Grinding Performance Integrated Experimental Evaluation on Alumina Ceramics with Leaf-Vein Bionic Grinding Wheel

In order to enhance the grinding performance of alumina ceramic materials, the surface of the grinding wheels are ablated by laser radiation before grinding, and the three types of leaf-vein bionic grinding wheels with different micro-groove pitches are formed to compare the grinding experiments with normal grinding wheels. The grinding forces and surface roughness were gauged and the morphological characteristics of ground workpiece surfaces were studied. The results showed that with the increase of groove pitch, the normal grinding force was reduced by 9.6-63%, while the tangential grinding force is reduced by 8.3-42%. The groove can promote the flow of coolant, accelerate the heat dissipation and chip removal in the grinding area, reduce the damage of the workpiece and the wear of the grinding wheel, so the vein bionic grinding wheel had more tremendous processing advantages. Among the four kinds of grinding wheels, the leaf-vein bionic grinding wheel with groove pitch equal to 8mm obtained the best grinding effect. The vein-shaped groove had a positive impact on the grinding process.

Microscopic Wear Characteristics of Ceramic Grinding Wheel in Creep Feed Grinding

This paper deals with the microscopic wear characteristics of ceramic (Seeded Gel, SG) grinding wheels used in creep feed grinding. Creep feed grinding experiments with SG grinding wheels were carried out compared to rose-pink alumina (RA) grinding wheels. To clear the wear characteristics of the wheel working surface in creep feed grinding, changes in the shapes of grain cutting edges were observed by a field emission-scanning electron microscope (FE-SEM). This is a self-sharpening phenomenon based on micro fractures generated on the top of SG grain cutting edges. On the other hand, large fracture and attritious wear effected RA grain cutting edges. In addition, the features of any grain cutting edges were evaluated using attritious wear flat percentage. Changes in attritious wear flat percentage of SG grits maintained constant value and were stable. From these results, the influence of wear mode of the grinding wheel on grinding characteristics parameter, such as grinding force and workpiece surface roughness, is understood.

Effect of Types of Grinding Fluid on Grinding Characteristics of CMSX4

Nickel-based heat-resistant alloys are widely used for fabricating the turbine blades in gas turbine engines. An increase in the number of such engines operated by air carriers will increase the demand for high-efficiency machining of nickel-based heat-resistant alloys. However, the high-efficiency grinding of nickel-based heat-resistant alloys is challenging because of their low thermal conductivity and thermal diffusivity, high chemical activity, large work-hardening properties, and high-temperature strength. In this work, the authors propose a high-efficiency grinding technique that uses speed-stroke grinding of nickel-based heat-resistant alloys, and aim to clarify the optimum grinding conditions for the proposed grinding method. The workpiece material is CMSX4 used for the turbine blades. A Cubitron + WA grinding wheel and WA grinding wheel mounted on a linear motor-driven surface grind machines are used for grinding, and the grinding force, surface roughness, and grinding ratio are investigated with the removal rate maintained constant. Two types of grinding fluid are prepared: solution and soluble. From the experiments, it is found that wet grinding features a lower grinding force, smaller surface roughness, and higher grinding ratio when compared to dry-cut grinding. The improvement in the grinding ratio at high table speeds is significant, and it is found to be greater for the soluble-type fluid than for the solution-type fluid.

Cortical bone grinding mechanism modeling and experimental studyfor damage minimization in craniotomy

Craniotomy, as a part of neurosurgery, implies a safe opening of the skull with mechanical equipment. Grinding is a traditional machining method that can accurately and efficiently remove bone tissue. Aiming at low-damage and high-efficiency bone grinding, this study analyzed the kinematic law of a single abrasive grain during the grinding process. The theoretical model of grinding force was established based on the calculation of specific energy and friction force. The grinding test platform was set up, and the full factorial experimental design was performed to link the grinding force evolution with different processing parameters. The experimental results obtained on porcine femurs validated the model predictions where the grinding force grew with feed speed and grinding depth; it exhibited a decreasing trend with rotation speed, followed by increasing one.

Improvement of Shape Error for Slender Parts in Cylindrical Traverse Grinding by Part-Deformation Modelling and Compensation

Achieving geometrical accuracy in cylindrical traverse grinding for high-aspect slender parts is still a challenge due to the flexibility of the workpiece and, therefore, the resulting shape error. This causes a bottleneck in production due to the number of spark-out strokes that must be programmed to achieve the expected dimensional and geometrical tolerances. This study presents an experimental validation of a shape-error prediction model in which a distributed load, corresponding to the grinding wheel width, is included, and allows inclusion of the effect of steady rests. Headstock and tailstock stiffness must be considered and a procedure to obtain their values is presented. Validation of the model was performed both theoretically (by comparing with FEM results) and experimentally (by comparing with the deformation profile of the real workpiece shape), obtaining differences below 5%. Having determined the shape error by monitoring the normal grinding force, a solution was presented to correct it, based on a cross-motion of the grinding wheel during traverse strokes, thus decreasing non-productive spark-out strokes. Due to its simplicity (based on the shape-error prediction model and normal grinding force monitoring), this was easily automatable. The corrective compensation cycle gave promising results with a decrease of 77% in the shape error of the ground part, and improvement in geometrically measured parameters, such as cylindricity and straightness.

Investigation on the Effect of Dynamic Fracture Toughness to Zirconia Ceramic Grinding Performance with Different Grain Sizes

To reveal the material removal mechanism of zirconia ceramics, an improved prediction models of the critical grinding force and maximum subsurface damage depth models are developed based on the dynamic fracture toughness. The effects of three different grain sizes on the material removal mechanism during brittle- ductile transition process of zirconia ceramics is analyzed through grinding experiments. And the influence of grain size on grinding force, workpiece surface roughness, surface fragmentation rate and subsurface damage depth in grinding are discussed. The results of the experiment results indicated that the value of dynamic fracture toughness tends to decrease with an increase in equivalent grinding thickness, and the ductile removal range of zirconia ceramics expands for the reason that the critical grinding force considering dynamic fracture toughness is higher than the static grinding force considering static fracture toughness, and the maximum subsurface damage depth is closer to actual maximum subsurface damage depth. Besides the smaller the grain size of zirconia ceramics, the higher the surface quality of grinding.

Brush grinding aluminum alloy mechanism of single steel wire based on finite element approach

In the process of surface treatment, steel wire brush can not only efficiently remove surface contaminants, such as deteriorated paint film and rust, but also increase the adhesive strength. However, the associated brush mechanics of material removal is still not clear. In order to reveal the brush mechanics of material removal, this paper assumed the tip of steel wire were ball–cone shaped, constructed contact force model, and calculated the brush grinding force under different process conditions based on finite element approach. The simulated results show that the brush grinding can be changed from plastic plowing to chip formation when the penetration depth is increased to 10 μm, then changed from chip formation to plastic plowing when the inclination angle is increased to 30°, respectively. The simulated value of brush force rises with the increasing penetration depth and inclination angle, which was consistent with the experimentally obtained values, and the relative errors are within 9%. The quantity of material removal increases with the ascending of penetration depth, and decreases with the ascending of inclination angle. This paper provides guidance to understand the mechanics of material removal, predict the brush grinding force, and contribute well to an automatic grinding control application.

On the Grinding Performance of Alumina Wheels in Ultrasonic Vibration-Assisted Grinding of Hardened GCr15 Steel

Composite manufacturing with multiple energy fields is an important source of processing technology innovation. In this work, comparative experiments on the conventional grinding (CG) and ultrasonic vibration-assisted grinding (UVAG) of hardened GCr15 steel were conducted with WA wheel. The grinding wheel wear patterns and chips were characterized. In addition, grinding force, force ratio, and ground surface quality were investigated to evaluate wheel performance. Results illustrate that the interaction between abrasive grains and workpiece in UVAG process has the characteristics of high frequency and discontinuity. The wear property of abrasive grains is changed and the grinding force is decreased because the generation of micro-fracture in abrasive grains improves the grinding wheel self-sharpening. Better surface quality is obtained, the surface roughness is reduced by up to 18.96%, and the number of defects on the machined surface is reduced through the superior reciprocating ironing of UVAG. Accordingly, WA wheel performance is improved by UVAG.