Drilling of composites is currently rife with damage phenomenon such as spalling, delamination, edge chipping, fiber pull-outs, crack formation, thermal residual stresses and excessive tool wear.
Exit-ply delamination has been identified as the most deleterious damage
phenomenon for structural components as it results in a significant loss of strength and stiffness of the laminate and, consequently its load carrying capacity. Identification and prevention of delamination therefore becomes particularly important for composite components subjected to compressive, shear.
it has been seen that the main cause of delamination is thrust force and feed rate, so by obtaining critical values of these parameters we can reduce delamination.
Dear Mr Pandey. I recommend to you make a Design of Experiment. In this sense, you need to fixed values for entry variables (such as drill diameter, cutting speed, feed, etc), and make the experiments to measure hole quality and thrust force. I think that factorial design is good for this task. With all the measures values you can analyze the results and obtain the relation between bad quality holes and the entrance variables.
Thank you Mr. Daniel Martinez Krahmer for your helpful suggestion but I'm trying to follow some mechanistic approach to obtain optimal value of thrust force to minimize delamination.
Good. Then, you need to reduce thrust force. There are two ways: 1) decrease the feed and 2) use drills with modify point to improve the geometry of the hole exit.
I will trait to search some paper for you.
I think that the attach information would be useful for you. I use as keywords: burr drilling.
More information:
https://www.google.com.ar/search?q=geometry+point+drill+to+reduce+burr+hole+exit&espv=2&biw=1242&bih=566&site=webhp&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj6sr2q44rPAhWClZAKHfoDAKEQ_AUIBigB&dpr=1.1
You can measure the thrust force by using kiztler dynamometer throughout the hole drilling as one cycle. if you analyse the output suitably, you are able to reduce the delamination.
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