Low-pressure casting is an advanced casting production technology. The casting is made by pressurizing the chamber and forcing the metal up into the mould. The metal in the fill tube operate as the riser; this gives low pressure die casting very favorable casting yields.
A slower filling velocity allows greater flexibility in design and the use of sand cores to cast the more complicated parts and also results in a much lower happening of turbulence, significantly reducing the possibility of air entrapment.
The rapid solidification rates coupled with low-pressure results in castings by finer grain size, smaller dendrite arm spacing, and improved mechanical properties.
Low pressure permanent mold casting is important more than ever well-matched for the production of numerous aluminum automotive parts.
For more information please see this article : Bullet Points in design of gating system to preventing Surface Turbulences (Published by Farsheed Eftekhari)