Cutting Parameter Selection for Efficient and Sustainable Repair of Holes Made in Hybrid Mg–Ti–Mg Component Stacks by Dry Drilling Operations

Abstract

Drilling is one of the most common machining operations in the aeronautic and aerospace industries. For assembling parts, a large number of holes are usually drilled into the parts so that they can be joined later by rivets. As these holes are subjected to fatigue cycles, they have to be checked regularly for maintenance or repair, since small cracks or damage in its contour can quickly cause breakage of the part, which can have dangerous consequences. This paper focuses on finding the best combinations of cutting parameters to perform repair and maintenance operations of holes in stacked hybrid magnesium–titanium–magnesium components in an efficient, timely, and sustainable (without lubricants or coolants) manner, under dry drilling conditions. For the machining trials, experiments were designed and completed. A product of a full factorial 23 and a block of two factors (3 × 2) was used with surface roughness as the response variable measured as the mean roughness average. Analysis of variance (ANOVA) was used to examine the results. A set of optimized tool and cutting conditions is presented for performing dry drilling repair operations.

Repairing Hybrid Mg–Al–Mg Components Using Sustainable Cooling Systems

“…As this work is part of a broader research project that involves different geometries, material combinations, cutting conditions, tools, and lubrication/cooling systems, the methodology is similar to that followed in other previous works [105][106][107][108] and is based on the guidelines given by Montgomery [122].…”

“…The tools, with reference HSS-E-PM A1 1257, were purchased from Garant (Hoffmann Iberia, San Fernando de Henares, Madrid, Spain). [105][106][107][108]. Also, there were interesting works of other researchers in the literature, thus allowing comparisons to be drawn [15,24,26,27,80,81,[95][96][97][98][99][100][101][102][103][104].…”

“…Although the literature contains an important number of experimental works with regard the machining of hybrid components, only some of them addressed hybrid components based on magnesium. Most studies focused on machining processes [105][106][107][108][109][110][111][112][113] and tried to find the optimal combination of machining conditions and lubrication/cooling systems by means of experimental tests, taking the surface roughness required in a particular industry sector or application as a response variable. Others dealt with friction and wear between contact materials [114,115], the effects of pre-treatments on the adhesion of hybrid materials [116], innovative techniques for forming these types of components [117,118], or identification of some of the most prominent issues.…”

Feasibility Study of Hole Repair and Maintenance Operations by Dry Drilling of Magnesium Alloy UNS M11917 for Aeronautical Components

“…As discussed above, there are still gaps in our knowledge about magnesium alloys. There are not many scientific works that discuss the problems during solid drilling of these alloys, and we found only one work specifically about re-drilling or core drilling operations in magnesium alloys: Rubio et al [30] studied this process, but for hybrid Mg-Ti-Mg components. This type of machining is used in the repair process of damaged holes, which is common in the aeronautical sector where the holes are machined to a larger diameter to insert oversized rivets.…”

“…This type of machining is used in the repair process of damaged holes, which is common in the aeronautical sector where the holes are machined to a larger diameter to insert oversized rivets. These repairs must be carried out with great care to avoid damage to the machined parts [30]. These types of operations can be framed as low performance operations since productivity is a secondary objective.…”