Rejection Rate Minimization of Cast Iron Components …
57
Grey
Cast iron
Ductile Cast
iron
Mould
Induction furnace
(1550˚C)
Ladle (1450˚C)
Casting
Fettling
Cleaning
Raw materials
Mg Treatment
& Inoculants
Inoculants
Sand
Binder
Additives
Water
Sand mixer
Sand reclamation
Scraps
Fig. 2 Casting process of grey and ductile cast iron
will vary based on the furnace and individual foundry circumstances [5]. In ductile
cast iron, inoculation agent such cerium (Ce) is added in induction furnace itself
which produces nodular form of graphite followed by cementite phase. The inoculate Ce and slow solidification normally promotes formation of chunky graphite [6].
In industry, to minimize the slag inclusion and smooth metal flow, ceramic filter is
used in the gating system. The nodularity of graphite varies with respect to thickness
of the component [7].
This work concentrates on the major defects on the selected components which
nurtures the rejection rate and its cause. The defect formation is due to material, machine, method and man (4M’s). Hence, various experimental tests have
been extensively conducted starting from raw material to manufacturing process.
For better understanding and supporting the decisions on the selected components,
metallurgical and mechanical testing is also done.
2 Experimental Procedure
Due to the presence of various defects in cast products, during inspection 30–45% of
harvester cup, chain link and non-return valves are rejected. Some of the defects in
the components are shown in Fig. 3, and the corresponding percentage of rejection
57
Grey
Cast iron
Ductile Cast
iron
Mould
Induction furnace
(1550˚C)
Ladle (1450˚C)
Casting
Fettling
Cleaning
Raw materials
Mg Treatment
& Inoculants
Inoculants
Sand
Binder
Additives
Water
Sand mixer
Sand reclamation
Scraps
Fig. 2 Casting process of grey and ductile cast iron
will vary based on the furnace and individual foundry circumstances [5]. In ductile
cast iron, inoculation agent such cerium (Ce) is added in induction furnace itself
which produces nodular form of graphite followed by cementite phase. The inoculate Ce and slow solidification normally promotes formation of chunky graphite [6].
In industry, to minimize the slag inclusion and smooth metal flow, ceramic filter is
used in the gating system. The nodularity of graphite varies with respect to thickness
of the component [7].
This work concentrates on the major defects on the selected components which
nurtures the rejection rate and its cause. The defect formation is due to material, machine, method and man (4M’s). Hence, various experimental tests have
been extensively conducted starting from raw material to manufacturing process.
For better understanding and supporting the decisions on the selected components,
metallurgical and mechanical testing is also done.
2 Experimental Procedure
Due to the presence of various defects in cast products, during inspection 30–45% of
harvester cup, chain link and non-return valves are rejected. Some of the defects in
the components are shown in Fig. 3, and the corresponding percentage of rejection