Md Nasir, Nur Syuhada (2021) Parameters optimization of micro drilling process for CFRP using two flute solid carbide drill bit. Masters thesis, Universiti Teknikal Malaysia Melaka.
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Parameters optimization of micro drilling process for CFRP using two flute solid carbide drill bit.pdf - Submitted Version Restricted to Registered users only Download (18MB) |
Abstract
Today, composites material is an alternative to the metal components in the airliner bodies and structures because of its lightweight material characteristic which can contribute to reducing aircraft fuel consumption. Carbon Fibre Reinforced Polymer (CFRP) has multiple plies of material that is piled together in reinforced laminates component form with different material properties throughout the structure. Micro hole on CFRP panel is required for acoustic panel of an aircraft engine. However, drilling process for CFRP material is typically challenging due to high structural stiffness of the composite, low thermal conductivity of polymer and thermally stable of its carbon fiber. Poor resin areas between adjacent laminated plies are prone to drilling-induced damage such as delamination that compromises the material structural integrity. Delamination always related to thrust force during machining process. It can lead to lower hole accuracy of the drill hole entry and exit. Therefore, the optimum parameter for drilling process such as machine spindle speed and feed rate are essential to improve the quality of the hole as well as increase the tool life span. In order to understand the behaviour of CFRP material during machining process, tribological study using Ball-on-disk (BOD) tester was conducted to evaluate properties of CFRP material towards frictional force and wear rate. As the applied load increase, the average frictional force also increased. The result contributed to the selection of the optimum range of parameter for the micro drilling process. The thrust force during machining and hole accuracy at hole entry and exit are investigated by using variable spindle speed and feed from 8,000 to 12,000 rpm and 0.001 to 0.015 mm/rev, respectively. Hence, from the Taguchi L9 (32) experiment the feed rate of 0.001 mm/rev was eliminated to proceed for the optimization stage due to its’ insignificant impact on the investigated variable. Based on one-way ANOVA results from Taguchi L9 (32) experiments, the significant parameter for thrust force was cutting feed rate with p-value = 0.004, while hole accuracy was analysed by S/N ratio, in which feed rate achieved 1st rank and spindle speed at the 2nd rank for the significant factor. The optimisation and validation of micro-drilling parameters with respect to the thrust force and hole accuracy in machining of CFRP material were subsequently investigated. The experiments were systematically carried out by 2-Level Factorial experiment. The mathematical models for thrust force, 1st hole entry accuracy, 20th hole entry accuracy, 1st hole exit accuracy and 20th hole exit accuracy were developed in this stage. In addition, analysis of variance (ANOVA) was also carried out to check the significance of the models. Three validation experiments are conducted to determine the error percentage of thrust force and hole accuracy. Based on the results, the error was less than 10% for hole accuracy measurements while for thrust force an error of 17.70% was recorded. However, since the desired response for thrust force was to “minimize”, hence the value can be acceptable. The optimum conditions for minimum thrust force and high hole accuracy were found to be at spindle speed of 10,762 rpm and feed rate of 0.01 mm/rev.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Drilling and boring, Composite materials |
| Subjects: | T Technology > T Technology (General) T Technology > TJ Mechanical engineering and machinery |
| Divisions: | Library > Tesis > FKP |
| Depositing User: | F Haslinda Harun |
| Date Deposited: | 29 Sep 2022 11:59 |
| Last Modified: | 29 Sep 2022 11:59 |
| URI: | http://eprints.utem.edu.my/id/eprint/26002 |
| Statistic Details: | View Download Statistic |
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