Vrinda Engineering

Vrinda Engineers can ensure excellent permanent mold castings from India and China and is very price competitive. Vrinda Engineers has audited, qualified and worked with QS-9000 and ISO certified permanent mold casting factories in India and China . We are dedicated to managing your project on-site in China and delivering parts to you at lower prices but the same quality, service and terms as a domestic supplier.

Some of the products made using Gravity Die casting process are Housings, Junction boxes, impellers, Valve bodies, Flanges, Manifolds, Actuator bodies, Compressor parts, Electrical fittings parts, Covers.

Permanent mould casting get their name from the fact that the process utilizes permanent metal moulds instead of temporary sand moulds for the casting process. Cast iron is the most commonly used mould materials as it offers great reliability during casting. The cores are made from other metals or sand. The cavity surfaces of the moulds are coated with fine layers of materials that have good heat-resistant properties such as clay or sodium silicate.

The moulds used in casting are pre-heated upto 200 ºC (392 ºF) before the molten metal is poured into the cast cavity. Casting has to be done with care in order to ensure that proper thermal balance in maintained throughout the casting process. This is done through a variety of ways including external cooling techniques using water or relevant radiation techniques.

Permanent mould casting, while not offering the same level of design flexibility and ease pattern usage as sand castings, it has the advantage of offering relatively lower design and development costs as well as production costs. At Vrinda Engineers, we have the expertise to undertake permanent mould castings of complex components of diverse application in various industrie

Molten metal is poured into cast iron molds, coated with a ceramic mold wash. Cores can be metal, sand, sand shell, or other materials. When completed, the molds are opened and the castings are ejected.

Instead of using sand as the mold material, a metal is used as a mold. Typically cast iron or Meehanite (a dense cast iron) is used as the mold material and the cores are made from metal or sand. Cavity surfaces are coated with a thin layer of heat resistant material such as clay or sodium silicate.

The molds are pre-heated up to 200 ºC (392 ºF) before the metal is poured into the cavity. The cavity design for these molds do not follow the same rules for shrinkage as in sand casting molds, due to the fact that the metal molds heat up and expand during the pour, so the cavity do not need to be expanded as much as in the sand castings. However, care has to be taken to ensure proper thermal balance, by using external water cooling or appropriate radiation techniques.

At a production run of 1000 or more parts, permanent mold castings produce a lower piece cost part.Typical part sizes range from 50 g to 70 kg (1.5 ounces to 150 lb). Typical materials used are small and medium sized parts made from aluminum, magnesium and brass and their alloys. Typical parts include gears, splines, wheels, gear housings, pipefittings, fuel injection housings, and automotive engine pistons.

Other Permanent Mold Castings

Slush Casting: Slush Casting is a special type of permanent mold casting, where the molten metal is not allowed to completely solidify. After the desired wall thickness is obtained, the not yet solidified molten metal is poured out. This is useful for making hollow ornamental objects such as candlesticks, lamps, statues etc.

Corthias Casting: Corthias Casting is another variation of the permanent mold casting, where a plunger is used to pack down the molten metal form the sprue hole. This allows for thinner walls and greater details to be produced.

Low Pressure Permanent Mold Casting: Low Pressure Permanent Mold Casting is yet another variation of the permanent mold casting. Here, instead of using gravity to assist in the metal pour and flow in the mold, a low pressure of upto 1 atmosphere gas is applied to the molten metal. This maintenance of pressure on the melt causes complete fill of the mold and compensates for any shrinkage on cooling. Thin wall castings can be made. Mechanical properties are about 5 % superior to permanent mold casting. Since no riser is used (unlike a regular casting), the yield is generally higher since the metal in the pressurized feed tube is still molten and the mold is ready for the next shot right away.

Vacuum Permanent Mold Casting
Vacuum Permanent Mold Casting is yet another variation of the permanent mold casting. This is similar to the low-pressure permanent mold casting, where a vacuum is used instead of a pressure. Thin wall castings can be made as in the low-pressure permanent mold casting. In addition, the yields are high since no risers are used. Since vacuum is used instead, the purity of the metal is maintained. The mechanical properties of the casting are 10 to 15 % superior to the traditional permanent mold casting. Castings range in size from 200 g to 4.5 kg (6 oz to 10 lb).