Sintered metal is a solid product made through the process of powder metallurgy from different types of metals and alloys including aluminum, copper, bronze, nickel, brass, steel, stainless steel, nickel and titanium. The solid metal powder parts are formed by pressing metal powder into a coherent mass without heating the metal to its melting point. Metal powder can be formed from solid metal bars or stock shapes using different processes such as grinding, chemical decomposition, atomization and centrifugal disintegration.
Atomization is the most commonly used method as it effectively produces powder from almost any metal by separating molten metals into separate particles which then freeze into solid form. This powder is then used in sintering. The complete process that produces sintered metal parts is called powder metallurgy, or PM. It is widely used for manufacturing various components for industries such as electronics, automotive, hardware, computer and lawn and garden industries because it produces a minimal amount of waste. In fact, approximately 97% of the original material ends up in the finished parts, making it a cost effective fabrication solution for high volume parts, especially those made of costly metals. In addition, using this method, consistent parts can be fabricated even in large quantities with relatively accurate tolerances and repeatability.
The process used to create sintered metal involves three basic steps. First, the metal is made into a powder form, at which point it can be combined with another metal to form an alloy, or fabricated as a pure component of one metal. Sintering is able to maintain the physical properties of the materials used as it is a simple process that does not require much alteration of the elements. In the second step, the powdered metal is poured into a die or mold cavity in the shape of the desired part and compacted at room temperature under great pressure. The amount of pressure required will be determined by the type of metal used as some are more malleable than others.
In the die, the powders are compacted into a solid shape. The metal mass is then removed from the die and put into a furnace under extreme heat. This part of the process, called sintering, fuses the metal particles together without melting them, forming a rigid, high strength and porous component. The porosity of the part can be altered according to the desired level of flow, both of liquids and air, of the finished product based on its intended application.