CLASSIFICATION OF CASTINGS
Castings are classified into steel castings, cast iron castings, cast copper castings, cast aluminum castings, cast magnesium castings, cast zinc castings and cast titanium castings. Each type of casting can be further divided into different types according to its chemical composition or metallographic structure. For example, cast iron can be divided into gray cast iron, nodular cast iron, vermicular cast iron, malleable cast iron, alloy cast iron, etc.
According to different casting methods, castings can be divided into ordinary sand casting, metal casting, die-casting, centrifugal casting, continuous casting, investment casting, ceramic casting, electroslag recasting casting, bimetallic casting, etc. Among them, ordinary sand casting is the most widely used, accounting for about 80% of the total casting output. And aluminum, magnesium, zinc and other non-ferrous metal castings, mostly die casting.
Castings are metal molding objects obtained by various casting methods, that is, molten liquid metal is injected into prepared casting molds by pouring, injection, suction or other casting methods, and the objects with certain shapes, sizes and properties are obtained after cooling and polishing.
THE INVESTMENT CASTING
In the investment casting process, a wax pattern is coated with a ceramic material, which, when hardened, adopts the internal geometry of the desired casting. In most cases, multiple parts are cast together for efficiency by attaching individual wax patterns to a central wax stick called a sprue. The wax is melted out of the pattern – which is why it is also known as the lost wax process – and molten metal is poured into the cavity. When the metal solidifies, the ceramic mold is broken off, leaving the near net shape of the desired part. Finishing, testing and packaging complete the process.
1.Tooling and Pattern Making – A tool is built to customer-provided specifications. Cold wax is then injected into the tool to create a wax pattern/prototype that will hold precise dimensional requirements in the final casting.
2.Pattern Assembly – Individual wax patterns are attached to the sprue.
3.Dipping and Coating – Successive layers of ceramic and stucco are applied to form a hard shell.
4.De-Waxing and Firing – The molds are flash-fired to remove the wax and sprue materials and then heated to 1,800º and placed on a sand bed, ready for pouring.
5.Casting – Molten metal is poured into the hollow mold and then cooled.
6.Knockout – The ceramic shell is broken off, and the individual castings are cut away.
7.Finishing – Excess metal is removed, surfaces are polished and castings are heat treated.
8.Testing and Inspection – Castings undergo high-tech testing and inspection to ensure that they meet dimensional tolerances and specifications.
9.Packing and Shipping – Castings are securely packaged for shipping to the customer.
Investment casting is an excellent process for producing an extensive array of parts and items, from industrial components to consumer products such as jewelry. Examples of investment casting have been found from over 5,000 years ago in Egypt and China. Among the key advantages of this process is that it produces near-net-shape castings, which require little machining and finishing compared to other processes. It can also produce intricate, complex parts with high levels of precision, consistency and reliability. Huiyuhaoye utilizes the investment casting process to produce a wide range of industrial and commercial parts up to 250 pounds. We employ a broad range of specialized alloys in addition to steel and aluminum to produce a near-endless variety of castings for many industries and applications.
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