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details DESIGN


Many Features Integrated With Near Net Shape Process


JITEN SHAH, PRODUCT DEVELOPMENT & ANALYSIS, NAPERVILLE, ILLINOIS CASTING PROFILE


Cast Component: Exhaust housing for marine engine.


Material: Aluminum 356-T5 alloy. Weight: 31.2 lbs. Dimensions: 21.4 x 19 x 7.2 in.


Application: Outboard marine engine.


procurement, machining and assembly costs associated with individual compo- nents. Additionally, the overall product quality was improved by eliminating the potential risks of failure, such as gasket relaxation and torque retention. As-cast cooling passages improved thermal effi ciency of the exhaust housing.


A


n exhaust housing produced by BRP-US Inc., Spruce Pine, N.C., for an outboard marine engine was converted from a 28-piece subassembly by integrating the exhaust, cooling, steer- ing and engine mount housing into a single piece. T e OEM saved a net total of $75 per unit through reducing or eliminating


As-cast surface fi nish minimizes secondary machining.


• T e molding media is a refractory slurry, which provides a smoother surface fi nish compared to the conventional sand casting processes.


Lost foam provides fl exibility for placement of the integral cooling passage features.


• T e lost foam pattern assembly is an exact replica of the fi nished casting shape. Typically the pattern is made out of multiple foam sub-components glued together, which eliminates the parting plane constraints and the need for cores.


• T e casting orientation and gating system are adjusted to achieve the desired fi lling and solidifi cation pattern, unlike other casting processes where parting plane dictates casting orientation.


18 | METAL CASTING DESIGN & PURCHASING | Jul/Aug 2013


• T e as-cast surface fi nish depends upon the quality of the refractory coating, alloy, process parameters, the cast- ing’s overall size, wall section thickness and the gating and risering system.


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