Engineering and Technology Journal

Abstract

The term deep hole originally reffered to hole depth over (5* diameter)
Deep hole drilling is a collective name for method for machining both short and
deep holes. In deep hole drilling cutting fluid supply and chip transport play an
important role in machining of hole depths of more than (100*diameter).
The cutting tip geometry has a significant effect on a drills performance and
on the quality of the machined holes by effecting on chips shape and
thickness, distribution of the cutting forces, and on the flow of the cutting
fluid at the cutting edge. The gun drill is normally divided in three parts:
1.Drill tip 2. Shank. 3. Driver.
Depending on the application, the most common tool tip material is C2
carbide, which is one of the harder grades. This paper deals with expermental
effect of gundrill tip geometry on the following properties of the hole: Hole
straightness , Error shape in roundness , Dimension tolerance and Surface
roughness. According to improvements of gun drill tip geometry in this work, the
deep drilled holes properties are significantly improved with the following results
: Hole straightness ( 7 μm) , Error shape in roundness ( 5 μm) , Dimension
tolerance ( 7 μm) and Surface roughness ( Ra 1.2 μm).