Wheel Depth Of Cut Research Articles

Fundamental Investigation of Ultrasonic Assisted Surface Grinding of Inconel 718

Inconel 718 has high yield strength, corrosion resistance, heat resistance and fatigue resistance, and possesses a lower thermal conductivity, leading to high grinding force and heavy wheel damage in grinding of this material. Against these problems, ultrasonic assisted grinding (UAG) can be the potential candidate for high efficiency processing of Inconel 718. The current work is, hence, to clarify the fundamental UAG characteristics of Inconel 718 by experimentally investigating the effect of vibration amplitude on grinding force, actual material removal and work-surface roughness under different process parameters such as the wheel rotational speed, wheel depth of cut and vibration amplitude. Summarizing the obtained results revealed that the grinding forces and the actual material removal in UAG are significantly smaller and larger, respectively, than those in conventional grinding. It is also found that ultrasonic vibration can improve the work-surface finish even at deep wheel depth of cut.

Evaluation of grinding-induced subsurface damage in optical glass BK7

Optical glass BK7 is widely used in optical industries but the grinding process of it with aggressive machining parameters (e.g., fast infeed rate, big depth of cut) easily leads to subsurface damage (SSD). Many methods have been proposed to evaluate SSD but they unavoidably changed or even destroyed the ground BK7 surfaces, required expensive equipment and operator skills, or needed tedious preparation works. In this paper, an explicit relation between SSD and Rz in the BK7 grinding process is established based on the analytical calculation of the classic brittle material crack system and the grinding kinematics. To validate the relation, the SSD values evaluated by the proposed relation are compared with the values obtained in both the experiments and other previous studies. The results indicate that the proposed relation can nondestructively and conveniently evaluate grinding-induced SSD, in situ and ex situ, by using a simple handheld profilometer. Furthermore, the proposed relation is transformed into another two forms, relating SSD with grinding process parameters (such as undeformed chip thickness, wheel and workpiece speed and wheel depth of cut). The two transformed relations indicate that the proposed relation can not only evaluate SSD after the grinding process but also optimize process parameters to control SSD during the grinding process. The study of this paper is expected to be meaningful in the SSD measurement and design, manufacture and application of optical glass BK7.

A New Ultra-Precision Grinding Method for Manufacturing the Wavy-Tilt-Dam Mechanical Face Seals

This article reports a new ultra-precision grinding method for manufacturing wavy-tilt-dam mechanical face seals. It uses a horizontal rotary table, a horizontal swing table, and a vertical linear axis to perform micro-infeed grinding with a slightly inclined cup wheel using line contact kinematics at constant wheel depth of cut. The rotation motion of the rotary table, swing motion of the swing table, and reciprocating motion of the linear axis were numerically controlled so that the grinding contact arc between the cup wheel and the seal ring was a highly accurate approximation of the curves on the wavy-tilted surface bounded by its inner and outer peripheries and the trajectory of the contact arc formed the wavy-tilted surface. The sealing dam was generated when the rotary table rotated about the rotational axis and the swing table was locked in a position where the two end points of the grinding contact arc had the same height. This was expected to be an efficient method to manufacture wavy-tilt-dam mechanical seal faces with extremely high form accuracy and low surface roughness.

Effect of the Grain Depth of Cut on Cross Sectional Profile - Theoretical Analysis of Ground Surface Roughness

Roughness is important criterion of ground surface. When the surface roughness is demanded to be smooth, it is required to make the grinding conditions optimum. To optimize the grinding conditions, relationship between grinding conditions and ground surface roughness must be known. Therefore, it has been attempted to reveal the effect of grinding conditions on the roughness of ground surface over the years. From previous researches, it becomes possible to estimate the ground surface roughness with statistical grinding theory. However, there are some parameters, such as wheel depth of cut and distribution of abrasive grain, are not factored in the theory. In this paper, fundamental research on cross sectional profile is carried out to consider the relationship between the wheel depth of cut and ground surface roughness.

An experimental study of ultrasonic vibration-assisted grinding of polysilicon using two-dimensional vertical workpiece vibration

An experimental study of polysilicon grinding with ultrasonic vibration assistance was presented. The two-dimensional (2D) vertical vibration was applied on the workpiece directly and vibrated perpendicular to both the workpiece and grinding wheel. The grinding forces were measured using a three-component dynamometer, and the surface conditions were examined using a surface profilometer and a laser microscope. The experimental results showed that the grinding force and surface roughness with ultrasonication were much less than those in conventional grinding. In the case of ultrasonication, the wheel speed and worktable feed rate would have a more positive effect on the grinding force decrement/increment, especially for the tangential force while the wheel depth of cut had a negative effect. The surface condition of the ground polysilicon surface was improved with the assistance of ultrasonication. This research indicated that the 2D ultrasonic vibration-assisted grinding technique can be an effective method for the high-efficiency machining of hard brittle polysilicon material.

Elliptical Ultrasonic Assisted Grinding (EUAG) of Monocrystal Sapphire – Surface Formation Characteristics

This study investigates surface formation characteristics in elliptical ultrasonic assisted grinding (EUAG) of monocrystal sapphire. During EUAG process, the workpiece is imposed to ultrasonically vibrate in two directions, i.e., vertical and parallel to work-surface, by using an elliptical ultrasonic vibrator. In our previous work, the vibrator has been produced by bonding a piezoelectric ceramic device (PZT) on a metal elastic body. When two alternating current voltages with a phase difference are applied to the PZT at the same frequency that is close to the resonant frequency of the longitudinal and bending mode of the vibrator, two dimensional ultrasonic vibrations are generated simultaneously, resulting in an elliptical motion on the end face of the vibrator. In this paper, to clarify the work-surface formation characteristics in EUAG of sapphire material, grinding experiments are carried out involving sapphire substrate. In experiments, work-surface roughness is measured, and the ground work-surface morphology is examined by scanning electron microscope (SEM). The experimental results are summarized as: (1) Compared with conventional grinding (CG), the elliptical vibration leads to a decrease of surface roughness up to 25% in EUAG; (2) The surface roughness has a monotonously increasing trend with the increasing wheel depth of cut in both EUAG and CG, but has little variation with the worktable feed rate. As the wheel speed increases, the surface roughness decreases until it reaches a minimum, and then increases in a monotonous trend in both EUAG and CG; (3) The surface quality in EUAG has a significant improvement, and it is prone to achieve the ductile regime grinding of sapphire compared with CG. These indicate that the elliptical ultrasonic assisted grinding is an efficient technique for high performance machining of monocrystal sapphire.

Plastic deformation depth modeling on grinding of gamma Titanium Aluminides

This work reports on the subsurface plastic deformation depth (PDD) as a result of grinding of γ-TiAl, where the effects of grit size and shape, workpiece speed, and wheel depth of cut were studied. A grinding model based on a stochastic distribution of the chip thickness was used to estimate the expected maximum normal force per grit (\({F''_{n\:{\rm max}}}\)), which was correlated to the PDD. It was found that the PDD shows a linear correlation with \({F''_{n\:{\rm max}}}^{0.5}\). The results suggest that the indentation model is still valid for grinding if \({F''_{n\:{\rm max}}}^{0.5}\) is used as a PDD predictor variable instead of the total grinding force.

E15 A Method to Increase Material Removal Rate in Tangential-feed Centerless Grinding Performed on Surface Grinder(Grinding technology)

In our previous study, a new centerless grinding method using surface grinder was proposed. However, the material removal rate was very small owing to the low worktable feed rate. This paper describes a practical method for increasing removal rate while workpiece roundness is maintained at a high level. In this method, the worktable feed rate is adapted appropriately so that the wheel depth of cut is kept constant during grinding. The actual grinding experimental results showed that the same level of workpiece roundness can be achieved only with a half of grinding cycle time once the worktable feed rate is adapted appropriately instead of the constant feed rate during grinding.

Fuzzy Rules for Surface Roughness of Ground Steels

This paper presents a comprehensive model for predicting surface roughness due to grinding. Fuzzy rules are provided, to estimate roughness for any practical combination of (1) wheel hardness grade, (2) abrasive grain size, (3) dressing condition, (4) table speed, (5) wheel depth of cut, and (6) coolant application. The rule-base can be adapted to account for the effect of (7) different workpiece material hardness, (8) wheel rotational speed, and (9) equivalent wheel diameter. The 86 rules are intuitive, and are particularly useful for production and/or embedded control applications.

An Investigation of Surface Grinding Characteristics for Titanium Alloy with CBN Wheel

This study performs an experiment to investigate the effect of process variables such as rotational cutting speeds of the wheel, feed rate of the work-table and grinding depth of cut on surface roughness and the fluctuations of grinding forces for Ti-6Al-4V titanium alloy. STP-1623 ADC surface grinding machine, grinding wheel with CBN material sintering and Ti-6Al-4V titanium alloy workpiece are used in the experiment. The roughness of the grinding surface was measured by the roughness measuring instruments and the fluctuations of grinding forces were measured through dynamometer after each surface layer ground from the workpiece in the experiment. The grinding performance can be ascertained from the signal fluctuations phenomena of the grinding forces both along normal and tangential directions, which may also be utilized as an index for the quality of surface finish judgment. The results show that excellent surface quality being always consistent with the stable grinding force fluctuations and can be obtained under the conditions of slow feed rate of the work-table, high revolutions of the wheel and shallow depth of cut.

The optimisation of the grinding of silicon carbide with diamond wheels using genetic algorithms

Modelling and optimisation are necessary for the control of any process to achieve improved product quality, high productivity and low cost. The grinding of silicon carbide is difficult because of its low fracture toughness, making it very sensitive to cracking. The efficient grinding of high performance ceramics involves the selection of operating parameters to maximise the MRR while maintaining the required surface finish and limiting surface damage. In the present work, experimental studies have been carried out to obtain optimum conditions for silicon carbide grinding. The effect of wheel grit size and grinding parameters such as wheel depth of cut and work feed rate on the surface roughness and damage are investigated. The significance of these parameters, on the surface roughness and the number of flaws, has been established using the analysis of variance. Mathematical models have also been developed for estimating the surface roughness and the number of flaws on the basis of experimental results. The optimisation of silicon carbide grinding has been carried out using genetic algorithms to obtain a maximum MRR with reference to surface finish and damage.

Experimental investigations of machining characteristics and removal mechanisms of advanced ceramics in high speed deep grinding

Machining characteristics and surface integrity of advanced ceramics, including alumina, alumina–titania, and yttria partially stabilized tetragonal zirconia, were studied under high speed deep grinding conditions. Material removal mechanisms involved in the grinding processes were explored. The material removal in the grinding of alumina and alumina–titania was dominated by grain dislodgement or lateral cracking along grain boundaries. The removal for zirconia was via both local micro fracture and ductile cutting. It was found that under a feed rate of 500 mm/min and for all the wheel speeds used, an increase in the wheel depth of cut (DOC) from 0.1–2 mm slightly improved the ground surface finish, but greatly prolonged the wheel life. This increase did not deepen the subsurface damage layer for the alumina and alumina–titania, but resulted in a slightly deeper damage layer for the zirconia.

Finite element simulation of straight plunge grinding for advanced ceramics

The objective of this work is to model the grinding forces and the associated stress and deformation fields generated in a ceramic workpiece during plunge surface grinding. A two-dimensional finite element model is constructed with the grinding parameters and the mechanical properties of the workpiece as input variables. The size of the geometric model is several times larger than the size of the cutting zone, using approximately 5200 rectangular solid elements with a finer mesh in the cutting zone and with fixed remote boundaries. The loading in the cutting zone is imposed by displacement vectors proportional to the local undeformed chip thickness, which is a function of grinding parameters. For a given set of inputs, the model predicts the normal and tangential forces generated by the grinding wheel, as well as the deformation and the stress fields within the workpiece. As an example, the simulation is applied to a silicon nitride workpiece. Analysis of the stress fields developed in this material suggests that shear failure within the cutting zone is the dominant mode of subsurface failure, which could lead to the formation of shear micro- cracks at the grain interfaces. The depth of the subsurface shear failure zone increases with an increase in maximum undeformed chip thickness or the wheel depth of cut. The resulting local grinding force vectors, maximum stresses and damage zone sizes are predicted as a function of maximum undeformed chip thickness (or the wheel depth of cut).

Effect of grinding parameters on the reliability of alumina

In the present study, the effect of grinding parameters on the reliability of alumina specimens is investigated. The reliability is characterized by using the Weibull statistics. The grinding parameters investigated are the wheel depth of cut (downfeed), the table speed and the peripheral speed of wheel (wheel speed). The downfeed is varied from 10 to 30 μm per pass, the table speed from 0.17 to 0.27 m/s, the wheel speed from 20 to 33 m/s. The effect of the grinding parameters can be combined into a single parameter, the maximum grit depth of cut. The reliability shows strong dependence on the maximum grit depth of cut. The Weibull modulus can be as high as 10.9 as a low value of the maximum grit depth of cut is used. Nevertheless, the Weibull modulus is only 6.9 for the case that a high value of the maximum grit of cut is applied.

硬ぜい材料の研削における材料端部の欠けの推定

This paper aims to establish a practical way for predicting the size of chipping at work corner by grinding force. This is based on the idea that the grinding force on an abrasive grain must act as the concentrated loading force for the extension of well developed crack causing the chipping.To find the relationship between the size of chipping and grinding force, the grinding experiments with a single diamond point of three dimensional shape were carried out on optical glass in a wider range of grinding conditions (wheel depth of cut, work feed rate and tip radius of the point). An analysis is performed to estimate the grinding force on the model that the force integrates the traction on the contact face between grain and work during a traverse of the grain that is passing over a prior groove.The experimental results show that the 3/2 power of the chipping size is proportional to the maximum grinding force during a traverse of grain. The grinding force calculated from the grain depth of cut based on the grinding geometry is not always consistent with the real force measured in the experiment, because the real grinding process includes the fracture type material removal (over-cut groove) and the large backward deflection of the grinding system due to grinding force (under-cut groove). The real grinding force is smaller than the calculated one in the over-cut groove, while it is larger in the under-cut groove. More exact evaluation for the grinding force, or the chipping size can be made by compensation of grain depth of cut using some experimental results and the analytical model proposed here.

Study on grindability of ferrite

This paper aims to clarify the effects of grinding conditions on bending strength in surface grinding of various ferrites with the resin bond diamond wheel. The main conclusions obtained were as follows. At a constant material removal rate, the strength improves with increased wheel depth of cut and decreased workpiece speed. It is desirable to grind at higher peripheral wheel speed and under the critical workpiece speed presented in this paper. Grinding the ferrite of higher brittleness, the wheel depth of cut limited to hold 50% of their inherent strength becomes lower. The effect of various grinding conditions on bending strength becomes more larger in the order of Sr, Mn-Zn and Cu-Ni-Zn. When using the diamond grain of the lower toughness, the bending strength becomes higher, and the wheel wear occurs faster. Considering both bending strength and wheel wear rate, the best concentration of wheel is 100. The ground surfaces exhibit that the fracture process during grinding becomes more brittle in the order of Sr, Mn-Zn and Cu-Ni-Zn.

Relationship between Strength Degradation and Grain Depth of Cut during Grinding Si<sub>3</sub>N<sub>4</sub>

The strength degradation of silicon nitride ceramics up-cut surface ground under different conditions were studied by specific grinding energy and maximum grain depth of cut statistically analyzed by new direct evaluation method of successive cutting point spacing. Main results are summarized as follows; (1) Strength decreases with increase in wheel depth of cut and with decrease in specific grinding energy, and dose not depend on the change of table speed under the grinding conditions with a wheel including large grain size (#100; grain diameter=125-150μm). (2) Strength degradation is much large by 70-80% compared to inherent strength of the work at the range of more than 0.5-1.0μm in mean value of maximum grain depth of cut.

Jig Grinding of Alloy Tool Steel with Electrodeposited CBN Wheels. Effects of Grinding Conditions on Grinding Characteristics.

Jig grinding is well known as a precision internal machining process for high precision products such as dies and fixtures. Investigation to realize high productivity and high accuracy is performed with different electrodeposited CBN wheels under various grinding conditions. Grinding characteristics such as grinding forces, torque and surface roughness were measured. The main results obtained are as follows. (1) Grinding accuracy improved with an increase in peripheral speed of grinding wheel. (2) Grinding forces and torque decrease with an increase in peripheral speed of wheel but increase with wheel depth of cut and work feed rate. (3) Grinding forces and torque increase with the cumulative stock removal which is caused by the progress of attritional wear of CBN abrasive grains. (4) A clear reduction of grinding forces is caused by quill motion overlapping the main axis and is induced by the decrease in the mean chip volume and/or the mean chip cross-sectional area.

平面研削におけるだれに関する研究 砥石と工作物の相対変位に起因するだれの形成機構

Some machine parts, such as cutting tools and shearing blades, have importance in their corner shapes. The corner dullness which deteriorates the corner shapes is often generated at the ends of ground machine parts. This paper deals, both theoretically and experimentally, the mechanism of generating the dullness under one-pass-plunge grinding and following results are obtained. (1) Entrance dullness, being generated at the wheel entrance part, and exit dullness, being generated at the wheel exit part, are different in shape. The height of exit dullness is about three times as much as the entrance. (2) Shapes of the dullness, theoret-ically obtained under consideration of the wheel-workpiece relative displacement and utilizing the one-freedom vibration model, show good agreement with measured results. (3) Height of the exit dullness increases with wheel depth of cut, table speed, and grinding stiffness under usual grinding condition. (4) Height of exit dullness decreases with equivalent mass, dumping coefficient, and spring constant of the grinding machine.

Measurement of Grinding Temperature of Active Grains Using Infrared Radiation Pyrometer with Optical Fiber

The temperature of the cutting grains on the grinding wheel just after cutting is measured using a new type of infrared radiation pyrometer with optical fiber and InAs cell. The mean temperature of cutting grains is hardly influenced by the wheel depth of cut or the workpiece speed, but decreases with increase of the wheel speed. The maximum temperature of cutting grains at the cutting point is approximate to the melting point of the work material of steel. The change in the working conditions of cutting grains after every revolution of the wheel is observed.