Riser

   Riser has the function of prevent  a kind of flaw caused during in the solidification process: shrinkage.It is necessary know the place the riser will be put in the mould and your volume.

   Was used the “module’s method”, by ALMEIDA, Fundição: Mercado e Processos Metalúrgicos, one of method more used. This method consist in break the item in piece more simple, cylinders in this case, and find the module, division of volume for área will be contact in the mould’s wall. The riser should be in the region with the module is most bigger.The first region is the head, and the second region is the body of rivet. The figure 1 show the calculations founded. Hc2 is the height of body, dc2 diameter of body, and Ac2, Vc2 and Mc2 are respectively the área, volume and module with region 2. Hc1 is the height of rivet’s head, dc1 is the diameter of rivet’s head. Again, Ac1, Vc1 and Mc1 are respectively the área, volume and module with region 1. The kind of riser used is open in the top because is more easy your construction and the gas leaves.

Figure 1: Calculations of module

Source: own

To define the height of riser, by ALMEIDA, Fundição: Mercado e Processos Metalúrgicos, used the equacion 1. V is the riser’s volume, k’’ is a constant and depend the situation of casting, in general cases your value embrace is 6.  R is the coeficiente of volumetric contraction and for the aluminium are 6,5. Vp is the volume of item.  The figure 2 show the calculations to found the volume and height of riser, H.

The figure 3 show the measures of riser in a 2d representation.

Figure 2: Volume and height of riser

Source : own

Figure 3: Representation 2d of riser

Source: own

It is important emphasize the heigt of riser round off 23 milimeters for reasons of security

Bibliography:

ALMEIDA, Gloria de. Fundição: Mercado, Processos e Metalurgia. 2000. Disponível em: <http://www.metalmat.ufrj.br/wp-content/uploads/2012/05/Fundi%C3%A7%C3%A3o-mercado-processos-e-metalurgia.pdf>. Acesso em: 16 NOV 2017.