The
expected useful life of a new or reclaimed brake drum is highly dependent
on its conditions of service and the environment it works in. It is standard
practice for industrial users of cranes, to repair brake drums which have
been corroded/eroded by use and/or the environment, by undercutting the
worn area and rebuilding the surface with welding or metal spray, then
possibly chrome plating prior to grinding to size.
The steelmaking department of BHP Long Products Division at Whyalla, South
Australia, has extremely testing conditions - both in service and by the
environment.
The use of C-Ramic densification technology to extend the working life
of repaired brake drums has been proven in this highly demanding situation.
Monitoring the performance of the braking systems
for Nos.1 and 2 BOS charging cranes allowed a direct comparison between
different coatings, since two brake drums are used on each motor and
each individual drum is rotated weekly, to be either in service or on
stand by.
Drums of different surface finish were paired
up and run against each another.
The following results were obtained over a period of one year - the
figures below indicate the time "installed" and the time "in service"
for each particular type of drum before excess wear resulted in deterioration
in performance and removal from operation.
The remarkable improvement in the performance of the C-Ramic densified
arcsprayed 420 stainless steel indicates a substantial change in the
wear mechanism on the surface of the brake drum.
The C-Ramic process has filled the inherent porosity of the 420 stainless
with a fully bonded and sealed ceramic and given it awhole new range
of properties:
