Cast Terminals VS Forged Terminals, What’s the difference?
Forging and casting are the two predominant types of processes used to manufacture battery terminals. Commonly referred as a “forged” or “cast” terminal.
During the casting process molten brass is either poured or drawn using a vacuum into a mould, where it is formed into the desired terminal shape and allowed to cool. Once the terminal has cooled minor modifications such as drilling and trimming are made, allowing for quick and inexpensive production. While a cast terminal may be easier and less expensive to manufacture, the process of allowing the molten brass to solidify leads to porosity, which are essentially inconsistencies in the material structure that unaccounted for can lead to cracking, oxidation, pitting in the finishing, and a reduction in the terminal’s structural integrity. To counteract this deficiency, manufacturers are forced to design with larger tolerances which lead to heavier terminals in order to achieve the desired structural integrity.
In contrast to casting, a forged terminal begins as a solid piece of metal referred to as a “billet”. This billet is then subjected to heat and intense pressure, which compresses the material to form a raw forging. These raw forgings are “forged” into different profiles to allow for the creation of different terminal designs. These forgings are then trimmed and machined to form the final shape and application of the desired terminal.
Due to the immense pressure that the billet undergoes during the forging process, the metal is less porous compared to cast terminals and has an interlocking and aligned grain structure that follows the contour of the terminal. Although this can only be viewed under a microscope, this structure results in improved strength, durability, and resistance to corrosion and oxidation. Due to the more consistent properties of forging, greater structural integrity can be achieved and delivered with a lighter terminal. The downside however of the forging process is cost. It is a more complex form of manufacture, requiring the brass to be of a greater spec. than that used in the casting process. Although the forging process may be more time consuming and costly than cast, they offer significant benefits to the consumer.
Another process that is used for battery terminal manufacture is extrusion. This is the same process used to form aluminium channels and sections. Some terminal marketing incorrectly claim this process to be forging. It is not, although better than casting it is still far inferior to forging in that it does not give the interlocking and aligned grain structure and strength delivered by forging.