The treatments to rough castings

When we get the rough castings, we need to do some treatments to improve or inspect the casting quality. These treatments include heat treatment, anti-rust treatment, rough machinating, repairing etc.

Heat Treatment

In order to improve or change the original organization of castings, eliminate stress, improve casting performance, prevent the casting deformation and damage, sometimes, we need to do the heat treatment. Casting heat treatment are generally normalizing, quenching, annealing, and graphitization treatment.

Annealing will reduce the internal stress and hardness, to get a even material. When you make some large flat plates, or the hardness is too high to affect the machining, then you will to do the annealing treatment.

Normalizing will improve the original organization to reach higher physical properties, such as higher tensile strength.

Quenching usually get higher surface hardness of castings. There are some different types of quenching treatments.

For example, high manganese steel castings demanding wear resistance and sufficient toughness, and its internal organization should be austenite. To do this, the quenching of the castings, castings heated to austenite region is about to make it fully austerities, quenched rapidly chilling the water, so that the change of austenite too late to keep down. This process is also called water toughening treatment or solution treatment.

Reshaping and Repairing

Casting deformation may happen in the solidification and heat treatment process of the cooling, so the dimensions will exceed the casting tolerance. Reshaping mainly do by mechanical force at room temperature or high temperature. The surface defects of castings mainly used to repair welding. The rough surface will be generally grinded by grinding wheel.

Rough Machining

Before delivery, according to technical conditions, some foundries will do the rough machining to the castings. Rough machining could find inside flaws and defects, and can reduce the rough weights, so the machined metal chips could be reused by foundries. Most of iron foundries in China have the capability of rough machining.

Anti-rust Treatment

All rough castings and machined castings need some level of anti-rust treatment, especially like Dandong Foundry in China, they are near to ocean, so anti-rust treatment will be more important. Anti-rust treatment prior to delivery to prevent rust during transport and storage. Usually, we use the anti-rust oil for machined parts, and anti-rust primer painting for the rough castings.

There are some other treatments after castings, such as finish painting, surface coating, polishing etc. We will talk more about this issue later, please keep the updated articles in the blog of Dandong Foundry.

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