Geometric Optimization of Drills Used to Repair Holes in Magnesium Aeronautical Components

Fernando Berzosa,J. Paulo Davim,Beatriz de Agustina,Eva María Rubio

doi:10.3390/met10111534

Fernando Berzosa, J. Paulo Davim + Show 2 more

Open Access

https://doi.org/10.3390/met10111534

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Abstract

Magnesium alloys are used in the aeronautical sector due to their excellent strength/weight ratios, motivated by the reduction of weight that their use entails. In this sector, drilling is one of the most common operations, if not the most, due to the large number of holes that are used in joining processes, mainly by riveting. The appearance of cracks is a risk to the structural safety of the components, such that it is necessary to regularly check them for maintenance and/or repair tasks. The present study tries to determine the optimization of the characteristics of the twist drills, which are re-sharpened successively to restore the cutting edge after use, as well as the operating parameters in machining. For this purpose, a full factorial experimental design was established, analyzing through the analysis of the variance (ANOVA) the response variables. Surface integrity was considered to carry out a global vision of the quality obtained, covering as response variables the surface roughness, the size of the burrs and the modification of the hardness produced, in addition to a topological characterization by optical means of machined surfaces. The main conclusion is that it is possible that the geometric optimization of the tools and the operating parameters considered in this study in drilling processes allow them to be performed, while maintaining quality and environmental requirements, and at the same time, maximize the productivity of operations.

Highlights

In recent times there has been a strong demand in the transport sector, which includes the aeronautical, aerospace and automobile industries, in terms of reducing the energy consumed, mainly due to economic and environmental constraints
An important method of reducing fuel consumption is to achieve a reduction in the mass of vehicles, by using lighter materials, among which are light alloys such as titanium, aluminum or magnesium, which have excellent ratio density/mechanical strength [1,2,3,4,5,6]
After performing the individual drilling tests, the surface quality of the machined surface in each one was measured, at two distances from the top face of the specimen and at four points spaced 90◦, for which it was quantified using the parameters of Ra, Rz and RSm, considering the average obtained from the four measured points

Summary

Introduction

In recent times there has been a strong demand in the transport sector, which includes the aeronautical, aerospace and automobile industries, in terms of reducing the energy consumed, mainly due to economic and environmental constraints. This reduction allows vehicles to transport a greater number of passengers or goods, over an increased distance, or increased fuel efficiency. The parts used in the aeronautical sector, in addition to maintaining the characteristics of strength, rigidity and low density, must comply after processing and meet very strict standards in terms of quality requirements, among which are dimensional, shape and roughness [1,2]. The maintenance and repair of the used parts is especially important, due to the high cost derived from the imposed requirements, which determines that these parts are repaired and reused instead

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