GMW GMW16789 [ Revised ]

Material Description. The objective of this specification is to minimize visual surface anomalies. This specification defines the acceptance limits of several types of surface anomalies. Also, described herein, are internal casting discontinuity limits. 

Symbols. Not applicable. 

Typical Applications. This specification applies to surface and internal casting anomalies of any exhaust manifold casting or the cast portion of any maniverter, regardless of the process or exhaust manifold material, including, but not exclusively, GMW13 and GMW3164.

Remarks. Various areas of an exhaust manifold are subject to different stresses. During the visual inspection phase of process monitoring, particular attention shall be paid to casting anomalies such as shrinks, inclusions, blows, excess metal resulting from core or mold chip-out that could affect flow or clearance, flash, porosity, and machining defects – all of which may have a deleterious effect on the exhaust manifold (or maniverter) strength if permitted to exceed a certain size in specific locations.