Articles & Columns

This article describes the shapes and sizes of diamond particles produced through standard manufacturing processes. The uses for these different types of particles are also explained, with an emphasis on particles used in superfinishing powders and slurries.

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.

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.

EDM cutting conditions change throughout the cutting process as the part thickness and the level of dielectric contamination fluctuates. This article describes an experimental setup that can monitor these fluctuations and adjust the EDM's settings to maintain an optimal spark.

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. Real-world examples are given of users who have improved their operations by changing the type of wire they were using.

Modular toolholding systems save shops money in several ways, according to this article. By making it possible to use the same tools on several machines, for example, a modular toolholding system can allow a shop to reduce its tool inventory. This article explains many other savings in addition to tool inventory reduction.

EDMing removes material at such high temperatures that the process produces metallurgical changes in the material surrounding the cut. This article discusses the various surface effects and how they can be detected and measured. It also reviews the different methods for correcting or removing the surface flaws and roughness caused by EDMing.

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.

Blades for contour bandsawing vary in their materials, their tooth set and selection, their width and the way they are welded. This article discusses how each of these variables contributes to the blades' ability to cut intricate shapes without seizing or wearing prematurely. Blade lubrication is also covered.

High-performance aluminum-alloy workpieces are prone to residual stresses that can lead to part distortion. This article reviews the milling tools and practices that affect these stresses. Some tools and practices alleviate the stress, while others allow the machinist to mill the part without adding more stress.

Cermet inserts have evolved into cutting tools capable of finish-turning steel reliably at high speeds. This article traces the developments that have led to modern cermets and describes the properties that enhance the performance of these tools. The development of coatings for cermets is also covered.

New plunge-and-turn tools make it possible to perform several tasks, such as grooving, turning, back turning and face grooving, with the same tool. This article discusses the design and use of these tools as well as the types of cutoff tools currently on the market. Recommendations for tool selection, speeds and feeds are given for various work materials.

Programming a cut with an abrasive waterjet is complicated by the fact that the stream of water deflects as it passes through the workpiece. This article describes newer controller technology that can adjust the traverse speed to minimize deflection at corners and curves.

To meet their customers' demands, mold and die shops are milling hardened steels at high speeds. This article discusses the use of coated carbide inserts to handle the heat generated by these operations. Specifically, the article talks about recently developed aluminum-titanium-nitride coatings, which reportedly are much more stable at elevated temperatures than other coatings.

The development of the CVD thick-film diamond process has made it possible to produce tools that can machine abrasive work materials without losing their cutting edge. In this article, the technology for producing the diamond film and the brazing of these thick-film chips onto inserts is described.

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.

Casting a pattern of light on a part and viewing that pattern at a different angle through a grating with the same pattern creates a moire pattern that can reveal small changes in the part's shape. This article tells how this phenomenon can be used by machine vision systems to measure part dimensions or pinpoint variations from a specified contour.

Software-based video tool inspection systems can read tool geometries much more precisely than other measurement systems. This article looks at the technology behind these systems and explains how this technology detects and measures tool edges and angles.

Tunable tools can be adjusted to dampen vibration. However, shops must have the right equipment to tune them quickly and precisely. This article describes an instrument that can provide the necessary feedback. A system that uses a mill's vibration frequency to sense problems with the tool is also described.

This article makes the argument that grinding is still a useful and necessary process despite the advancements that have made the turning of hardened workpieces possible. The article discusses the precision and finish possible with grinding, and it compares the cost of grinding to other machining processes.