Suitability of natural rocks as materials for cutting tools

This study presents an investigation of the usability and suitability of natural rocks as cutting tool materials. Therefore, indexable inserts are manufactured from eight different rocks and two mono minerals in this study and are used for turning of an aluminium alloy. Besides that, a characterization of the rock properties is performed. The wear of the rock tools and the surface roughness of the workpiece generated by the tools are used to evaluate their operational behaviour. Subsequently, the rock properties and the corresponding operational behaviour are used to assess the suitability of the rocks as cutting tool material. The results show that rock inserts can be used as cutting material for the turning of an aluminium alloy showing a width of wear marks between 83 and 1665 µm at the flank face after a cutting length of 500 m depending on the rock used. Furthermore, it is shown that rock tools are able to achieve surface roughness values which are comparable to those obtainable by using a conventional cemented carbide insert. The study shows that natural rocks can generally be used as alternative cutting material for the turning of aluminium. In addition a possible way for a systematic investigation and assessment of the suitability of natural rocks as cutting tool materials is presented, the relevance of the rock properties for the operational behaviour of the rock inserts is described and relevant future research topics concerning the use of rocks as cutting tool material are identified. Article highlights Demonstrating the possibility to use natural rocks as alternative environmentally friendly cutting tool material. Evaluation of operational behaviour and wear mechanisms of rock tools in turning aluminium. Identification of rock properties relevant for the operational behaviour of rock inserts.

Effect of Mechanical Properties of Al2O3/(W,Ti)C Ceramic Tool Material on Its Tribological Characterization

Ceramic cutting tools are mainly used in high-speed dry machining, thus the tool material is in high temperature friction state with the workpiece material during cutting. The tribological characterizations have a direct impact on the cutting performance of the tool. Therefore, tribological characterizations of two kinds of ceramic tool materials with different mechanical properties against hardened steel H13 were compared at the same temperature, one material is Al2O3/(W,Ti)C/Ni with Ni(marked as AWTN), another is Al2O3/(W,Ti)C without Ni(marked as AWT). Also, the variation of tribological characterizations of AWT ceramic tool material with different temperatures was emphatically investigated. The results showed that the average friction coefficients of AWT and AWTN decreased with the increase of sliding speed under the same load, and the friction coefficient of AWT was lower than that of AWTN. Although AWTN material had better flexural strength and fracture toughness than AWT at ambient temperature, yet better hardness of AWT material both at room temperature and high temperature led to the lower friction coefficient and lower wear rate, indicating that the hardness had a greater impact on the wear of ceramic tool materials. The friction coefficient of AWT decreased with the increase of load and increased with the increase of temperature. The wear mechanism of Al2O3/(W,Ti)C ceramic tool material was different at different temperatures. The conclusion of this research had important guiding significance for the selection of cutting tools and cutting parameters in order to improve the machining quality.

Structural Strength of Cemented Carbides

The concept “structural strength of tool materials” got further development. The refusals of cemented carbide cutting plates, when heavy machining were analyzed. It was shown that 70…80% of refusals are the microchipping of cutting edges, tool cutting part chipping, cutting plate macrofracture. To assess cutting plate total carrying capacity and the influence of different methods of cemented carbides modification, bending tests were held. Local fracture resistance and damageability of cutting edge were assessed under its continuous scanning.

Improving the efficiency of tools made of high-speed steels and hard alloys

The monograph is devoted to improving the efficiency of forming tools made from the most used tool materials: high-speed steels and hard alloys. For tools made of high-speed steels, a comparative assessment of the standards of industrially developed countries and the Russian Federation was carried out. The characteristic of operational and technological properties is given. High-speed steels and technologies are recommended to increase the efficiency of the tool. Recommendations on the types of tools are given. The properties of hard alloys and the areas of their rational application are analyzed. The structural materials of prefabricated and soldered tools are considered. Recommendations on the choice of hard alloys are given, directions for the creation of new compositions of hard alloys to increase the efficiency of the tool in the processing of hard-to-process heat-resistant steels and alloys are shown. It is intended for engineering, technical and scientific workers of the metallurgical and manufacturing industries. It can be used in the preparation of masters, postgraduates of technological universities.