Electroplated Diamond Wheels Research Articles

Precision grinding of BK7 glasses using conditioned coarse-grained diamond wheel

For precision machining of large-sized optical elements, more attention is being paid to the ground surface quality, the processing costs and the machining efficiency. Besides the commonly used fine-grained diamond wheels, the coarse-grained diamond wheel is now also expected to be a promising tool with lower wheel wear rate and higher efficiency. However, conditioning of this kind of wheel is always a difficult issue to deal with. In this article, the efficient conditioning of the electroplated diamond wheel and precision grinding of BK7 glasses were investigated. Through the single diamond grit wear simulation, D3 steel was chosen as the conditioning tool. The worn diamond abrasive morphology and Raman spectroscopy analysis revealed the conditioning mechanism. Under different conditioning stages, the BK7 glasses were correspondingly ground exhibiting different surface integrity and grinding forces. The experimental results indicated that the wheel’s run-out error could be rapidly reduced to 5.8 µm because of the blend graphitization, passivation, diffusion and microcrushing of the diamond abrasives. The precision ground BK7 glasses could achieve a surface roughness of Ra < 20 nm and a subsurface crack depth around 2 µm, illustrating that the electroplated coarse-grained diamond wheel could be an alternative for precision grinding large-sized optical elements in terms of high accuracy, cost-effectiveness and high efficiency.

High Efficient Precision Conditioning of the Electroplated Diamond Wheel and Grinding of Fused Silica Glasses

Generally, the fine abrasive diamond wheel is used to the precision/ ultra-precision grinding of large-size optical glasses, but there're some disadvantages, such as the frequent wheel conditioning, uncontrollable surface accuracy, and low processing efficiency. Coarse abrasive diamond wheel can implement a higher surface accuracy machining with large grinding ratio. However, to achieve precision grinding, efficient precision conditioning is very critical. The electroplated diamond grinding wheel(grit-size 151 μm) is rough trued using the Cr12 steel. The gathering heat speeds up the diamond wear, so the run-out error of grinding wheel is quickly down to below 10 μm. Combined with electrolytic in-process dressing technique(ELID), cup-shaped diamond roller is applied to precision condition the electroplated grinding wheel. The wheel's run-out error drops to within 6 μm, and the axial gradient error is reduced from 6 μm to 2.5 μm. By the wheel wear morphology and the Raman spectral curve, the conditioning mechanism is analyzed. In different wheel truing stage, the fused silica is surface ground respectively. Using the high run-out error grinding wheel, the optical glass is mainly removed in the form of brittle fracture. When the run-out error and axial gradient error reduce, the fused silica glass is ground mainly as plastic removal, with the surface roughness Ra 19.6 nm and subsurface crack depth 2 μm. Thus, the well trued coarse abrasive grinding wheel can be considered for precision machining optical elements.

Influences of Grinding Parameters on Forces in the Grinding of Microwave Ferrite Ceramic with Electroplated Diamond Wheel

Through the odd factor grinding experiment of microwave ferrite, the tangential and normal force were measured in different grinding parameters (wheel speed, feed rate, cutting depth, wheel size). According to the variation of the tangential force and normal force in different grinding parameters after grinding, the reasonable grinding parameters of microwave ferrite were explored. The results demonstrated that the grinding force had different variations in different grinding parameters. These could be the reference and guidance for the future processing of microwave ferrite materials.

Influence of Picosecond Laser Touch Dressing of Electroplated Diamond Wheels on the Dressing of SiC Vitrified Bond Wheel

Touch dressing of electroplated diamond wheels is a challenging technique used for precision form grinding. This paper presents an investigation to explore the capabilities of modern laser technology for touch dressing. A pulsed picosecond laser (ps-laser) beam (Yb:YAG) is used to cut diamond grains within a definite grain protrusion without noticeable thermal damage neither on the nickel bond material nor the diamond itself. A systematic study on laser irradiation parameters on cutting quality is presented. Series of experiments by dressing of SiC wheels using an ultrashort pulsed laser source as well as conventional touch dressed diamond wheel are carried out and both methods are compared. Significant advantages of the novel laser method are presented.

Influences of Grinding Parameters on Flexural Strength in the Grinding of Li-Spinel Ferrites with Electroplated Diamond Wheel

Through the odd factor grinding experiment of microwave ferrite, the residual flexural strength and surface roughness after grinding were measured in different grinding parameters(wheel speed, feed rate, cutting depth, wheel size). The surface of microwave ferrites was observed in high magnification through an optical microscope after grinding, in order to show the variation of surface roughness in different grinding parameters. The results showed that with the increase of the surface roughness, the residual flexural strength increased.

Experimental Study on the Surface Roughness with Mill-Grinding SiC Particle Reinforced Aluminum Matrix Composites

In view of the present machining status of SiC particle reinforced aluminum matrix composites, the electroplated diamond wheel (80# diamond grit) was used for mill-grinding the SiC particle reinforced aluminum matrix composites and the effect of speed ratio (q) and material removal rate (MRR) on surface roughness was studied based on experiments. The experimental results show that surface roughness almost increases with the increase of speed ratio. At the same material removal rate, surface roughness increases when raising material removal rate by raising feed rate singlely or raising depth of mill-grinding singlely; surface roughness has decreasing trend with raising material removal rate by increasing feed rate and depth of mill-grinding at the same time.

A study on laser touch dressing of electroplated diamond wheels using pulsed picosecond laser sources

An investigation to explore the possibility of touch dressing of electroplated diamond wheels using a pulsed picosecond laser (ps-laser) beam (Yb:YAG) is presented. The laser beam is irradiated on the wheel to cut the diamond grains within a defined grain protrusion without any thermal damage on the nickel bond. The laser parameters were systematically varied to achieve a reliable touch dressing process. The microscopic investigations prove thermal damages neither on the diamond grain nor on the bond. Series of SiC wheel dressing experiments were carried out to compare mechanical touch dressing of the electroplated diamond wheel with laser dressed wheels.

Ultrasonic-assisted micro-grinding with electroplated diamond wheels

Ultrasonic-assisted micro-grinding with electroplated diamond wheels

The Experimental Investigation of Face Grinding of Al2024/SiCp with Electroplated Diamond Wheel

In this paper experiments of the face grinding of Al2024/SiCp through the use of electroplated diamond wheel were carried out. The results indicated that high quality processed surface was achieved by face grinding machining, under the experiment conditions of this paper, the surface roughness was between Ra0.185 μm and Ra0.512μm, and the residual stress of processed surface was compressive stress. Grinding parameter had little effect on tangential force and normal force. Axial grinding force increased with the increasing of grinding depth and was stronger than grinding forces in other two directions.

Prediction of Grinding Force Distribution in Wheel and Workpiece Contact Zone

A novel method is reported for predicting the distribution of normal and tangential grinding forces in wheel and workpiece contact zone or along their contact arc. This work was motivated by the need to obtain the maximum force acting on individual active abrasive grains for establishing the probability of grain fracture and pullouts due to this force. Horizontal and vertical forces measured in the transient cut-in or cut-out stage of a grinding pass are utilized in this method to predict the horizontal and vertical forces acting on each portion of the contact arc. And then these forces are subsequently converted to tangential and normal forces per unit length along the arc to obtain the force distribution. To illustrate the application of this method, forces measured in the transient cut-out stage in the grinding of tungsten carbide with electroplated diamond wheels were employed to predict the force distribution, which was further applied to predicting the transient grinding power at the cut-in and cut-out stages. The predicted power was found to match very well with the measured power.

Investigation of Grinding Process of Particle Reinforced Matrix Aluminium Composites (PRAMCs)

In the paper, the experimental study of grinding process of 2024Al/SiCp composites with the electroplated diamond wheel was conducted. The results indicate that the surface roughness of the workpiece is between 0.554 μm and 1.2 μm. Increment of the spindle speed, reduction of the cut depth and decrease of the feed speed make the surface roughness value reduce. After grinding, compressive stresses on the machined surface can be obtained. During grinding, the normal grinding force is greater than the tangent force and the grinding forces increase as the increase of the feed speed and depth of cut.

セラミックスのヘリカルボーリング加工用電着ダイヤモンド工具の開発 : 第1報 : 工具底面形状と切れ刃干渉状態

セラミックスのヘリカルボーリング加工用電着ダイヤモンド工具の開発 : 第1報 : 工具底面形状と切れ刃干渉状態

An Investigation of High Speed Grinding with Electroplated Diamond Wheels

We describe collaborative work between NIST and the University of Massachussetts to evaluate the effect of high wheel speeds for grinding of silicon nitride with electroplated diamond wheels. Straight surface grinding experiments were conducted at wheel speeds of 85 m/s and 149 m/s using the same removal rate. Measurements are reported for the grinding forces, radial wheel wear, and surface roughness throughout the useful wheel life, and for the flexure strength after grinding. Although the forces tended to be somewhat lower at the higher wheel speed, the grinding performance was not necessarily better when compared in terms of wheel wear, surface roughness, and strength degradation. Preliminary measurements of acoustic emission illustrate possibilities for process monitoring.

High Speed Grinding of Silicon Nitride With Electroplated Diamond Wheels, Part 2: Wheel Topography and Grinding Mechanisms

This is the second in a series of two papers concerned with high speed grinding of silicon nitride with electroplated diamond wheels. In the first article (ASME J. Manuf. Sci. Eng., 122, pp. 32–41), it was shown that grinding of silicon nitride is accompanied by dulling of the abrasive grains and a significant increase in the grinding forces and power. High wheel speed caused more wheel wear, which was attributed to a longer accumulated sliding length between the abrasive grains and the workpiece. This second paper is concerned with the progressive change in wheel topography during grinding and how it affects the grinding process. A statistical model is developed to characterize the wheel topography during grinding in terms of active cutting grains and wear flat area. According to this model, continued grinding is accompanied by an increase in both the number of active grains and the wear flat area on the wheel surface as the wheel wears down. The measured increase in grinding forces and power was found to be proportional to the wear flat area, which implies a constant average contact pressure and friction coefficient between the wear flats and the workpiece. Increasing the wheel speed from 85 to 149 m/s significantly reduced the contact pressure, which may be attributed to a reduction of the interference angle, but had almost no effect on the attritious wear rate of the diamond abrasive. Therefore, more rapid wear of the diamond wheel at higher wheel speeds due to a longer sliding length may be offset by reduced contact pressures and lower grinding forces. [S1087-1357(00)00401-9]

High Speed Grinding of Silicon Nitride With Electroplated Diamond Wheels, Part 1: Wear and Wheel Life

An investigation is reported on high speed grinding of silicon nitride using electroplated single-layer diamond wheels. This article is concerned with wheel wear and wheel life, and a second paper (ASME J. Manuf. Sci. Eng., 122, pp. 42–50) deals with wheel topography and grinding mechanisms. It has been suggested that grinding performance may be enhanced at higher wheel speeds due to a reduction in the undeformed chip thickness. Grinding experiments were conducted at wheel speeds of 85 and 149 m/s with the same removal rate. Contrary to expectations, the faster wheel speed gave no improvements in surface finish, grinding ratio, or wheel life. Microscopic observations of the wheel surface revealed dulling of the abrasive grains by attritious wear, thereby causing a progressive increase in the forces and energy until the end of the useful life of the wheel. For all grinding conditions, a single-valued relationship was found between the wheel wear and the accumulated sliding length between the abrasive grains and the workpiece. A longer wheel life and improved grinding performance can be obtained when the operating parameters are selected so as to reduce the abrasive sliding length per unit volume of material removal. [S1087-1357(00)00301-4]

電着ダイヤモンド砥石の性能に対する砥粒物性の効果

In the manufacture of electroplated diamond wheels, the physical properties of diamond gritspecifically the wetting form of grit in touch with deposited layer and the coercive force of the gritaffect the holding of the grit on the wheel surface. These effects were studied for ED-A, B, C, SNDMB and MBG-T grits. The wetting ability and coercive force of the grit were found to correlate well with long wheel life, and the MBG-T grit showed good results in terms of these results.

Internal Grinding of High Strength Ceramic Workpiece Materials with Diamond Grinding Wheels

With increasing requirements for highly stressed components in respect to wear and friction behaviour, temperature stability and resistance to aggresive chemicals, ceramic materials have many advantages in comparison to metals. Beside these characteristics, high quality in dimension, shape and surface is often required. Ceramic components therefore often have to be ground or lapped. Up to now the influence of machine setting conditions and grinding wheel specifications on the grinding process has net been investigated very much. Therefore results about internal grinding of B 4 C, SiC, Al 2 O 3 , and Si 3 N 4 (hot pressed, reaction sintered) with resinoid and metal bonded and as well electroplated diamond wheels are explained. Results about G-ratios, grinding forces, workpiece roughness and shape deviations are described as function of cutting speeds, feed velocities, material removal rates and speed ratios. The dressing process of diamond wheels in combination with jet-sharpening is shown. The grinding wheel topography is described as function of sharpening period, jet pressure and abrasive flow rate.