Brass casting is actually an earlier metal thermal processing technology. The brass casting process has a history of about 6000 years. The definition of brass casting process: refers to the processing method in which solid brass is melted into liquid brass and poured into a mold of a specific shape, and then solidified and formed. In addition to casting brass, copper, iron, aluminum, tin, lead, etc. can also be cast. Ordinary casting materials are raw sand, clay, water glass, resin and other auxiliary materials. Special casting molds include: investment casting, lost foam casting, metal mold casting, ceramic mold casting, etc. (Raw sand includes: quartz sand, magnesia sand, zircon sand, chromite sand, forsterite sand, cyanite sand, graphite sand, iron sand, etc.).
The minimum temperature required for the brass casting process: Generally speaking, it is 960 degrees, which is about to crystallize. Generally, at least 980 is used, which is the lowest casting temperature. This is high-zinc brass, and low-zinc brass is even higher.
The advantages of brass casting process: low manufacturing cost, large process flexibility, complex shapes and large castings can be obtained, and occupy a large proportion in mechanical manufacturing, such as machine tools accounting for 60 to 80%, automobiles accounting for 25%, and tractors accounting for 25%. 50～60%.
Commonly used brass casting methods: There are generally three brass casting methods, which have been proven to be suitable for brass casting. Metal casters can choose to use different methods for testing, and should not let themselves be restricted.
1. Lost wax casting:
Usually bronze casting with lost wax casting, but can also be used for brass and really used for any other metal. By using wax molds, covered with ceramic shells, craftsmen can inject molten alloy to replace wax. The shell of a small mess will reveal the brass pieces. Lost wax casting requires a high degree of attention to detail when used. Artists or metal casters who create decorative copper pieces or sculptures will find that the lost wax casting technique will meet their needs far better than other techniques and methods.
2. Die casting casting:
Die-cast brass casting uses another method. Die casting is usually used in commercial foundries, because the initial start-up cost is small and the foundry is poor. By creating a reusable mold, made from steel, the caster will be able to create products with the same score. If the caster or artist is planning to make a product that is a multiple that can be found in a viable market, that mold made of brass should be used.
3. Sand casting:
Sand casting is probably the oldest casting, and is still a commonly used method, especially for small foundries. The brass is poured into a sand mold to create a unique appearance, which may be the first choice of craftsmen. Sand casting is often the most economically wise small foundry. If the casting is not incredibly attractive, then this method is many desirable.
The brass casting process usually includes:
1. Preparation of casting molds (containers that make liquid metal into solid castings). The casting molds can be divided into sand, metal, ceramic, clay, graphite, etc. according to the materials used, and can be divided into disposable and semi-permanent according to the number of times of use. Mold and permanent mold, the pros and cons of mold preparation are the main factors affecting the quality of castings;
2. Melting and pouring of cast metals, cast metals (casting alloys) mainly include various types of cast iron, cast steel, and cast non-ferrous metals and alloys;
3. Casting processing and inspection. Casting processing includes removing foreign bodies on the core and surface of castings, removing pouring risers, shoveling burrs and drape seams and other protrusions, as well as heat treatment, shaping, anti-rust treatment and rough machining.
The casting process can be divided into three basic parts, namely casting metal preparation, mold preparation and casting processing. Casting metal refers to the metal material used for casting castings in the production of casting. It is an alloy composed of a metal element as the main component and added with other metals or non-metal elements. It is customarily called a casting alloy, mainly including cast iron, Cast steel and cast non-ferrous alloys.
How to increase the hardness of brass casting:
Add trace amounts of cobalt (0.2%, 0.4%, 0.6%) to aluminum brass (72.5Cu-22.7Zn-3.4Al), study the effects of trace cobalt, smelting and casting technology and processing parameters on the mechanical properties of strips produced by rolling Performance impact. Explore the use of aluminum brass to replace the currently widely used elastic copper alloy materials. The results of the feasibility study of tin phosphor bronze show that: cobalt can effectively reduce the grain size of the as-cast alloy, change the shape of the grain, improve the tensile strength and hardness of the alloy, and ensure that the alloy has good ductility. Aluminum brass 0.4% cobalt is added to it. The brass strip produced by reasonable processing technology has better performance than tin phosphor bronze. The 0.25mm thick strip has a tensile strength of 840.4MPa and an elongation of 2.8%; the Vickers hardness value is 228 The maximum tensile strength (805MPa) of the QSn6.5-0.1 strip in the bit hard state is increased by 4.4%, which meets the requirements of the use of elastic elements; at the same time, because the brass contains 22.7% of zinc, it can effectively reduce the cost. Has practical application value.
