Hot Drilling of 6082 Aluminium Alloy

In traditional machining drilling is a major and common holemaking process in which lubrication and cooling are very important to improve the machining. The idea proposed in this paper regards the metal heating during the drilling operation by means of an infrared lamp. In this way a reduction in thrust force and torque is expected, since the material properties have been changed. Some experimental tests are carried out on Al 6082 in dry drilling operation, using a conventional milling machine and cobalt-coated HSS twist drills 2.5, 5, 7 mm in diameter. The spindle speeds range from 5000 to 15000 Rpm, the feeds range between 0.0076–0.042 mm/rev, the temperature is varied in the range of 40–140°C. Besides, Flat-top cylinder Indenter for Mechanical Characterization (FIMEC) tests for material characterization are carried out to obtain the yield stress of material varying temperature. The main result is a significant reduction of the thrust force (from 10 to 34% depending on the process conditions). By analysing the data of forces as a function of temperature, a minimum value of force is always found in correspondence of a temperature depending on drill diameter and feed. The influence of each parameter is investigated. The experimental data in terms of force are also correlated to the measured yield stresses to study the influence of material properties on drilling machining. Further study must be developed to investigate the torque, the mechanisms of chip formation and the tool wear.