Brazed Diamond Wheel Research Articles

Influence of grit friability and grit distribution pattern on dry grindability of WC-6Co by single layered brazed diamond wheels

Single-layered brazed diamond wheels, composed of uni-layered diamond grits, metal binder, and metal core, have potentially good thermal conductivity to dissipate heat from the grinding zone. Considering this characteristic feature, the current study aims to explore the performance and suitability of various indigenously developed single-layered brazed diamond tools in plunge-grinding of fine-grained cemented carbide in a challenging dry atmospheric condition. Single crystalline synthetic diamond particles with different strengths and friability were utilized to develop indigenous diamond wheels with random and patterned grit distribution. The current study explores the role of diamond-grit friability and grit distribution patterns to identify the most suitable wheel for dry grinding of WC-6Co composite. Detailed analysis of the wheel morphology, signifying the fracture behavior of the diamond grit used, justified the variation in the grinding forces, tool life, and ground surface roughness. Irrespective of the grit and distribution type, all wheels showed saturation of dynamic changes in work-surface topography with the number of passes and more sensitively to the degree of increase of uncut chip thickness. Grinding wheels containing friable diamond grits with irregular granular structures performed better than the high-strength, cubo-octahedral grains during the dry grinding experiments.

Experimental investigation on the feasibility of high-efficiency and precision grinding of silicon carbide ceramics with monolayer brazed diamond wheel

To explore the feasibility of high efficiency and precision grinding of brittle ceramics, the experimental grinding tests were conducted on SiC ceramics with monolayer brazed diamond wheels. The monolayer diamond grinding wheel with 80/100 mesh size diamond grains was brazed using high-frequency induction techniques. The binarization method was proposed to quantitatively characterize the brittle removed areas from the whole ground surface and oblique polishing method was used to assess the subsurface damage depth of the ground SiC samples. The results show that the maximum undeformed chip thickness (agmax) plays a crucial role in the material removal mode. When agmax increases from 0.08 µm to 1 µm, the brittle-removal ratio increases rapidly from 8.20 % to 48.24 % and the subsurface damage depth increase from 3.48 µm to 9.14 µm by 162.6 %. The grinding wheel speed also has a significant influence on the brittle-removal ratio. With the gradual increase of grinding wheel speed (vs) from 20 m/s to 160 m/s, the brittle-removal ratio of the ground surface decreases from 34.24 % to 25.56 %, and the depth of subsurface damage decreases from 5.68 µm to 3.58 µm by 36.97 %. The effect of the grinding depth on the ground surface and subsurface is comparatively not remarkable. The influence of grinding parameters on the grinding process of SiC ceramics indicate that high speed, creep infeed and deep depth grinding method makes it possible to realize high efficiency and low damage machining for SiC ceramics with monolayer diamond wheel.

Study on grinding of SiCp/Al composites by micro-textured monolayer brazed diamond wheel

Study on grinding of SiCp/Al composites by micro-textured monolayer brazed diamond wheel

The making and performance of patterned-monolayer brazed diamond wheel produced with Ag-based novel active filler

Present paper delineates a novel route adopted for successfully manufacturing single layer brazed patterned diamond wheels with enhanced attributes. A pneumatic pick-drop methodology is used for placing the grits in a uniform and patterned manner. Instead of commonly used Ni-Cr alloys, a novel formulation of μ-TiC inoculated composite Ag-Cu-Ti filler has been preferred, which helped in arresting crack formation at the root of grit brazement and simultaneously ensured high bond wear characteristics. Addition of μ-TiC particles substantially improved wear characteristics of basic Ag-Cu-Ti alloy but tend to impair its wetting ability on diamond surface with increase in its wt% in the composition. Therefore, its presence in the filler was restricted to only 2 wt% to keep such compromise within acceptable level. Wheels developed using active Ag-Cu fillers were further subjected to performance evaluation by grinding of WC-Co cermets. The operating parameters were changed in such a way that wheels experienced increasing order of grinding-aggressiveness. The degree of aggressiveness in the grit-work interaction has been defined by a unifying scalar quantity, termed as “aggressiveness number”. No trace of wheel loading was observed even in the most aggressive condition due to uniformly spaced grits. The failure counts of diamond grits are also related to this scalar. A detailed analysis is presented to address the suitability of μ-TiC reinforcement in the formulation of active Ag-Cu filler in the light of the grinding force and grit retention ability of the wheels.

Precision grinding of cemented carbides based on a multi-layer brazed diamond wheel using an electrolyte containing carbon nanotubes

Carbon nanotubes (CNTs) were added into the electrolyte to improve electrolytic dressing grinding performance of a brazed multi-layer diamond wheel containing titanium. The effect of CNTs on the electrolytic dressing performance of the grinding wheel was studied. The grinding force, residual stress, roughness and morphology of the machined surfaces were recorded in the grinding experiment of cemented carbides, and the grinding performance was evaluated based on these. The experiment results expressed that the CNTs improved the electrolytic dressing performance of the grinding wheel, which allows the worn grits to smoothly fall off and maintain the sharpness. The grinding force and residual stress were reduced when the CNTs were added into the electrolyte. Moreover, there was a grand advancement in the machined surface quality when the CNTs were used as an additive to the electrolyte. The machined surfaces produced by the brazed wheel using an electrolyteadded CNTs showed predominantly smooth grinding marks. Ductile-mode removal was predominantly observed in the grinding experiments. Adding CNTs to an electrolyte can help achieve high-precision grinding of difficult-to-cut materials with a brazed multi-layer diamond wheel.

Brazing diamond grits onto AA7075 aluminium alloy substrate with Ag–Cu–Ti filler alloy by laser heating

The brazing of diamond is a promising way to fabricate grinding wheels for efficient machining and precision grinding. This work investigated the feasibility of bonding diamond grits onto Aluminium Alloy 7075 (AA7075) substrate with a Ag–Cu–Ti filler alloy via laser fusion brazing. The interfacial microstructures and the strength of the brazed diamond joints were studied. The cross-section of the brazed diamond joint consists of a molten filler alloy layer, a molten pool, a heat effect zone, a columnar crystal zone and an equiaxed crystal zone. Within the interface of the filler alloy/substrate metal, microstructures observed possibly were Ag(s.s), Al(s.s), TixAl, Al2Cu and Mg intermetallic compounds. A layer of TiC with a thickness of about 30–50 nm was found at the bonding interface of the diamond/filler alloy. The averaged peak shear force of the brazed joints was found to be approximately 39.8 N. The abrasion grinding test indicated that the diamond/AA7075 brazed joint was adequate for grinding. However, the pulled-off of grit was found to be the primary failure of this type of brazed joint. This work broadened the brazing diamond technique and the range of applications of brazed diamond wheels for efficient grinding.

Precision grinding of engineering ceramic based on the electrolytic dressing of a multi-layer brazed diamond wheel

A multi-layer brazed diamond wheel was produced by combing compression molding and vacuum brazing technology. In addition, electrolytic dressing was used to overcome the shortcoming that it is difficult for worn diamonds to fall off the brazed wheel owing to the high bonding strength between the diamonds and brazing alloy. A special electrolyte solution was prepared for electrolytic dressing of the multi-layer brazed diamond wheel, and grinding experiments with a Si3N4 ceramic were conducted to compare the grinding performance of the multi-layer brazed diamond wheel before and after electrolytic dressing. The results indicated that the prepared electrolyte solution could effectively allow the worn diamond grit to fall off the bonding matrix, which can improve the sharpness of the brazed wheel and obtain a good cutting ability. The grinding force of the multi-layer brazed diamond wheel after electrolytic dressing was smaller than that of the brazed diamond wheel during conventional grinding. Moreover, significant improvements in the surface roughness and topography of the ground surface were successfully achieved by using electrolytic dressing of the multi-layer brazed diamond wheel. Periodic electrolytic dressing of the multi-layer brazed diamond wheel has been shown to be an efficient method for realizing the precision machining of engineering ceramics.

Grinding characteristics of aluminium alloy 4032 with a brazed diamond wheel

An investigation was conducted to assess the grinding characteristics of aluminium alloy 4032 (AA4032) when ground with a brazed diamond wheel, especially at high-grinding speed. The grinding forces, the ground surface of the workpiece and the wear of the brazed wheel were examined. The results indicated that grinding AA4032 using the brazed diamond wheel is feasible. The ground surface was formed by ductile material removal, and the smooth areas, pile-up areas, ploughing grooves, adhesion areas and small holes of the ground surface were characterised. By increasing the grinding speed, the grinding forces and surface roughness were significantly reduced, but the force ratio was increased, possibly due to the reduction of friction between the diamond grains and the workpiece. Flattening wear was found to be the main wear mode of brazed diamonds on the wheel. Chip adhesion tended to occur in areas with insufficient intergrain distance and was also observed on the top surface of grains, especially flattened grains. It is expected that this work will contribute to broadening the range of applications of brazed diamond wheels.

Precision Grinding of Ultra-fine Cemented Carbide Based on Electrolytic In-process Dressing of a Multi-layer Brazed Diamond Wheel

Precision Grinding of Ultra-fine Cemented Carbide Based on Electrolytic In-process Dressing of a Multi-layer Brazed Diamond Wheel

Experimental research on performance of monolayer brazed diamond wheel through a new precise dressing method—plate wheel dressing

The application of monolayer brazed diamond wheels in machining hard–brittle materials is always limited for the high transverse roughness on the ground surface of the workpiece. In the present investigation, a new dressing method, namely plate wheel dressing, was proposed for monolayer brazed diamond wheels in order to reduce the surface roughness of workpiece by micro-removing the over-protruded grits. To evaluate the effect of the dressing method, the grinding performance of the dressed diamond wheel was investigated in grinding SiC ceramics. Results obtained show that the contour of the grits was improved greatly and the quality of the workpiece was pretty good to meet the requirement of precision grinding. The transverse surface roughness Ra value reduced to the minimum value, i.e., 0.086 μm. This plate wheel dressing method can realize the precise dressing of the monolayer brazed diamond wheel.

Surface Integrity of AlSiC Composites Ground by Monolayer Brazed Diamond Wheels

Monolayer brazed diamond wheel were used to grind AlSiC composite with different volume fraction of SiC. The effects of diamond mesh size of the grinding wheels and the volume fraction of SiC in AlSiC composite on the surface integrity of ground AlSiC composite were investigated. It is found that the surface roughness of ground AlSiC composite with 20% SiC is increased with the reduction of diamond grit’s size because of the clogging of diamond wheel. With the increasing of the volume fraction of SiC, there are more fractured and cracked SiC particles on the ground surface of AlSiC composite. On the other hand, the finer diamond grits (70/80) induce the finer fractured SiC particles on the ground surface of AlSiC with 50% and 70% SiC.

Surface Integrity of AlSiC Composites Ground by Monolayer Brazed Diamond Wheels

Monolayer brazed diamond wheel were used to grind AlSiC composite with different volume fraction of SiC. The effects of diamond mesh size of the grinding wheels and the volume fraction of SiC in AlSiC composite on the surface integrity of ground AlSiC composite were investigated. It is found that the surface roughness of ground AlSiC composite with 20% SiC is increased with the reduction of diamond grit’s size because of the clogging of diamond wheel. With the increasing of the volume fraction of SiC, there are more fractured and cracked SiC particles on the ground surface of AlSiC composite. On the other hand, the finer diamond grits (70/80) induce the finer fractured SiC particles on the ground surface of AlSiC with 50% and 70% SiC.

Experimental Investigation on Electrochemical Grinding of Inconel 718

Electrochemical grinding (ECG) is a variation of electrochemical machining (ECM), in which material is removed from the workpiece by simultaneous electrochemical reaction and mechanically abrasive action. It offers a number of advantages over conventional grinding, such as low induced stress, large depths of cut, and increased wheel life. It has been reported that ECG was employed in machining stainless steel 304, metal-ceramic hard alloy of WC-Co groups, and Tungsten carbide. Inconel 718 is used extensively in aerospace because of their excellent combination of high specific strength (strength-to-weight ratio) which is maintained their fracture resistant characteristics, and their exceptional resistance to corrosion at elevated temperature. The machinability of Inconel 718 is generally considered to be poor owing to several inherent properties of the materials. Poor thermal conductivity, chemically reactivity and low elastic modulus are the common problems.In this paper, ECG is employed to process Inconel 718. To prolong the wheel life, the brazed diamond wheel is introduced to be a tool instead of the electrodeposited diamond wheel. Experiments illustrated that the tool durability has been improved from 15hours to 50hours when a brazed diamond wheel was employed to replace an electrodeposited diamond wheel. In addition, a proper high applied voltage and electrolyte temperature was verified to be conductive to improve the maximum electrode feed rate and material removal rate. A electrode feed rate of 6.6mm min-1 was obtained at 30V and 36°C, respectively.

Tribological characteristics in high-speed grinding of alumina with brazed diamond wheels

In this work, two brazed diamond wheels fabricated by brazing in vacuum were used to grind alumina at different grinding speeds. During the process, the horizontal and vertical grinding forces were measured by a force measurement device. The grinding forces, specific grinding energy, and friction in grinding of alumina at low and at high speeds were investigated. The results show that the friction coefficient decreases with the increase of the grinding speed and also relates to the grinding mode. A nearly proportional relationship between grinding power per unit width (Pm) and the rate of plowed surface area generated per unit time per unit width (Sw) reveals the effects of friction in grinding and most of the grinding energy is expended by friction. The surface energy per unit area generated by plowing friction (Js) for high-speed grinding is found to be lower than for low-speed grinding.

Performance of brazed diamond wheels fabricated in hydrogen/methane plasmas or a vacuum

The ambience in which brazed diamond wheels are fabricated has an important effect on the sharpness of the brazed diamond grits and on the hold of the filler alloy on these grits. In this work, brazed diamond wheels were fabricated using NiCr alloy either in a 0.05-Pa vacuum or in H2/CH4 plasmas at a temperature of 1,020°C for 5 min. The surface of the diamond grits brazed in H2/CH4 plasmas and protruding out of the filler alloy is not graphitized. The layer of carbide formed on the interface between the filler alloy and diamond brazed in H2/CH4 plasmas allows the liquid filler alloy to soak the diamond grits better. This is good for the filler alloy gaining a firm hold on the diamond grits. Diamond grits brazed in H2/CH4 plasmas undergo compressing stress due to the penetration of carbon into the filler alloy. There is a white band, which denotes firm metallurgical bond, between the filler alloy and the substrate of a brazed diamond wheel fabricated in H2/CH4 plasmas or in the 0.05-Pa vacuum, but the bandwidth in the brazed diamond wheel fabricated in H2/CH4 plasmas is almost twice that in the brazed diamond wheel fabricated in the 0.05-Pa vacuum. Grinding tests showed that the percentages of both whole grain fractures and pullouts from the matrix of diamond grits brazed in H2/CH4 plasmas are lower than those of diamond grits brazed in the 0.05-Pa vacuum.

Hot-filament chemical vapor deposition of amorphous carbon film on diamond grits and induction brazing of the diamond grits

The production of a high-quality brazed diamond tool has gradually drawn the attention of the tool industry. Hot-filament chemical vapor deposition (CVD) of amorphous carbon film on diamond grits was conducted. The deposited diamond grits were used to make brazed diamond tools by induction heating. Amorphous carbon film (1–2μm thick) was deposited onto the diamond surface. The diamond grits protruding from the filler alloy maintain their sharpness after induction brazing of the deposited diamond grits. Discontinuous irregular carbides are distributed evenly on the brazed diamond surface in the filler alloy. This considerably enhances the bonding strength between the filler alloy and diamond grits. Grinding tests of the brazed diamond wheels show a low percentage of pullouts from the matrix and whole grain fracture for the deposited diamond grits brazed by induction heating.

An experimental investigation of temperatures and energy partition in grinding of cemented carbide with a brazed diamond wheel

An experimental investigation is reported of the temperatures and energy partition in the grinding of cemented carbide with a vacuum brazed diamond wheel. During the experiments, the temperature distributions along the workpiece surface were measured using a sandwiched foil thermocouples and the energy partition to the workpiece estimated using a temperature matching method. The effects of the various grinding conditions, including wheel velocity, feed rate, and depth of cut, on the temperatures and the energy partition were investigated. The measured temperature responses were found to be in good relation with the analytical results of a moving heat source with a triangular distribution at the grinding zone. It was found that the grinding temperatures measured under different grinding conditions varied from 10°C to 100°C. The energy partition to the workpiece in dry grinding was found to be from 35% to 70%. Based on the energy partition values obtained from the experiments, the diamond tip temperature was calculated and found to be over the temperature necessary for the graphitization of diamond if the circular grain contact of radius is smaller than a critical value.

Experimental Study on Performance of Monolayer Brazed Diamond Wheel through Chemical-Mechanical Dressing

The dressing methods of monolayer diamond tool have recently been developed increasingly because a substantial improvement of the ground surface roughness could be achieved with the dressed monolayer diamond tools. In this paper, a new dressing method was proposed, namely chemical-mechanical dressing of the diamond grits. Dressing experiments were carried out on the monolayer brazed diamond grinding wheel. The grit-tip distances from the base of wheel substrate were measured before and after dressing. Grinding experiments were conducted on K9 optical glass after each dressing interval. The roughness parameters of the ground surfaces were measured. The outcome of this attempt appeared highly encouraging, and the dressing of monolayer brazed diamond grinding wheel is effective with the chemical-mechanical dressing.

Force and Energy in Grinding Zirconia Ceramics by Brazed Monolayered Diamond Wheels

An investigation was undertaken to explore the grinding energy and removal mechanisms in grinding zirconia by using brazed diamond wheels. The grinding forces were measured and the morphological features of ground workpiece surfaces were examined. The results indicate that material removal mechanisms are dominated by the combined removal modes of brittle and ductile. The prevailing removal mechanism for the ground surface of zirconia changes from brittle to ductile when the maximum chip thickness change from large to small.

Temperatures in Grinding Cemented Carbide (YT30) with a Vacuum Brazed Diamond Wheel

An experimental investigation is reported on the temperatures and energy partitions involved in the grinding of cemented carbide (YT30) with a vacuum brazed diamond wheel. The grinding temperature at the wheel-workpiece interface was measured using a pair of grindable foil thermocouples and the energy partition to the workpiece was evaluated by matching the analytical temperatures to the measured results. Effects of the various grinding conditions, including wheel velocity, feed rate and depth of cut, on the temperatures and the energy partition were investigated. It was determined that the wheel velocity was the most significant factor in governing the temperature relative to the depth of cut and feed rate. The maximum temperature rise at the contact zone was below 25°C in the present study. Microscopic examination of the ground surfaces and the ground detritus revealed that brittle fracture was the dominant material-removal mode. This may be one of the reasons for the low grinding temperature in grinding YT30 with a vacuum brazed diamond wheel. The energy partition values to the workpiece obtained under different grinding conditions varied from 3.3% to 20% for dry grinding YT30.