Author Archives: lzladmin

NDT for Castings

What is the NDT? Nondestructive testing – NDT – use test methods to examine an object, material or system without impairing its future usefulness. Non-destructive testing is often required to verify the quality of a product or a system. Commonly used techniques are AET – Acoustic Emission Testing ART – Acoustic Resonance Testing ET – […]

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Thermal Treatment

Special mechanical properties are obtained in many alloys through accurate control of chemistry, manufacturing and heat treating. Reliable ingot producers can supply foundries with ingot and heat treating specifications designed to obtain specific mechanical properties. However, while certain mechanical properties are improved, it is at the expense of others. For example, tensile and yield strengths […]

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Alloys A380.0 and B380.0

These alloys are used for casting general purpose die castings. They have good mechanical properties and are used to make housings for lawn mowers and radio transmitters, air brake castings, gear cases and air-cooled cylinder heads. Castability—Fluidity, pressure tightness and resistance to hot cracking all are good. Machinability-Although the machinability of A380.0 and B380.0 is considered good, carbide-tripped tooling is recommended because of the alloy’s […]

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Alloy 356.0 and A356.0

Alloy 356.0 has excellent casting characteristics and has largely replaced alloy 295.0. Permanent mold castings of this alloy are used for machine tool parts, aircraft wheels and hand wheels, pump parts, tank car fittings, marine hardware, valve bodies and bridge railing parts, as well as for aileron control sectors, rudder control supports, fuselage fittings and […]

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Alloy Designations

Aluminum casting alloys in the U.S. are numbered according to a three-digit (plus decimal) system adopted by the Aluminum Assn. (AA) in 1954 and approved by the American National Standards Institute in 1957 (ANSI H35.1). The American Society for Testing and Materials (ASTM), the Society of Automotive Engineers (SAE), and the Federal and Military specifications […]

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Permanent Mold

What is the Permanent Mold? Here, the two halves of the mold are made of metal, usually cast iron, steel, or refractory alloys. The cavity, including the runners and gating system are machined into the mold halves. For hollow parts, either permanent cores (made of metal) or sandbonded ones may be used, depending on whether the core can be extracted from the part without damage after casting. The surface of the mold is coated with clay or other hard refractory material – this improves the life of the mold. Before molding, the surface is covered with a spray of graphite or silica, which acts as a lubricant. This has two purposes– it improves the flow of the liquid metal, and it allows the cast part to be withdrawn from the mold more easily. The process can be automated, and therefore yields high throughput rates. Also, it produces very good tolerance and surface finish. It is commonly used for producing pistons used in car engines, gear blanks, cylinder heads, and other parts made of low melting point metals, e.g. copper, bronze, aluminum, magnesium, etc.

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aluminumcasting-china

WHY CASTING?   Metal casting process begins by creating a mold, which is the ‘reverse’ shape of the part we need. The mold is made  from a refractory  material, for example, sand. The metal is heated in an oven until it melts, and the molten metal is  poured into the mould cavity. The liquid takes the shape of cavity, which is the shape of the part. It is cooled until it solidifies. Finally, the solidified metal part is removed from the mould. A large number of metal components in designs we use every day are made by casting. The reasons for this include: (a) Casting can produce very complex geometry parts with internal cavities and hollow sections. (b) It can be used to make small (few hundred grams) to very large size parts (thousands of kilograms) (c) It is economical, with very little wastage: the extra metal in each casting is re-melted and re-used (d) Cast metal is isotropic – it has the same physical/mechanical properties along any direction.

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