Articles & Columns

The author gives an overview of the most common hardness testing methods: Rockwell, Brinell, Vickers and Knoop.

An expert on heat treating write about the advantages and disadvantages of available approaches and systems: stainless steel foil, atmospherically controlled furnaces, pressure-quench vacuum furnaces and two-zone vacuum furnaces. There's also a sidebar on cryogenic treatment of metals.

A new turning tool emits an electric signal when its insert reaches a predetermined wear point or breaks. Called Sensor Tool, sections of the coated insert are ablated by a laser, thereby creating an electronic circuit.

A look at the various types of CNC lathes available to shops contemplating stepping up from a manual machine. The pros and cons of the following lathes are discussed: combination, cutoff, slant-bed, twin-spindle and turn/mill. The author also touches on available options.

Part I: The author discusses how to maintain and repair machine tool spindles and what causes spindles to run out of round. Common sources of out-of-round spindles include loose bearings and improperly ground spacers. In-machine spindle repair is also discussed. Part II: There are three common ways to repair tapered toolholders: regrinding, replacing damaged material and chrome-plating. The author discusses each, along with its price, and gives advice about choosing an option.

Grinding burn is a general term used to describe various types of thermal damage that occur to the workpiece during grinding. The author supplies detailed information about each type of burn and offers advice for preventing it

Capability is determined by how well a process produces parts. Three measures of capability are important to a machinist: gage, machine and process. The author provides a detailed description of capability and suggests ways to quantify if a process is or isn't capable.

Cutting forces cause the boring bar to deflect, which can lead to vibration and damaged workpieces. The author gives an overview of available boring bars and offers guidelines for selecting one for a specific application.

DNC can mean either Direct Numeric Control or Distributed Numeric Control. Either way, a DNC links a shop's computers and machine tools and saves times. A DNC eliminates manual transcription of NC data, the downtime caused by shop personnel having to make programming entries and transporting part programs between engineering and their machines.

The author discusses three recent advancements in electrical discharge machining: the use of linear motors on EDMs, wire EDMs with an automatic slug-removal capability and dielectric fluid additives that yield finer part finishes.

Metalworking companies have a "cradle-to-grave" responsibility for the fluids they use. Improper disposal can lead to costly fines. Article discusses the ramifications of improper disposal and how to develop a plan to constantly improve the condition of a shop's metalworking fluid.

Due to the exceptional strength of IN 100, INCO 718 and other nickel-based alloys, they're difficult to machine. The author, who spent 40 years endmilling these aerospace materials, discusses their unique characteristics and methods for successfully machining them.

The author provides guidelines shops can follow when selecting a PC-based CAD/CAM system. Selection guidelines include: CAD functionality, CAM functionality, NC code output, vendor evaluation and hardware selection.

The use of shrink-fit toolholders continues to grow, mainly because, compared to conventional holders, they secure tools more tightly and extend the life of cutting tools. Article includes an overview of available systems and comments from users of shrink-fit holders.

The author offers tips about making interrupted cuts while turning. He also discusses the differences between interrupted cuts in turning and milling and various types of materials.

Discussion of different types of bonds used to make superabrasive grinding wheels. Author provides tables with price comparisons, physical properties and operating parameters for various bonds.

Equipping toolchangers with nylon abrasive-filament brushes can greatly enhance process economics and the flow of parts. Case histories of in-machine deburring operations support these contentions, and the author describes how such systems should work.

Salaries earned by metalworking professionals, including machinists, production engineers, manufacturing engineers and corporate managers. Salaries are broken down by region, size of company and type of shop or manufacturing facility.

Overview of the new machine tool technologies introduced at IMTS 2000. Among them are linear motors for axes travels, ballscrew chillers, a new way to lubricate linear guideways and controlling machining processes via the Internet.

Author discusses the advantages of CVD-diamond tools compared to other types of diamond tools. He also explains how CVD-diamond tools are manufactured and gives case histories involving their usage.