An Analysis of Electroplated cBN Grinding Wheel Wear and Conditioning during Creep Feed Grinding of Aeronautical Alloys

Cubic boron nitride (cBN), in addition to diamond, is one of the two superabrasives most commonly used for grinding hard materials such as ceramics or difficult-to-cut metal alloys such as nickel-based aeronautical alloys. In the manufacturing process of turbine parts, electroplated cBN wheels are commonly used under creep feed grinding (CFG) conditions for enhancing productivity. This type of wheel is used because of its chemical stability and high thermal conductivity in comparison with diamond, as it maintains its shape longer. However, these wheels only have one abrasive layer, for which wear may lead to vibration and thermal problems. The effect of wear can be partially solved through conditioning the wheel surface. Silicon carbide (SiC) stick conditioning is commonly used in the industry due to its simplicity and good results. Nevertheless, little work has been done on the understanding of this conditioning process for electroplated cBN wheels in terms of wheel topography and later wheel performance during CFG. This work is focused, firstly, on detecting the main wear type and proposing a manner for its measurement and, secondly, on analyzing the effect of the conditioning process in terms of topographical changes and power consumption during grinding before and after conditioning.The authors gratefully acknowledge the funding support received from the Spanish Ministry of Economy and Competitiveness and the FEDER operation program for funding the project "Optimizacion de procesos de acabado para componentes criticos de aerorreactores" (DPI2014-56137-C2-1-R)

Development of Composite Grinding Wheels for Hard and Soft Metals

This research investigates the performance of grinding wheel in terms of its internal granular particles and their effect on the surface finish for both soft and hard metals subjected to both dry and wet conditions of use. The study considers the properties of materials of construction including hardness of the granular particles and their size and distributions that affects the grinding wheel efficiency in abrading of soft and hard metal surfaces. Furthermore, in order to improve grinding performance, the mechanism of clogging the cutting surface of the grinding wheel as a function of for example, the surface properties of granular particles and the chips formed during the grinding operation have been considered. Objective of this project is to study the overall sharpness of the grinding wheel in terms of its internal granular particles and their effect on the surface finish for both soft and hard metals at different conditions of use. The properties of materials of construction including hardness of the granular particles that affects the grinding wheel efficiency in abrading of soft and hard metal surfaces have been studied. During this project two novel grinding wheels, namely single grooved and crossed grooved wheels, have been developed and their performance has been compared with a selected commercial grinding wheel, the design of grinding wheels incorporated an innovative surface profile which has been shown to be capable of taking potentially large depths of cut at high wheel and workpiece speeds to create a highly efficient material removal process. This aggressive processing generated high temperatures in the contact zone between the wheel and workpiece. The voltage measured by oscilloscope during grinding of different workpiece materials including mild steel, brass and aluminium bars was related to the temperature generated between wheels and workpiece materials. Temperatures in the ground surface can be predicted with a knowledge of the specific grinding energy and the grinding parameters used. Specific grinding voltage recorded at high specific material removal rates demonstrated a constant value of specific grinding heat dependent on cutting and contact conditions, improving accuracy of the predictive model. 4 Cutting and contact conditions in the different grinding wheels vary dependent on their surface patterns. This thesis shows how temperature, contact stresses, material removal rates vary with the surface profile, size and orientation of the abrasive particles of the grinding wheel, affecting the performance of the grinding wheel during the grinding operations. Redesigning grinding wheels by making grooves on surface of wheel, material removal rate was increased and less voltage has been recorded. Also, time for redressing wheels was reduced. The wheel surface of crossed grooves shape showed a significant improvement in grinding of soft materials e.g. aluminium. Finally, the different stress distribution, including von_Mises, principal stresses and shear stresses, in the grinding wheels and the three workpiece bars during the grinding process were investigated using Finite Element Analysis (FEA) technique. The maximum von-Mises stress value of the brass bar was found to be 173.2 MPa. Hence the strength of produced grinding wheel calculated as 207 MPa which was extensively higher than the maximum von-Mises stress value obtained from FEA profile, resulting 19.5% higher strength in crossed grooves wheel

New insights into the methods for predicting ground surface roughness in the age of digitalisation

Grinding is a multi-length scale material removal process that is widely employed to machine a wide variety of materials in almost every industrial sector. Surface roughness induced by a grinding operation can affect corrosion resistance, wear resistance, and contact stiffness of the ground components. Prediction of surface roughness is useful for describing the quality of ground surfaces, evaluate the efficiency of the grinding process and guide the feedback control of the grinding parameters in real-time to help reduce the cost of production. This paper reviews extant research and discusses advances in the realm of machining theory, experimental design and Artificial Intelligence related to ground surface roughness prediction. The advantages and disadvantages of various grinding methods, current challenges and evolving future trends considering Industry-4.0 ready new generation machine tools are also discussed

Study of Micro-hardness of High-Speed W9Mo4Co8 Steel Plates in Pendulum Grinding by Abrasive Wheel Periphery

In cutting tool assembly, grinding is the most important technological step of the finishing treatment, largely determining the workmanship. An increase of micro-hardness after grinding relative to the original one indicates the dominant role of abrasive tool force impact on the ground surface. A decrease, in contrast, evidences a significant softening under the influence of heat source. This research based on nonparametric statistics to predict the effect of wheel characteristics with abrasives 25A, 92A/25A, 34A, 5A, EKE, 5NQ, TGX, 5SG and with graininess 46 (F46), 60 (F60), 80 with different porosities (structure numbers 6-12), and the expected measures of position and dispersion on the micro-hardness of the surface of a high-speed cutting plate (HSCP) made of W9Mo4Co8 steel. It was found that grinding this HSCP by wheels 5NQ46I6VS3, 5SG46K12VXP, 5SG60K12VXP, 5SG46I12VXP, 25AF46M12V5–PO, 25AF46M12V5–PO3, 25АF46M10V5–PO, 25AF46M10V5–PO3, 25AF46K10V5–PO3, 25AF60M10V5–PO3, 25AF46L10V5–KF35, EKE46K3V, 92A/25AF46L6V20 occurred without surface softening for 50% of the details from the operating batch

Texturing methods of abrasive grinding wheels: a systematic review

Creating textures on abrasive wheels is a strategy that allows a significant improvement in grinding operations. The reduction of the internal stresses in the workpiece and the temperature during the grinding operation generates an increase in the dimensional accuracy of the workpiece and a longer tool life. Textured abrasive wheels can be produced in many different ways. Depending on the processing method, the dimensional accuracy of the tool and its applicability is changed. Some methods can produce tools with three-dimensional grooves; there are also methods that are employed for the re-texturing of grooves after the grooved zone wears out. In the literature, the benefits of textured grinding wheels over traditional wheels have been extensively discussed. However, information on the particularities of texturing methods is still lacking. To clarify the advantages, limitations, and main advances regarding each of the groove production methods, the authors of this article carried out a systematic review. The objective of this work is to establish the factors that are affected by groove production methods and the technological advances in this area. The benefits and drawbacks of various grooving techniques are then reviewed, and potential study areas are indicated.This research was funded by FCT national funds, under the national support to R&D units grant, through the reference projects UIDB/04436/2020, UIDP/04436/2020, UIDB/00690/2020, UIDP/00690/2020, and SusTEC (LA/P/0007/2020). This work is within the scope of the Sharlane Costa Ph.D. degree in progress, financially supported by the Portuguese Foundation for Science and Technology (FCT) through the PhD grant reference 2021.07352.BDinfo:eu-repo/semantics/publishedVersio

Texturing methods of abrasive grinding wheels: a systematic review

Creating textures on abrasive wheels is a strategy that allows a significant improvement in grinding operations. The reduction of the internal stresses in the workpiece and the temperature during the grinding operation generates an increase in the dimensional accuracy of the workpiece and a longer tool life. Textured abrasive wheels can be produced in many different ways. Depending on the processing method, the dimensional accuracy of the tool and its applicability is changed. Some methods can produce tools with three-dimensional grooves; there are also methods that are employed for the re-texturing of grooves after the grooved zone wears out. In the literature, the benefits of textured grinding wheels over traditional wheels have been extensively discussed. However, information on the particularities of texturing methods is still lacking. To clarify the advantages, limitations, and main advances regarding each of the groove production methods, the authors of this article carried out a systematic review. The objective of this work is to establish the factors that are affected by groove production methods and the technological advances in this area. The benefits and drawbacks of various grooving techniques are then reviewed, and potential study areas are indicated.This research was funded by FCT national funds, under the national support to R&D units grant, through the reference projects UIDB/04436/2020, UIDP/04436/2020, UIDB/00690/2020, UIDP/00690/2020, and SusTEC (LA/P/0007/2020). This work is within the scope of the Sharlane Costa Ph.D. degree in progress, financially supported by the Portuguese Foundation for Science and Technology (FCT) through the PhD grant reference 2021.07352.BD

Lubrication and cooling in creep feed grinding

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