Search Results for core size

Lightweight structural cores are used on aircrafts to reduce weight and increase payload and fight distance. This article discusses the classification of lightweight structural cores, namely, honeycomb, balsa, and foam. It reviews the four primary manufacturing methods used to produce honeycomb: adhesive bonding and expansion, corrugation and adhesive bonding, corrugation and braze welding, and extrusion. The article describes cell configuration and properties of honeycomb. It discusses the factors influencing specification of structural cores, including materials, size, density, mechanical properties, environmental compatibility, formability, durability, and thermal behavior. The article provides information on the benefits and concepts of a sandwich panel containing lightweight structural cores.

Surface coatings are essential in all facilities that process nuclear materials or use nuclear fission for power generation. This article describes the coatings used in two basic types of Generation 3 nuclear reactor designs in the United States and their containment size. These reactors are the boiling water reactor (BWR) and pressurized water reactor (PWR). The article provides information on the loss-of-coolant accident (LOCA) identified as the design basis accident (DBA), which can rapidly de-water the core of an operating nuclear reactor. To avoid LOCA, both the BWR and the PWR include emergency core cooling systems. The article describes a DBA test and other coating performance parameters necessary for safety-related coating systems. It provides a detailed account of the selection criteria of coating types in a nuclear plant. The article concludes by highlighting protective coating strategies in Generation 3 Plants.

Cores are separate shapes of sand that are placed in the mold to provide castings with contours, cavities, and passages that are not otherwise practical or physically obtainable by the mold. This article describes the basic principles of coremaking and the types of core sands, binders, and additives used in coremaking. It discusses the curing of compacted cores by core baking and the hot box processes. The article provides an overview of the core coatings, assembling and core setting, coring of tortuous passages, and cores in permanent mold castings and investment castings. It also discusses the design considerations in coremaking to eliminate cores and compares coring with drilling.

Cores are separate shapes, of sand, metal, or plaster, that are placed in the mold to provide castings with contours, cavities, and passages. Cored holes should be designed simply as the intended function of the casting permits. This article describes the designing of casting for the use of sand cores and to eliminate cores, with illustrations. It provides general rules for designing cored holes in investment castings. The article discusses the general principles of coremaking with illustrations. It concludes with a comparison between coring and drilling.

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.

Hardenability is a composition-dependent property of steel and depends on carbon content and other alloying elements as well as the grain size of the austenite phase. This article provides an overview of a wide range of testing procedures used to determine and quantify hardenability of shallow-hardening, low-carbon, plain carbon, and low-alloy medium-carbon steels ranging from classical fracture and etching, Grossmann hardenability, and Jominy end-quench testing to manual and computerized computational methods. The article then uses this as a backdrop for the implementation of the core concepts of hardenability in a variety of predictive tools for calculating hardenability. The Caterpillar 1E0024 Hardenability Calculator, a personal computer-based program, calculates the Jominy curve based on the steel composition. The article also describes the method for boron and nonboron steels, with calculation examples for 8645 steel and 86B45 steel.

Liquid impingement erosion has been defined as progressive loss of original material from a solid surface due to continued exposure to impacts by liquid drops or jets. This article focuses on the core nature of erosion by liquid impingement, due to the greater appreciation of the distinctions between the different forms of erosion. It discusses steam turbine blade erosion, aircraft rain erosion, and rain erosion of wind turbine blades. The article describes the mechanisms of liquid impact erosion and time dependence of erosion rate. It reviews critical empirical observations regarding both impingement variables (velocity, impact angle, droplet size, and physical properties of liquids) and erosion resistance of materials, including the correlation between erosion resistance and mechanical properties and the effects of alloying elements and microstructure. The article also provides information on the ways to combat erosion.

This article provides general guidelines for casting design to provide progressive solidification, minimize heat concentration, eliminate cores, and prevent distortion. Casting design also affects tolerances. Casting tolerances depend on the alloy being poured, the size of the casting, and the molding method used. Designers can predict the effect of the design on the structure of the final part using solidification simulation models, namely finite element and finite difference models, and rapid prototyping. The article concludes with a short note on how the quality is assured in the foundry.

Sand casting processes are typically classified according to the type of binder present in the molding sand mixture. This article discusses common sand casting processes and design considerations related to shape, gating, feeding, and pattern making methods. It describes the composition of sand and binder normally used, and provides information on the aluminum casting alloys produced. The article discusses precision sand casting and sand reclamation, and includes information on health and safety considerations.

The ultrasonic machining (USM) process consists of two methods, namely, ultrasonic impact grinding and rotary USM. This article lists the major ultrasonic components that are similar to both rotary USM and ultrasonic impact grinding. It also provides schematic representations of the components used in rotary USM and ultrasonic impact grinding. The article describes the operations of the components of the rotary ultrasonic machine and ultrasonic impact grinding machine. It discusses the applications of the rotary ultrasonic machine: drilling, milling, and surface grinding. The article concludes with information on machining characteristics of ultrasonic impact grinding.

This article discusses the types of patterns used for a specific application such as loose patterns, match plate patterns, cope and drag patterns, and special patterns. It describes the principles of the patternmaking techniques used to make expendable molds and for metal casting processes such as die casting and permanent mold casting. The article reviews the pattern features and mold production considerations used in the pattern design, namely, parting line considerations, addition of gates and risers, core prints, and locating points. It examines the pattern allowances for ensuring a dimensionally correct final pattern. A variety of materials and advanced composite materials used in the manufacture of patterns are discussed. The article evaluates the factors influencing the selection of type of patterns for specific castings.

Honeycomb is a product consisting of very thin sheets attached to form connecting cells. This article briefly explains the construction, core characteristics, properties, and testing methods of the honeycomb structures. It discusses the special processes carried out in customizing the shape of core to fit customer's specific needs. The article provides information on the basic concept of creating sandwich structures and its corresponding aspects like material selection, design guidelines, and structural efficiency.