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Casting - Casting process simulation

Casting process simulation was initially developed at universities starting from the early '70s, mainly in Europe and in the U.S., and is regarded as the most important innovation in casting technology over the last 50 years. Since the late '80s, commercial programs (such as AutoCAST and MAGMA) are available which make it possible for foundries to gain new insight into what is happening inside the mold or die during the casting process.

Casting - Casting process simulation

Casting process simulation uses numerical methods to calculate cast component quality considering mold filling, solidification and cooling, and provides a quantitative prediction of casting mechanical properties, thermal stresses and distortion. Simulation accurately describes a cast component's quality up-front before production starts. The casting rigging can be designed with respect to the required component properties. This has benefits beyond a reduction in pre-production sampling, as the precise layout of the complete casting system also leads to energy, material, and tooling savings.

Casting - Casting process simulation

The software supports the user in component design, the determination of melting practice and casting methoding through to pattern and mold making, heat treatment, and finishing. This saves costs along the entire casting manufacturing route.

Casting (metalworking) - Sand casting

Sand casting requires a lead time of days, or even weeks sometimes, for production at high output rates (1–20 pieces/hr-mold) and is unsurpassed for large-part production. Green (moist) sand, which is black in color, has almost no part weight limit, whereas dry sand has a practical part mass limit of 2300 - 2700 kg. Minimum part weight ranges from 0.075 - 0.1 kg. The sand is bonded together using clays, chemical binders, or polymerized oils (such as motor oil). Sand can be recycled many times in most operations and requires little maintenance.

Casting defect - Sand casting

Sand casting has many defects that can occur due to the mold failing. The mold usually fails because of one of two reasons: the wrong material is used or it is improperly rammed.

Casting (fishing) - Casting techniques

Fly fishermen use artificial flies as a lure and use lighter rods and lines. They develop much finesse casting the flies, using motions of the hand and arm, so the flies land with great accuracy into or onto the water and mimic the behaviour of real flies.

Glass casting - Sand casting

Sand casting involves the use of hot molten glass poured directly into a preformed mould. It is a process similar to casting metal into a mould. The sand mould is typically prepared by using a mixture of clean sand and a small proportion of the water-absorbing clay bentonite. Bentonite acts as a binding material. In the process, a small amount of water is added to the sand-bentonite mixture and this is well mixed and sifted before addition to an open topped container. A template is prepared (typically made of wood, or a found object or even a body part such as a hand or fist) which is tightly pressed into the sand to make a clean impression. This impression then forms the mould.

Casting (metalworking) - Die casting

The die casting process forces molten metal under high pressure into mold cavities (which are machined into dies). Most die castings are made from nonferrous metals, specifically zinc, copper, and aluminium-based alloys, but ferrous metal die castings are possible. The die casting method is especially suited for applications where many small to medium-sized parts are needed with good detail, a fine surface quality and dimensional consistency.

Casting (metalworking) - Centrifugal casting

Industrially, the centrifugal casting of railway wheels was an early application of the method developed by the German industrial company Krupp and this capability enabled the rapid growth of the enterprise.

Casting (metalworking) - Sand casting

Sand casting is one of the most popular and simplest types of casting, and has been used for centuries. Sand casting allows for smaller batches than permanent mold casting and at a very reasonable cost. Not only does this method allow manufacturers to create products at a low cost, but there are other benefits to sand casting, such as very small-size operations. The process allows for castings small enough fit in the palm of one's hand to those large enough only for train beds (one casting can create the entire bed for one rail car). Sand casting also allows most metals to be cast depending on the type of sand used for the molds.

Casting defect - Continuous casting

A longitudinal facial crack is a specialized type of defect that only occurs in continuous casting processes. This defect is caused by uneven cooling, both primary cooling and secondary cooling, and includes molten steel qualities, such as the chemical composition being out of specification, cleanliness of the material, and homogeneity.

Tape casting - Slurry casting

During casting it is important to cast a perfectly flat surface without streaks, for this different casting mechanisms have been designed to minimise slip streams in the slurry. The blades that flatten and thin the cast surface are called doctor blades. These come in different shapes such as thick or thin flat cutting surfaces, rounded edges and knife blade-shaped edges. For tapes that are cast thinner than 50 micrometer, the coating is not applied from the top, but from the side (slot-die coater) or bottom (lip coater and micro gravure coater).

Tape casting - Slurry casting

The slip material is transported in pipes from tanks to the casting machine. The slip may be filtered before being applied, to remove imperfect particles. The cast slurry is called a green layer or green sheet (this is not referring to the colour of the sheet), and needs further processing such as cutting and drying.

Casting (metalworking) - Centrifugal casting

Centrifugal casting is both gravity- and pressure-independent since it creates its own force feed using a temporary sand mold held in a spinning chamber. Lead time varies with the application. Semi- and true-centrifugal processing permit 30–50 pieces/hr-mold to be produced, with a practical limit for batch processing of approximately 9000 kg total mass with a typical per-item limit of 2.3–4.5 kg.

Casting (metalworking) - Investment casting

Investment casting derives its name from the fact that the pattern is invested, or surrounded, with a refractory material. The wax patterns require extreme care for they are not strong enough to withstand forces encountered during the mold making. One advantage of investment casting is that the wax can be reused.

Glass casting - Kiln casting

Kiln casting involves the preparation of a mould which is often made of a mixture of plaster and refractory materials such as silica. A model can be made from any solid material, such as wax, wood, or metal, and after taking a cast of the model (a process called investment) the model is removed from the mould. One method of forming a mould is by the Cire perdue or "lost wax" method. Using this method, a model can be made from wax and after investment the wax can be steamed or burned away in a kiln, forming a cavity. The heat resistant mould is then placed in a kiln equipped with a funnel-like opening filled with solid glass granules or lumps. The kiln is heated to between 800 C and 1000 C, and as the glass melts it runs into and fills the mould.

Casting (metalworking) - Investment casting

The process is suitable for repeatable production of net shape components from a variety of different metals and high performance alloys. Although generally used for small castings, this process has been used to produce complete aircraft door frames, with steel castings of up to 300 kg and aluminium castings of up to 30 kg. Compared to other casting processes such as die casting or sand casting, it can be an expensive process. However, the components that can be produced using investment casting can incorporate intricate contours, and in most cases the components are cast near net shape, so require little or no rework once cast.

Casting (metalworking) - Continuous casting

Continuous casting is used due to the lower costs associated with continuous production of a standard product, and also increased quality of the final product. Metals such as steel, copper, aluminum and lead are continuously cast, with steel being the metal with the greatest tonnages cast using this method.

Casting (fishing) - Casting techniques

Salt water anglers usually use heavier rods and lines They often use lures and bait which are heavier than flies. Heavier again are the rods and lines used in surfcasting. Specialized, two-handed casting techniques are used to cast the lure or bait the added distances required in many cases to reach feeding inshore fish. In these casts the entire body, rather than just the arms, are utilized to deliver the cast, which may travel many hundreds of feet.

Casting defect - Sand casting

The first type is mold erosion, which is the wearing away of the mold as the liquid metal fills the mold. This type of defect usually only occurs in sand castings because most other casting processes have more robust molds. The castings produced have rough spots and excess material. The molding sand becomes incorporated into the casting metal and decreases the ductility, fatigue strength, and fracture toughness of the casting. This can be caused by a sand with too little strength or a pouring velocity that is too fast. The pouring velocity can be reduced by redesigning the gating system to use larger runners or multiple gates. A related source of defects are drops, in which part of the molding sand from the cope drops into the casting while it is still a liquid. This also occurs when the mold is not properly rammed.

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