Which
Molten Aluminum Transfer System
Is For You? The best method for moving molten metal from the furnace to the mold is
different in each shop and depends on a number of variables. RANDY OEHRLEIN, CARLEY FOUNDRY INC., BLAINE, MINN.; JOHN HALL, CMH MANUFACTURING CO., LUBBOCK, TEXAS; AFS PERMANENT MOLD CASTING COMMITTEE (2E).
T
he use of rotary impel- ler degassing with flux injection, hydrogen gas
level detection equipment, and evalu- ation techniques for grain refining or silicon modification can put high quality metal within reach of nearly every aluminum metalcasting facility. Furnace temperature control technol- ogy has become increasingly efficient and accurate, as has mold and gating design through computer simulation. However, these advancements can be ineffective if the molten metal transfer
process (the step between melting and pouring) is not effectively controlled. It is a common assumption that
hand ladling is the most cost-efficient and flexible way to transfer molten aluminum and automated transfer is too expensive for small-to-medium sized aluminum facilities. A recent survey of the aluminum
casting industry revealed a wide variety of methods used to transfer molten metal from the furnace to the mold. Te responses came from a wide cross-section of the industry and provide a snap-shot
of aluminum metalcasting processes as well as practical advice from individu- als within the field—what they like and dislike about aluminum molten metal transfer systems and how they rate them in terms of cost, safety, process controls, ease of use and flexibility. Te survey respondents represent
workers in job shops and captive shops with anywhere from 25-250 employees in industry sectors such as automotive, aerospace, defense, cookware, internal combustion engines, pumps, construc- tion, office equipment, lighting and medical. Of the respondents, 31% use the gravity permanent mold process, 25% use green sand and 28% use chemically bonded sand. Investment and die casting each are used by 8% of respondents.
Hand Ladles Hand ladles provide considerable
The chart depicts temperature lost when the metal is and isn’t pre-heated. 36 | MODERN CASTING August 2012
flexibility, offer a wide range of sizes and can be used to pour various alloys with an ease of change. Hand ladles also provide low purchase cost, are relatively easy to maintain, are con- sidered highly reliable and allow for a variable pour rate. Tese perceived benefits, however, come with some less than desirable issues. One of the most commonly cited
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