WHAT IS ALUMINUM PERMANENT MOLD?

Permanent mold refers to the tooling used to produce aluminum castings. Molds are built from cast iron or tool steel material. The permanent mold process offers high mechanical properties, dimensional repeatability, a good surface finished, reduced machining, at a lower cost.

In the permanent mold process, the aluminum flows into the mold cavity through the runner system. When the aluminum has solidified, the mold is opened and the casting is removed. Subsequently, another casting is poured in the same mold cavity.

WHAT IS SEMI-PERMANENT MOLD?

Semi-permanent mold refers to a casting produced using a sand core to form an internal passage. As the metal flows into the mold cavity, the aluminum surrounds the sand core while filling the mold cavity. When the casting is removed from the mold the sand core is removed from the casting leaving an internal passage in the casting.

WHAT IS TILT-POUR?

In the tilt-pour process, with the parting line of the mold in the horizontal position, molten aluminum is ladled into a ‘pour cup’ attached to the mold. The tilt-pour casting machine then rotates 90 degrees in a slow and controlled rate. As the metal travels down the runner system, the metal enters the mold cavity in a tranquil manner reducing turbulence and oxide.

WHAT IS PROGRESSIVE SOLIDIFICATION?

When aluminum solidifies the material has a volumetric .7% shrinkage value. To produce a high quality aluminum permanent mold casting, the foundryman must not only fill the mold cavity but proper feeding of the cavity eliminates internal casting shrinkage. As the metal slowly enters the bottom of the mold cavity, the metal in the mold cavity begins to solidify and shrink. The metal entering the cavity above this immediate area is feeding the area which is solidifying. This filling-feeding-solidifying completes the progressive solidification through the top of the mold cavity.