Diamante A&T Contents
Issue 96

Year XXV - March 2019

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Front Cover: POLIGEM SRL
Via Ernesto Rizzi 13/p, 20077 Melegnano (MI), Italy

Poligem is a private independent company that has been a leader in the superabrasive market since 1996. Thanks to the experience accumulated in the synthesis, selection and grinding of the diamond, Poligem has been for years a constant presence in Europe in the tools, abrasives and non-conventional diamond applications sectors. From natural diamond to synthetic diamond, from polycrystalline diamond to Cubic Boron Nitride, Poligem is able to respond with the best solution to the needs of the industry.

www.poligem.it




In the Spotlight

08) The use of industrial diamond: applications and outlooks

14) International Chips joins the Surfaces Group




Diamond Tools

17) Analysis of the wear behaviour of diamond impregnated tools used for the core drilling of concrete with statistical lifetime prediction

by M. Kansteiner1, D. Biermann1, N. Malevich2, M. Horn2, C.H. Müller2, M. Ferreira3, W. Tillmann3
1 Institute of Machining Technology, TU Dortmund, Dortmund, Germany
2 Statistics with Applications in the Field of Engineering Sciences, TU Dortmund, Dortmund, Germany
3 Institute of Materials Engineering, TU Dortmund, Dortmund, Germany

Abstract: At the EURO PM 2017 a first approach for the analysis of the wear in core drilling processes of concrete based on statistical features was presented. Due to promising results of this first approach, and to increase the data basis, further experiments with the same tools were conducted. Beside a conventional concrete (C20/25), a second concrete (C100/115), with different composition and properties, was machined. Like before, the presented analysis is based on process force measurements and a microscopic analysis of the segments to detect diamond breakouts. Statistical methods were used to detect such certain events. Additionally, a lifetime estimation for single diamonds is carried out, which allows to forecast the breakout of single diamonds. Hence, the time when half or all of the diamonds visible in the beginning are broken out can be forecast.



26) Influence of the distance between single diamonds on the scratching behavior on concrete

by W. Tillmann1, D. Biermann2, C.H. Müller3, S.A. Yonan1, M. Ferreira1, L. Wojarski1, M. Kansteiner2, M. Becke1
1 Institute of Materials Engineering, TU Dortmund, Dortmund, Germany
2 Institute of Machining Technology, TU Dortmund, Dortmund, Germany
3 Statistics with Applications in Engineering Sciences, TU Dortmund, Dortmund, Germany

Abstract: The cutting performance of diamond tools is determined by the number of single diamond crystals, which are either directly brazed onto a turning wheel or are mixed and sintered with metallic powders. Thus, the lifetime of the tools is affected by the amount of matrix material, into which single diamonds are embedded, and consequently the distance between them. Within the scope of this paper, tools with only two diamond crystals with varying distances between each other were fabricated in order to simulate different diamond ratios. These distances ranged from 1-2 mm for brazed tools and between 2-3.6 mm for sintered tools. To analyze the influence of the different distances on the wear and machining behavior, the tools were moved linearly over inhomogeneous concrete substrates, while the clamping force was steadily increased. The measured process forces and wear of the diamonds were quantified and set into relation.



Industrial Diamond

36) Influence of microstructure and composition on the mechanical properties of thermally stable diamond composites

by J.N. Boland, X. Li, C. Harbers, D. Williams
CSIRO Energy, Pullenvale, Australia

Abstract: An extensive research program has been undertaken to exploit the physical and mechanical properties of thermally stable diamond composites (TSDC) for rock cutting and drilling operations in the exploration, mining, manufacturing and civil construction industries. Having previously demonstrated the superior abrasive wear resistance of TSDC as well as discovering a viable bonding process for the insertion of TSDC as cutting elements into steel tooling, the most outstanding issues to be further investigated are the tensile, transverse rupture and impact strengths of TSDC. By combining the results of these mechanical property measurements of a series of TSDC samples, some important factors that influence strength properties, including microstructural design and careful attention to chemical and phase composition of TSDC material, are discussed.



Sintering

46) The geometrical model of sintering

by Silvia Baselli, Alberto Molinari
University of Trento, Trento, Italy

Abstract: Powder particles are uniaxially cold compacted into rigid dies to obtain the green part. This process causes an extensive plastic deformation: structural defects are accumulated in the metallic powder and the contact area between particles increases. The structural and geometrical condition of the powder particles influences the mass transport phenomena responsible for sintering shrinkage. We can distinguish two kinds of "sintering activity": geometrical and structural. The geometrical activity deals with the different extension of the contact areas. The structural activity is related to the increased volume diffusivity due to the presence of structural defects. The self activation mechanism of sintering also contributes to the structural activity. However, literature models poorly reflect the real green microstructure because the extension of the contact areas is neglected. This work aims to develop a shrinkage kinetic equation that accounts for the actual condition of the powder particles.



News and Events

60) 2018, record-breaking year for the italian machine tool industry




Concrete Cutting

66) Tyrolit, safety for surface treatment

72) Dazzini Macchine: metals cutting experience in Rotterdam

76) 90-year-old link between New York and New Jersey broken