Riser (casting)

Feeder or riser is a term used in foundry technology and describes geometric Angus body on castings, in the shape of the Lunkervolumendefizit should be placed in the casting solidification and which are removed in the cleaning process of the castings. Feeder on steel castings are removed with autogenous flame cutting, by taking advantage of the Oxydationswärme burned by the oxygen supplied to the material in the so-called kerf and removed.

Thus, should a feeder avoid the formation of voids in a casting and has different tasks in a mold:

• Control the direction of solidification of the cast melt ( possible directed to the feeder back )
• Compensating the reduction of the specific volume of the cast melt during the phase transition liquid / solid
• Venting of the mold during the casting (except blind feeder )

The shape of feeders is usually cylindrical and led out of the mold, rare Spherical and as blind feeder ( feeder is completely hidden from the forming fabric ).

The cylindrical or spherical shape is selected on the basis of good to very good volume / surface ratio ( module as a geometric index for solidification rate ).

" Feeder variants " Nature Speiser, insulating feeders, Exothermspeiser: By isolating or additional heating of the feeder as the feeder to the casting dimensions can be made ​​smaller, which leads to a material saving ( better Gussteilausbringen ).