Drilling of long fiber reinforced polymer composite laminates

Composite materials are increasingly being used to substitute other materials such as metals and their alloys in many engineering applications, especially in the aviation industry. A number of research have been implemented to study the mechanics of the composite material itself, with only a few studies on the machining processes of the composite such as the drilling process which is one of the most important stages of manufacturing. Fiber reinforced polymer (FRP) is one type of composite material being studied for its machinability. Although the advantage of the FRP lies in its ability to vary its fiber orientation layout to customize its strength, this factor also complicate the choice of the process parameters such as the tool geometry, feed rate, speed, etc., during the drilling process. A poor choice of parameters selection will give rise to undesirable effect (e.g. delamination and fiber pull-out) in the hole which affects its quality and thus, leads to problems in the assembly and integration process. This project aims to study the material behavior of carbon fiber reinforced polymer CFRP of three different fiber orientation (00, 0/900 & 0/45/-45/900) and Satin Weave Type CFRP composite material. For the former CFRP, the physical drilling process has already been done on nine pieces of specimens by the previous FYP student. The aim of this project is to quantify the quality of the drilled holes in terms of delamination, damage zone size and fiber pull-out with respect to its process parameters, namely, feed rate, drilling speed, drill type and fiber orientation layout. Regarding the latter CFRP, the specimens are manufactured and drilling process is performed on them to determine the maximum thrust force experienced by the specimens and its relevant power consumption. Finally, these quantitative results are analyzed to determine the optimal drilling parameters for obtaining the minimal defect holes. In conclusion, to achieve the minimal damage to the front side of the UD-CFRP composite specimens, the optimal drilling parameters for fiber layout, drill type, speed and feed rate are 0/45/-45/90 degree, dagger drill, 2000 rpm and 0.08 mm/rev respectively. With regards to the back side of the specimen, the optimal drilling parameters are 0/90 degree, reamer drill, 2000 rpm and 0.12 mm/rev. For the Satin Weave Type CFRP composite specimens, in order to achieve the minimal maximum thrust force for the following process parameters; specimen thickness, drill type, speed and feed rate, the optimal values are 2 mm, dagger drill, 3000 rpm and 0.08 mm/rev respectively. To consume the least amount of power during drilling, the optimal process parameter values are 3 mm, dagger drill, 1500 rpm and 0.08 mm/rev.Bachelor of Engineering (Mechanical Engineering