Statistical and microscopic investigation of disc segment wear related to sawing Ankara andesites

Abstract

Despite the advancement in the technology, and the introduction of many synthetic materials, hard rock still keeps its vital importance in daily constructive and decorative consumption. The hard rock processing sector has shown a rapid development since 1930. Turkey has also been affected by this development and many numbers of hard rock processing factories have been established in the last 15 years. The import of basic machines, equipment and consumables in these factories constitutes a major economic problem in this sector. Disc consumption is the most important economic expenditure during the processing of hard rocks. Unsuitable manufacturing of discs and inappropriate adjustment of machine parameters to the rocks to be cut, causes the discs to deteriorate rapidly, leading to eventual economic loss [1]. The circular diamond saw blade contains a steel core which has diamond impregnated segments brazed on the periphery (Fig. 1). The segments (metal bonds) have two basic functions. These are to hold the diamond tight and to erode at a rate compatible with the diamond loss. Due to a large variety of sawing conditions many metal matrix compositions are in general use. Bonds based on copper, various bronze compositions, and on cobalt, tungsten, and tungsten carbide as well as combinations thereof cover a wide range of stone sawing applications. Sometimes small additions of iron, nickel, etc. are made to aid the manufacturing process or in the belief that the addition improves diamond retention or matrix wear properties; however, the complexity of compositions encountered in production practice, which in same cases comprise seven components, makes a scientific approach to the total problem extremely difficult or even impossible [2]. In general, many factors affect the stone cutting by a circular saw blade. These factors can be written in three groups (as shown in Table 1) [3]. The first important factor is the engineering properties of the material. The clue of the suitable values of parameters to reach the effective result is constant parameters. The physico-mechanical, mineralogical and petrographical properties must be analyzed before the sawing test and these results must be used in the producing part of the segment and saw blade. The performance of the sawing with a disc cutter is affected by diamond type, the size of diamond, the concentration of diamond and the properties of the metal bond (matrix). In general, the diamond crystals must have sufficent strength to withstand the repeated cutting forces during the granite sawing process. If the diamond is too weak in strength, it will easily produce macro-cracks and crushed particles. It will also cause the blade to act hard so that possibly glazing will occur. Conservely, if the diamond has very high strength and toughness, it will be difficult to fracture it to produce new cutting points and edges. In addition, it will be polished to give the blade a glazed appearance. The choice of the optimum diamond type for a given application depends on many factors, such as the stone type, the cutting conditions, the type and the quality of the machine, etc. [4]. Luo and Liao [4] report that various studies have been conducted to investigate the effects of the diamond type and size of wear and sawability in the processing of stone with diamond saw-blades. Jennings and Wright [5] stated that hard materials usually require a smaller size diamond than do softer stones because the load per particle is not sufficiently high and greater clearence is required for swarf. Conversely, if large diamond grits are used on hard materials, the penetration of the *Corresponding author. Department of Applied Science, University of Arkansas at Little Rock, Arkansas 72204, USA. Fax: +1-501-5698020. E-mail address: aseyuboglu@ualr.edu (A.S. Eyuboglu).