Effects of Different Lubricating Oils and Ceramic Ring Overhang (CRO) on the
Ricardo Sammy, Kedar Tilak, Almex USA Inc., Long Beach, California, USA
Surface Appearance of 6xxx Series Alloy Billets
Track: BILLET PROCESS & EQUIPMENT - Casting, Casthouse, Environmental Health & Safety
ABSTRACT—It is well known that the extent of the ceramic ring overhang (CRO), as well as the chemical
and physical properties of the lubricating oil used during D.C. casting of billets has a strong influence on the surface finish as it relates to the presence of common surface defects such as laps, dimples, drags and tears. The present paper reports the results of a study involving the use of a conventional casting Lubricant A against a lower viscosity casting Lubricant B, when casting 10-inch diameter AA 6061 alloy billets. The paper also describes the effect of reducing the CRO from 1.5mm to 0.25mm (0.06 inches to 0.01 inches). The CRO is found at the interface between the top of the graphite ring and the bottom of the ceramic ring. During the course of the study, the design and dimensions of the graphite ring and mold tang length were kept constant. In addition, the casting process parameters were also kept constant. The paper illustrates that the individual lubricating oil properties combined with increased CRO can directly impact the billet surface roughness. The paper presents comparative illustrations of the as-cast billet surface finish.
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