Auxiliary device for prevention of problems with the use of mini risers (s. Riser type) on mold surfaces of various compaction classes (Fig. 1, ASK Chemicals).
The spring mandrel (Fig. 2, ASK Chemicals) establishes a separating sand layer between the mini riser and the casting so that a perfectly smooth casting surface is achieved in this area. Moreover, the spring mandrel protects the mini riser from destruction by the compaction process in the molding plant. The separating sand layer ought to have a height of approx. 40 % of the feeder neck diameter. The use of spring mandrels ensures reduction of riser contact areas, as well as decrease of surface defects and pattern wear.
Fig. 2: Spring mandrel, (Foseco Foundry Division Vesuvius GmbH)