Facial reconstruction

Search LJMU Research Online

Browse Repository | Browse E-Theses

Micron Diamond Processing of Advanced Ceramics

Ait Ouarab, L (2020) Micron Diamond Processing of Advanced Ceramics. Doctoral thesis, Liverpool John Moores University.

[img]
Preview
Text
2020aitouarabphd.pdf - Published Version

Download (6MB) | Preview

Abstract

Grinding is one of the most complex manufacturing processes in industry and understanding its physics is difficult due to the stochastic nature of the process. In this thesis, the influence of the abrasive grit’s shape and size on the grinding process is considered. A number of parameters are investigated to set a classification of the abrasives based on the grit’s shape and size. These parameters are determined according to image analyses of a large number of abrasive grits. Based on this investigation, the shapes of the abrasive grits could be classified into 21 groups. Typical grit shapes will fall into only few categories dominating the shape population. These dominant shapes are ellipsoid, sphere, quadrilateral frustrum, quadrilateral pyramid and tetrahedron pyramid. After the abrasives are assessed, a test rig for multiple grit scratching and wire saw cutting rig were developped and a series of multiple grit grinding tests are performed. For this purpose, series of scratching tests have been conducted with five different diamond abrasives. The cutting forces and the acoustic emission were used to characterize the grinding mechanism during this experiment. The machining performances of the abrasive grits are evaluated in consideration of the effect of different grit shapes on the grinding process outputs including force and acoustic emission. The experimental results show a high influence of the proportion of different grit shapes on grinding force: abrasive grits with rounded shape imply high cutting forces, while grits with pyramidal shape generate low cutting forces. Furthermore, based on the proportion of the dominant shapes in an abrasive sample a force model of the cutting force and the shape proportion of the abrasives was established. The force model and the experimental results emphasised the importance of taking into consideration the abrasive’s shape as a significant parameter that influences the grinding process. The online grinding surface creation monitoring was carried out by processing the acoustic emission signals. The acoustic emission signals are analysed in both the time and frequency domains. The results show that the signal feature extraction in the frequency domain gives excellent indication in correlation to the surface creation with different abrasive geometrical characteristics.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Grinding; Diamond abrasives; Grinding force; abrasive shape
Subjects: Q Science > Q Science (General)
T Technology > T Technology (General)
T Technology > TN Mining engineering. Metallurgy
Divisions: Engineering
Date Deposited: 03 Jul 2020 19:30
Last Modified: 30 Jul 2020 00:50
DOI or Identification number: 10.24377/LJMU.t.00013120
Supervisors: Chen, X and Opoz, T
URI: http://researchonline.ljmu.ac.uk/id/eprint/13120

Actions (login required)

View Item View Item