Stefan Velicu

Diagnosis of Screw Compressors Condition by Analyzing the Lubricating Oil

This research paper presents the analysis of the superficial layer wear of the moving metallic components in a screw compressor, depending on the presence of metal particles in the oil resulted from friction, wear and fatigue processes. The data presented are useful for the analysis of the structural modifications that occur and develop during the operation of a screw compressor, with the possibility to predict a failure. The study of the structural changes can be made by various nondestructive testing methods, namely by analyzing the oil at certain time intervals/hours of operation of the compressor

The Preliminary Study of Machinability during Milling of Titanium Alloy (Ti-6Al-4V)

Titanium and its alloys have found wide application in the aerospace, biomedical and automotive industries owing to their good strength-to weight ratio and high corrosion resistance. However, these alloys have very poor machinability, which is attributed to their inherent high strength maintained at elevated temperature and low thermal conductivity leading to high cutting temperatures. This paper presents the findings of an experimental investigation into the effects of cutting speed, feed rate and depth of cut when milling titanium alloy Ti-6Al-4V. The cutting forces were the response variables investigated. This experimental investigation is translated into a mathematical model of cutting forces designed on the basis of the results obtained from this research.

Experimental Investigation of Cutting Forces at Milling Titanium Alloys Comparing to Others Hard Alloys

This paper presents the experimental procedure of cutting forces measurement, results of the experimental research and their interpretation for the milling of titanium alloys comparing to other hard alloys. Furthermore, there are established the polynomial regression functions to determine the cutting forces depending on the cutting regime parameters: cutting speed, feed rate and depth of cut.