Discussion in 'Metal casting & moulding' started by parneetsinha, May 6, 2014.
Which products are manufactured by gravity casting process?
Also known as permanent mold casting
Gravity casing or permanent old casting is used typically for low temp alloys, such as aluminum or brass, where wall thicknesses are too thick for die casting. Look up permanent mold casting.
There is a form of die casting called Gravity Die Casting, which is a low-pressure system and generally requires thicker walls than can be achieved with High Pressure Die Casting.
Many die casting suppliers offer both systems. Tooling for gravity is less complex and therefore less costly, so it is more suited to lower volume production.
As long as the thicker walls can be accommodated by the design, the part cost is acceptable and the production volume matches up, there isn't much reason why all kinds of product cannot be manufactured by the gravity die cast process.
Short Answer â€“ almost anything (Car parts, pump housings, brackets, knobs, commercial and industrial tool parts, furniture, appliance components, etc.) An easier question to answer would be what cannot be produced using gravity casting. Steel and Aluminum are common tilt poor materials.
Longer Answer -
As for casting processes there are two basic methods of casting: 1). Tilt /pour (which is your gravity casting), and 2). Centrifuge casting.
Tilt Pour â€“ is the process where metal is melted (the melt) in a crucible and then tipped over and dumped into the mold. The mold and its venting method are oriented so that gravity does all the work of filling the mold and pushing out the air as the liquid metal fills the cavity. Tilt pour can be done by hand - which method has been around for thousands of years. Babylonian coins were poured onto open face molds, or the metal was puddled and then worked after the pour.
Today Tilt pour is commonly performed with machines to provide a safer environment for the casting personnel.
Centrifuge â€“ involves simultaneously spinning the mold like a top, or Ferris wheel, as the metal is poured into the mold. This shortens the time it takes for the mold to fill due to the added pressure of the spinning action. If the mass of what is being poured is of any significance the cost of the pour may be more than for the traditional tilt pour method due to the increased complexity of the machine and power requirements to spin the mass fast enough to make a difference in the fill time.
There is no limit to what products can be manufactured with this casting process.
Reactive metals include Titanium, Magnesium, and a number of exotic alloys.
Limits on tilt pour have more to do with the type of metal you want to melt and the intricacy of the parts you desire to make. Reactive metals (or molten metals which oxidize, or burn, when exposed to regular air) require an inert environment to be cast in â€“ either an argon atmosphere or a partial vacuum. Components with intricate details or very thin walls such as jewelry or pump blades, or melting metals that have higher melt point temperatures, may require the metal to be forced into the mold faster so that the mold cavity is filled before the metal solidifies. This is when the centrifuge method may be preferred. Because medical and aerospace parts tend to both use reactive metals and more intricate parts - these two industries use the centrifuge process more so than tradition iron based industrial components.
I would add a couple of more features of gravity or permanent mold casting.
The mold used to make the casting is metal. Cooling rates are very high. Thin walls and fine details are difficult due to surface tension of the alloy and the relatively low pressure of the metal feed.
Permanent mold casting is also used to make products of maleable iron. This is most commonly seen in C clamps. The process involves pouring iron into a metal mold. The high cooling rate causes the iron to chill into white iron. This is cast iron where the carbon does not have time to come out of solution and the material is very brittle martensite with no graphite. The white cast iron is then heat treated and the graphite comes out of solution in globs of graphite separated by metallic iron. The resulting part is ductile and closely resembles the properties of ductile iron. Handles and levers were also made of maleable iron.
Aluminum, plastics products also manufactured by gravity casting process
some of the components manufactured by gravity castings are Aluminum, brass, Automobile components, general engineering components etc.,
Hii to all,
I want to ask how work on products which are manufactured by gravity casting..I have no more knowledge about it.. I think it is the
process with pouring of liquid or molten metal for making the product ..
The terms low-pressure die casting and gravity die casting are terms used outside the U.S. for what in the U.S. is called low pressure permanent mold and gravity permanent mold casting. Although they each use metal dies, because of the lower pressures involved they are restricted to heavier section parts, often resulting in higher cost because of the less efficient use of the alloys involved and the slower processing time. They also require a sprayed-on protective coating on the die cavities, which means looser tolerances and rougher surface finishes.
Примеры гравитационного литья. Металл течет под действием силы тяжести. Нет газ или поршень давление. В результате художественно-декоративная или отливки технические металлические
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