Articles

When hole depths exceed four times the drill diameter, problems with cooling and chip evacuation can arise. This article discusses these problems and the drill geometries, machining parameters and coolant options that can minimize them. Charts are included giving speeds and feeds for various workpieces and drill diameters.

For drilling standard holes in metal, there are three primary types of drills: twist, spade and indexable insert. This article discusses the pros and cons of each design and the applications for which each might be appropriate. Factors considered include hole depth, tool cost, drill speed, coolant delivery, tool inventory required, machine tool requirements and expected tool life.

Ion implantation bombards a tool's surface with accelerated metal ions. According to this article, the process increases tool life and the performance of tool coatings. Two theories explaining why the process works are also discussed.

Guide bushings are used in difficult holemaking applications to ensure that the drill produces round straight holes. This article discusses the types of bushings commonly used and the materials they are made from. Guidelines for sizing bushings for a given operation are also supplied.