Metals casting

The industrial value of furfuryl alcohol is a consequence of its low viscosity, high reactivity, and the outstanding chemical, mechanical, and thermal properties of its polymers, corrosion resistance, nonburning, low smoke emission, and exceUent char formation. The reactivity profile of furfuryl alcohol and resins is such that final curing can take place at ambient temperature with strong acids or at elevated temperature with latent acids. Major markets for furfuryl alcohol resins include the production of cores and molds for casting metals, corrosion-resistant fiber-reinforced plastics (FRPs), binders for refractories and corrosion-resistant cements and mortars. 

Letterpress is printed directly by the rehef method from cast metal or plates on which the image or printing areas are raised above the nonprinting areas. Ink rollers apply ink to the surface of the raised areas, which transfer it directly to paper. Flat-bed cylinder presses are available but most letterpress is printed on rotary presses. 

Electrical conductivity is comparatively easy to measure, whereas thermal conductivity is not. Electrical conductivity values for the important cast alloys are Hsted in Table 2. Eigure 1 schematically shows the electrical conductivity of cast copper-base alloys compared with various other cast metals and alloys. The equation Y = 4.184 + 3.93a gives an approximation of thermal conductivity in relation to electrical conductivity, where Tis in W/(m-K) at 20°C and X is the % lACS at 20°C. 

Ductility Tests. The ductihty of plated metals differs considerably from the corresponding thermally cast metals. Additionally, ductihty which is an important property if parts are to be deformed after plating, varies with the chemical composition of the plating solution, as well as the operating conditions of a given plating process. Ductihty can also be important when plated parts are stressed in use. Some metal deposits have coefficients of... 

Recently, dry wire-pipe ESPs are being cleaned acoustically with sonic horns (Flynn, 1999). The horns, typically cast metal horn bells, are usually powered by compressed air, and acoustic vibration is introduced by a vibrating metal plate that periodically interrupts the airflow (AWMA, 1992). As with a rapping system, the collected particulate slides downward into the hopper. The hopper is evacuated periodically, as it becomes full. Dust is removed through a valve into a dust-handling system, such as a pneumatic conveyor, and is then disposed of in an appropriate marmer. 

Guss-beton, m. cast (or poured) concrete, -blase, /. flaw in a casting, blowhole, -blei, n. cast lead, -block, m. ingot, -bruch, m. broken castings, cast-metal scrap specif., cast-iron scrap. 

Typical marine propellers are fixed pitch and small in diameter with veiy thin, but broad, blade sections. They are made from either cast metal, corrosion-resistant metal alloys such as copper, or composite materials. Marine propellers normally operate at 60 percent efficiency due to the proximity of the ship s hull, which limits the overall diameter of the propeller and disturbs the efficient flow of water through the blades. As a result, the blades have to be veiy wide to produce adequate thrust. Marine propeller designers use innovations such as overlapping blades and wheel vanes to offset those problems and improve efficiency. 

A vaneaxial fan consists of an axial flow wheel within a cylinder combined with a set of air guide vanes located either before or after the wheel. The vaneaxial fan is designed to move air or gases over a wide range of volumes and pressures. It is generally constructed of sheet metal, although cast metal fan wheels are sometimes furnished. 

Thermal conductivity can be as low as one-eighth that of solid metal in the case of steel 7 W/m°C. The electrical resistance (specific) of copper, zinc and silver is about twice that of the cast metal, and of aluminium as much as five times, depending on spraying conditions. Adhesion in tension should... 

Conventional machining operations are used preferably from the same plastic to be used in the product (Chapter 8, SECONDARY EQUIPMENT). Different casting techniques are used that provide low cost even though they are usually labor intensive. The casting of unfilled or filled/reinforced plastic used include TS polyurethane, epoxy, structural foam, and RTV silicone. Also used are die cast metals. 

With only a few noticeable exceptions, metals and their alloys possess a distinct shape. To generate the principal shape, metals are said to be wrought or cast. Wrought metals receive their shape through deformation steps cast metals receive their shape through solidification steps. Materials of construction are available in both wrought and cast forms. Each group is discussed separately. 

Table 4.4 presents wastewater flow characterization for the foundry industry by casting metals. Also presented in this table is the level of process water recycle, and the number of plants surveyed with central wastewater treatment facilities for all of the processes at that plant. The discharge flow represents all processes within the specific metal casting facilities. 

Many toxic pollutants were detected in the process wastewaters from metal molding and casting processes. The toxic pollutants detected most frequently in concentrations at or above 0.1 mg/L were phenolic compounds and heavy metals. The pollutants include 2,4,6-trichlorophenol, 2,4-dimethyl-phenol, phenol, 2-ethylhexyl, cadmium, chromium, copper, lead, nickel, and zinc. Each type of operation in the foundry industry can produce different types of pollutants in the wastewater stream. Also, because each subcategory operation often involves different processes, pollutant concentrations per casting metals may vary. 

Hollow sand casting is a relatively simple process for making cast metal objects that for thousands of years was the most widely used of all casting methods. For the most basic castings, the molds are made from ordinary silica sand mixed with water so as to keep the sand particles compacted together to maintain the required hollow-shaped form. The hot, fluid... 

Metal Casting Techniques. Many ancient cast metal objects were made by the cire perdue (lost wax) casting process, which involves pouring molten metal into a one-piece mold and letting it solidify modem fakes are usually cast in two halves that are then joined. A casting fin, or a fine line of filed solder on a cast object, usually reveals that the casting is modem. 

Gerin, J. (1972), Cast Metals Technology, Addison-Wesley, New York. 

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