Search Results for secondary operations

Refractory metals are typically processed from powders into ingots that are subsequently swaged into round bars or rolled into plates. Secondary operations are required to fabricate more complex refractory metal components. This article discusses two such secondary operations, namely, machining and joining processes for tungsten, tungsten heavy alloys, molybdenum, tantalum, niobium, and rhenium components. It describes the various types of metal joining processes, including mechanical fastening, brazing, and welding.

This article describes the secondary operations for cemented carbide parts, namely, diamond grinding, honing, electrical discharge machining, and brazing after sintering to achieve desired results, such as specified size, shape, edge condition, and surface finish.

Powder metallurgy (PM) stainless steels, as with conventional PM steels, are often used in the as-sintered condition. In addition to cost considerations, minimization of postsinter handling and secondary operations is also preferred because it reduces the potential for contamination of the parts with particulates and residues, which can result in the appearance of surface rust. This article provides information on various secondary operations, including tumbling, re-pressing, resin impregnation, annealing or heat treating, brazing, machining, and welding. It describes those aspects relating to welding of PM stainless steels, specifically, the effects of density, residual porosity, and sintered chemistry on weldability. Further, the article investigates the influence the sintering atmosphere has on machinability, as well as differences created by the presence of residual porosity.

Certain metal products can be produced only by powder metallurgy; among these products are materials whose porosity is controlled. Successful production by powder metallurgy depends on the proper selection and control of process variables: powder characteristics; powder preparation; type of compacting press; design of compacting tools and dies; type of sintering furnace; composition of the sintering atmosphere; choice of production cycle, including sintering time and temperature; and secondary operations and heat treatment. When the application of a powder metallurgy part requires high levels of strength, toughness, or hardness, the mechanical properties can be improved or modified by infiltration, heat treatment, or a secondary mechanical forming operation such as cold re-pressing or powder forging. The article also discusses the effect of the secondary processes on P/M mechanical properties.

Powder forging is an extension of the conventional press and sinter powder metallurgy process, which is recognized as an effective technology for producing a variety of parts to net or near-net shape. This article focuses on the material considerations, such as powder characteristics, alloy development, and inclusion assessment; and process considerations, such as process stages, tool design, and secondary operations; of ferrous alloy powder forging. The mechanical properties of powder forged materials are also reviewed. The article discusses the quality assurance tests for powder forged materials: the part dimensions and surface finish measurement, magnetic particle inspection, metallographic analysis, and nondestructive testing. It concludes with a discussion on the applications of powder forged parts with examples.

Powder metallurgy is a near-net shape process capable of producing complex parts with little or no need for secondary operations such as machining, joining, or assembly. However, the inability to produce certain geometrical figures such as transverse holes, undercuts, and threads frequently necessitates some machining, particularly drilling. This article provides a discussion on the measures that can optimize the machining of P/M materials. It reviews the factors influencing machinability of P/M components, including workpiece and tool material properties, cutting conditions, machine and cutting tool parameters as well as some P/M material and production process parameters. These parameters discussed include the particle size, part geometry, porosity, compaction and sintering methods. In addition, the article presents guidelines for the various machining processes, namely, turning and boring, milling, drilling, grinding, reaming, burnishing, tapping, and honing and lapping.

Casting offers a great amount of component design flexibility. This article discusses six casting design parameters that drive the geometry of casting design from a process standpoint. It provides information on the design of junctions and addresses considerations of secondary operations in design. The article describes the factors that control casting tolerances and presents specific tips for designing castings with uniform wall thickness, unequal sections, thin sections, economical coring, functional packaging, and core design. The article provides a framework for analyzing all manners of manufacturing as possible conversion candidates for casting. It concludes with a discussion on different metalcasting design projects.

This article discusses the production of low-alloy steel parts by powder forging, focusing on the material considerations, such as hardenability and inclusion assessment; and process considerations, including sintering and reheating, metal flow, and secondary operations. It presents the mechanical property data for copper and graphite powders mixed with an iron powder base to produce materials that generally contain 2″ Cu, including tensile, impact, and fatigue properties. Heat treatment procedures used in developing the properties of the prealloyed powder forged materials are also covered. Finally, the article describes the process steps and cost considerations in metal injection molding (MIM) and tabulates the composition, and mechanical properties of MIM low-alloy steels.

Metal injection molding (MIM) is a metalworking technology that has its origins as a commercial technology only dating back to the early 1970s. This article explores why the MIM is the preferred solution for many fabricated components. It illustrates the MIM components required for different end-use markets such as electronics and telecommunications, medical, automotive, power hand tools, industries, and firearms.

This article focuses on the fractography features of the conventional powdered metal (PM) process for ferrous powders. It discusses porosity, which is one of the inherent features present in components produced by conventional press-and-sinter processes, and green cracks, which are the most common fracture issue in conventional PM processes. It explains the effect of post-sintering operations. The article also presents the common ferrous powder metallurgy materials.

This article focuses on the principles and applications of high-sputter-rate dynamic secondary ion mass spectroscopy (SIMS) for depth profiling and bulk impurity analysis. It begins with an overview of various factors pertinent to sputtering. This is followed by a discussion on the effects of ion implantation and electronic excitation on the charge of the sputtered species. The design and operation of the various instrumental components of SIMS is then reviewed. Details on a depth-profiling analysis of SIMS, the quantitative analysis of SIMS data, and the static mode of operation of time-of-flight SIMS are covered. Instrumental features required for secondary ion imaging are presented and the differences between quadrupole and high-resolution magnetic mass filters are described. The article also reviews the optimum method for analysis of nonmetallic samples and high detection sensitivity of SIMS. It ends with a discussion on a variety of examples of SIMS applications.

This article describes the capabilities, limitations, advantages, and disadvantages of the powder metallurgy (PM) gear manufacturing process. It discusses the types of gears that can be produced by PM and presents the design guidelines for PM gears. The article provides information on gear tolerances and performance of PM gears. It also explains various procedures to inspect and test the mechanical properties, dimensional specifications, and surface durability (hardness).

Vacuum induction melting (VIM) is often done as a primary melting operation followed by secondary melting (remelting) operations. This article presents the process description of VIM and illustrates potential processing routes for products, which are cast from VIM ingots or electrodes. It describes the VIM refinement process, which includes the removal of trace elements, nitrogen and hydrogen degassing, and deoxidation. The article concludes with information on the production of nonferrous materials by VIM.

This article describes the operation and capabilities of surface analysis methods of metals, including scanning electron microscopy, electron probe microanalysis, transmission electron microscopy, secondary ion mass spectroscopy, and X-ray photoelectron spectroscopy. It provides information on the capabilities, typical uses, spatial resolution, elemental analysis detection threshold and precision, limitations, sample requirements, and operating principles of the scanning auger microprobe.

Machining or material removal processes are secondary manufacturing operations that are used to achieve precise tolerances or to impart controlled surface finishes to a part. This article summarizes rules for designing parts to improve machined part quality and reduce machining costs in mass and batch production environments. It discusses the factors affecting the total cost of a machining operation, including raw material costs, labor costs, and equipment costs. The article describes three types of machining systems, namely, general-purpose machine tools, production machining systems, and computer numerically controlled (CNC) machining systems. It reviews general design-for-machining rules that are applicable to all parts, regardless of the type of equipment used to produce them. Special considerations for production machining systems and CNC machining systems are discussed. The article describes the structure and typical uses of computer-aided process planning and design-for-manufacturing programs.

This article provides background information needed by design engineers to create part designs optimized for plastics and plastic manufacturing processes. It describes the four essential elements of plastic part development, namely, material, process, tooling, and design, and provides general design rules for the plastic forming processes covered. It also discusses the steps involved in design validation and verification.

Batteries and fuel cells are popular forms of portable electrical energy sources. This article discusses the operation and corrosion problems inherent in batteries and fuel cells. Batteries are classified into two groups: primary or nonrechargeable batteries and secondary or rechargeable batteries. Fuel cells are classified into five types: phosphoric acid fuel cell (PAFC), solid polymer electrolyte fuel cell, alkaline electrolyte fuel cell, molten carbonate fuel cell (MCFC), and solid oxide fuel cell. The article presents reactions that occur during charging and discharging of lead-acid batteries, PAFCs, and MCFCs.

This article presents a simple cost/pricing system that is reasonably accurate and could easily be recalculated if the yearly cost of any of the basic cost components change. Using the example of a commercial heat treating facility, the operational details are categorized as atmosphere processes, induction processes, aluminum processes, high-heat processes, and secondary processes. For the purpose of calculating the heat treatment processing cost per hour and the selling price for a piece of equipment, the costs are separated into direct costs, allocated costs, capitalized cost, and general and administrative costs. The article discusses the techniques involved in allocating costs to the group of equipment, and presents a description on the cost analysis of endothermic gas.

Gallium-base components can be found in a variety of products ranging from compact disk players to advanced military electronic warfare systems, owing to the factor that it can emit light, has a greater resistance to radiation and operates at faster speeds and higher temperatures. This article discusses the uses of gallium in optoelectronic devices and integrated circuits and applications of gallium. The article discusses the properties and grades of gallium arsenide and also provides information on resources of gallium. The article talks about the recovery techniques, including recovery from bauxite, zinc ore and secondary recovery process and purification. The article briefly describes the fabrication process of gallium arsenide crystals. Furthermore, the article gives a short note on world supply and demand of gallium and concludes with research and development on gallium arsenide integrated circuits.