Tesi sul tema "Fine grinding"

Abstract Wood powders are used in numerous applications such as thermoplastics and filters, and a lot of research effort has been put into developing novel ways of utilising them. The mechanical processing of wood powders, especially at particle sizes below 100 µm, has been reported in several studies, but they lack information on the effect of fine grinding conditions on the particle morphology and cellulose crystallinity, both of which are important parameters in the further processing of wood powders and in their various applications. This makes it very difficult to design and optimise fine grinding processes with different applications in mind. The aim of this thesis was to study the dry fine grinding of wood in several impact-based fine grinding mills in order to find out their effect on the properties of the wood and to study the energy required for the mechanical processing of the resulting powders. The effect of the main operational parameters on the properties of dried Norway spruce wood and the energy consumption was studied using three impact-based fine grinding mills that were capable of pulverising the wood down to a median particle size of less than 25 µm. It was found that the impact events occurring in media mills can be used for the production of very fine wood powders with lower cellulose crystallinity and rounder shaped particles having more uniform shape distribution than powders pulverised to a similar size range by means of impact events in non-media mills. A practical estimate was obtained for the minimum specific energy consumption in fine grinding in mills involving grinding media that could be utilised as a target for optimisation. Impact-based media milling under cryogenic conditions can be used to obtain different Norway spruce wood powders from those produced under ambient grinding conditions, i.e. without the freezing effect of nitrogen liquid. The energy efficiency of fine grinding can be enhanced by choosing cryogenic rather than ambient conditions. The moisture content of the wood has greater influence on the size and shape of the particles when milling is accomplished under ambient conditions. Torrefaction can reduce the energy consumption in impact-based media mills for median particle sizes over 17.4 µm (± 0.2 µm), while the shape and cellulose crystallinity of the particles are not significantly affected by torrefaction pretreatment as a function of energy consumption
Tiivistelmä Puujauheita käytetään laajalti erilaisissa sovelluksissa, kuten esimerkiksi biokomposiiteissa ja suodattimissa. Tämän lisäksi on olemassa paljon tutkimustietoa siitä, kuinka puujauheita voitaisiin hyödyntää laajemminkin. Puu voidaan mekaanisesti prosessoida alle 100 µm:n kokoluokkaan, mutta yksityiskohtaista tietoa kuivahienojauhatuksen olosuhteiden vaikutuksesta jauheiden morfologiaan ja selluloosan kiteisyyteen ei ole saatavilla. Puujauheen morfologialla ja selluloosan kiteisyydellä on kuitenkin merkittävä vaikutus sovelluksia ja jatkojalostusta ajatellen. Puun kuivahienojauhatuksen tiedon puute hankaloittaa merkittävästi prosessin suunnittelua ja optimointia erilaisia sovelluksia varten. Tämän väitöskirjan tavoitteena on selvittää iskuihin perustuvien hienojauhimien vaikutukset puun ominaisuuksiin ja tutkia mekaanisen prosessoinnin energiatehokkuutta hienojauhatuksessa. Tutkimuksessa selvitettiin kolmen erilaisen iskuun perustuvan hienojauhatusmyllyn pääasiallisten operointiparametrien vaikutusta kuivatun metsäkuusen ominaisuuksiin ja energiankulutukseen. Jokaisella hienojauhimella onnistuttiin tuottamaan puujauhoja, joiden mediaanikoko oli alle 25 µm. Iskuihin perustuvalla jauhinkappalemyllyllä saatiin tuotettua puujauhoa, jonka selluloosan kiteisyys on alhaisempi ja partikkelimuodot pyöreämpiä verrattuna samankokoisiin puujauhoihin, jotka on tuotettu iskuihin perustuvilla jauhinkappaleettomilla hienojauhatusmyllyillä. Työssä saatiin käytännöllinen arvio kuivatun metsäkuusen hienojauhatuksen minimienergiankulutukselle iskuihin perustuville jauhinkappalemyllyille, mitä voidaan käyttää kyseisten myllytyyppien optimoinnin tavoitteena. Työssä havaittiin lisäksi, että kryogeenisiä jauhatusolosuhteita käyttämällä voidaan tuottaa erilaisia puujauhoja verrattuna puujauhoihin, jotka prosessoidaan ilman nestetyppijäädytystä, kun jauhatus suoritetaan iskuihin perustuvalla jauhinkappalemyllyllä. Ilman nestetyppijäädytystä puun kosteuspitoisuudella on merkittävämpi vaikutus puujauhojen ominaisuuksiin kuin kryogeenisissä olosuhteissa jauhetuilla. Kryogeenisillä jauhatusolosuhteilla voidaan parantaa myös jauhatuksen energiatehokkuutta. Torrefioinnilla voidaan vähentää hienojauhatuksen energiankulutusta iskuihin perustuvilla jauhinkappalemyllyillä, kun tavoitekoon mediaani on yli 17,4 µm (± 0,2 µm). Torrefioinnilla ei ole vaikutusta selluloosan kiteisyyteen tai partikkeleiden muotoon energiankulutuksen funktiona

In recent years, a great deal of interest has been shown in developing methods for preparing super—clean coal containing less than 2% ash and 0.5% sulfur. New techniques for recovering fine coal, such as micro—bubble flotation, can achieve the desired result provided mineral matter is sufficiently liberated. To achieve sufficient liberation, however, it is often necessary to grind to a mean particle size finer than 10 microns. Since conventional ball mills are highly inefficient in this fine size range, the stirred ball mill has been proposed as a more suitable means for ultrafine grinding.
Master of Science

La poudre de silicium métallurgique (MG-Si, pureté 99 %) ont été étudiées, en se focalisant particulièrement sur les particules fines (taille comprise entre 1 et 10 μm) Ce matériau est utilisé dans l’industrie siliconière pour la synthèse directe du diméthyldichlorosilane et est obtenu par broyage de blocs de silicium. Les propriétés de cette poudre sont cruciales pour le procédé industriel, à la fois en termes de surface spécifique, composition chimique et coulabilité. Comprendre l’influence des particules fines, qui dégradent la coulabilité, et leur origine au cours du broyage est donc d’une importance cruciale. Une nouvelle caractérisation, chimique et cristallographique, des poudres de MG-Si montre que les particules fines sont en moyennes moins chargées en éléments d’alliage que les particules plus grosses. La structure cristalline du silicium est inchangée au cours du broyage, sauf pour les particules superfines (taille inférieure à 1 μm). Celles-ci présentent des zones amorphes : cela montre qu’elles sont soumises à des contraintes plus importantes au cours du broyage, comme cette transformation étant obtenue au-delà d’un seuil de pression. Le comportement du MG-Si en broyage a été étudié pour la première fois. A l’échelle de la particule unique, il est confirmé que les fissures suivent une propagation transgranulaire. De plus, des particules fines peuvent être produites au cours d’un unique événement de broyage, en raison de l’activation simultanée de multiples systèmes de fissures qui peuvent brancher entre elles. La taille critique en-deçà de laquelle la déformation plastique est énergétiquement plus favorable que la propagation de fissure a été estimée à environ 1 μm par une méthode basée sur l’indentation. Ces deux résultats sont cohérents avec la répartition des éléments d’alliages en fonction de la taille de particule. A l’échelle multiparticulaire, une étude pilote en broyeur à tambour tournant a été menée. Les résultats de cette étude ne sont pas disponibles dans cette version publique du manuscrit. Veuillez vous reporter au manuscrit complet. Les conséquences sur la coulabilité de la présence de particules fines dans la poudre de MG-Si produite par broyage ont été caractérisées par mesures d’angle de repos, de dynamique de compaction et en fluidisation. En particulier, un nouveau comportement d’élutriation a été identifié et décrit : l’élutriation séquentielle se produit lorsque des particules fines sont initialement présentes dans le lit fluidisé et se caractérise par l’envolement d’abord des inférieures à environ 30 μm puis seulement des particules de taille supérieure. Ce comportement n’est pas observé en l’absence de fines dans le lit initial. L’explication de ce phénomène pourrait se trouver dans la formation de clusters polydisperses, formés seulement en présence de particules fines. En parallèle de l’élutriation séquentielle, des mesures électrostatiques avec un électromètre externe à la colonne ont montré la présence de potentiels très importants (10 kV), dont le signe correspond à la gamme de taille de particules envolées. Ceci suggère que l’adhésion au sein des clusters pourrait être électrostatique
Metallurgical-grade silicon (MG-Si, 99 %) powders were extensively investigated, particularly focusing on the fine particles (whose size is between 1 and 10 μm) comprised in these powders. This material is a reactant widely used in the silicones industry for the Direct Synthesis and is obtained by size reduction of millimetric silicon lumps. Powder properties are major stakes of the industrial process. Smaller sizes favor high specific surfaces and high rates of production, but can decrease the lowability, thus inducing poor heat evacuation resulting in hot spots and a decrease in selectivity. Such lowability issues are particularly associated with fine particles, hence understand the generation of these particles during grinding is of critical importance. New chemical and crystallographic characterization of MG-Si is presented, showing that fine particles contain on average less alloying elements than larger particles, yet their crystallographic structure is preserved through grinding. On the contrary, superfine particles (smaller than 1 μm) exhibit amorphous zones: this transformation is pressure induced, showing that these particles experience larger stresses during the grinding step. The behavior of MG-Si in grinding mills has been studied for the first time. At the single particle level, it has been confirmed that transgranular fracture is preferred in MG-Si. Moreover, fine particles can be produced from a single fracture event, due to multiple crack propagation and branching. The critical size under which plastic deformation preferentially occurs over fracture has been evaluated to be approximately 1 μm. These two facts are consistent with a lower level of impurities in fines, yet remaining crystalline, and with superfines exhibiting amorphous areas. At the multiple particle level, pilot scale batch milling experiments have been performed. The results are not included in this public version of the manuscript, please refer to the full manuscript. The consequences of the presence of fine particles in ground MG-Si powder on lowability has been assessed by means of angle of repose, compaction tests and fluidization experiments. A new elutriation behavior has been observed and characterized: for naturally ground MS-Si powders (including fine particles), particles smaller than 30 μm are entrained first, then only larger particles. This was not the case in absence of fine particles. The explanation may probably lie within the presence of polydisperse clusters, formed only in presence of fine particles. Parallel to this elutriation behavior, electrostatic measurements with an external electrometer showed that high potential with sign correlated with the type of particle elutriated are attained during elutriation. This may suggest that electrostatics is responsible for cluster formation

Le procédé de broyage en voie humide est une opération intéressante permettant la production de particules fines ou de nanoparticules. La caractérisation de la taille des particules est une donnée essentielle pour l'interprétation des données, le contrôle et l'optimisation de ces procédés selon divers aspects. Il y a un manque de connaissances relatif à la caractérisation de la taille de particules en relation avec les procédés de broyage en voie humide. Cette caractérisation est spécifique pour différentes raisons. (i) Les dispersions traitées par broyage contiennent souvent des impuretés et (ou) des additifs. Nous savons assez peu comment les impuretés et les additifs influencent la taille des particules en suspension dans ces procédés. (ii) Lors de procédés de broyage en voie humide, des dispersions de différentes concentrations peuvent être utilisées. Il est important de savoir comment la concentration de la dispersion peut influencer la mesure de la taille des particules lors du procédé. (iii) La modification de la taille moyenne des particules, résultant de leur fragmentation, est rapide. (iv) Le degré de polydispersité dans le produit change au cours du temps. (v) La nature des interactions entre les particules change; avant broyage les particules sont non-colloïdales, elles le deviennent après un certain temps d'opération. De même, il y a un manque de connaissances permettant de comprendre comment la qualité du produit broyé final est affectée lors du broyage. Dans cette étude nous explorons plusieurs aspects de la caractérisation de taille et de la qualité du produit au cours d'un procédé de broyage en voie humide du CaCO3, réalisé à l'aide d'un broyeur à billes agité. La spectroscopie acoustique qui est une technique connue pour ses potentialités en matière de caractérisation de taille de dispersions en ligne, sous des conditions réelles de procédés et sans nécessiter une dilution des échantillons, a été utilisée dans cette étude en complément de la diffusion dynamique de la lumière. Ce travail a montré sous quelles conditions les effets des impuretés et des additifs etc. sur la taille des particules en suspension pouvaient être déterminés par spectroscopie acoustique. De plus, nous avons comparé et analysé les résultats des mesures de taille obtenus avec les deux techniques. Les différences observées ont été analysées. Nous avons montré que la diffusion multiple observée à forte concentration en solide lors des procédés de broyage en voie humide pouvait conduire à une mauvaise interprétation des résultats relatifs à la taille des particules. En outre, la qualité est un concept relatif. Dans ce travail, nous avons adopté une démarche pour mesurer les effets de différents paramètres sur les caractéristiques du produit broyé en se basant sur une définition de la qualité telle que dans la norme ISO 9000 :2005. La démarche a permis de prendre en compte différents paramètres opératoires importants (tels que les conditions de fonctionnement du broyeur, la mesure de la taille des particules et les propriétés du matériau), ainsi que différentes propriétés caractéristiques du produit (comme la taille moyenne des particules, la largeur de la distribution de taille, la stabilité de la dispersion, le taux d'impuretés, l'énergie spécifique apportée au système et l'apparence visuelle du produit). Nous avons montré que nous pouvions établir une relation entre les paramètres opératoires et différentes qualités de produits obtenus par un procédé de broyage en voie humide
Wet grinding process is an interesting means of producing fine and nano particles. The particle sizing plays an important role in interpretation, control and optimization of various aspects of the wet grinding process. There is a lack of knowledge in understanding different aspects of particle sizing during a wet grinding process. The particle sizing in a wet grinding process is typical in the sense: (i) The dispersions in a wet grinding process, often, involve additives and (or) impurities. It is less known how impurities and additives influence the particle size of the dispersions in the wet grinding process. (ii) In a wet grinding process, dispersions of different concentrations may be used. It is less known how dispersions of different concentration may influence the particle sizing in a wet grinding process. (iii) In a wet grinding process, the change in average particle size of the product is rapid due to relatively fast breakage of the particles. (iv) The degree of poly dispersity in product changes with grinding time. (v) The nature of interaction between particles is non-colloidal before grinding process; this interaction becomes colloidal after a certain grinding time. Similarly, there is a lack of knowledge to understand how quality of final ground product is influenced in a wet grinding process. This study investigates the different aspects of particle sizing and product quality of aqueous dispersions of CaCO3 in a wet grinding process carried out in a stirred media mill. Acoustic attenuation spectroscopy that is known for measuring particle size of dispersions on line, under real process conditions and without diluting the sample has been employed in the study in addition to the technique of dynamic light scattering. The study brings out the conditions in which the effects of impurities and additives etc. on particle size of the dispersions may be determined using acoustic attenuation spectroscopy. Furthermore, the study compares and analyze the particle sizing results obtained though acoustic attenuation spectroscopy and dynamic light scattering. The causes of differences in the results of two techniques have been investigated. We report presence of multiple scattering at high concentration of the dispersions during wet grinding process that result in misleading results of the particles sizes. Quality is an intangible concept. In order to understand how different operating parameters influence product quality, we propose a method based upon the definition of quality as defined in ISO 9000:2005. The method takes into consideration the important operating parameters of wet grinding process (such as the operating condition of the mill, the measurement of particle size and the material) and important product characteristics ( such as average particle size, range of width of particle size distribution, stability of dispersion, degree of impurities, specific energy input and physical appearance). We bring out how a relationship between operating parameters and products of different grades may be established in a wet grinding process

Aujourd’hui, sur le poids total d'un véhicule, on sait recycler 70% sous forme de ferrailles et 5% sous forme de métaux non ferreux. L’enjeu porte donc sur les 25% restant (RBA), actuellement mis en décharge et principalement représentés par des matières plastiques, caoutchoucs, verres, bois, mousse, etc. La tache est énorme puisque le parc annuel des voitures à recycler compte plus que 1,8 million d'unités. Le traitement des RBA et en particulier de la partie fine (< 15 mm), généralement non-traitée et qui représente une grande partie de la mise en décharge, est le but primordial de la présente recherche. Afin de réduire leur volume et de récupérer toutes les fractions métalliques, des nouvelles techniques ont été mises en œuvre en laboratoire, ainsi qu'aux échelles semi-industrielle et industrielle. Il est proposé un criblage à sec, à 4 mm, des fines 0-15 mm. Ensuite la fraction 4-15 mm est traitée par lavage, magnétisme et courants de Foucault. La fraction 0-4 mm est traitée à sec par magnétisme et tablage pneumatique. Sur la fraction 0-15 mm, on récupère environ 13% en poids sous forme de produit magnétique, 5% sous forme de métaux non ferreux et 37% sous forme d'un stérile faiblement combustible

This study provides a comprehensive understanding of the fine particle grinding process in stirred media mills. Calcium carbonate was chosen as the feed material. The experiments were firstly conducted in a laboratory scale vertically stirred media mill under various grinding conditions. The operating variables including specific energy, rotational speed, solids concentration, grinding media type, chemical additives (dispersant) were investigated. Then, the process was scaled up to a pilot scale mill. The performance of the pilot scale mill was compared to the laboratory scale mill regarding the product size (e.g. d80 ) and instantaneous power draw. Positron Emission Particle Tracking technology (PEPT) was used as a tool to study the motion of the grinding media in the laboratory scale stirred media mill. Some new stirrers were proposed and analysed. The PEPT results obtained under different operating conditions were demonstrated and analysed. The Discrete Element Method (DEM) based on the Hertz-Mindlin contact model was implemented to simulate the motion of the grinding media in both laboratory scale and pilot scale mills. A new type of stirrer is accepted by Imerys and used to produce the calcium carbonate in the industrial scale of grinding process. The energy saving is obtained up to 3 %compared to the standard stirrer currently used.

Les applications industrielles des minéraux naturels, de granularité fine à ultra fine, exigent des produits, de distributions granulométriques et de facteurs de forme contrôles, adaptés à chaque application. La classification pneumatique est réalisée sur un classificateur équipé d'une turbine de 50 mm. Il est étudié: la détermination de l'influence des variables opératoires sur le classement granulométrique de populations de particules de dimensions inferieures à 50 m, de nature et de formes différentes (calcite, talc et muscovite) ; l'analyse du processus de classification par les courbes de partage granulométrique et la détermination des effets de la forme des particules sur les résultats de la classification ; la modélisation du classificateur. Une série d'essais de classification a été effectuée sur chacun des produits étudiés, suivant un plan factoriel composite centre 2#3 avec pour facteurs: le débit d'air, la vitesse du rotor, le débit solide d'alimentation. L’interprétation des résultats met en évidence, dans certaines conditions opératoires, des perturbations dans le processus de classification des particules ultrafines, inferieures a environ 2 micromètres, marquées par un relèvement de la courbe de partage, attribuable à des agglomérations interparticulaires qui diminuent l'efficacité de la classification. Les données expérimentales des séparations granulométriques sont représentées de façon satisfaisante par le modèle de Lippek. Un modèle multiplicatif conduit a une prédiction satisfaisante de la dimension de coupure corrigée d50c, avec un coefficient de détermination ajusté r2 (a) supérieur à 0. 94 pour les trois matériaux étudiés, les valeurs de d50c étant comprises entre 4 et 12 micromètres pour la calcite, 8 et 24 micromètres pour le talc, 8 et 40 micromètre pour le mica. L’imperfection de la séparation pour les dimensions supérieures à 2 micromètres est indépendante des conditions opératoires pour les particules isodiamétriques. Les variables opératoires expliquent les variations des imperfections pour les particules lamellaires

Compte tenu des exigences de plus en plus draconiennes sur la qualité des poudres utilisées dans l'industrie pharmaceutique, les cosmétiques, les céramiques etc qui doivent être de plus en plus fines avec des diamètres moyens précis, le contrôle de la distribution granulométrique dans les opérations de réduction de taille est devenu une préoccupation majeure. Dans ce travail de thèse qui porte sur l'étude du broyage du carbone dans un broyeur à billes agité humide, nous nous sommes donc attachés à définir les conditions de fonctionnement permettant d'obtenir des produits de granulométrie déterminée. Pour cela, une étude de l'influence des paramètres opératoires sur la cinétique de fragmentation et l'écoulement à travers le broyeur a été réalisée. Elle a permis la mise au point d'un modèle du broyage continu dont les paramètres peuvent être utilisés pour calculer les fonctions de sélection et de broyage à partir desquelles il est possible d'identifier les mécanismes de fragmentation mis en jeu. Une étude par analyse d'images et des mesures de potentiel de surface et de tension superficielle ont montré qu'ils ont une influence importante sur la forme et les propriétés de surface des fragments produits. Enfin, l'allure de la distribution granulométrique du produit obtenu ne pouvant être modifiée que de façon limitée en jouant sur les paramètres opératoires du procédé de broyage, l'étude théorique d'une boucle de broyage-sélection a été réalisée et a conduit à la mise au point d'un élutriateur centrifuge permettant la récupération de la fraction fine et le recyclage en continu de la fraction grosse

La modélisation de la fragmentation ultrafine d'une poudre de zircone commerciale (SEPR) a permis de déterminer les paramètres pertinents qui permettent d'évaluer l'efficacité de l'opération de broyage. De plus, l'évolution granulométrique a pu être expliquée sur la base d'un modèle de bilan de population. L’étude des propriétés physicochimiques et structurales des poudres obtenues par différentes techniques de broyage a permis d'apprécier l'efficacité de chaque technique, mais surtout de comparer la réactivité chimique de ces poudres. Le broyage à sec, à haute densité énergétique, a montré son efficacité dans l'obtention d'alliages céramiques, alors que le broyage humide a montré son efficacité dans la production de poudres divisées, à très grandes surfaces spécifiques. La combinaison de ces deux techniques a permis la réalisation de poudres très réactives. La spectrométrie Mössbauer a permis de suivre l'évolution du fer dans les systèmes ZrO2-Fe2O3, à la suite de traitements mécaniques et thermiques. Cette technique a mis en évidence les différences de réactivités chimiques entre les poudres, ainsi que l'influence des conditions opératoires de broyage sur les propriétés finales des poudres. La dilatométrie a permis de quantifier la réactivité des poudres au frittage. Un broyage humide est indispensable pour l'obtention de céramiques nanocristallines (<100 nm) consolidées (>95%) lors d'un frittage naturel (<1250°C). Cependant, la structure particulière des poudres obtenues par mécanosynthèse permet un frittage sous charge à très basse température (<1000°C) ce qui permet la réalisation de matériaux nanocristallins (<50 nm) denses (>90%). De plus, les paramètres de mise en forme et de frittage doivent être parfaitement contrôlés pour conserver une taille de grain nanométrique

High Efficiency Deep Grinding (HEDG) combines high depths of cut, high grinding wheel speeds with high work piece feed rates to deliver a very high stock removal process that can produce components free of surface damage. High contact temperatures are a characteristic of the process and this produces a mass of hot grinding sparks being ejected from the grinding zone. Neat oil cutting fluids are typically used in HEDG due to their excellent lubricity, but the high grinding wheel speeds employed leads to high levels of highly volatile cutting fluid mist in the machine canopy. This mist can mix with the hot grinding sparks being ejected from the grinding zone to create a potential fire hazard. The project aim was to produce a cutting fluid application strategy for the HEDG regime, focusing on establishing the thermal characteristics of cutting fluids in order to determine the optimum cutting fluid for the HEDG process. The cutting fluid application strategy also involved investigating the optimum means by which to apply the cutting fluid, based on minimising amount of cutting fluid used in the process and in reducing the potential fire hazard. The characteristics that have a thermal impact on the grinding process are the cooling, lubrication, ignition and misting properties of the fluid. A series of tests were established to investigate these properties and therefore allow different fluids to be compared and contrasted for their suitability for the HEDG regime based. Once an optimal cutting fluid had been established, the project then investigated the optimal method of applying this fluid, with particular reference to the type and design of the nozzle used to apply the fluid to the grinding zone. As part of these trials, a series of benchmark tests were also conducted using long established cutting fluid application techniques to enable the benefits of the new strategy to be evaluated. The project concluded that high viscosity neat oil ester based cutting fluids were the best fluids to be used in the HEDG regime due to they excellent lubricity and low misting properties coupled to their relatively high resistance to ignition when compared to neat mineral oils. The studies also found that using a high viscosity ester based fluid and then applying it using a coherent jet nozzle, significant reductions in the grinding powder and specific grinding energy could be achieved whilst significantly lowering the amount of mist in the machine, thus reducing the potential fire hazard and the volume of cutting fluid used by the process.

Nous avons conçu des outils méthodologiques permettant de construire une modélisation globale des opérations de broyage et de broyage - classification, en prenant en compte les différents phénomènes mis en jeu: cinétique de broyage, écoulement des particules, classification. L’utilisation des formulations classiques du génie des procédés a permis d'introduire la notion de fraction résiduelle, représentative des performances de ces procédés. Des modèles complets ont été bâtis et validés à la fois dans le cas d'un broyeur à billes agité et dans celui d'un broyeur à jets opposés et à lit fluidisé avec classificateur mécanique intégré. Pour ce dernier appareil, et après avoir mis au point des protocoles expérimentaux visant à identifier les contributions des différents processus, la cinétique de broyage a été caractérisée par une loi d'évolution simple, une expression analytique de la courbe de partage du sélecteur a été obtenue et il a mis en évidence la présence d'un volume actif de broyage inclus dans la zone des jets. Des développements d'ordre purement théorique ont été d'autre apportés: modélisation des réseaux de classificateurs par une chaine de Markov, méthode de recherche des fonctions de broyage et de sélection par optimisation

Ce travail a pour objectif de caractériser la fragmentation ultrafine. L’étude est réalisée avec un broyeur à jets d'air dans lequel les particules mises en mouvement par insufflation d'air comprimé entrent violemment en collision. Le matériau réalisé, de la gibbsite Al(OH)3 obtenue industriellement à partir de la bauxite, se présente sous la forme de grains polycristallins complexes de taille moyenne égale à 100 microns. Une méthode d'étude originale basée sur l'analyse des courbes granulométriques couplée à l'analyse morphologique a permis de montrer que la fragmentation s'opère selon trois mécanismes: l'éclatement, l'écaillage et l'attrition. Il en résulte trois populations granulométriques dont les tailles moyennes sont 75, 20 et 7 microns composés par quatre types morphologiques, les blocs compacts, les éclats, les écailles et les fines. En comparant les résultats obtenus dans un broyeur à jets d'air à ceux obtenus par compression dans un broyeur annulaire et par compression-cisaillement dans un broyeur vibroinertiel, on constate que les produits ont une morphologie identique bien que les répartitions pondérales varient avec le type de broyage. On conclut que la structure du matériau joue un rôle déterminant dans la fragmentation

L'objectif de ce travail est de comprendre l'influence des particules très fines sur le phénomène de ré-agglomération lors du broyage. Des billes de verre de taille 0 à 20 µm avec un pourcentage massique variant entre 0 à 1% sont ajoutées dans un tas granulaire de billes de verre de 200 à 300 µm dans un tambour tournant cylindrique de diamètre et longueur 10 cm. La présence des particules fines montre un effet ambivalent sur la stabilité du tas granulaire. Nous avons établi un diagramme de stabilité du milieu granulaire en fonction de la concentration de particules fines et cherché à quantifier l'effet des fines combiné avec d'autres paramètres (humidité relative et vitesse de rotation du tambour). La stabilité d'un tas granulaire dans un tambour tournant est déterminée par la mesure de son angle maximum de stabilité θm. Dans un premier temps, nous avons étudié l'évolution de cet angle à des vitesses de rotation différentes. Les expériences montrent qu'à faible concentration (< 0; 15%), le tas se déstabilise par avalanches lorsque le tambour tourne, θm diminue lorsqu'on augmente la quantité de fines. Quand la vitesse de rotation augmente, le mouvement du tas évolue du régime d'avalanche intermittent au régime d'écoulement continu. En revanche, lorsque la concentration des fines est supérieure à 0,15%, la déstabilisation du tas se traduit par un phénomène de stick-slip à la paroi du tambour, et la quantité de fines augmente la stabilité du tas. Ce comportement apparemment contradictoire est lié au fait que la localisation de la déstabilisation est modifiée. Dans le régime des faibles concentrations, les avalanches commencent à la surface du tas, et le remplissage de l'espace intermédiaire entre les grosses billes par les fines rend la surface de plus en plus lisse, ce qui déstabilise le tas. Par ailleurs, les fines induisent une augmentation de la cohésion du tas par la nucléation des ponts capillaires entre les grains. Ainsi, dans le régime des fortes concentrations, le tas granulaire se comporte comme un corps solide et la déstabilisation a lieu à l'interface tas-tambour. Nous avons également étudié l'influence de l'humidité relative sur la stabilité et montré que dans le régime de faible concentration de particules fines, la déstabilisation est indépendante de l'humidité. D'autre part dans le régime des hautes teneurs en fines, une humidité relative élevée induit une forte cohésion due à la condensation capillaire entre les grains et le tambour ce qui entraîne une augmentation de l'angle maximum de stabilité.

Grassland fuels quickly respond to moisture changes in the environment, and successfully ignite more readily compared with other wildland fuel types. In recent years in New Zealand grasslands, wildfire ignitions have increased due to recreational activities on public conservation land. Ignition sources have included off-road vehicles, sparks from machinery, and campfires, cooking stoves, etc. This research investigated ignition thresholds for fully cured tussock (Festuca novae-zelandiae) and exotic (Agrostis capillaris) grasses, with the aim of providing a scientific basis for wildfire prevention through decision-support tools for activity controls. Five ignition sources of concern to the Department of Conservation were tested in the laboratory, and results were validated against field experiments. Experiments were innovative, and were designed to simulate ignitions from: hot exhaust systems on off-road vehicles (hot metal); sparks from vehicle exhausts (carbon emissions); grinding operations (metal sparks); smouldering debris dropped onto grass fuels from hot vehicle parts (organic embers); and ordinary cigarette lighters (open flame). Fuel moisture content (MC), and wind speed were varied, but ambient temperature and relative humidity were kept relatively constant in the laboratory. Logistic regression was used to analyse data for each ignition source, except organic embers because no ignitions occurred. Ignition thresholds were determined for a probability of ignition success of 50%, and all models were statistically significant. The thresholds are listed in terms of model accuracy for each experiment: open flame was 28% MC without wind, and 55% MC with light wind (1 m/s); metal sparks was 37% MC; hot metal, with a wind speed of 2 m/s and MC of 1%, was 398ºC hot metal temperature; and carbon emissions was 65% MC. The results represent a significant contribution to knowledge of the ignition behaviour of grassland fuels. Further research is required to verify and extend the results; but, initial findings provide a scientific basis for management, investigations of wildfire causes, and decisions around controls on recreational activities to protect highly sensitive ecosystems and natural areas from damaging wildfires.

碩士
國立臺北科技大學
生物科技研究所
101
Since the economical development of emerging countries in the world, the rising global demand of aquaculture and seafood as animal protein source of food has became a new trend. But, the general animal protein source in current aquaculture feed - fishmeal, has facing shortage in volume due to El Nino phenomenon, and therefore induced the raising of price in recent years. To satisfying the continuous rising demand of fishmeal, it makes the overfishing problem and has been considering to impacts the marine ecosystem, and also impacts the development of whole aquaculture industries. Using plant protein to replace animal protein in aquaculture feed has been researched and useful, soybean is the most productive candidate because of total harvest volume and relative advantage in nutrition value. The soybean product - soy protein concentrate is applied to be the role in purpose for replacing fishmeal as general protein source in the future. Currently, the general methods to produce soy protein concentrate including dilute acid washing, alcohol extraction, those wet method produced lots of waste water and polluted air, and their subsequent processing especially drying process, is high in energy cost while in the world’s energy depletion situation. Using fine grinding and particle size separation technique for plant protein separation has been researched for some plant legumes, selective grinding phenomenon occurred in fine grinding process could be applicable in protein enrichment purpose. We used repeated impact mill combined with a leveled particle size classification, to compared the liberation of soybean meal under different impact conditions. We found fine grinding method could make liberation with soybean meal, which separated coarse fraction with 42.72% in protein content and fine fraction in 57.24%. However, although we found liberation occurred with soybean meal, using a single fine grinding-classification step to achieved the purpose of soy protein concentrate production is not succeed.

A pilot scale study was conducted on ultra-fine grinding in a horizontal stirred mill. The main objectives were to investigate grinding kinetics, the influences of rheology and effects of bead size on performance criteria. The main criteria were breakage rate, particle size reduction, product size distribution and power consumption. The results confirm the "first-order" breakage rates in stirred mills. The product size distributions are best represented by the Rosin-Rammler equation. A method of determining breakage rates versus particle size is demonstrated which shows that the 10% top size fraction is most appropriate for the determination of specific breakage rates. The slurries ground exhibit Newtonian to pseudoplastic to yield pseudoplastic behavior over the range of conditions studied, corresponding to coarse low percentage solids to fine high percentage solids. The flow curves of grinding products were modeled using the Casson equation. It was shown that yield stress is the dominant rheological parameter which influences the grinding performance. A Low yield stress favors high breakage rates, narrow size distributions, and increased production of -10 μm fines. The bead sizes and its composition play a very important role in stirred mills. There exists an optimum ratio of bead size to feed size with respect to breakage rate, size reduction ratio and size distribution. The ratio was confirmed to be about 20/1. The existence of fine beads in grinding media has negative effects on grinding performance.

IsaMill is a stirred type mill used in mineral industry for fine and ultra-fine grinding. The difficulty in obtaining the internal flow information in the mill by experimental techniques has prevented the development of the fundamental understanding of the flow and generating general methods for reliable scale-up and optimized design and control parameters. This difficulty can be effectively overcome by numerical simulation based on discrete element method (DEM). In this work a DEM model was developed to study particle flow in a simplified IsaMill. The DEM model was validated by comparing the simulated results of the flow pattern, mixing pattern and power draw with those measured from a same scale lab mill. Spatial distributions of microdynamic variables related to flow and force structure such as local porosity, particle interaction forces, collision velocity and collision frequency have been analyzed. Among the materials properties of particles, it is shown that by decreasing particle/particle sliding friction coefficient, the particle flow becomes more vigorous which is useful to grinding performance. Restitution coefficient does not affect the particle flow significantly. A too low or too high particle density could decrease grinding efficiency. Although grinding medium size affects the flow, its selection may depend on the particle size of the products. Among the operational variables considered, the results show that fill volume and mill speed proved to be important factors in IsaMil process. Increase of fill volume or mill speed increases the interaction between particles and agitating discs which results in a more vigorous motion of the particles. Among the mill properties, particle/stirrer sliding friction plays a major role in energy transfer from stirrer to particles. Although there exists a minimum collision energy as particle/stirrer sliding friction increases, large particle/stirrer sliding friction may improve grinding performance as it has both large collision frequency and collision energy. However, that improvement is only up to a critical particle/disc sliding friction beyond which only input energy increases with little improvement on collision frequency and collision energy. Reducing the distance between stirrers or increasing the size of disc holes improves high energy transfer from discs to particles, leading to high collision frequency and collision energy. Among the different stirrer types, the energy transfer is more effective when disc holes are present. Pin stirrer shows increased collision energy and collision frequency which also result in a high power draw. Using the DEM results, a wear model has been developed to predict the wear pattern of the discs. This model can be used to predict the evolution of the disc wear with the time. It is shown that energy transfer from discs to particles are increased when discs are worn out. An attempt has also been made to analyze the microdynamic properties of the mill for different sizes. It is shown that specific power consumption and impact energy are correlated regardless of the mill size and mill speed.

碩士
國立成功大學
資源工程學系碩博士班
95
Muscovite is close to nano-sized layer structure, accord with general orientation that composite develops in recent years, in addition to having fine chemistry, physical property, stability and excellent properties in anti-ultraviolet, anti-static, heat resistance,electricity insulation. It is worth probing into the mineral material which for one studies thoroughly.But electric charge is high among the muscovite layer. Bond strength is strong, so particle reducing and further exfoliating is quite difficult to carry on. This research purpose is utilizing proper physics and chemical way to reduce muscovite particle size and bond strength among the layer. The respect in physics grinding: under the similar grinding condition with the same concentration of slurry and same type of media with identical diameter, the milling efficiency of the “attrition mill” is obviously superior to “ball mill”.And using the “attrition mill” having better efficiency to carry on particle reducing, the efficiency of high concentration of slurry (weight percentage is 35%) is better at the very start. But with grinding time increasing viscosity raises quickly, so the efficiency of low concentration of slurry (weight percentage is 10%) is better contrariously. In addition, under the same concentration of slurry, particle size will reduce with grinding time increasing, but the efficiency won,t increase after grinding 48hr.The potassium ions of layer can be released after destroying, but that is little quantity, accounts for 0.53% of the original ore at most. The respect in the chemical ion replacing: particle size can be reduced after potassium ion exchanging with lithium ion in the layer. Its CEC value can be improved from original 3.42 meq/100g to 118.86meq/100g. And the muscovite particle size is related to potassium ion replacement among layer. Based on the test results, the particle size will be smaller if the finer potassium ion replacement of muscovite. The remnant amount of the potassium ion among layer can drop to 35.90% from 48.15% of the original ore.

碩士
國立中正大學
機械工程學系暨研究所
103
With the growing development of the modern manufacturing industry, precise and ultra-precise processing technologies are playing an important role in recent years. Computerized numerical control machine tools have become the basic manufacturing equipments in high-tech industry and are being widely used in the factory. In response to the highly competitive market, the machine tools manufacturers will naturally tend to produce highly precise products. Currently there is relatively less research on geometric error modeling and measurement technology of five-axis CNC machine tools. Therefore this thesis focuses on geometric error modeling and the analysis of the measurement method of the eccentricity error of orthogonal rotary axes. The thesis analyzes the geometric error sources and establishes the error motion equations on five-axis CNC grinding machine tools. By using the homogeneous transformation matrix (HTM), this thesis proposes the geometric error model of the five-axis machine tool and verify the validity of the error model. Also this thesis analyzes the measurement method of the geometric error of A-axis and spindle on the five-axis CNC grinding machine tool. The homogeneous transformation technology is used to get the forward kinematics, the corresponding element of the ability matrix and inverse solution, and then NC data equations are obtained according to the relation of the moving parts on the machine tool. Five different measuring postures are designed to measure the coordinates of the workpiece origin ( 、 、 ) and the active parameters.

碩士
國立勤益科技大學
工業工程與管理系
105
Grinding machine in the machine tool industry is a high-precision machinery, hydrostatic bearings in the wheel spindle mechanism plays an important role, are high-precision parts, hydrostatic bearing processing stability is very important, grinding wheel spindle diameter and hydrostatic bearing bore Assembly together, the two-axis hole with the gap must be stable, the oil between the two oil film will be even between the average wheel can improve the accuracy and stability of the operation, so how to control the grinding process and grinding process parameters are sufficient Understand and master, is to enhance the grinding and hydrostatic bearing cylinder diameter of the main key. CNC grinding process, the impact of parts processing process parameters of many factors, if only based on technical experience to determine the parameters of the set value, easily lead to process instability and thus improve the rate of non-improvement, the application of six standard deviation method to improve the steps DMAIC five Stage, the case study is carried out to study the grinding process of the cylindrical diameter of the hydrostatic bearing in the internal and external diameter of the case company, and the optimization mode of the grinding process of the inner and outer diameter of the hydrostatic bearing is constructed. The key factors and the best experimental level combination in the grinding process of the cylindrical diameter of the hydrostatic bearing are found out. The key factors are experimented by the reaction surface method to find the optimum parameters of the key factors, The results show that Cpk0.82 upgrade to Cpk1.52 process capability has improved significantly, showing with Taguchi method combined with the reaction surface method for grinding process parameters optimization is feasible, the results of this study can also provide domestic grinding machine manufacturing industry as a product quality The reference.

碩士
國立臺灣科技大學
機械工程系
98
There are three methods for finishing cylindrical gears, finish hobbing, finish shaving, and finish grinding. Grinding processes can be further divided into two types: form grinding and generating grinding. In the form grinding process, it is the line contact between the grinding wheel and the gear surface. In addition, because of advances in higher efficiency and easier way to achieve the purpose of flank correction through the wheel modification, compared with the generating grinding process, the form grinding is suitable for gears with large-size and large-module. Up to now, many grinding machines in Taiwan are imported from abroad, and the key techniques are also relied on foreign manufacturers. For the gear machines, because of complicated calculation in programming NC codes, the sophisticated manufacturing software needs to be provided to generate dressing and grinding NC codes automatically. Therefore, in this thesis, we establish the mathematical model for form grinding machine. First, we develop the mathematical model of gear profile for cylindrical gear and its profile modification methods, and then the axial profile of the grinding wheel are derived based on the form grinding theory and the gear profile. Additionally, a correction method for the wheel profile is proposed. We derive the machine settings of the five-axis CNC gear profile grinding machine from the given machine settings of a universal gear profile grinding machine. According to the derived machine settings, the grinding path for form grinding process can be determined, and it can be used to program the grinding NC code. Finally, we use Visual Basic 2008 as a tool to develop the manufacturing program of five-axis CNC gear profile grinding machine.

碩士
國立臺灣科技大學
機械工程系
99
In order to improve the precision of the cylindrical gear with large-size diameter, the cylindrical gear is grinding by profile grinding wheel. There are three processes of existing simultaneous five-axis CNC gear profile grinding machine, which including dressing, grinding, and on-machine measurement. The motion of this machine is more complicated, and its precision and price are high. Once the collision of machine happens, the workpiece is declared no longer useable and the clamping fixture is damaged. Critically, the charge of the repair for the damage of machine is expensive. In order to avoid the collision of machine, dry run is implemented to test whether the NC path is correct or not before actual manufacturing. Because of the complicated process, it needs to take long time for testing. At this time, the machine is idle and the production efficiency is reduced. Having this in mind, we develop the 3-D virtual reality simulation system in this study to easily simulate the NC path which the user had planned. It’s not only saves the time for dry run, but also avoids the collision of machine. We use Visual basic 2008 as the developing platform in this study, and the 3-D graphical library of OpenGL as the foundation of graph showing to develop the 3-D virtual reality NC path simulation and collision detection system. The simulation system is divided into three parts: (1) the complier of NC code, (2) the building of 3-D volume pixel, and (3) the detection of collision.

For a solid carbide tapered end-mill, every flute includes a flute surface and a rake face along a helical side cutting edge, and the end-mill core is at the center and is tangent to all the flutes. The flutes significantly affect the tools cutting performance and life, and the core radius mainly affects the tools rigidity. Mainly, two methods are adopted in industry to grind the flutes; these are: the direct method and the inverse method. In the direct method, a flute is ground using a standard grinding-wheel moving in multi-axis machining to generate the rake face and the flute surface. However, the flute is the natural outcome of the grinding process without any control. On the other side, the inverse method employs the concept of inverse engineering to build a grinding-wheel that accurately grinds the end-mill flutes. This yields a free-form grinding-wheel profile that is used on a 2-axis grinding machine; however, the flute shapes are only exact on one section of the end-mill; when the grinding-wheel moves along the side cutting edge to smaller sections; the deviation of the generated flute from the designed one will be increased. Thus, neither can this method grind the rake face with the prescribed normal rake angle, nor generate the side cutting edge in good agreement with its design. Moreover, the grinding-wheel profile is very difficult and expensive to make. To address these problems, a practical and optimal approach for five-axis grinding of prescribed end-mill flutes is proposed by; first, establishing a 5-axis flute grinding theory describing the wheels locations and orientations during grinding the rake faces with constant normal rake angles; Second, introducing a simple grinding-wheel consisting of lines and circular arcs; and finally, applying an optimization algorithm to optimize the grinding-wheel shape and path. Overall, this approach significantly advances the CNC programming technique for the 5-axis flute grinding, and can substantially increase the quality of the solid carbide end-mills and lays a good foundation for the CAD/CAE/CAM of end-mills. The advantages of this approach over the other approaches are verified using computer simulation.

碩士
中華大學
機械工程學系碩士在職專班
100
Purpose of this paper is created a professional system that can design Lone-cone and manufacture by turning and grinding on five-axis machine tools. In general, manufacture the long-cone by special five-axis machine tools. because the grind of the long-cone is a unique processing technology. Now, CAD / CAM system which we know is universal, they can't effectively and quickly design and manufacture cone and they promote system uninterrupted. So, how to improve processing efficiency and processing accuracy become very important on two requirements that design complexity and high machining accuracy. Its solution in the development of a professional system, and its related technology integrated into existing CAD / CAM system, you can achieve the above purpose. Therefore, we will use secondary development to create professional system on CATIA of CAD / CAM software. This professional system consists of five modules that Modeling cone curve module、Processing planning module、Cutting simulation module、Interference checking module and Special post-processor module. We determine the best location of rotation point W which on the 5-axis machine tool axis B by using "vector" to generate optimal processing path in processing planning. Finally, manufacture long-cone to confirm this system. When we use this system to design and manufacture cone, we can decrease more time that from one week to one day. Another on upgrading machining accuracy, it is enhance greatly that promote accuracy from 20μm to 8μm and verify the effectiveness of this system.

碩士
國立臺灣科技大學
機械工程系
99
During the large-size gear manufacturing by form grinding, the actual tooth surfaces will be different from the theoretical tooth surfaces because of the clamping fixture, machine error, and force or heat deflection. Therefore, the gear tooth deviation should be measured and then the flank correction is implemented based on the gear tooth deviation to improve the precision of gear. In domestic gear industry, most gears are off-machine measurement after manufacturing, but the errors and the time-consuming between loading and unloading will reduce the precision of gear and the efficiency of production. For this reason, we develop the on-machine measurement and the precision evaluation software for cylindrical gear on the five-axis CNC gear profile grinding machine. It can immediately measure the gear tooth deviation on-machine after grinding, calculate the values of gear tooth deviation, draw the figures of deviation curve, and evaluate the accuracy grades of gear tooth. In addition, this evaluation result can be the foundation for the follow-up research about closed-loop flank correction technology. Here, the scanning measurement is implemented on this on-machine measurement to increase the speed and the precision of measurement, and the developed measuring processes include (1) the flank deviation, (2) the lead deviation, (3) the pitch deviation, and (4) the flank topographic deviation. In this thesis, the definitions of gear tooth deviation are referred to Germany and American national standards, the NC programming is referred to the measuring paths of Klingelnberg P40 gear measuring center, and the mathematical models for position of measuring probe are also derived based on the theoretical involute curve. We use Visual Basic 2008 as a tool to develop the evaluation software for gear tooth accuracy. Finally, we use the 3-D virtual reality NC path simulation and collision detection system, which are developed by Chin-Yu Chang in the precision transmission laboratory of NTUST, to simulate the NC codes of on-machine measurement. The mathematical model for the position of the measuring probe derived in this thesis is verified by the result of simulation.

碩士
國立虎尾科技大學
機械與機電工程研究所
103
The non-smart phones from early times have developed into flat-surfaced and arc-shaped smart phones nowadays. Arc-shaped phones serve ergonomic in design, so when on the calls, speakers'' cheeks can adjust closely with the phones. The audio quality of arc-shaped phones is much clearer than the flat-surfaced ones. They have flexibility, and have become a hit of new generation smart phones. The touch glass panel left countless micro-crack after its outer-edge profile cutting and a high stress concentration is deduced around there. Hence, this defect should be improved by chamfer grinding technique. But the hardness and brittleness of the glass substrate are too high to easily induce surface crack and edge-indentation while performing the mechanical machining. Also, a lot of difficulties encountered during the machining process due to its natures of high strength and low thermal conductivity. It belongs to a typically difficult-to-cut material. Furthermore, the chamfer of the outer-edge profile with arc-surface is more difficult to process than that of the flat-surface due to its bent surface configuration. In order to comply with the variations of geometrical style of phones and breakthrough the embarrassment in chamfer machining of the related curved-surface products in industry, seeking the development and establishment of the key technique for chamfer has become an important concern that the industry needs to strive. This study used CAD/CAM software to construct the geometrical model of a mobile-phone with arc type. Appropriate cutting-path and machining strategy are designed and planned, and confirmed by a simulation pertaining to cutting-tool moving path. Furthermore, a commercial software for cutting simulation is used to verify the numerical control program generated from the above plan and to check the correctness of the proposed methodology in a virtual reality cutting environment. The contact situations between the wheel and workpiece during the chamfer grinding processes are investigated and these actions whether fulfill a five-axis chamfer machining manipulation requirement are further confirmed. Vacuum chuck fulfilling this arc-surface geometry is designed and fabricated and used to clamp the thin glass substrate on a jig platform. A five-axis machining center associated with grinding wheel is used to perform the experiment for the chamfer grinding of the glass substrate. Full-factorial experiment of process parameter combinations such as wheel profile, grinding velocity, feed rate, chamfer width and working environment was organized for chamfer grinding. Grinding wheels with flat or round profile along the peripheral direction, and a traditional diamond electroplated burs were used as chamfer grinding tools. In addition, the bent-surface glass substrate chamfer experiments were conducted by two kinds of five-axis controller, respectively. Tool maker microscope was used to detect the chamfer surface morphology, edge-indentation and dimension uniformity on the chamfer width zone, and the experimental results are analyzed thoroughly and compared crossly with each other. The chamfer surface edge-indentation is used as an objective function for better process parameter determination, which is subjected to surface damage constraint. It is expectedly that the quality of surface damage and edge-indentation may fulfill the requests for industry. The results show that the controller made in Taiwan may not work properly in pair with a newly developed machine-tool in the laboratory, a small rotation error is deduced accompanied by B-axis, which results in worse dimension uniformity on chamfer width grinding. An undercut phenomenon occurred at the bottom of the arc-surface when the chamfer grinding on the concave surface side of the arc-glass by using a flat profile grinding wheel. An inclination angle of the grinder-axis should be adjusted in machining strategy design to avoid the interference point between the grinding wheel and arc-surface. But the results pertaining to chamfer surface damage has only a little difference by using these two geometrical profile wheel. Smaller chamfer surface damage is obtained under the condition of higher grinding velocity and lower feed rate. Water soluble cutting fluid offers a better cooling and lubrication actions in the primary grinding zone, the edge-indentation is thus reduced as compared with that of blowing air. Smaller surface damage and edge-indentation are obtained from the innovative strategy of chamfer grinding used in this study as compared with that of the traditional diamond electroplated burs due to a higher grinding velocity attained in the former grinding technique.