Casting is an economical and convenient metal forming process with a wide range of applications and relatively low costs, serving as the foundation of the manufacturing equipment industry. There are numerous casting methods, which are typically classified based on mold materials, mold characteristics, filling conditions, and solidification conditions.
Classification by Mold Material, Filling Conditions, and Solidification Conditions
Based on differences in mold materials, filling conditions, and solidification conditions, casting can be divided into sand casting and special casting.
(1) Sand Casting
Sand casting is a method where sand molds are prepared using molding sand and filled under gravity. It offers advantages such as broad adaptability and low cost, making it the most widely used casting method. Depending on the molding process, sand casting can be classified into manual molding and machine molding. Manual molding is flexible, requires simple tooling, and is highly adaptable, making it suitable for castings of various shapes. Machine molding boasts high production efficiency and good casting quality, but involves higher equipment and tooling costs and longer preparation times, making it suitable for batch or mass production of small to medium-sized castings.
(2) Special Casting
Special casting refers collectively to casting methods that differ significantly from sand casting in terms of mold materials, filling conditions, and solidification conditions. In simple terms, casting methods other than sand casting are categorized as special casting. Currently, there are over 20 types of special casting methods, with commonly used ones including investment casting, lost foam casting, permanent mold casting, die casting, low-pressure casting, centrifugal casting, shell molding, ceramic mold casting, and squeeze casting.
Classification by Mold Characteristics
Based on differences in mold characteristics, casting methods are divided into expendable mold casting and permanent mold casting.
1. Expendable Mold Casting
The mold can only be used for a single casting. Methods in this category include sand casting, investment casting, shell molding, plaster mold casting, magnetic mold casting, and vacuum full mold casting. Mold materials are typically non-metallic.
2. Permanent Mold Casting
The mold can be reused multiple times. Methods in this category include permanent mold casting, die casting, squeeze casting, centrifugal casting, vacuum suction casting, and continuous casting. Mold materials are primarily metallic, though graphite molds are also used.
Classification by Liquid Metal Filling and Solidification Conditions
Based on differences in filling and solidification conditions, casting methods are divided into gravity casting and non-gravity casting.
1) Gravity Casting
Filling and solidification occur solely under the influence of gravity, with no additional external forces applied. Gravity casting is also known as free pouring or gravity pouring. Methods in this category include sand casting, permanent mold casting, magnetic mold casting, and investment casting.
2) Non-Gravity Casting
In addition to gravity, filling and solidification involve external forces such as pressure or centrifugal force. Methods in this category include die casting, centrifugal casting, low-pressure casting, and vacuum suction casting.
