of a Layer Clad from Fe – C – Si – Mn – Cr – Ni – Mo – V Powder Wire

Analysis of Microstructural Parameters of a Layer Clad from Fe – C – Si – Mn – Cr – Ni – Mo – V Powder Wire

Microstructure and Tribological Properties of Metal Layer Deposited by Arc Cladding of Powder Wire Containing Titanium Powder

Microstructure and Tribological Properties of Metal Layer Deposited by Arc Cladding of Powder Wire Containing Titanium Powder

Вплив складу шихти порошкових дротів на механічні властивості та корозійну стійкість електродугових покриттів

Electric arc spraying of coatings is common in many branches of industrial production, in particular to restore the geometry of machine parts worn in operational conditions, to increase their protection against abrasive and gas-abrasive wear (at the same time, both at climatic and at technologically determined elevated temperatures). Coatings sprayed using powdered wires are characterized by high chemical heterogeneity, which significantly distinguishes them from electric arc coatings made of solid wires. This is due to the different chemical composition of the droplets formed from the molten powder wires and carried by the air jet to the surface of the substrate, forming a coating on it. The charge with alloying elements in its composition (including difficult-to-melt ones such as FH, B4C, FHB) does not have time to fully melt and mix with the melt of the steel shell. It is clear that because of this, the melt droplets of flux-cored wires dispersed by an air jet will have a different chemical composition and , as a result, the coatings formed from these droplets on the surface of the substrate will be characterized by high heterogeneity and significant chemical heterogeneity, which will affect their physical and mechanical properties at different operating temperatures and especially when exposed to corrosive environments. To ensure high corrosion resistance of electric arc coatings in aggressive environments, it was necessary to reduce their chemical microheterogeneity and achieve a sufficiently high chromium content (it should be more than 12 wt.%) in each of its lamellae. To achieve this goal, ingredients were added to the composition of the charge, which enabled the formation of eutectics with a low melting temperature, with the dissolution of such refractory components of the powder wire charge as carbides, borides, refractory metals and alloys. Microhardness measurements showed that the highest hardness was achieved by electric arc coatings made of powder-coated wires №. 2 (20X16Р3Н2ГС) and powder-coated wires №. 5 (Х17Р3С). This happened due to the presence in the charge of 3 wt.% of boron, which entered their charge as part of the FHB-2 ferrochromiumboron powder. Phase analysis of these EDPs revealed the segregation of finely dispersed FeCrB and FeCr2B borides in their ferrite structure. However, the cohesive strength of these coatings did not exceed 100 MPa. This was explained by the fact that during filing, residual first-order tensile stresses could occur in their structure, which, as a rule, contribute to the cracking of the coatings during their subsequent mechanical processing. Therefore, before applying coatings from such powdered wires, the base for spraying should be heated to 150...200ºС. Conclusions. 1. To ensure complete fusion of the components of the powder-coated wire charge with each other and with its steel sheath, it is proposed to add Fe-Mn, Fe-Si ferroalloy powders to the powder-coated wire charge, which are able to interact with the refractory components of the charge with the formation of low-temperature eutectics. The legality of such a component composition of the charge of flux-cored wires as an effective method of reducing the melting temperature of the components has been experimentally substantiated. 2. The addition of ferrosilicon, ferromanganese powders and self-fluxing alloy PН-10Н-01 to the charge of flux-cored wires based on ferrochromium and ferrochromium ensured high hardness of electric arc coatings, low heterogeneity of the chromium content in the lamellae, and, as a result, high corrosion resistance, which comparable to that of stainless steel

Economically alloyed powder wires and method their multilayer plasma surfacing in nitrogen medium

A method and powder wires are developed for multilayer plasma surfacing with heat-resistant highhardness steels such as R2M9Yu steel additionally alloyed by nitrided ferrochrome and titanium. The surfacing method with low temperature heating and surfacing materials prevent the formation of cracks during the surfacing process and ensure the hardness of the deposited metal up to 59...60 HRC without additional heat treatment. It is established that the main phases in the deposited metal are a solid solution of α-iron, carbides and carbonitrides based on iron, tungsten, chromium, molybdenum, aluminum and titanium.

Рroperties of wear resistance nickel-free steel with secondary curing for building up stamps of metal hot processing

Problem. The problem, i.e. the reduction of energy and resource consumption during surfacing of a stamping tool can be solved by using dispersion-hardening alloys, limitedly alloyed with chromium (up to 3%), increasing the amount of carbide phase due to the introduction of carbide-forming elements, replacing nickel with manganese, and using surfacing with a de-current additive for their application. The purpose of the work is to increase the wear resistance and heat resistance of secondary hardening surfacing steels by improving the composition of alloying powder wires due to the optimization of the content of titanium, molybdenum and chromium. Methodology. Surfacing was performed with a TS-17M welding tractor under a flux of flux-cored wires with a de-energized additive fed into the main part of the welding bath. Surfacing modes – Iд≈300......320 A; Ud≈34...36 V; Un≈23.7 m/h; Up.e.≈93.75 m/h. The participation rate of the de-energized additive varied within 0...75%. Results. The increase in the content of the [TiC] phase contributed to the increase in the heat resistance of Cr-Mn-Ti alloys based on iron. The introduction of [Mo] stabilized the value of hardness at elevated temperatures, increased heat resistance and hardness during dispersion hardening and additional diffusion formation of the carbide phase during aging. Originality. To increase the alloying of the deposited metal, surfacing with de-current additive was proposed, which allowed to increase the assimilation coefficients of alloying elements. Practical significance. Production tests of stamps welded with these steels made it possible to increase their durability by 1.8 times compared to 5KHNM steel.

Effect of Titanium on the Structure and Properties of Clad Metal from Powder Wires of Fe – C – Si – Mn – Cr – W– V and Fe – C – Si – Mn – Cr – Mo – Ni Systems

Effect of Titanium on the Structure and Properties of Clad Metal from Powder Wires of Fe – C – Si – Mn – Cr – W– V and Fe – C – Si – Mn – Cr – Mo – Ni Systems

Influence of twist pitch on hysteretic losses and transport J c in overpressure processed high J c Bi-2212 round wires

Bi-2212 is the only high field, high-temperature superconductor (HTS) available in the macroscopically isotropic, multifilament high J c round wire (RW) form capable of generating high uniformity fields with minimum-screening current errors. However, the heat treatment that enables impressively high J c (4.2 K, 30 T) values that can attain ∼5000 A mm−2 also produces significant filament bonding (bridging). Filament bridging appears to significantly enhance hysteretic losses of the filaments themselves by coupling neighboring, nominally independent filaments, enabling shielding currents to flow across multiple filaments as though they were one filament of much larger diameter. Wire twisting can be employed to reduce filament-to-filament eddy current coupling losses due to induced currents flowing across the matrix, but twisting is less effective in reducing increased losses from bridging. Here, we compare the twist-pitch dependence of the losses of overpressure processed (OP) high J c Bi-2212 RWs with partially bridged filaments to those found in OP Bi-2212 RWs with discrete, not-bridged filaments. We show that filament sub-bundles in standard, partially-bridged wires that have some superconducting connections between filaments can exhibit significant coupling (much larger effective filament diameter), but twisting still reduces their hysteretic losses to values close to or below the ITER Nb3Sn wire loss specification, even though Bi-2212 wires have significantly larger J c values. Although it has been reported that twisting can reduce wire J c by damaging filaments, we found no reduction in transport J c , even for nominal twist pitches of 12 mm in 0.8 mm diameter wires. Evaluation of more-recent, higher J c Engi-Mat powder wires showed that their reduced filament bridging and improved longitudinal connectivity significantly improved transport J c and reduced the J c normalized losses, signaling that J c can be further improved without commensurate increase in losses. This important result strengthens the argument for production of high field, low loss HTS magnets made with Bi-2212 RWs.

Зносостійкі покриття на алюмінієвих сплавах

Aluminum alloys are widely used in industry. Recently, they are used as a replacement for steel for the manufacture of pulleys, gears, columns of hydraulic rotary transmissions of grabs, etc. This reduces the weight of the parts and reduces carbon emissions into the atmosphere. However, aluminum alloys have low abrasive wear resistance, so their use is possible with coatings on the surface. High-speed gas flame spraying (HVOF) was carried out on the equipment (Diamond Jet Hybrid gun). Arc coatings with a thickness of 500 µm were applied using FMI metallizer and FMI-2 powder wire (Cr6Al6B3Fe-base). PEO (oxido ceramic) coatings were synthesized on D16T aluminum alloy in an electrolyte of 3 g/l KOH + 2 g/l liquid glass (sodium silicate) with a pulsed current at a frequency of 50 Hz, with the ratio of the densities of the cathode and anode currents Jc/Ja+15/15 A /dm2. The duration of the PEO process is 60 min. The open porosity of the coatings was determined by the method of hydrostatic weighing. The phase composition of the surface layers was studied using a DRON-3.0 diffractometer. HVOF (VC) and PEO coatings have been found to have 3 to 4 times higher wear resistance than high carbon hardened steel 100Cr6 and 2 times higher than galvanic chromium coatings, but have high energy consumption. Two methods have the lowest energy consumption: electric arc spraying of coatings and hard anodizing. At the same time, the wear resistance of such coatings is significantly lower than that of coatings obtained by the PEO and HVOF (VC) methods. For the restoration of worn parts, the most appropriate methods are HVOF (VC) and electric arc spraying, as they allow applying thick coatings up to 5 mm. Conclusions: It was established that the studied HVOF (VC), PEO, EDP and hard anodized coatings significantly increase the abrasive wear resistance of aluminum alloy parts. HVOF (VC) and electric arc spraying methods can be used to protect new and worn parts from wear. PEO and hard anodizing methods can be used to protect against wear on new parts only. The use of these methods increases the wear resistance of parts made of aluminum alloys to the level of steel and allows replacing steel and cast iron with aluminum alloys with coatings, reducing the weight of parts and carbon emissions into the atmosphere.

Impact and abrasion wear resistance of the hardfacings based on high-manganese steel reinforced with multicomponent carbides of Ti-Nb-Mo-V-C system

Structure formation and impact-abrasion wear resistance of the hardfaced layers deposited by flux-cored arc welding with powder wires of a high-manganese austenitic steel – (Ti, Nb, Mo, V)C high-entropy(-like) carbide system, were investigated and compared to the impact-abrasion resistance of the commercially available high-manganese steel-based hardfacing as well as with high-speed and mild carbon steels. Flux for the flux-cored wires was prepared by adding the equimolar mixture of TiC, NbC, VC and Mo2C powders to the Si-alloyed ferromanganese and arc shielding components. Microstructure investigations of the hardfaced layers show, that its structure consists of an austenitic matrix and complex carbide reinforcements, in form of uniformly distributed fine-grained particles. Its impact-abrasion wear resistance is more than three times higher than that for hardfacing, deposited with commercially available high-manganese steel-based electrodes and almost equal to the high-speed steel samples tested under the same conditions.

The Use of Surfacing Materials to Increase the Durability of Disc Harrow Working Elements

Introduction. For surface tillage operation there widely used disc harrows, working bodies of which are discs wearing out during operation. The wear intensity of discs depends on the wear resistance of their working surfaces, working modes and properties of the cultivated soil. It has been found that an effective way to increase the life of discs is surfacing them with wear-resistant materials. The aim of the work is to study the wear out of surfacing materials, which can be used to harden discs and to make recommendation for the use of these materials in the repair departments of agricultural enterprises. Materials and Methods. Surfacing with electrodes T-590 and powder wires PP-Np200Kh15S1GRT, VELTEK-N560.02 and PP-Np280Kh9F7SG4 were taken as test materials. For wear tests of materials in abrasive mass, there was used an apparatus to simulate the moisture content and composition (sandy loam or loam) of the soil. In the disk-pad tests, the effect of abrasive particle size, load and sliding friction velocity on the wear of the materials was studied. In field tests, wear of the disks made of 65G steel, surfaced toothed and solid disks were monitored. Results. Laboratory studies of the materials revealed the effect of soil moisture and composition, load, abrasive grit and sliding friction velocity on wear. The main factor determining the wear resistance of materials is their structural state. The indexes of wear resistance of surfacing were determined during the laboratory tests and confirmed by field tests. Discussion and Conclusion. Surfacing with flux-cored wire PP-Np280Kh9F7SG4 has the highest wear resistance of the studied materials. The technology of hard-facing disks with modern materials, in particular with flux-cored wire PP-Np280Kh9F7SG4, can be implemented in repair departments of agricultural enterprises when they have the equipment for hard-facing and sharpening of working surfaces.