Small Scale World

What is Gravity Casting and How is Gravity Casting Used

Die casting is the method used for forcing molten metal into mold cavities under high pressure. Die casting is very versatile and hence, is the widest used method for casting a metal. Die casting is same as permanent mold casting the only difference is that the metal is injected into the mould at very high pressure of 10-210 Mpa. This results in a more uniform part, usually good dimensional accuracy and also good surface finish.

The different metals and alloys that can be used in die casting are zinc, aluminum, copper, magnesium, tin and lead. Ferrous metals can also be used for die casting, die casting method is generally used for applications in which a large quantity is medium or small sized parts are required with detail, good dimension and fine surface finish.

There are namely two equipments used for die casting cold chamber and hot chamber process.

Cold Chamber process: In the cold chamber category of die casting, a cold chamber of each module is filled with molten metal. The time exposure provided for the molten metal to plunge the walls of the mold is less. This clod chamber process method is very useful for metals like aluminum, copper and metals that easily alloy with iron at high temperatures.

Hot Chamber process: In the hot chamber process method of die casting, the pressure that is connected to the die cavity is forever and permanently in molten metal. As the plunger moves towards the open position that is towards the non – pressurized area, the inlet port connected to the pressurizing cylinder is uncovered.

The die casting molds which are used in this method are expensive and take usually take long production time. These die casting modules are also called as “dies’

Advantages of Die Casting: The method of die casting gives excellent dimensional accuracy. The dimensional accuracy is as good as 0.1mm for the first 2.5cms and 0.005 for the first inch. Die casting also provides with smooth cast surfaces. Small and thin walls and can be made using the method of die casting walls as tiny as 0.75mm approximately can be casted. Inserts like thread insert, high strength bearing surfaces and heating elements can also be inserted using the Die Casting method. Die casting also helps in reducing or even completely eliminating the use of secondary machining operations. The use of Die Casting method also helps to reduce the production time and a huge number of articles can be produced in a very short time. Die casting method also helps to retain as well as increase the tensile strength of the metal. It offers tensile strength as high as 415 MPa that is 60ksi.

Disadvantages of Die Casting: The casting weight is very less hardly between 30 grams and 10 kgs. Also the size of the material that needs to be casted using the Die Casting method needs to small say around 600mm. the process of Die Casting requires high budget and can pile up high initial cost. Die Casting method makes the metal porous up to some extent. In the Die Casting method the thickest section needs to be less than 13mm or 0.5 inches.

Gravity Casting Information, Gravity Die Casting, and Gravity Casting Information

Metal Casting is more than just an excuse to play with molten metal it is actually a great way to create art and complicated pieces of machinery or other items that would otherwise be nearly impossible to make. Metal Casting is really a great way to save money…while playing with molten metal.

The reason that Metal Casting has survived the test of time is a matter or efficiency. Some of the earliest casting examples have been found in China dating back thousands and thousands of years. In fact every major civilization from the Egyptians to the Romans practiced metal casting. This skill came back into vogue during the Renaissance and has continued to advance and evolve from there. While Sand Casting is the most popular casting process there are many, many more processes available to the backyard foundries.

Not everyone is going to be casting heavy pieces like engine parts or cast their own motorcycles. So for those that just want to make decorative pieces you will not be using the same casting process as these heavy duty casters.  For artists creating small scale statues or embellishes and for hobbyists that need a decorative touch to their model plane or boat might want to consider using gravity casting for their needs.

Gravity casting seems to be especially useful when dealing with aluminum and other light alloys. The basic idea behind this casting process is pretty much exactly what the name suggests. The metal is introduced into the mold by the force of gravity. Most other casting process either use natural pressure difference like the kind in certain sand casting procedures or they use forced pressure like in centrifugal casting to get the molten metal into the mold. 

One of the most common uses for gravity casting is when permanent molds are going to be used. Also called a die, the permanent mold is really only economical for those planning on using the same mold numerous times and will need to keep the quality at a constant level. While some temporary molds can be repeatedly used the quality of the finished product will begin to suffer over time. With die molds the quality will remain the same. Die molds should be seen as an investment. Yes, they will be more costly then other molds; however they will outlast cheaper options for molds. With Permanent molds, they are created using cast iron, steel, and other metals.

Gravity casting is used for the permanent mold process with pleasing results. Gravity casting is usually used when the finished product is more visually based then structurally based which is why this method is a favorite of artists and even some jewelers. The loss of strength is due to the lack of pressure used in this process. For those that need the strength but still want to use gravity casting, more of the molten metal will need to be used which will increase the weight.

Relying on gravity will take patience, although it will be needed for larger products.

If you have never tried gravity casting then you should, because you just may be surprised by what such a simple thing like gravity can create. For the sake of humor, make an apple and see what happens.