Experimental Investigation of Microcutting Mechanisms in Granite Grinding

Author(s):  
Lj. Tanovic ◽  
P. Bojanic ◽  
R. Puzovic ◽  
M. Milutinovic

This paper shows the results of investigations performed in the brittle materials microcutting at the Faculty of Mechanical Engineering, Belgrade University. The interactions between a single diamond grain and the machined granite are analyzed. The change in the normal cutting force as a function of grain penetration speed and depth was experimentally established in microcutting of two types of granite originating from Serbia. Based on the grain traces on granite and the generated cracks, the critical grain penetration depth for the formation of brittle fracturing was established. The experiments are intended to assist in the optimization of the grinding process as technology dominant in the granite finishing.

Author(s):  
LJ. Tanovic ◽  
P. Bojanic ◽  
R. Puzovic ◽  
S. Klimenko

This paper offers an experimental study of the microcutting mechanisms in marble grinding to aid the optimization of the marble grinding process. The necessity for investigating these mechanisms is dictated by the increased use of marble in many applications and the fact that grinding and polishing processes are the dominant technologies used to meet surface finish requirements in this natural material. The experiments are aimed at the determination of the normal component of the cutting force and of the grain traces in microcutting with a single diamond grain. The investigations carried out make provisions for establishing critical grain penetration and cutting depths and allow the prediction of the normal cutting force component as a function of grain penetration speed and depth.


Author(s):  
Miloš Pjević ◽  
Ljubodrag Tanović ◽  
Goran Mladenović ◽  
Biljana Marković

The paper presents experimental results of microcutting brittle materials (granite). The analysis was conceived on the observed interaction between the workpiece and two tools of different shapes. Experiment was based on scratching the workpiece surface with diamond tools. Applied tools had tip radius R0.2 and R0.15 mm. The experiment determined the changes in the value of perpendicular and tangential components of the cutting force based on the geometric properties of tools, as well as the changes of the specific energy of microcutting granite (Jošanica and Bukovik types). The experiment has shown that reduction of tool radius causes reduction of the cutting force intensity and specific cutting energy. Because of its physical/mechanical properties, more energy is required for micromachining granite “Jošanica” than “Bukovik.” Based on the topography of the surface, the value of critical tool penetration depth was established, after which the brittle fracture is no longer present. For granite “Jošanica” values of critical penetration depth are 6 and 5 μm when micromachining with tools R0.2 and R0.15 mm, while for Bukovik those values are 6.5 and 5.5 μm. The paper should form the basis for understanding the phenomena which occur during microcutting brittle materials.


Author(s):  
Na Qin ◽  
Z. J. Pei ◽  
W. L. Cong ◽  
C. Treadwell ◽  
D. M. Guo

A mechanistic model for cutting force in ultrasonic-vibration-assisted grinding (UVAG) (also called rotary ultrasonic machining) of brittle materials is proposed for the first time. Fundamental assumptions include: (1) brittle fracture is the dominant mechanism of material removal, and (2) the removed volume by each diamond grain in one vibration cycle can be related to its indentation volume in the workpiece through a mechanistic parameter. Experiments with UVAG of silicon are conducted to determine the mechanistic parameter for silicon. With the developed model, influences of six input variables on cutting force are predicted. These predicted influences trends are also compared with those determined experimentally for several brittle materials.


2013 ◽  
Vol 797 ◽  
pp. 246-251
Author(s):  
Shan Shan Hu ◽  
Cheng Gang Chen ◽  
Ying Ning Hu ◽  
Dong Rui Zheng

t is known that cutting force is the key to reasonably select cutting parameters, and the base to study the cutting mechanism. Genetic Algorithm and multiple regression analysis were adopted to achieve cutting force predicted model of multi-diamonds fast milling hard-brittle materials with defined diamond grains pattern by single diamond fast milling hard-brittle materials experiments. Results show that cutting force predicted model by genetic algorithm has higher precision than that model by multiple regression, and the cutting force prediction method based on genetic algorithm is more suitable for those hard-brittle materials which components are relatively soft and simple. Predicted model can afford another study direction for processing analysis of diamond tools, tools making and processing parameters selection from the view of diamond grain practice cutting.


2010 ◽  
Vol 1 (1) ◽  
pp. 136-143
Author(s):  
Robert Keresztes ◽  
Gabor Kalacska

Nowadays parts made of up-to-date engineering plastics are used more and morein mechanical engineering practice. These machine-elements are produced most frequentlyby injection molding or by one cutting process. The injection molding technology are usedgenerally for great number of pieces, in case of serial production while cutting processes arepreferred to piece (unit) or smaller number production.We used lathe and measured the main- and feeding-directional cutting force at differentengineering polymers (cast PA6, POM C and UHMW PE HD 1000). The analysis made canbe well used in practice.


2014 ◽  
Vol 627 ◽  
pp. 29-34 ◽  
Author(s):  
Vichaya Thammasing ◽  
Somkiat Tangjitsitcharoen

The purpose of this research is to develop the models to predict the average surface roughness and the surface roughness during the in-process grinding by monitoring the cutting force ratio. The proposed models are developed based on the experimentally obtained results by employing the exponential function with four factors, which are the spindle speed, the feed rate, the depth of cut, and the cutting force ratio. The experimentally obtained results showed that the dimensionless cutting force ratio is usable to predict the surface roughness during the grinding process, which can be calculated and obtained by taking the ratio of the corresponding time records of the cutting force Fy in the spindle speed direction to that of the cutting force Fz in the radial wheel direction. The multiple regression analysis is utilized to calculate the regression coefficients with the use of the least square method at 95% confident level. The experimentally obtained models have been verified by the new cutting tests. It is proved that the developed surface roughness models can be used to predict the in-process surface roughness with the high accuracy of 93.9% for the average surface roughness and 92.8% for the surface roughness.


2019 ◽  
Vol 3 (2) ◽  
pp. 36
Author(s):  
Behrouz Takabi ◽  
Bruce L. Tai

Machining of brittle materials is common in the manufacturing industry, but few modeling techniques are available to predict materials’ behavior in response to the cutting tool. The paper presents a fracture-based finite element model, named embedded cohesive zone–finite element method (ECZ–FEM). In ECZ–FEM, a network of cohesive zone (CZ) elements are embedded in the material body with regular elements to capture multiple randomized cracks during a cutting process. The CZ element is defined by the fracture energy and a scaling factor to control material ductility and chip behavior. The model is validated by an experimental study in terms of chip formation and cutting force with two different brittle materials and depths of cut. The results show that ECZ–FEM can capture various chip forms, such as dusty debris, irregular chips, and unstable crack propagation seen in the experimental cases. For the cutting force, the model can predict the relative difference among the experimental cases, but the force value is higher by 30–50%. The ECZ–FEM has demonstrated the feasibility of brittle cutting simulation with some limitations applied.


2009 ◽  
Vol 416 ◽  
pp. 593-597
Author(s):  
Jian Yun Shen ◽  
Xi Peng Xu

Brittle materials are popularly used as engineering materials for excellent properties. But the properties of brittle materials are different and special, and cause to different surface formation mechanism during the grinding process. In the study, surface roughnesses after grinding with different mesh size diamond wheels were measured. Combined with scanned surface topographies, the relation between the surface roughness and the properties of these brittle materials was discussed. It could be found that the material properties led to the different surface characteristics of brittle materials.


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