The Manufacturing Outlook

chris lynn

A foundry produces more than metal components for engines, railroads, and pipes. Moreover, they fabricate components for machines that make many essential consumer products. The majority of manufactured goods rely on metal castings.

Foundry sand is clean, evenly sized, high-quality silica sand used in the casting processes of a foundry. The bonded sand is used to create molds or patterns for ferrous (iron and steel) and non-ferrous (copper, aluminum, brass) metal castings. Shakeout sand from finished metal castings is frequently salvaged in the foundry sand process.

Casting techniques

Green sand is silica sand with trace amounts of bentonite clay, water, and sea coal. In general, the type of metal being cast influences the proportions of minor ingredients and the needed sand gradation. Before the reclaimed green sand can be reintroduced into the casting process, it must be cooled using a thermal procedure. The majority of foundries employ green sand casting as a method of production.

No-bake casting is a common technique for producing "core molds" or lower batches of complex castings for ferrous and non-ferrous metals. This technique delivers a chemical binder/catalyst to the sand immediately before filling the mold, causing a chemical reaction that hardens the sand and maintains the shape of the mold. As this reaction is temperature-dependent, it is crucial to maintain a stable and uniform sand temperature to enhance the quality of the cast product.

Why does the temperature of foundry sand fluctuate?

Variations in how foundries dry and cool their reclaimed green sand or store and distribute their no-bake sand can affect the sand temperature. As foundry sand is a key component of the casting process, utilizing too hot or cold sand reduces casting quality and has detrimental effects throughout the production line. When molten metal is put into a mold containing overheated green sand, scrap rates and bentonite consumption are likely to increase. Too hot or too cold no-bake sand causes irregular timing and consumption of catalysts/binders.

How can technology be utilized to control the temperature of sand?

Rotary cooling drums are a typical method for lowering the temperature of shakeout foundry sand. The sand is put into one end of a spinning, inclined drum while air enters the other. Slowly moving downwards through the drum, the sand is cooled by direct contact with air.

Vibrating fluid bed coolers are another popular method for cooling foundry sand. Sand is transported on a vibrating, perforated deck, and Pressurized air flows upward through the deck to fluidize and cool the sand as it is carried from one end to the other without direct contact.

Unfortunately, neither rotational drums nor vibrating fluid beds permit the homogeneous cooling of all sand particles. Additionally, both processes require air permits and could be more efficient in terms of cost per ton of sand processed.

Moving bed heat exchangers (MBHEs) based on vertical plate technology are a more effective and efficient cooling method because they can guarantee an even, stable, and exact end sand temperature.

Within these MBHEs, pioneered and field-tested by Solex Thermal Science, the foundry sand moves downhill between stainless steel plates in a gradual and regulated manner. Within the plates, cold water flows counter-current to cool the sand to the correct temperature by conduction.

The foundry sand does not come into touch with water or air. In addition, the gradual, regulated downward flow of the sand ensures that all particles, regardless of particle size variation, are cooled uniformly. This eliminated variations in the foundry sand's output temperature.