Search Results for propelling abrasive materials

Mechanical cleaning systems are used to remove contaminants of work surface by propelling abrasive materials through any of these three principal methods: airless centrifugal blast blade- or vane-type wheels; compressed air, direct-pressure dry blast nozzle systems; or compressed-air, indirect-suction (induction) wet or dry blast nozzle systems. This article focuses on the abrasive media, equipment, applications, and limitations of dry and wet blast cleaning. It discusses the health and safety precautions to be taken during mechanical cleaning.

Thermal spray coatings (TSCs) are surface coatings engineered to provide wear-, erosion-, abrasion-, and corrosion-resistant coatings for original equipment manufacture and for the repair and upgrading of in-service equipment. This article presents an overview of five thermal spray processes and the specific flame and arc spray processes used to preserve large steel components and structures. It describes the TSC selection guide and an industrial process procedure guide for applying aluminum and zinc TSCs onto steel.

Thermal spray coating involves certain precoating operations, such as cleaning, surface preparation, and masking, that are critical to the overall quality of the coating system. In addition to these, certain other elements are considered prior to the coating, namely, customer requirements, coating function, part geometry, substrate metallurgy, structure, and thermal history. This article provides a detailed account of the various processes of surface preparation, namely, cleaning, roughening, dry abrasive grit blasting, and machining and macro roughening processes. It outlines the masking and fixturing techniques and stripping of coatings.

This article focuses on the corrosion and deterioration of components on recreational and small workboats. It discusses the materials selection and corrosion control for the components. These components include hulls, fittings, fasteners, metal deck gear, winches, backing plates, lifeline supports, inboard engines, cooling systems, propulsion systems, electrical and electronic systems, plumbing systems, masts, spars, and rigging.

This article provides information on the factors influencing the selection of the proper corrosion-resistant coating system. It focuses on the proper execution of surface preparation and the available surface preparation methods. The preparation process includes the removal of visible contaminants, removal of invisible contaminants, and roughening of the surface. Solvent or chemical washing, steam cleaning, hand tool cleaning, power tool cleaning, water blasting, and abrasive blast cleaning, are some preparation methods discussed. The article describes the most common application techniques of coating as well as the equipment used. An overview of some of the most common coating inspection points and inspection equipment is also provided.

Abrasive finishing is a method where a large number of multipoint or random cutting edges are coupled with abrasive grains as a bond or matrix material for effective removal of material at smaller chip sizes. This article provides a broad overview of the various categories of abrasive products and materials, abrasive finishing processes, and the mechanisms of delivering the abrasives to the grinding or machining zone. Abrasive finishing processes, such as grinding, honing, superfinishing, microgrinding, polishing, buffing, and lapping, are discussed. The article presents a brief discussion on abrasive jet machining and ultrasonic machining. It concludes with a discussion on the four categories of factors that affect the abrasive finishing or machining: machine tool, work material, wheel selection, and operational.

This article reviews the steps involved in presurface-preparation inspection: substrate replacement; removal of weld spatter, rounding of sharp edges, and grinding of slivers/laminations; and removal of rust scale, grease, oil, and chemical (soluble salt) contamination. It focuses on surface preparation methods that range from simple solvent cleaning to hand and power tool cleaning, dry and wet abrasive blast cleaning, centrifugal wheel blast cleaning, chemical stripping, and waterjetting for the application of the coating system. In addition, the article provides a description of the Society for Protective Coatings' (SSPC) standards and NACE International standards as well as the International Organization for Standardization (ISO) standards and International Concrete Repair Institute (ICRI) guidelines for surface cleanliness.

In all grinding operations, care must be used in the selection of wheels and abrasive belts to meet finish and tolerance requirements without damaging the workpiece. This article discusses the major aspects of the grinding wheel, including production methods, selection considerations, standard marking systems, abrasives, and bonding types. It compares bonded wheel grinding with abrasive belt grinding. The article reviews the types of grinding fluids and discusses their importance in grinding operations. It describes the specific grinding processes and provides recommendations for grinding and grinding wheels.

This datasheet provides information on composition limits, processing effects on physical and mechanical properties, and fabrication characteristics of high-strength forging alloy 7076.

Ceramic coatings are applied to metals to protect them against oxidation and corrosion at room temperature and at elevated temperatures. This article provides a detailed account of the factors to be considered when selecting a ceramic coating and describes the characteristics of various coating materials, namely, silicate glasses, oxides, carbides, silicides, and cermets. It reviews ceramic coating methods: brushing, spraying, dipping, flow coating, combustion flame spraying, plasma-arc flame spraying, detonation gun spraying, pack cementation, fluidized-bed deposition, vapor streaming, troweling, and electrophoresis. The article also includes information on the evaluation of the quality of ceramic coatings.

Finishing refers to a wide variety of processes that generally involve material removal in one form or another to generate surfaces with specific geometries, tolerances, and functional or decorative characteristics. This article discusses four major finishing methods, namely, abrasive machining, electropolishing, mass finishing, and shot peening. In each case, it describes subtypes, process variations, and the associated equipment.

This article provides a discussion on the mechanisms of wear and their interactions with gaseous corrosion. The wear mechanisms include abrasive, erosive, fretting, and sliding. The measurement of degradation on combustion walls in coal-fired boilers is discussed. The article concludes with information on the common coating techniques used for wear-corrosion control.

Coating of cast irons is done to improve appearance and resistance to degradation due to corrosion, erosion, and wear. This article describes inorganic coating methods commonly applied to cast irons. The coating methods include plating, hot dip coating, conversion coating, diffusion coating, cladding, porcelain enameling, and thermal spray. Organic coatings have a wide variety of properties, but their primary use is for corrosion resistance combined with a pleasing colored appearance. The article discusses the various types of organic coatings applied to cast irons. Practically any degree of smoothness or roughness and requirement for color and gloss can be filled by organic coatings. The article describes abrasive blast cleaning, abrasive waterjet cleaning and finishing, vibratory finishing, barrel finishing, and shot peening for processing iron castings.

This article provides a detailed account of the process development, cutting principle, and components of the abrasive waterjet cutting process. The advantages of abrasive waterjet machining are summarized. The article also discusses the factors affecting the cut quality, and the applications and limitations of abrasive waterjet cutting.

This article is a comprehensive collection of summary charts that provide data and information that are helpful in considering and selecting applicable processes alternative to the conventional material-removal processes. Process summary charts are provided for electrochemical machining, electrical discharge machining, chemical machining, abrasive jet machining, laser beam machining, electron beam machining, ultrasonic impact grinding, hydrodynamic machining, thermochemical machining, abrasive flow machining, and electrical discharge wire cutting.

This article describes the use of conventional machining techniques, laser cutting and water-jet cutting for producing finished composite parts. It explains two representative polymer-matrix composites--graphite and aramid composites--and discusses the machining and drilling problems such as delamination and fiber or resin pullout. The article describes machining and drilling techniques and the necessary tools and cutting parameters. It presents a description of laser cutting. The article also provides information on the advantages, disadvantages, cutting characteristics, and applications of water-jet cutting and abrasive water-jet cutting.

Wear is mechanically-induced surface damage that results in the progressive removal of material. Because different types of wear occur in machinery, many different types of wear tests have been developed to evaluate its effects on materials and surface treatments. This article provides an explanation on mechanisms, forms (sliding, impact, and rolling) and the causes of wear. It describes the wear measuring methods, including the mass loss method, wear width method, and scar depth method. The units used to report wear vary with type of wear and with the purpose for which the data are to be used. Listing the considerations of tribosystem analysis, the article provides information on selection of ASTM wear test methods grouped by wear type. The article concludes by tabulating the testing geometries and parameters that are commonly controlled and reported when conducting wear tests.

This article considers the main characteristics of wear mechanisms and how they can be identified. Some identification examples are reported, with the warning that this task can be difficult because of the presence of disturbing factors such as contaminants or possible additional damage of the worn products after the tribological process. Then, the article describes some examples of wear processes, considering possible transitions and/or interactions of the mechanism of fretting wear, rolling-sliding wear, abrasive wear, and solid-particle erosion wear. The role of tribological parameters on the material response is presented using the wear map concept, which is very useful and informative in several respects. The article concludes with guidelines for the selection of suitable surface treatments to avoid wear failures.

This article begins with a description of the advantages and disadvantages of thermal spraying. It provides a discussion on the importance of substrate processing prior to coating and the role of undercutting in repair. The article reviews the steps for substrate preparation, namely, cleaning, roughening, masking, and preheating. Information on the equipment and process variables of dry abrasive grit blasting are also provided. The article describes the roles of spray stream and the spray pattern for all thermal spray processes. It discusses the defects arising from poor temperature control and from the variables influencing the manipulation of the spray torch. The article concludes with helpful information on calculating the process efficiency of thermal spraying.

Erosion, cavitation, and impingement are mechanically assisted forms of material degradation that often contribute to corrosive wear. This article identifies and describes several tests that are useful for ranking the service potential of candidate materials under such conditions. The tests, designed by ASTM as G32, G73, G75, and G76, define specimen preparation, test conditions, procedures, and data interpretation. The article examines the relative influence of various test parameters on the incubation and intensity of cavitation, including temperature, pressure, flow velocity, and vibration dynamics. It concludes with a discussion on data correlations and the relationship between laboratory results and service expectations.