Search Results for relay steel

This article contains a table that lists the electrical conductivity and resistivity of selected metals, alloys, and materials at ambient temperature. These include aluminum and aluminum alloys; copper and copper alloys; electrical heating alloys; instrument and control alloys; relay steels and alloys; thermostat metals; electrical contact materials; and magnetically soft materials.

Gas analysis by mass spectrometry, or gas mass spectrometry, is a useful analytical tool for investigations performed in controlled atmospheres or in vacuum. This article provides sufficient information to determine if gas mass spectrometry can produce the data required and to determine the type of instrument necessary for a particular application. It discusses the working operations of gas mass spectrometer components, namely, the introduction system, ion sources, mass analyzers, and the ion detector. The article also provides information on resolution of a gas mass spectrometer determined by the width of the source slit and the collector slit. Finally, it describes the instrument set-up for gas mass spectrometry, and shows how to analyze the test results of gas mass spectrometry.

Electrical contacts are metal devices that make and break electrical circuits. This article provides information on materials selection criteria and failure modes of make-break contacts. It describes the property requirements for make-break arcing contacts, namely, electrical conductivity, mechanical properties, chemical properties, fabrication properties, and thermal properties. The article presents a brief note on brush contact materials and their interdependence factors for sliding contacts. It also describes the type of commercial contact materials for electrical contacts, namely, copper metals, silver metals, gold metals, metals of the platinum group, precious metal overlays, tungsten and molybdenum, aluminum, and composite materials. Finally, the article provides information on composite manufacturing methods, and tabulates the physical, and mechanical properties of electrical contact materials, including copper, silver, gold, platinum, palladium, and composites.

This article focuses on the various types of corrosion-related failure mechanisms and their effects on passive electrical components. The types include halide-induced corrosion, organic-acid-induced corrosion, electrochemical metal migration, silver tarnish, fretting, and metal whiskers. The passive electrical components include resistors, capacitors, wound components, sensors, transducers, relays, switches, connectors, printed circuit boards, and hardware.

Electrical contacts are made of elemental metals, composites, or alloys that are made by the melt-cast method or manufactured by powder metallurgy (PM) processes. PM facilitates combinations of metals that ordinarily cannot be achieved by alloying. This article describes the processing, properties, and performance of electrical contacts based on PM or hybrid composite technologies with refractory metals and compounds. These metals and compounds include tungsten, molybdenum, carbide-based composites, and silver-base composites. The article explains composite manufacturing methods, namely, PM methods, internal oxidation, and hybrid consolidation. The availability of the refractory metals and compounds in various product forms are also reviewed.

Control of temperature and furnace atmospheres has become increasingly critical to successful heat treating. Temperature instrumentation and control systems used in heat treating include temperature sensors, controllers, final control elements, measurement instruments, and set-point programmers. This article describes these items and discusses the classifications and control of furnace atmospheres. The article also describes the surface carbon control devices available for the wide variety of furnace atmospheres and evaluation of carbon control. Finally, the article provides a set of guidelines for safety procedures that are common to all industrial heat treating furnace installations.

Stray current can be defined as a current in structures that are underground or immersed in an electrolyte that most often accelerate corrosion on a structure where a positive current leaves the structure to enter the earth or an electrolyte. This article provides a description of the principles of stray current and a discussion on the major types of stray current and their properties and prediction methods. It discusses the consequences of stray current and describes the interference tests used for mapping the path of the stray currents. The article also highlights the methods of mitigating the source of stray current.

A tin deposit provides sacrificial protection to copper, nickel, and many other nonferrous metals and alloys. Tin also provides good protection to steel. Tin can be deposited from either alkaline or acid electrolytes. This article explains the compositions and operating conditions of these electrolytes.

Electrical contacts are metal devices that make and break electrical circuits. This article describes the property requirements such as electrical conductivity, mechanical properties, chemical properties, fabrication properties, and thermal properties of make-break arcing contacts. The article also focuses on brush contact materials and their interdependence factors for sliding contacts. In addition, the article discusses the properties, manufacturing methods, and applications of electrical contact materials, including wrought materials such as copper metals, silver metals, gold metals, precious metal overlays, tungsten, molybdenum, and aluminum, and composite materials. It concludes by discussing the composite manufacturing methods such as infiltration, press-sinter, press-sinter-repress process, press-sinter-extrude process, internal oxidation, and preoxidized-press-sinter-extrude process, and coprecipitation.

This article provides an overview of electromagnetic fields (EMFs) and discusses their direct and indirect effects on human health. It provides a detailed description of the exposure levels of EMFs in residential and work environments. The article examines the international and European standards and regulations regarding occupational exposure to EMFs encountered in industrial activities. It discusses the categories of work equipment or activities that may expose the worker above and under the orientation value. The article also describes the main principles underlying the protection system adopted for the frequency range of 50 Hz to 10 MHz.

Induction heating system control is straightforward after the design and application of the coil and power supply required for the job. This article provides an overview of the basic components of an induction heating system, including a machine controller (computer or programmable logic controller), interface wiring, an operator interface, and safety controls. It also provides information on programming devices and temperature controllers, such as manual, auto, and auto-manual temperature controllers.

This article discusses stress relaxation testing on metallic materials, as covered by ASTM E 328. It reviews the two types of stress relaxation tests performed in tension, long-term and accelerated testing. The article illustrates load characteristics and data representation for stress relaxation testing used for the most convenient and common uniaxial tensile test. It concludes with information on compression testing, bend testing, torsion testing, and tests on springs.

Magnetically soft materials are characterized by their low coercivity, an essential requirement for irons and steels selected for any application involving electromagnetic induction cycling. This article provides information on ferromagnetic material properties and how they are affected by impurities, alloying additions, heat treatment, residual stress, and grain size. It also describes classification and testing methods for magnetically soft materials such as high-purity iron, low-carbon steels, silicon steels, iron-aluminum alloys, nickel-iron alloys, iron-cobalt alloys, ferrites, and stainless steels. The article also addresses corrosion resistance and provides insights on the selection of alloys for power generation applications, including motors, generators, and transformers. A short note on the design and fabrication of magnetic cores is also included.

This article discusses the ferromagnetic properties of soft magnetic materials, explaining the effects of impurities, alloying elements, heat treatment, grain size, and grain orientation on soft magnetic materials. It describes the types of soft magnetic materials, which include high-purity iron, low-carbon irons, silicon (electrical) steels, nickel-iron alloys, iron-cobalt alloys, ferritic stainless steels, amorphous metals, and ferrites (ceramics). Finally, the article provides a short note on alloys for magnetic temperature compensation.

Heat treating furnaces require different control systems and integration for achieving optimum technical results and enabling safe operation. This article focuses on atmosphere furnaces, with some coverage on controls for vacuum furnaces. Heat treating operations require reliable monitoring and control of motion and position of various mechanical components with the help of mechanical limit switches, proximity sensors, and distance- and position-measuring devices. Using inputs from both flow meters and sensors, such as thermocouples and oxygen sensors, flow measurement control systems must be able to adjust the flow of gases for process optimization. The operator interface of a furnace-control system displays critical information such as the furnace temperature, atmosphere status, alarms, electronic chart recorders, recipe, and maintenance. A supervisory control and data-acquisition (SCADA) system is used to monitor, collect, and store data from multiple pieces of equipment.

This article provides an overview of the basic theory of infrared (IR), including emissivity and E slope. It explains how the IR thermometer works, and provides guidance on choosing a thermometer, in particular, deciding between a two-color and a single-wavelength thermometer and installing and maintaining them. The article discusses typical applications of induction heating, and describes how the IR thermometer controls the temperature. While the majority of the article discusses spot thermometers, thermal imagers, which are fast and are used for both research and control of the induction process, are also addressed.

Eddy-current inspection is a nondestructive evaluation method based on the principles of electromagnetic induction. Eddy-current methods are used to identify or differentiate a wide variety of physical, structural, and metallurgical conditions in electrically conductive ferromagnetic and nonferromagnetic metals and metal parts. Giving a brief introduction on the uses of eddy-current inspection, this article discusses the operating principles and the principal operating variables encountered in eddy-current inspection, including coil impedance, electrical conductivity, magnetic permeability, lift-off and fill factors, edge effect, and skin effect. It further describes different aspects of eddy current testing such as the selection of inspection frequencies and the types and configurations of inspection coils. The article also deals with the eddy current instrumentation and the discontinuities that are detectable by eddy-current methods.

This article focuses on the recycling of metals including iron and steel, stainless steel, superalloys, nickel, aluminum, copper, precious metals, lead, magnesium, tin, titanium, and zinc. It provides information on the identification and sorting of scrap metals and discusses the equipment and procedures used for small-scale and large-scale scrapping operations.

This article provides information on radial friction welding, which adopts the principle of rotating and compressing a solid ring around two stationary pipe. The process evolution of this welding is illustrated. The article also examines the equipment used and operating steps. It also illustrates a prototype of radial friction-welding machine and concludes with a discussion on applications that would be suitable for radial friction welding.

This article discusses the presses, auxiliary equipment, and dies used in the blanking and piercing of commonly used magnetically soft materials, namely, low-carbon electrical steels and oriented and nonoriented silicon electrical steels. It describes the effect of stock thickness and work metal composition and condition on blanking and piercing. The article provides an overview of the influence of burr height on stacking factors and presents a discussion on the lubrication and core plating of electrical steels that ease the process.