Delamination is considered as a major problem in drilling of composite materials. which degrades the mechanical properties of these materials. The thrust force exerted by the drill is considered as the major cause of delamination; and one practical approach to reduce delamination is to use a back-up plate under the specimen. In this paper. https://www.spidertattooz.com/Nyrkki-terassormus-Teras-316L/