A METHOD FOR THE ASSESSMENT OF THE ROLLING CONTACT FATIGUE OF MODERN ENGINEERING MATERIALS IN LUBRICATED CONTACT

It is widely recognised that apart from scuffing, rolling contact fatigue (RCF) is one of the most predominant failure types in highly loaded non-conformal friction joints. The fatigue life of machine parts depends on many factors that can be divided into three groups: design, technology and operating conditions. The main factors influencing pitting are material properties, the geometry of the tribosystem, surface finish, dimensional precision, and working conditions as well as the physicochemical properties of the lubricant. The aim of this paper is to present the experimental method for determining fatigue life of modern engineering materials in lubricated rolling contact. The developed method allows an investigation into the effect of all these factors on rolling contact fatigue (pitting). The method is employed by using a modified four-ball testing machine denoted as T-03. The modification embraces the replacement of testing specimens. The upper ball is replaced with a cone that can be made of various materials. The method exhibits good resolution and is time and cost effective. It was successfully applied to the investigation into various types of surface coatings including single, multilayer and duplex coatings. This method can be employed by using a widespread four-ball apparatus

Identification of Residual Stresses in a Surface Layer of Ti6AL4V and Inconel 718 after Process of Peripheral Milling

Titanium based alloy – Ti6Al4V and nickel based alloy – Inconel 718 belong to the group of difficult-to-cut materials. Thanks to their unique properties they can be used in constructions that need to withstand the high reliability requirements which are required inter alia in the aircraft industry. The physical properties of cutting layer, including residual stresses, play an important role during exploitation of products made out of difficult-to-cut materials. In the article, the method of residual stresses determination is described and the exemplary results of carried out studies are provided. Described method is based on the measurement of the defects in the crystal lattice. The carried out studies show that the state of residual stresses, in a subsurface layer, can be formed by the selection of machining conditions

A METHOD FOR THE ASSESSMENT OF THE ROLLING CONTACT FATIGUE OF MODERN ENGINEERING MATERIALS IN LUBRICATED CONTACT

It is widely recognised that apart from scuffing, rolling contact fatigue (RCF) is one of the most predominant failure types in highly loaded non-conformal friction joints. The fatigue life of machine parts depends on many factors that can be divided into three groups: design, technology and operating conditions. The main factors influencing pitting are material properties, the geometry of the tribosystem, surface finish, dimensional precision, and working conditions as well as the physicochemical properties of the lubricant. The aim of this paper is to present the experimental method for determining fatigue life of modern engineering materials in lubricated rolling contact. The developed method allows an investigation into the effect of all these factors on rolling contact fatigue (pitting). The method is employed by using a modified four-ball testing machine denoted as T-03. The modification embraces the replacement of testing specimens. The upper ball is replaced with a cone that can be made of various materials. The method exhibits good resolution and is time and cost effective. It was successfully applied to the investigation into various types of surface coatings including single, multilayer and duplex coatings. This method can be employed by using a widespread four-ball apparatus

Testing of the Resistance to Scuffing of Spiral Bevel Gears: Test Rig, Method, and Results of Verification Testing

In spite of long-term development of the technology of bevel gear production, the automotive industry reports various operational demands such as the need of the size and mass reduction of gears without lowering their durability and reduction of friction leading to a decrease in the energy losses and a decrease of the tendency to scuffing. What is more expected, EU regulations may impose the use of new generation gear oils (ecological-friendly) providing the proper operational properties of the transmission. In view of these demands, a new, bevel gear test rig and scuffing test method have been developed at ITeE-PIB. The idea resulted from a necessity to improve reliability of tests—popular gear tests are run mostly on spur gears having the tooth geometry significantly different than bevel gears. The test rig, test method, and results of verification testing are presented. The effect of various gear oils and the deposition of a low-friction coating on the resistance to scuffing were investigated. It is shown that the new test rig fulfils the research requirements and that the new test method has a good resolution

Metal concentrations in hair of patients with various head and neck cancers as a diagnostic aid

Head and neck cancers are one of the most frequent cancers worldwide. This paper attempts to evaluate disturbances of homeostasis of the necessary elements (calcium, magnesium, zinc, copper, iron, manganese) and changes in the levels of toxic metals (lead, cadmium, cobalt, chromium VI) in hair of patients with head and neck cancers, as well as people without a diagnosed neoplastic disease. In order to quantify the necessary elements and toxic metals, a method using ICP-MS and ICP-OES techniques had been developed and validated. The studies have shown that patients with head and neck cancer used to drink alcohol and smoked much more frequently than healthy individuals, both in the past and presently. Statistically significant differences in concentrations of average metal content in the group of patients with head and neck cancers compared to the control group were confirmed. Significant differences in metal content between the group of patients with head and neck cancers and healthy individuals were found which enabled distinguishing between the study groups. To this end, a more advanced statistical tool, i.e. chemometrics, was used. The conducted research analyses and the use of advanced statistical techniques confirm the benefits of using alternative material to distinguish the patients with head and neck cancers from the healthy individuals

IJTC2007-44244 THE PROBLEMS OF APPLICATION OF PVD/CVD THIN HARD COATINGS FOR HEAVY-LOADED MACHINE COMPONENTS

ABSTRACT The authors developed test methods for investigation of heavy-loaded coated machine elements: scuffing and pitting. Results of their investigation indicate the very positive role of coatings for increasing resistance to scuffing. The authors stated that the role of usually toxic lubricating additives can be taken over by the thin coating. The crucial problem is pitting. Comprehensive research indicates that steel components with typical PVD coatings (eg. TiN, CrN) usually do not exhibit a satisfactory fatigue life. However the results of experiments performed by the authors for new coatings are encouraging. INTRODUCTION The development of transmissions and bearings is characterized by continuously increasing levels of torque and power, increased service life, improved efficiency and stringent noise requirements. Over recent years, the opportunities provided by conventional technologies to increase performance have been exploited. The breakthrough technologies for heavyloaded steel parts are thin hard coatings. At present, thin hard coatings are commonly used on cutting and forging tools (nearly 80% cutting tools and over 40% forging tools are coated). The proportion of mechanical components that are coated is extremely small (less than 2 %). The description of the pitting wear is summarized i