Aspects Of Grinding Research Articles

An integrated model of tool grinding: challenges, chances and limits of predicting process dynamics

The objective of manufacturing technology, to reduce machining costs, increase product quality and optimize process setups, is only achievable by considering the entire manufacturing process and its interrelations. Especially in tool grinding, strong interactions exist between workpiece dynamics, grinding wheel engagement, structure deformations and cutting process conditions, which makes an integrated model necessary. This paper introduces a tool grinding model that combines time-dependent dynamical aspects of the grinding wheel and workpiece with local varying contact conditions to predict the final workpiece geometry and cutting forces with a high resolution in space and time. The model is capable to reproduce systemic effects on cutting forces and ground geometries which only occurs in the interplay of all system components. The model is also positively tested in representing influences of process parameters and in optimizing the machining. The excellent agreement of simulations and experimental data shows the model’s potential in manufacturing technology, but also in investigating grinding aspects, which are not fully understood yet.

Reduced models of grinding wheel topography and material removal to simulate dynamical aspects in grinding

Increasing competition and short product life cycles make it necessary to optimize and evaluate the outcome of manufacturing processes. In tool grinding, models for the final workpiece geometry and cutting forces are of particular interest. To establish a valid general grinding model, we investigated the cutting process and the influence of local grinding wheel engagements on the material removal. We consequently developed models of material removal and grinding wheel topography, which capture the main correlations in grinding. In combination, temporal cutting forces and final workpiece geometry are predictable and are in excellent agreement with experimental data. The introduced models are valid for grinding in general, since they are solely based on the geometry and process parameters, and hence are applicable for manufacturing process optimization.

The use of computational fluid dynamics in the analysis of fluid flow and thermal aspects in grinding

A numerical model based on computational fluid dynamics is developed to analyze fluid flow and thermal aspects in grinding. The model uses multiphase fluid flow with heat transfer based on the volume-of-fluid method, convection, conduction in solids and a multiple reference frame model of the porous grinding zone. Fluid velocity vectors, useful flow rate, grinding temperatures and energy partition are predicted using the model. In lieu of direct measurements of these quantities, the verification relies on the indirect assessment of surface integrity. The simulation results provide adequate agreement with the measured residual stress, depth of heat-affected zone and full width at half maximum profile with respect to the grinding temperatures.

Significance of grinding burn on high speed steel tool performance

Despite rapid developments in cutting tool material, traditional HSS still finds applications such as broaching, intermittent cutting, thread cutting and even finish turning of ductile materials using moderate spindle speeds. Performance of HSS tool largely depends on structure–property relationship. Traditionally, HSS tools are finish ground; however, very little attention is paid to grinding aspects in grinding of HSS especially, metallurgical specifications. During grinding, HSS experiences thermal related defects such as grinding burn; which results in phase transformation of the material over specific depth. The severity of grinding burn is largely depending on the grinding condition. Beneficial effects on performance of HSS tools can be obtained, if degree of burn is contended. This is illustrated in the case study on turning of commercial pure aluminium.

Evaluation of surface characteristics of ground CVD-SiC using cast iron bond diamond wheels

The precision and efficient machining of CVD-SiC ceramic to required quality has not been well established yet. In this paper, a comparative study was conducted to investigate the special aspects in grinding of CVD-SiC ceramic, with ELID method or rotary dressing method. The stability of surface roughness, effects of material properties and dressing methods on grinding results, effects of material properties and dressing methods on surface stress state, and microscopic analysis of ground CVD ceramics by both methods were well analyzed. In addition, a wheel-workpiece interaction model was proposed for the two dressing methods.

96/04689 Some aspects of grinding of high ash indian coal in a prototype ball mill

96/04689 Some aspects of grinding of high ash indian coal in a prototype ball mill

Aspects in Grinding of Ceramics

Aspects In the grinding of ceramics have been investigated. Si3N4, ZrO2, SiC, and Al2O3 were ground with resin‐bonded diamond wheels of grit numbers ranging from 80 to 800. Microstructural observations of ground surfaces show that grinding occurs predominantly by flow mode in Si3N4 and ZrO2, and by fracture and grain pullout in SiC and Al2O3. The measurement of grinding force shows that grinding resistances in Si3N4 and ZrO2 are significantly larger than those in SiC and AI2O3. As the grit number of the grinding wheel increases, maximum surface roughness significantly decreases in Si3N4, ZrO2, and SiC, but it apparently does not change in AI2O3. This unexpected result in AI2O3 is discussed in terms of the observed grinding mode and microstructure.

Thermal Aspects of Grinding: The Effect of the Wheel Bond on Heat Transfer to an Abrasive Grain

Heat generated during grinding can cause thermal damage to the workpiece and wheel. It is therefore important to understand the thermal aspects of grinding. This paper addresses heat conduction into the wheel, by considering a single abrasive grain in contact with the workpiece. In particular, the effect of the bond material on conduction into the grain is investigated. The results for the grain surface temperature are given in terms of parameters describing the geometry and thermal properties of the grain and bond. The beneficial effect of a high thermal conductivity for both the grain and the bond is clearly demonstrated.

Grinding energy study using a new laboratory tumbling mill assembly

AbstractWith the express aim of developing a new concept, ‘Energy Index’, wherein theoretical energy considerations and practical application will be in agreement, the energy aspects of grinding by a tumbling mill were investigated.For this purpose, a specially designed tumbling mill assembly has been constructed at the University of British Columbia. The assembly consists of three interchangeable cylindrical laboratory-mills of different diameters, together with an automatic speed control system and a torque meter. Experiments were conducted to determine the driving characteristics of tumbling mills and some of the factors affecting comminution energy. It was found that the required torque for grinding remained almost constant throughout the grinding operation, regardless of the material being ground, and the torque for a flat-faced cylindrical mill containing feed material was -about 20 percent less than that containing no feed material. The introduction of a new index – Energy Index – which is a functi...