Multi-Objective Optimization in Single-Shot Drilling of CFRP/Al Stacks Using Customized Twist Drill

In recent years, the use of CFRP with titanium and/or aluminum to form materials for stacking has gained popularity for aircraft construction. In practice, single-shot drilling is used to create perfectly aligned holes for the composite-metal stack. Usually, standard twist drills, which are commonly...

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Main Authors: Muhammad Hafiz Hassan, Jamaluddin Abdullah, Gérald Franz
Format: Article
Language:English
Published: MDPI AG 2022-03-01
Series:Materials
Subjects:
Online Access:https://www.mdpi.com/1996-1944/15/5/1981
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author Muhammad Hafiz Hassan
Jamaluddin Abdullah
Gérald Franz
author_facet Muhammad Hafiz Hassan
Jamaluddin Abdullah
Gérald Franz
author_sort Muhammad Hafiz Hassan
collection DOAJ
description In recent years, the use of CFRP with titanium and/or aluminum to form materials for stacking has gained popularity for aircraft construction. In practice, single-shot drilling is used to create perfectly aligned holes for the composite-metal stack. Usually, standard twist drills, which are commonly available from tool suppliers, are used for practical reasons. However, existing twist drill bits exhibit rapid wear upon the drilling of composite-metal stack layers in single shot, due to the widely contrasting properties of the composite-metal stack, which causes poor surface quality. The stringent quality requirements for aircraft component manufacturing demands frequent drill bit replacement and thus incurs additional costs, a concern still unresolved for aircraft component manufacturers. Owing to highly contrasting properties of a composite-metal stack, it is obvious that standard twist drill cannot fulfil the rigorous drilling requirements, as it is pushed to the limit for the fabrication of high-quality, defect-free holes. In this work, customised twist drills of a tungsten carbide (WC) material with different geometric features were specially fabricated and tested. Twenty drill bits with customised geometries of varying chisel edge angle (30–45°), primary clearance angle (6–8°), and point angle (130–140°) were fabricated. The stacked-up materials used in this study was CFRP and aluminum alloy 7075-T6 (Al7075-T6) with a total thickness of 3.587 mm. This study aims to investigate the effect of twist drill geometry on hole quality using drilling thrust force signature as indicator. All drilling experiments were performed at spindle speed of 2600 rev/min and feed rate of 0.05 mm/rev. Design of experiments utilising response surface methodology (RSM) method was used to construct the experimental array. Analysis of variance (ANOVA) was used to study the effect of parameters and their significance to the thrust force and thus the hole quality. The study shows that the most significant parameter affecting the drilling thrust force and hole surface roughness is primary clearance angle, followed by chisel edge angle. Correlation models of CFRP thrust force (<i>Y</i><sub>1</sub>), Al7075-T6 thrust force (<i>Y</i><sub>2</sub>), CFRP hole surface roughness (<i>Y</i><sub>3</sub>), Al7075-T6 hole surface roughness (<i>Y</i><sub>4</sub>) as a function of the tool geometry were established. The results indicated that the proposed correlation models could be used to predict the performance indicators within the limit of factors investigated. The optimum twist drill geometry was established at 45° of chisel edge angle, 7° of primary clearance angle, and 130° of point angle for the drilling of CFRP/Al7075-T6 stack material in a single-shot process. The error between the predicted and actual experiment values was between 6.64% and 8.17% for the optimum drill geometry. The results from this work contribute new knowledge to drilling thrust force signature and hole quality in the single-shot drilling of composite-metal stacks and, specifically, could be used as a practical guideline for the single-shot drilling of CFRP/Al7075-T6 stack for aircraft manufacturing.
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spelling doaj.art-c71391adbd7a4cff8491b26dc134ace02023-11-23T23:21:53ZengMDPI AGMaterials1996-19442022-03-01155198110.3390/ma15051981Multi-Objective Optimization in Single-Shot Drilling of CFRP/Al Stacks Using Customized Twist DrillMuhammad Hafiz Hassan0Jamaluddin Abdullah1Gérald Franz2School of Mechanical Engineering, Universiti Sains Malaysia, Nibong Tebal 14300, MalaysiaSchool of Mechanical Engineering, Universiti Sains Malaysia, Nibong Tebal 14300, MalaysiaLaboratoire des Technologies Innovantes, UR UPJV 3899, Avenue des Facultés, Le Bailly, 80025 Amiens, FranceIn recent years, the use of CFRP with titanium and/or aluminum to form materials for stacking has gained popularity for aircraft construction. In practice, single-shot drilling is used to create perfectly aligned holes for the composite-metal stack. Usually, standard twist drills, which are commonly available from tool suppliers, are used for practical reasons. However, existing twist drill bits exhibit rapid wear upon the drilling of composite-metal stack layers in single shot, due to the widely contrasting properties of the composite-metal stack, which causes poor surface quality. The stringent quality requirements for aircraft component manufacturing demands frequent drill bit replacement and thus incurs additional costs, a concern still unresolved for aircraft component manufacturers. Owing to highly contrasting properties of a composite-metal stack, it is obvious that standard twist drill cannot fulfil the rigorous drilling requirements, as it is pushed to the limit for the fabrication of high-quality, defect-free holes. In this work, customised twist drills of a tungsten carbide (WC) material with different geometric features were specially fabricated and tested. Twenty drill bits with customised geometries of varying chisel edge angle (30–45°), primary clearance angle (6–8°), and point angle (130–140°) were fabricated. The stacked-up materials used in this study was CFRP and aluminum alloy 7075-T6 (Al7075-T6) with a total thickness of 3.587 mm. This study aims to investigate the effect of twist drill geometry on hole quality using drilling thrust force signature as indicator. All drilling experiments were performed at spindle speed of 2600 rev/min and feed rate of 0.05 mm/rev. Design of experiments utilising response surface methodology (RSM) method was used to construct the experimental array. Analysis of variance (ANOVA) was used to study the effect of parameters and their significance to the thrust force and thus the hole quality. The study shows that the most significant parameter affecting the drilling thrust force and hole surface roughness is primary clearance angle, followed by chisel edge angle. Correlation models of CFRP thrust force (<i>Y</i><sub>1</sub>), Al7075-T6 thrust force (<i>Y</i><sub>2</sub>), CFRP hole surface roughness (<i>Y</i><sub>3</sub>), Al7075-T6 hole surface roughness (<i>Y</i><sub>4</sub>) as a function of the tool geometry were established. The results indicated that the proposed correlation models could be used to predict the performance indicators within the limit of factors investigated. The optimum twist drill geometry was established at 45° of chisel edge angle, 7° of primary clearance angle, and 130° of point angle for the drilling of CFRP/Al7075-T6 stack material in a single-shot process. The error between the predicted and actual experiment values was between 6.64% and 8.17% for the optimum drill geometry. The results from this work contribute new knowledge to drilling thrust force signature and hole quality in the single-shot drilling of composite-metal stacks and, specifically, could be used as a practical guideline for the single-shot drilling of CFRP/Al7075-T6 stack for aircraft manufacturing.https://www.mdpi.com/1996-1944/15/5/1981CFRP/Al7075-T6thrust forcetwist drillsingle shot
spellingShingle Muhammad Hafiz Hassan
Jamaluddin Abdullah
Gérald Franz
Multi-Objective Optimization in Single-Shot Drilling of CFRP/Al Stacks Using Customized Twist Drill
Materials
CFRP/Al7075-T6
thrust force
twist drill
single shot
title Multi-Objective Optimization in Single-Shot Drilling of CFRP/Al Stacks Using Customized Twist Drill
title_full Multi-Objective Optimization in Single-Shot Drilling of CFRP/Al Stacks Using Customized Twist Drill
title_fullStr Multi-Objective Optimization in Single-Shot Drilling of CFRP/Al Stacks Using Customized Twist Drill
title_full_unstemmed Multi-Objective Optimization in Single-Shot Drilling of CFRP/Al Stacks Using Customized Twist Drill
title_short Multi-Objective Optimization in Single-Shot Drilling of CFRP/Al Stacks Using Customized Twist Drill
title_sort multi objective optimization in single shot drilling of cfrp al stacks using customized twist drill
topic CFRP/Al7075-T6
thrust force
twist drill
single shot
url https://www.mdpi.com/1996-1944/15/5/1981
work_keys_str_mv AT muhammadhafizhassan multiobjectiveoptimizationinsingleshotdrillingofcfrpalstacksusingcustomizedtwistdrill
AT jamaluddinabdullah multiobjectiveoptimizationinsingleshotdrillingofcfrpalstacksusingcustomizedtwistdrill
AT geraldfranz multiobjectiveoptimizationinsingleshotdrillingofcfrpalstacksusingcustomizedtwistdrill