Drilling & Boring

There are several types of feed units for drilling and tapping on the market, varying in capability and the type of drive. This article discusses the difference between units and suggests questions users should ask themselves before selecting a unit. Factors to be considered include the volume of production, cost engineering and tool requirements.

Solid-carbide drills made with advanced submicrograin carbide are capable of producing holes that meet tight specifications without secondary operations. This article explains how these tools produce reamer-like finishes while offering extended tool life and shortened cycle times. An accompanying article discusses coatings for solid-carbide drills.

Indexable-insert drills offer several advantages for producing short holes. This article describes the drills' features, uses and benefits. Tips are provided to help select the optimal tool, insert and machine settings. A trouble-shooting chart is included.

U.S. manufacturers are in a transition period, moving from inch to metric specifications. This article looks at the impact this change is having on the manufacturing and use of drills. The discussion also covers the advantages and disadvantages of going metric and the availability of metric drill sizes in the United States.

When machinists plan a boring operation, they must rely on general turning data. Typically, this data is developed from OD turning operations, not boring operations. This article provides cutting data and recommendations specifically for boring that take into account such unique problems as boring bar deflection and chips trapped inside the bore.

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.

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.

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.