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These properties make it a useful alloy for castings required aboard ship. It is often used in valves and steam fittings. It can be used in place of Composition G if its lower strength is adequate.
It is a general-purpose alloy having good corrosion resistance. Castings subjected to hydraulic pressures up to pounds can be made from this alloy. Typical uses are in propeller hubs, propeller blades, engine framing, gun-mount castings, marine-engine pumps, valves, gears, and worm wheels.
Manganese bronze has an excellent combination of corrosion resistance, strength, and ductility that makes it very useful for the various marine castings. It has the disadvantage of having a high solidification shrinkage and a comparatively high drossing tendency.
These disadvantages, however, can be overcome by proper design and casting procedures. It is a general-purpose alloy used for fittings, name plates, and similar applications. Naval brass is a yellow brass which has a higher corrosion resistance than commercial yellow brass. Higher strength and hardness can be obtained in some of the alloys by proper heat treatment.
Typical uses are for worm gears, bearing sleeves, pinions, and propeller blades. Fittings such as couplings, tees, ells, pump bodies, and valve bodies are cast from this alloy. It has a pleasing white color that makes it useful where the appearance of the cast part is important.
A long solidification range means that an alloy solidifies slowly over a wide range of temperature. Ordinary solder is such an alloy, and solidification over a long range is shown by the fact that the alloy remains mushy for quite a while during solidification. Alloys with short solidification ranges do not show this mushy behavior.
Manganese bronze, aluminum bronze, and the yellow brasses have a short solidification range, which cause their high solidification shrinkage. Composition G, Composition M, and hydraulic bronze have a long solidification range, which permits extensive growth of the dendrites. These alloys have a tendency toward interdendritic shrinkage and microporosity, with the result that piping in the riser is not so pronounced.
Solidification of all the alloys begins at the mold and core surfaces. The part of the alloy having the highest solidification temperature the copper-rich material solidifies first and a crystalline structure is formed.
This is the exterior shell of the casting. As the molten metal continues to cool, the parts of the alloy with the lower freezing temperature will crystallize on the already-growing dendrites. This process continues until the metal is completely solid. The center of the dendrite first part to solidify will have a composition corresponding to the high-freezing part of the alloy, while the outer parts of the dendrite will have a composition corresponding to the last part of the alloy to solidify.
Any lead or other insoluble material in the alloy will be trapped between the dendrites. Failure to properly feed alloys having a long solidification range results in micro-porosity and leakage under pressure. Flat-back patterns are preferred. As has been mentioned in Chapter 4, "Sands for Molds and Cores," the best properties for any sand mixture can only be obtained through proper mixing by the use of the sand muller.
Also, the maintenance of properties of a sand mixture can be accomplished only through continuous and correct sand-testing procedures. Most copper-base alloys will be cast in the all-purpose sand described in chapter 4. When time and materials are available, better results will be obtained by using the following recommended sand mixtures.
Compositions G and M. Sand used for these alloys should have properties within the following limits, depending on the size of the casting. The table of properties given below for hydraulic bronze can also be used as a guide for Compositions G and M.
For some types of work, a molasses water spray for the mold surface may be used. Facing sands are not generally used, but for heavy castings a plumbago coating may be used. Sand properties for castings of various weights and section thickness are given below: To overcome this condition, the sand should be worked with moisture content on the low side.
This is a good general rule to follow when casting any alloy, because water is almost always harmful to any alloy. Because of the high strength of manganese bronze, strong cores may be used with this alloy without causing excessive strains in the casting.
A graphite core wash may be used to make core removal from the casting easier. A sand having a permeability of 20, green strength of 7 p. Aluminum bronze alloys are difficult to cast in green sand molds because of the high drossing tendency of the alloys and the possibility of surface pinholes and porosity in the finished castings.
The defects caused by high moisture in the green sand molds can be minimized by using dry sand molds. It is recommended that dry sand molds be used as described in chapter 4. Property ranges for sand mixtures are as follows:. Cupro-Nickel and Nickel Silver. The cupro-nickel alloys and the nickel silver alloys should have a sand with a permeability between 40 and 60 and a moisture content between 4. The sand grain size should be about 95 Fineness Number, with an 18 percent clay content.
Nickel silvers are sensitive to gas from organic binders. Such binders, therefore, should not be used. Certain procedures are repeated here to stress their importance to copper-base alloy castings.
Cores used in making copper-base alloy castings should be strong and well vented. Care must be taken, however, not to make the cores too hard or hot cracks and tears will result. Refer to Chapter 4, "Sands for Molds and Cores," for representative core mixes, and to Chapter 6, "Making Cores," for coremaking techniques. Good molding practice as described in Chapter 5, "Making Molds," is the principal requirement when making molds for copper-base alloy castings. Extra precautions should be taken to ram the molds as uniformly as possible.
Uneven ramming will cause localized hard spots and agitation of the molten metal at these points because of nonuniform permeability. In high-zinc alloys, this will cause zinc to boil out and produce rough surfaces at the areas of agitation. Alloys containing aluminum will form dross at these areas and the castings will be dirty. Washes for copper-base alloy castings are used primarily to prevent metal penetration.
The wash most generally used in plumbago. Molasses water is sometimes sprayed on the mold surface to provide a stronger bond in the surface sand. A typical molasses-water mix contains one part of molasses thoroughly mixed with 15 parts of water. Because these two alloys are tin bronzes and subject to interdendritic shrinkage, the gating system should be designed to make maximum use of directional solidification.
Heavy bushings, or "billets," can be cast by two methods to obtain directional solidification. They can be molded horizontally, as shown in figure , by using a thin gate to provide a choking action and causing the metal to enter the mold quietly. The mold should be tilted with the riser end lower during pouring to provide an uphill filling of the mold. The mold is then tilted with the riser up to provide maximum gravity feeding. A second method of gating bushings is to use a circular runner with pencil gates.
This method, if used with a pouring temperature on the low side, will provide the best conditions for directional solidification. A third method may be used, which utilizes a tangential gate as shown in figure This method permits the metal to enter the mold with the least amount of agitation, but is not so good for directional solidification of the metal.
The runner is placed in the cope, and a reduction of at least 20 percent in cross-sectional area from the sprue to runner to gate is used. Manganese bronze castings can be gated successfully by using a reverse horn gate into the riser and gating from the riser into the casting is illustrated in figure When a number of small castings of manganese bronze or red brass are made in the same mold and gated from the same sprue and runner system, a gating system such as shown in figure can be used.
The runner is placed in the cope and the ingates in the drag. The castings are gated through small blind riser s. The dimensions indicated for the runner and ingates show the range in sizes that can be used and depend on the size of the castings.
Agate with a large cross section as shown in figure is used for thin castings made in nickel silver. This is a plate cast in nickel silver. Notice the many ingates to permit rapid filling of the mold and also the large size of the runner.
The gating system should also give uniform distribution of the metal in the mold. A gating system which resulted in a defective cupro-nickel check valve is shown in figure The improved method of gating that produced a pressure-tight casting is shown in figure Risers for these alloys will have to be made larger to obtain proper feeding. In connection with the risering of these alloys, it is only through experience and records of successful risering practice that correct risering procedures can be developed.
The correct placement of risers as well as the correct size is important. Good and bad risering practices are shown in figures , , , and Porosity in the casting caused low physical properties. A revised procedure is shown in figure Notice that risers were used on all of the flange sections.
This risering arrangement resulted in a casting with greatly improved physical properties because of the improved soundness. Similarly, the lack of risers on a high-pressure elbow, as shown in figure , resulted in microshrinkage in the flange section with low physical properties.
The revised risering system shown in figure resulted in improved physical properties in the casting. Risers for nickel silver and cupro-nickel alloys must be large to provide enough molten metal to feed heavy sections and to compensate for the high solidification shrinkage.
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Alloys of nickel and molybdenum may be added to the cold charge. Up to the time the charge is completely melted, the procedure is the same for both methods. They did, which you can sorta see here , and a little bit here , and a bit more here. The additions should compensate for any shortages in the desired analysis and any melting losses of zinc and lead. Stronger chilling action means that if two identical castings are made, one with a long solidification-range alloy and one with a short solidification-range alloy, the long solidification-range alloy will require larger chills or chills with higher heat capacity in order to obtain the same amount of directional solidification as the short solidification-range alloy.
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Supplemental tests using sensitive screening methods may be used in cattle in which the brucellosis status is unclear. Human Machine Interfaces Our signaling and display devices detect precisely the operating states at a glance. Refer to chapter 4, table 8 for typical molding sand mixes, and table 13 for typical core-sand mixes for steel castings. This can be done only through proper testing procedures. It is highly useful where a very hard material is needed to resist wear, but is more brittle than gray cast iron. For the most part, the purple helmets did look purple. The surface of the metal bath should be as free of slag as possible. We can expect the smartphone to get the upcoming Android Pie update soon after its stable release later this year. Because of this, the mold can be rammed lighter.
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These alloys are difficult to cast properly. After the flaring is finished, the melt should be skimmed. Degassing of aluminum can be accomplished with gaseous fluxes. Therefore, the atmosphere must not have too much excess air or the dross- formation and oxidation losses will be high. Occasionally, I will be featuring his work on Uni Watch. Machine-shop borings and turnings should not be used at all. At Balluff, this starts with training: As with all metals, the castings should be poured at the lowest temperature that will permit complete filling of the mold. Spindles, chucks, rotary and swivel tables. Additional goat info here. Aluminum is detrimental to red brass and sometimes causes lead sweat.