Cast Iron Housing
Cast iron housing means the iron castings
such as tractor gear boxes,
pump bodies and other casings
just like a box or house shapes.
Ductile iron series housings weight 40% less in comparison with
standard housings made with gray cast iron. Ductile iron series
housings are approximately 30% stronger than standard housings made
with gray cast iron. Therefore, ductile iron has been more widely
used for cast iron housings.
Ductile cast iron housings are designed to be lighter and more
compact than gray cast iron units. Since ductile cast iron is
stronger, these compact castings can commonly replace standard
castings. So, ductile cast iron parts will perform well in harsh
environments. As with all housed units, before applying, please
check the allowable load limit, bearing life and safety factors.
The material of cast iron housing basically includes ductile iron
and grey iron.
The housing material for the current standard bearing units is gray
cast iron (FC200). The FC200 material contains black lead and
graphite distributed as show in photo 1. When heavy shock loads are
applied to the housing, cracks spread along the black lead/graphite
strands and the housing may fracture. In FCD450 material, the black
lead and graphite nodules are distributed as shown photo 2. This
black lead/graphite distribution can prevent the spreading of
cracks. Also the shock resistance at low temperature, FCD450 is
superior to that of FC200.
The following is the comparison for
characteristics of ductile iron and gray iron for housing castings.
Normally, the shell molding process will be the most suitable
casting process for small housing products, however, it is more
costly than green sand casting process. As for the large casting
process, the resin sand casting process will be the most suitable
one in order to keep the good surface quality and dimensions.