Atmospheric air temperature influence in ABNT 4340 steel cylindrical grinding using CBn grinding wheel

• Grant number: 16/22114-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2017
• End date: January 31, 2018
• Field of knowledge: Engineering - Mechanical Engineering - Manufacturing Processes
• Principal Investigator: Eduardo Carlos Bianchi
• Grantee: Alan Polato Francelin
• Host Institution: Faculdade de Engenharia (FE). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil

Abstract

Grinding is a process of material machining performed on parts that have accurate dimensions and shapes, low roughness, or even parts of high hardness. In summary, the process improves the surface finish reducing the distances between peaks and valleys of the workpiece surface (roughness). The tool used is the grinding wheel, which consists of very hard material grains, known as abrasives, compressed and united in circular shape by a binder which may have different origins, vegetable or mineral. The correction can happen in three different ways. It can be tangentially, wherein the wheel grinds a flat surface, or cylindrical, wherein the grinding wheel works the circularity of a workpiece to leave it with the least possible deviation and centerless grinding, where the pieces pass through a mat the lead to tangential contact between two wheels rotating in the opposite direction of each other. In this paper, we are using the cylindrical grinding of diving, in which the workpiece is fixed and the grinding wheel moves to meet the surface to be imaged. The cutting edges of the abrasive grains during the process generate heat due to the increased contact area between the very edge and workpiece by generating a high amount of heat that must be removed from the work area to prevent the surface burning of the workpiece. The most widely used process for this purpose is the application of cutting fluid in abundance since it allows the best surface finish and can be reused. The biggest problem of such cooling is the generation of a toxic and highly hazardous mist to the machine operator. Furthermore, the wrong disposal of fluid causes contamination of groundwater and contaminate the living organisms that depend on this water. Therefore, to reduce oil consumption, one of the cutting fluid components established to MQL technology (minimum quantity lubrication) that uses oil in low quantity in the form of spray at high speed to create a film between the surface of the grinding wheel and the workpiece. In this paper uses a vortex tube for cooling the air aiming at the use of the MQL close to cryogenic conditions. The grinding wheel used in the tests is to CBN or cubic boron nitride, the second hardest material developed to date, second only to diamond. The AISI 4340 steel's characteristics qualify it for use as material of the workpieces. Among their industrial applications are parts subjected to high stresses, such as axles and gears. The parameters to be compared will be used to analyze the different conditions tested machining and the results allow it to be defined which is the condition of machining more suitable for this material and this particular wheel. (AU)