Machining

Stainless steel is one of the more difficult materials to cut. This article discusses the problems that can occur when turning various types of stainless steels, the reasons for these problems and ways to avoid them. Advice is given on diagnosing problems based on tool-wear patterns. The article also suggests ways to correct problems once they are discovered.

This article makes the case that a core drill is the best tool for opening existing holes. Being designed for the operation, the two-flute indexable drill can produce more accurate holes with less tool wear and breakage than alternatives such as boring bars, drills or endmills.

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.

When shops crank up the speed, they have to be prepared for the consequences, even if they're milling "easy-to-machine" aluminum.

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.

The advent of CNCs made new threadmaking technologies practical. Among these technologies are rigid tapping and thread milling. This article describes the uses, techniques and benefits of these two threadmaking methods.

There are some tapping situations that call for a rigid tapholder and some that call for a length-compensating holder. Often the choice depends on the capabilities of the machine and the CNC driving the tap. This article discusses why a machinist might choose one type of tapholder or the other.

Internal threads can end up undersized because of the work material's properties or because of changes to the hole's dimensions caused by plating or heat-treating processes performed after tapping. This article explains H- and D-limits and how to use them to specify a tap that will produce the right size thread, regardless of any post-tapping operations.

The fundamentals of wheel dressing and truing are reviewed in this article, which covers the proper maintenance of a wide variety of wheel bonds and abrasive types. The article also discusses different truing techniques and their appropriateness for different uses.

Researchers at the Center for Grinding Research performed a series of creep-feed grinding tests to determine the causes of the heat damage and striations they observed. The tests involved grinding slots and vertical faces. This report discusses the dynamics behind these problems and suggests ways to avoid them.

Standards governing grinding-wheel safety testing do not cover all superabrasive wheels. This article suggests that these standards should include them. The author explains why as he describes a typical superabrasive wheel and the dynamics of superabrasive wheel failure.

With wire EDM, the properties of the wire will have a large impact on the performance of the operation as well as the ease of rethreading. This article discusses the properties that ensure a good spark and reliable performance even when cutting at an angle.