Search Results for warm compaction

Warm compaction uses both powder heating and die heating to effect higher component densities, whereas warm die compaction uses only die heating to achieve higher density. This article explains the influences of green and sintered properties and pore-free density during compaction of materials. It provides information on the concept of pore-free density and process considerations: die heating and powder heating. The article concludes with a review of the tooling design for warm compaction.

This article provides an overview of the compaction of metal powder in a rigid die and reviews the compaction characteristics of stainless steel powders, including green density, compressibility, green strength, apparent density, flow rate, and sintered density. It describes the influence of compaction characteristics of stainless steel powders in tool materials selection, lubrication, annealing, double pressing/double sintering, and warm compaction.

This article describes several factors, which help in determining the compressibility of metal powders: particle shape, density, composition, hardness, particle size, lubrication, and compacting. It discusses the uses of annealing metal powders and describes compressibility testing of the powders. The article details green strength and its mechanism and the variables affecting the strength. It also discusses two test methods for determining the green strength: the Rattler test and the transverse bend test.

Iron powders are the most widely used powder metallurgy (P/M) material for structural parts. This article reviews low to medium density iron and low-alloy steel parts produced by the pressing and sintering technology. It explains different powder production methods, including Hoeganaes process, Pyron process, atomization of liquid metal, thermal decomposition and the electrodeposition process for carbonyl and electrolytic iron powders. It describes the types of compaction and sintering, explaining their effects of processing with designations. Further, the article deals with the mechanical and physical properties of ferrous P/M materials, which may depend on certain factors, namely microstructure, porosity, density, infiltration, re-pressing, chemical composition, and heat treatment.

Powder metallurgy (PM) processes include press and sinter hardening, metal injection molding, powder forging, hot isostatic pressing, powder rolling, and spray forming. This article provides an overview of PM processing methods and general considerations of heat treatment of PM parts that are case-hardened to obtain higher hardness, wear, fatigue, and impact properties. It describes the effects of porosity on heat treatment, alloy content on PM hardenability, and starting material on homogenization of PM steels. The article describes the properties, following heat treatment, of low-alloy steels tempered at 175 ºC for one hour, and lists recommended quench and temper parameters to achieve good wear resistance and core strength based on different ranges of porosity.

This article reviews various segments of the powder metallurgy (PM) process from powder production and powder processing through the characterization of the materials and their properties. It covers the processing methods for consolidating metal powders including options for processing to full density. The article outlines the freeform fabrication process, also known as additive manufacturing and describes finishing operations of PM parts. It concludes with information on the applications of PM parts.

This article begins with a discussion on general powder metallurgy design considerations that assist in the selection of the appropriate processing method. It reviews powder processing techniques, conventional press-and-sinter methods, and full-density processes to understand the design restrictions of each powder processing method. The article provides comparison of powder processing methods based on their similarities, differences, advantages, and disadvantages. It concludes with a discussion on design issues for the components of powder processing technologies.

Machinability is more important in extending the applications of powder metallurgy (PM). This article provides an overview of the machining process and machinability measurement of PM steels. It discusses various approaches to improve machinability, including the closure of porosity, green machining, presintering, microcleanliness improvement, free-machining additives, microstructure modification, and improvements in tool materials. The effects of free-machining agents on machinability and the sintered properties of PM steels are also reviewed.

Powder metallurgy (PM) has been called a lost art. Long before furnaces were developed that could approach the melting point of metal, PM principles were used. This article provides an overview of the major historical developments of various methods of platinum powder production. The development of production methods took place in various phases starting from prehistoric time, post-war period, to recent and commercial period. The article discusses the powder metallurgy of platinum, as well as the commercial and post-war developments of PM. Literature and trade associations are also discussed.

This article focuses on the significant fundamental powder characteristics, which include particle size, particle size distribution, particle shape, and powder purity, followed by an overview of general and individual powder production processes such as mechanical, chemical, electrochemical, atomizing, oxide reduction, and thermal decomposition processes. It also covers the consolidation of powders by pressing and sintering, as well as by high density methods. Further emphasis is provided on the distinguishing features of powders, their manufacturing processes, compacting processes, and consolidated part properties. In addition, a glossary of powder metallurgy terms is included.

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).

The two most important classes of materials that are manufactured via infiltration methods are copper- and silver-infiltrated refractory metals and refractory carbides, and copper-infiltrated steels. This article focuses on copper-infiltrated steels and discusses the basic requirements for infiltration, which is a technique that is only applicable to material systems that meet certain requirements. It addresses these requirements and describes the conventional (partial) infiltration process of powder metallurgy (PM) steel. The materials used in the process, such as matrix and infiltrant, are discussed. The article also details several criteria used to evaluate the performance of an infiltration process. It concludes with information on alloy steels and fully infiltrated steels.

Powder metallurgy compacting presses usually are mechanically or hydraulically driven, but they can incorporate a combination of mechanically, hydraulically, and pneumatically driven systems. This article provides a comparison of mechanical and hydraulic presses based on the cost, production rate, and machine overload protection. The article lists the classification of powder metallurgy parts based on complexity of shapes as suggested by the Metal Powder Industries Federation, such as Class I parts, Class II parts, Class III parts, and Class IV parts. It describes rigid tooling compaction and details the powder-fill ratio considerations for these classes. The article elaborates on the types of tooling systems and presses used for these classes. Some important factors and components used in designing a tool are also described. Finally, the article considers tool materials, including punches, core rods, and punch clamp rings.

The potential for introducing defects during processing becomes greater as the relative density of pressed and sintered powder metallurgy (PM) parts increases and more multilevel parts with complex geometric shapes are produced. This article discusses the potential defects in pressed and sintered PM parts: density variations, compaction and ejection cracks, microlaminations, poor degree of sintering, and voids from prior lubricant agglomerates. It describes the various methods applicable to green compacts: direct-current resistivity testing, radiographic techniques, computed tomography, and gamma-ray density determination. The article also discusses the methods for automated nondestructive testing of pressed and sintered PM parts: acoustic methods-resonance testing, eddy current testing, magnetic bridge comparator testing, ultrasonic techniques, radiographic techniques, gamma-ray density determination, and visual inspection.

Automated tape laying is a mature process used in both commercial and military aircraft applications. This article provides a brief history of the process and describes the use of commercially available flat and contour tape-laying equipment. It discusses the advantages and disadvantages of the tape laying. The article describes the various components of a ten-axis gantry-type tape laying machine and the tape laying process. It provides a discussion on typical material types and forms for tape laying and provides information on design guidelines for tape laying.

This article summarizes the general classification, mechanical properties, and applications of ferrous powder metallurgy (PM) materials for parts production. It discusses four principal ferrous PM alloy types: admixed elemental alloys, diffusion alloys, prealloys, and hybrid alloys. The article reviews the benefits and disadvantages as well as the effect of processing on the properties and material microstructure of these alloys. It contains tables that list the mechanical properties of various iron-copper and copper steels.

Beryllium is a metal with an unusual combination of physical and mechanical properties that make it particularly effective in optical components, precision instruments, and specialized aerospace applications. Almost all of the beryllium in use is a powder metallurgy (P/M) product. Beginning with an overview of the mining and refining processes of beryllium, this article discusses powder production and consolidation methods, beryllium grades and their designations, and the protective measures that have been enacted to reduce exposure to beryllium.

This article focuses on heat treatment of malleable and compacted-graphite irons to produce ferritic and pearlitic malleable irons. It describes the heat treatment cycles of malleable iron, including martempering, tempering, bainitic heat treatment, and surface hardening. The article provides information on the mechanical and physical properties of compacted-graphite irons, which are determined by the graphite shape and the pearlite/ferrite ratio.