How to produce quality metal castings in the foundry

To produce good quality metal castings in the foundry, the following basic guidelines must be adhered:

Proper Methoding
Rest on the engineering expertise of the Foundry Engineer to decide on the proper positioning of an item cavity in  the mold which become the basis in the design and fabrication of pattern as to the split line, the coring requirements, and other effects that a pattern should possess to enhance ease of location of risers and gates and pattern withdrawal at the mold forming stage.

Correct Design of Risers and Gating System
Refers to calculating riser and gating system dimensions and quantity to assure castings free from defects like shrinkage cavities, inclusions, misruns, and other surface imperfections.

Good Molding Practice
Covers the choice of reliable refractory materials and binders, sand preparations and setting of standardized sand and binder mixtures, mold coatings, and mold preheating prior to pouring melt into molds to avoid sand inclusions, porosity, run-out, and other related defects.

Effective Application of Chemical Metallurgy
Melting method plays a major factor in the attainment of a high quality metal castings in the foundry. First you have to be sure that the scrap charges are cleaned, classified and identified for the charge calculations to be effective in determining the alloying elements needed for a given target of metal composition. Treatment of molten metal in the melting furnace, be it, induction furnace, electric arc furnace, gas fired crucible furnace, or cupola, for fluxing, degassing and deoxidation must be strictly carried-out to completely eliminate dissolved hydrogen gas and oxygen which are the main source of gas porosities that may be present causing unsoundness in the castings. For example,  to degas and deoxidize non-ferrous melts, FOSECO products and other relevant suppliers, would be very effective material for melt treatment.

Temperature control is also a must in adjusting the correct superheat required for an equivalent section thickness of items to be poured.

Efficient Fettling and Cleaning Works
The use of shotblast machine to clean casting surfaces from sticking sand and scales, makes cleaning activity with ease and faster. For the removal of fins, risers and gates,  gas cuttiing, electric cutting, swing grinding and cut-off wheel equipment facilitates fettling and cleaning operations.


Enhancement of Mechanical Properties of Metals by  Physical Metallurgy
Mechanical properties of metals may be altered by the process called Heat Treatment. Depending on the needs, in general, metals can be softened by annealing and hardened by water or oil quenching.Normally, steel castings are annealed for ease of machining and maybe heat treated again following specifications on physical metallurgy, like normalizing, stress relieving, or hardening in accordance to customers' demand.