Diamante A&T Contents
Year XXIII - September 2017
Front Cover: DELLAS S.p.A
An example of leading-edge excellence in the stone cutting sector since 1973, in 40 years of activity, Dellas Spa has reached a leading position in the international market of the production and sale of diamond tools for marble, granite and engineered stone.
In the spotlight
10) Happy birthday Intermetal!
14) Legor Group presents the new BAG150 alloy with 50% silver content
17) G.B. F.lli Bertoncello, quality, experience and passion in the manufacturing of industrial furnaces
20) Elettron, not only metal bond
24) MWS, over 20 years of experience at diamond tools service
26) 1967-2017 Mummenhoff International, quality made in Germany
30) Design of high performance binders by understanding the protrusion and clearance dynamics of diamonds during the cutting processby A. Deborde, T. Commeau
Umicore Specialty Powders France, Grenoble, France
Abstract: Wear mechanisms are the main phenomena contributing to the good behavior of a diamond-impregnated tool. Abrasion tests commonly used to define diamond tools wear resistance (erosion, two-body and three-body abrasive wear tests) seem to be insufficient to adequately imitate the conditions encountered in industrial cutting operations. To better understand cutting mechanisms, a new wear test was developed based on a core-drill machine which measures the matrix wear as closely as possible to real stone machining conditions. The protocol consists of a non-destructive observation of diamonds on the segments to follow the wear of the metallic binder during the cutting process. Different grades of cobalt and a new iron-base matrix called STEP®10 were compared.
36) Analysis on the influence of tangential cutting speed on the polishing quality of ornamental stonesby Leonardo L. L. da Silveira1, Jefferson Camargo2, Antônio Artur3, Wana Dorigo4
1, 2, 4 CETEM - Mineral Technology Center, Cachoeiro de Itapemirim, Brazil
3 UNESP - Paulista State University “Júlio de Mesquita Filho”, Petrology and Metallogeny Department, Institute of Geosciences and Exact Sciences, Rio Claro, SP, Brazil
Abstract: Ornamental stones’ polishing in industrial scale is done on equipment called polishing machine and it can be semiautomatic or automatic. The polishing process comes from the friction generated by the rotational movement of abrasive tools (sectors) set on a cylinder head (called polishing head) and its pressure on the surface of the rock. The polishing head rotation speed cannot change in both types of equipment and it implies constant cutting speed. The possibility of changing the speed in which the grinding sector passes over the rock plates may enable optimizing the process, due to the great variety of lithological types used for ornamental means. Three Brazilian ornamental stones commercially known as Verde Labrador, Cinza Castelo and Preto Indiano were subjected to different wear conditions in order to perform such assessment. It was done by changing the loading pressure (0.1 and 0.2 MPa), polishing head rotation speed (300, 400, 500 and 600 rpm) and exposure time over the stone (1, 2 and 3) using a sequence of 9 magnesium abrasive sectors. It was noticed that the mid/low polishing head rotation speed (300/400 rpm) appeared to be more effective in getting better brightness results, in most of the cases.
46) GPR for ornamental stone deposits evaluationby Mohamed Elkarmoty, Stefano Bonduà, Roberto Bruno
University of Bologna, Department of Civil, Chemical, Environmental and Materials Engineering, Bologna, Italy
Abstract: Ground Penetrating Radar (GPR) can be used to detect fractures in quarries with limitation to the penetration depth and the resolution of the results. GPR was selected in our research work in quarries because it can give a subsurface image inside the rock mass either in 2D or 3D. This allows defining the actual characteristics of fractures which in turn allows to model fractures in 3D deterministic approach which is useful for evaluation of stone deposits and required for production optimization and waste minimization models. GPR could be used not only in a bench scale of a quarry but in a block scale as well. Consequently, production optimization can be sustainably applied in both scales.
54) Co/Nb binder for sintering polycrystalline diamondby M.M. Karimi1, U.U. Gomes1, R.S. Guimarães2, M. Filgueira2
1 Physics department, Federal University of Rio grande do Norte, Natal, Brazil
2 Northern Fluminense state university, Campos dos Goytacazes, Brazil
Abstract: The primary objective of the presented work is to study the sinterability of polycrystalline diamond (PCD) particles under high pressure high temperature (HPHT) sintering using a new metallic binder. For this reason a mixture of Co/Nb binder was prepared and being used to sinter diamond powder under HPHT condition and 10 wt% of binder was used. The mixed diamond and binder powders were capsulated and sintering was carried out at 1750°C under 7.7 GPa of pressure. Two different holding times of 3 minutes and 9 minutes (three successive 3 minutes) were used. Samples were studied according to relative density and hardness. Microstructural/structural studies were done via XRD and SEM/EDS to find any graphitization and microstructure evaluations during sintering. The results showed that diamond sintered body with this binder has higher hardness and better structural condition at longer holding time especially by avoiding graphitization during sintering and having lower difference between thermal expansion coefficients.
62) Microstructural characterization and wear resistance of different grades of cemented carbideby F.S. Gobber, M. Rosso
Politecnico di Torino, Department of Applied Science and Technology (DISAT), Turin, Italy
Abstract: The use of circular saw blades is spreading in the cut-off of metallic alloys: the high output rate and the smooth level of surface finish attainable is leading this technology to gain large parts of the cut-off tools market at the expense of more traditional tools such as band saws. The teeth profile as well as the tooth configuration are of fundamental importance for the blade performances; through a combination of blade rigidity and grinding wheel condition a good quality surface finish is attained for tools of commercial standard. In this paper, a general, state of the art study concerning relevant features of tungsten carbide is presented and discussed. A special attention is dedicated to cutting materials. Both plain (WC-Co, ISO grade K15) and mixed (WC-TiC/TaC-Co, ISO grades P40 and M20) cemented carbide grades were characterized and in particular their microstructural and mechanical behaviors were studied. Microstructural properties are related to wear resistance under pin on disc testing against a corrosion resistant iron based alloy (AISI 660). High rotating speed (70 m/min) and low load (5 N) were chosen to reproduce flank wear conditions during the cutting process. In agreement with some literature data, from the analysis of worn samples, different damaging mechanisms were identified mainly depending on the grain size.
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