Aluminum Extrusion Terminology - D - F

Die - A customized opening in an extrusion press, through which a heated aluminum alloy is pressed. The shape of this opening determines the final shape of the extruded product, which is the cross-sectional shape of the opening in the die.

Die Holder - A component of an extrusion press that holds the extrusion die and its components. The holder is located between the container and press platen and can be unlocked to withdraw the die. It can also perform additional functions, depending upon its design.

Ductility – A property of elasticity that determines how easily a material can be shaped or manipulated. Aluminum has high ductility, allowing for significant bending and stretching without creating stress fractures during the production process. This characteristic facilitates the fabrication of aluminum for a variety of end uses.

Dummy Block – A thick block of steel that fits tightly between the billet and the ram in an extrusion press. Its purpose is to prevent any back flow of the melted metal towards the ram during the extrusion process.

Electrical Conductivity – The ability of a metal to conduct or allow an electrical current to pass through it. It is inversely proportional to resistivity (Ohm’s Law) and is measured in terms relative to the conductivity of Annealed Copper, which is taken as the International Standard. Aluminum has an electrical conductivity of 37.8 × 106 S·m-1.

Electrostatic Spraying – A method of treating a metallic surface that uses the property of particle-attraction of electrostatic charges. The droplets of the sprayed substance (i.e. paint) are given an electrical charge and the part to be treated is given the opposite charge of high-voltage current. This polarity causes the droplets to be attracted to the surface, resulting in an even and durable coating.

Etching – The method used to change or texturize the surface of a metal, by permitting controlled corrosion through the use of an acid or other chemical agent as the etchant.

Extrusion – The process of creating desired metal lengths with uniform cross-sections by forcing heated aluminum billets through an extrusion press. The billet is pressed through a steel die of the desired shape with the help of a ram, so that the resultant part acquires the cross-sectional shape of the die.

Fabricate – To manufacture or construct components or final products with the use of a machine, structure, or equipment to assemble various parts. This includes the cutting, shaping, and machining of a raw material.

Feeder Plate – A steel plate that is placed before the extrusion die in an extrusion press. Its purpose is to change the dimensions of an aluminum billet to allow the extrusion of larger than normal dimensioned products.