The purpose of this experimental design was to determine which sets of conditions offered the best quality of aluminum melt used within company's foundry operations. Quality was defined in terms of specific gravity (percentage). Higher percentages yield parts of better quality. Lower percentages of specific gravity are revealed in the die cast part by bubbles (porosity) within the solidified metal. A part failure may result if excessive porosity is located where a portion of the part is subjected to stresses.

Three main areas (factors) were used in this experimental design: Temperature (High 1300F or Low 1200F), Fluxing (fluxed or unfluxed samples), and Location (Breakdown Furnace or Holding Pot). These three factors at two levels each generated eight experimental test conditions. This experimental design is referred to as a Factorial design.

The company is a major supplier of parts and assemblies to the pneumatic equipment industry.

Die cast parts and assemblies are made from aluminum or zinc. No alloys were used.

Sodium Fluoride Nitrate is used as a drossing flux to promote separation of the aluminum oxide (Al₂O₃) dross layer that forms on the surface of the melt.

Aluminum melt is obtained by melting 25 lb aluminum ingots at one end of the breakdown furnace and aluminum scrap, runners, overflow and rejected parts at the other end.

Melting temperature of the breakdown furnace is kept high to quickly form the melt. This approach is used to keep the die-casting machines at higher output levels.

The high temperatures associated with nonferrous (aluminum) molten metal processes cause hydrogen gas to become soluble within the melt. During the die-casting operation the metal cools causing the hydrogen to become insoluble. The insoluble hydrogen attaches to inclusions (impurities) within the melt, creating bubbles within the cast part. Typically, higher temperatures result in higher levels of soluble hydrogen. Higher levels of hydrogen result in an increase in the porosity (bubbles), thereby resulting in a decrease in the specific gravity (density) of the cast part.

The existing quality control process involves sampling die cast parts after they have cooled, then x-raying the part for internal porosity. If the excessive porosity is located at a critical area (e.g., threads, areas under pressure, etc.) the part is rejected, documented, and returned to the breakdown furnace to reclaim the aluminum.