Powder metallurgy 334 - this contains solution manual PDF

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Powder Metallurgy Powder Metallurgy is a continually and rapidly evolving technology embracing most metallic and alloy materials, and a wide variety of shapes. PM is a highly developed method of manufacturing reliable ferrous and non ferrous parts. Created by mixing elemental or alloy powders and compacting the mixture in a die, the resultant shapes are then heated or "sintered" in a controlled atmosphere furnace to bond the particles metallurgically. The high precision forming capability of PM generates components with near net shape, intricate features and good dimensional precision pieces are often finished without the need of machining. The PM process begins with thorough blending of carefully weighed powdered metals or alloys to produce uniform distribution of the particles. Typical metal powders include bronze, brass, nickel, silver, iron-nickel and various grades of stainless. The resultant blends may include specified quantities of die lubricants, graphite, and other additives. The second and probably most important stage of productions is the compacting or pressing stage. Predetermined amounts of blended powder are fed into die cavities and compacted into the desired shape, size and density. This “green compact” is pressed at room temperature with pressures ranging as low as 12 tons per square inch to as high as 40 tons per square inch, with production presses ranging from 5-100 tons. At this stage the parts have sufficient green strength for in-house transport and handling prior to the sintering operation.

Sintering takes place in a continuous belt-driven controlled atmosphere furnace at a temperature below the melting point of the primary metal constituent used. The sintering process bonds the powder particles together metallurgically by atomic transfer. Additionally, it evacuates the fillers and lubricants creating an increase of part strength along with a specific porosity level. Depending on the metal used and tailored density, tensile strength can range from 8,000 psi to 180,000 psi after sintering. Generally agreed among researchers that the primary driving force for sintering is reduction of surface energy. Part shrinkage occurs during sintering due to pore size reduction.

What are its capabilities? The PM process is capable of producing several hundred to many thousand parts per hour with close dimensional tolerances maintained part to part. PM provides for controlled permeability and allows for the use of inventive composites with unique properties. There is great versatility with a wide latitude of part shape and design along with extensive material flexibility. To summarize, the PM process provides close dimensional tolerance, minimal machining, good surface finish, and excellent part-to-part reproducibility from moderate to high volume part production. Powder metal parts have controlled porosity, enabling them to self-lubricate and filter gases and liquids. For that reason, powder metallurgy is a highly recommended process in fabricating parts that require intricate bends, depressions, and projections.

Common Powder Compacting Techniques 

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Pressing: The function principles of the mechanic press machines differ in how to ensure the upper punch main movement by cams, spindles and friction drives, eccentric, knuckle-joints or by the round table principle, independent if the die or lower punch movement is realized by cams or eccentric systems or other mechanically or hydraulically combined systems. The executions of auxiliary movements are also not decisive for a term-classification. These auxiliary movements can also base on pneumatic and hydraulic principles. In comparison to hydraulic press machines the maximum compaction forces of mechanical powder presses are limited and are placed in the range...