Vitrified Grinding Wheels Research Articles

Effect of the Granularity of Cubic Boron Nitride Vitrified Grinding Wheels on the Planar Technical Blades Sharpening Process.

The most widely used method for shaping technical blades is grinding with abrasive tools made of cubic boron nitride (cBN) grains and vitrified bond. The goal of this work was to determine the effect of grinding wheel grain size (cBN grain number according to FEPA standards: B126, B181 and B251), kinematics (grinding with the circumference, face and conical surface of the wheel) and feed rate (vf = 100; 150; 200 mm/min) on the effects of the grinding process evaluated by the cutting force of the blade after machining F, blade surface texture parameters (Sa, St, Smvr, Str, Sdq, Sdr and Sbi) as well as blade surface morphology. An analysis of output quantities showed that grinding wheels made of B181 cBN grains are most favorable for shaping planar technical blades of X39Cr13 steel in the grinding process.

Wear behavior of a new composite formulation, with TEOS addition, for abrasive vitrified grinding wheels

Vitrified grinding wheels are used in many manufacturing industries to shape and finish metals and other materials in an efficient way. This work addresses a new approach with the use of tetraethyl orthosilicate solution (TEOS solution or silica sol), as an additive, in vitrified abrasive composites for grinding wheels. Different types of composite were produced using always the same materials and processing methods, but with different TEOS contents. Compared with a reference abrasive grinding wheel, the addition of TEOS promoted an improvement in the abrasive tool performance. The new formulation for vitrified abrasive composites showed better dimensional stability during processing (drying and sintering), and could be applied to the production of grinding tools with high dimensional accuracy. With the addition of 3.75 wt% of TEOS there was an increase in the strength of the matrix bonds. The porosity of the composite increased by 7% (from 43.6 to 46.9%), also improving its wear properties, with the quadrupling of the grinding ratio of the abrasive composite. In addition, the surface roughness of the composite decreased (from Ra = 22.9 to 8.4 μm) allowing to improve the surface finish of the workpieces.

Effect of surfactants on vitrified bond diamond composites prepared by sol-gel and dispersibility of diamond

Vitrified ultrafine diamond grinding wheels are ideal for machining next-generation semiconductor power device material, such as SiC etc. However, a crucial problem limiting the application of ultrafine diamond originates from the dispersion of aggregates in vitrified bond. In this study, in can be confirmed that the preparation of uniformly dispersed diamond/vitrified bond composites using sol-gel technique is feasible. Surfactants with various types and additions interactively promote the dispersion of diamond, which make both the bending strength and diamond dispersion of the composites are suitable for precision grinding. The results are valuable for the preparation of vitrified grinding wheels with ultrafine diamond for precision machining of semiconductor.

Simulation of thermal loading on vitreous bonding bridges of vitrified grinding wheel

Simulation of thermal loading on vitreous bonding bridges of vitrified grinding wheel

Simulation of thermal loading on vitreous bonding bridges of vitrified grinding wheel

Simulation of thermal loading on vitreous bonding bridges of vitrified grinding wheel

On the use of grains recovered from spent vitrified wheels in resinoid applications

Vitrified grinding wheels are used in various end applications. They are easy to dress and have better mechanical properties. In general, grinding wheels are used till the stub portion. After usage, this stub portion is discarded as waste. Grains in this portion are fresh. Recovering and reusing the grain in the stub portion are both economically and environmentally beneficial. This work deals with the recovery and reuse of abrasive grains from vitrified brown alumina grinding wheel rejects. Grains are recovered using mechanical crushing processes. The recovered grains are used for production of resinoid cylindrical grinding wheel of 350 mm outer diameter. Performance of this grinding wheel was compared with standard grinding wheel of brown alumina grain in a CNC cylindrical grinding machine. The experiment was conducted by varying three feed rates (0.25, 0.5, and 1 mm/min). The trial wheel exhibits lower wheel wear and higher grinding ratio in all feed rates, without any loss in material removal rate. The difference in performance of the grinding wheel is correlated to the difference in toughness of the grains. It is shown that grains from vitrified rejects of brown alumina can be recovered and advantageously used in resinoid applications. This helps in reusing the otherwise wasted abrasive, thereby reducing pollution to the environment.

Specifying the Process Parameters for Diamond Dressing of Grinding Wheels

Theoretical and experimental investigations have provided a deep insight into the process of diamond dressing of vitrified grinding wheels under the mechanisms of micro- or macrofracture of abrasive grits. This permits determining the process parameters dressing in coarse and finish grinding operations. The authors propose equations for finding the depth of dressing for various types of have been proposed for different wheel working layer states.

RPM-SYNCHRONOUS GRINDING - Investigation and comparison of surface topography of Synchro-Finish manufactured workpieces

The innovative RPM-Synchronous Grinding process enables highly efficient manufacturing of various geometries in an ordinary plunge grinding process. An oscillation of the infeed axis, which is coupled to the rotary workpiece spindle axis, like in conventional non-circular grinding approaches is not required. This is achieved by using a fixed ratio of grinding wheel- and workpiece speed and also a non-circular grinding wheel geometry. In this first test series, practice-orientated circular steel-workpieces are Synchro-Finish ground with conventional vitrified grinding wheels for finishing applications. The surface topography of the Synchro-Finished parts is evaluated and compared with conventionally ground workpieces.

Multi Criteria Optimization Approach for Dressing of Vitrified Grinding Wheel

Multi Criteria Optimization Approach for Dressing of Vitrified Grinding Wheel

Effects of sintering in a high magnetic field on properties of vitrified bond and vitrified CBN composites

Vitrified bond CBN grinding wheels are being widely used due to their superior performance. Also, advantages of vitrified grinding wheels are high elastic modulus, stable chemical property, and low thermal expansion coefficient. Brittleness and low strength are key factors restricting the development of vitrified bond CBN grinding wheels. In this paper, the sintering in a high magnetic field was innovatively introduced into the manufacturing of vitrified bond CBN grinding wheels, and the effects of sintering in a high magnetic field on properties on vitrified bond and vitrified CBN composites were systematically investigated. Vitrified bond was characterized using three-point bending, scanning electron microscopy, X-ray diffraction. It was observed that microstructure of vitrified bond could be changed, grain orientation could be controlled and average grain size could be decreased in a high magnetic field, while vitrified bond strength could be simultaneously improved. High quality vitrified bond could be obtained by appropriately adjusting the strength and direction of high magnetic field. Results demonstrated that vitrified bond properties were improved when the magnetic field strength was 6 T. In order to highlight the high magnetic field effect on the vitrified CBN composites, the ordinary CBN abrasives and nickel plated CBN abrasives were used respectively. Microstructures, bending strengths of vitrified CBN composites were compared in different high magnetic fields. When the magnetic field strength was appropriate (less than 6 T), the binding characteristic of vitrified bond CBN composites with nickel plated CBN abrasives was greatly improved. The highest bending strength value of vitrified CBN composites was 79.5 MPa in 6 T high magnetic field.

Surface Modification of SiC Powders in Vitrified Grinding Wheel by In-situ Sol-gel Method

Surface Modification of SiC Powders in Vitrified Grinding Wheel by In-situ Sol-gel Method

Direct Photonic Fusion of Vitrified Bonding Materials

The purpose of this study is to show the effects of the direct fusion of raw materials used for vitrified grinding wheels by photonic interactions. The paper describes the construction of a sintering apparatus that employs a pulsed neodymium: yttrium aluminum garnet (Nd:YAG) laser to fuse a combination of raw materials such as ball clay, feldspar, and borax to form a partially-crystalline glass material. The experimental results show that lasers can replace traditional methods of glass frit formation by fusing raw materials used in the manufacture of glass bonds for vitrified grinding wheels. X-ray diffraction data shows that a glass with short range order has formed using the new method. The work described herein provides a new avenue for glass frit formation applied to grinding wheel manufacture.

Safety of stationary grinding machines – impact resistance of work zone enclosures

Guards on machine tools are intended to protect persons from being injured by parts ejected with high kinetic energy from the work zone of the machine. Stationary grinding machines are a typical example. Generally such machines are provided with abrasive product guards closely enveloping the grinding wheel. However, many machining tasks do not allow the use of abrasive product guards. In such cases, the work zone enclosure has to be dimensioned so that, in case of failure, grinding wheel fragments remain inside the machine’s working zone. To obtain data for the dimensioning of work zone enclosures on stationary grinding machines, which must be operated without an abrasive product guard, burst tests were conducted with vitrified grinding wheels. The studies show that, contrary to widely held opinion, narrower grinding wheels can be more critical concerning the impact resistance than wider wheels although their fragment energy is smaller.

Sposoby impregnacji narzędzi ściernych ze spoiwem ceramicznym z użyciem stałych środków smarnych

Sposoby impregnacji narzędzi ściernych ze spoiwem ceramicznym z użyciem stałych środków smarnych

Experimental Analysis and Modelling of Grinding AISI D3 Steel

Grinding of hardened steels for the realisation of better surface quality of the workpiece is an essentiality of high productivity environments. The surface grinding of high carbon high chromium steels like AISI D3 with a production level grinding wheel used in the industry is the driver of the present research article. The experimentation is done in dry as well as pool cooling conditions to ascertain the better of the two conditions in providing a better set of cutting forces and surface finish. A mathematical model for evaluating the forces generated during grinding is evolved and on comparison of the results obtained from the model with the ones from experimentation is found to be correlating. The usage of production level vitrified grinding wheel has shown good results in terms of lower forces generated and good surface finish during surface grinding. The results are optimised and the set of inputs which yield good surface finish and low forces are given. Dry grinding of AISI D13 yields good surface finish than wet grinding. Surface finish of 0.14 microns is achievable using dry grinding.

Development of TSV Reveal Process Using Very Fine Si/Cu Grinding and Metal Contamination Removal

Three-dimensional integrated circuits (3D-ICs) using through silicon via (TSV) have been developed as an emerging technology that can lead to significant progress (1–4). Among various TSV processes, the via-middle process has potential for wide spread use because formation of small-sized TSVs is relatively easy in the via-middle process. However, TSV reveal process must be performed for electrical contact in the via-middle process. This TSV reveal process is important because it can influence the metal contamination and stacking yield of 3D-ICs. Conventionally, TSV reveal is performed by Si grinding and Si dry etching (5). A disadvantage of that method is the resultant TSV depth deviation, which can cause bonding failure during wafer/chip stacking. In (6), TSV leveling was performed by introducing a chemical mechanical polishing (CMP) step after deposition of the backside insulator. However, the revealed TSVs break during CMP step if they exceed a certain height. To overcome these problems, we developed a novel TSV reveal process comprising direct Si/Cu grinding and metal contamination removal (7,8). First, simultaneous grinding of Cu and Si was performed using a novel vitrified grinding wheel. In situ cleaning with a high-pressure micro jet and the inelastic porous structure of the grinding wheel suppressed the adhesion of Cu contaminants to the Si, and TSVs were leveled and exposed. Next, an electroless Ni-B film was deposited on the Cu surface of the TSVs. The Si was etched with an alkaline solution, whereas the Cu was protected by the Ni-B film. An insulator was deposited, and then the insulator on the top surface of the TSV was removed. We achieved the backside reveal of TSVs without TSV depth deviation and suppressed Cu contamination to less than 1e11 atoms/cm2. However, after direct Si/Cu grinding with an 8000 grit grinding wheel, the average surface roughness of Si was 5–10 nm, which is larger than that after chemical mechanical polishing (CMP). In this paper, we developed vitrified grinding wheels with very high grit numbers (#30,000 and #45,000) and present an improved version of our TSV reveal process. The average surface roughness of Si after Si/Cu grinding was approximately 3 nm for the 30,000 grit grinding wheel and 1 nm for the 45,000 grit grinding wheel. This value is equivalent to that after CMP. The improved process produced a uniform reveal of 4-um-diameter TSVs without TSV depth deviation and Cu contamination. The Cu contaminant concentration on Si region between TSVs was small (<3e10 atoms/cm2). This process will reduce the cost of the TSV reveal process and considerably improve the TSV yield.

Grinding Wheel Loading Evaluation Using Digital Image Processing

Wheel loading entails chip accumulation in porosities between grains or welding to the top of cutting grains. It is considered one of the most prevalent problems in grinding Nickel-based super alloys. Identification of wheel loading is an important issue for optimizing the dressing intervals, but it can be a time consuming and an expensive process. A novel technique based on digital image processing to determine the loading areas over the surface of CBN vitrified grinding wheels using the toolbox of MATLAB is presented in this paper. The optical characteristics of the metal chips, the abrasive grains and wheel bond are considered. Experiments were performed to examine the repeatability of the proposed technique. The results were verified by the use of a scanning electron microscope. Based on the proposed technique, the effects of cutting parameters on the loaded area to wheel surface ratio in relation to grinding performance were studied empirically.

Grain mill test for sintered microcrystalline aluminum oxide abrasive grains

In this contribution results from physical and technological testing of different sintered microcrystalline aluminum oxide abrasive grains are presented. For the physical testing an innovative test stand based on a grain mill was used. Significant differences of the measured friction forces were obtained for two different sintered microcrystalline abrasive grain types. In the technological testing vitrified grinding wheels were used for an external cylindrical profile grinding process. In the values of the grinding forces, the surface roughness and the profile deviation good correlations to the results from physical testing showed up. Also at grinding with a higher load coincident tendencies of the grinding force values were detectable. Drawing conclusions it can be declared that the results from the physical testing allow evaluating the grinding performance of the tested grain types. In further experiments the impact of different percentages of the microcrystalline grit was analyzed. It turned out that the friction forces in the physical testing increased accordingly with the percentage of microcrystalline grit while the grinding forces in the technological testing showed a non-linear interdependency to the percentage of microcrystalline grit. To give reasons for these effects an advanced approach for modeling the interdependencies of microcrystalline grit percentage was formulated.

Analysis and design of recessed vitrified grinding wheels: Part 1 – small cup wheels

Grinding wheels are tools used to form precision components and continue to be used to increase production rates due to their ability to remove high volumes of material at high speeds. There is a demand to increase the speed of rotation of the grinding wheel in order to achieve high removal rates, especially with vitrified grinding wheels. The increase in speed creates a situation where the grinding machine and the operator are subjected to a possible catastrophic failure of the wheel due to the stresses generated in the coarse brittle structure of the vitrified grinding wheel. Calculations were conducted to determine maximum stress in parallel-sided and recessed cup wheels. Relevant factors of safety and bursting speed were also calculated and compared with experimental data. The paper proves the usefulness and applicability of a method developed for taking account of stress concentrations at the recess of small cup-shaped grinding wheels.

A historical review of wear mechanisms and the structure of vitrified micro grinding wheels

This paper presents a historical review of the wear and the structure of vitrified grinding wheels. This review describes the tribological issues surrounding use of vitrified grinding wheels and is discussed in three ways. The first explains the relationship between grinding wheel wear and wheel performance and discusses the interactions between abrasive grain and workpiece material and how it relates to grinding wheel performance; the second investigates the issues surrounding the composition of the vitrified bonding system and how it affects wheel wear, whilst the third explores the effect of reactions in vitrified bonds during thermal treatment of the grinding wheel that affect the performance of vitrified grinding wheels during subsequent processing of common engineering materials. The paper provides a timely review of the microstructural aspects of vitrified grinding wheels.