Atomization, by far the most common of these methods, separates molten, liquid metal into small beads that are frozen into a solid form.
Powdered metal is formed from solid metal bars or stock shapes into differing grades of fineness in order to be used in a wide variety of applications for which solid metal is not suitable. It can be made from a wide variety of metals, or combinations of metals including iron, aluminum, nickel, copper, bronze, titanium and brass. Industries such as electronics, pharmaceutical, cosmetic, automotive and industrial all use elements of powdered metals in a number of different functions.
While there are a number of different methods for fabricating parts from powdered metal, it is widely used in the process of powder metallurgy for the fabrication of rigid and porous metal components. Aluminum powdered metal, bronze metal parts and iron powder metal are all common examples of the types of metals which are used from a powder form. Solid metals can be made into powder using a variety of techniques including atomization, chemical precipitation, centrifugal disintegration and hydrogen reduction.
The most commonly used of these methods is atomization. The process of atomization separates molten, liquid metal into small separate beads that are then frozen into a solid form, creating a type of powder. The powder can vary in terms of granule size according to the desired finished product results.
The fabrication process of powder metallurgy uses powder metal in the construction of parts and components of varying complexities. It is composed of three different stages of production. After the initial process of metal powder formation, the powdered metal is forced into a die or mold cavity until it is completely filled. These are typically simple hollow shapes that are able to be used repeatedly to make solid parts from metal powder.
Both heat and pressure are used in this formation process. The die or mold is put under great pressure in order for the powdered metal to adhere together into a solid shape. The product is then further heated in a furnace to a temperature just below the metal’s melting point. This ensures the bonding of the metal particles together in a rigid and high strength part. Using a metal powder also allows for various grades of porosity to be achieved in the finished products.
Producing powdered metal parts results in very little waste as the material is forced into an enclosed die. In fact, approximately 97% of materials used during the process end up in the parts and not as scraps, making powder metallurgy both cost effective and environmentally responsible.