railway training

1. C SHOP
C-CORROSION Treatment shop deals with the corrosive
treatment of the railwaybody parts.There mainlytwo types
of anti-corrosion method are used,one is phosphatic
treatment and other is powder coating.
Phosphatic treatment:-
The process consists of the followingstages:
a) degreasing-all scale, rust, grease oil and foreign matter
shall be removed from the surface by the supply of air(60-
700
C) with the mixture of caustic soda(40%),soda
ash(25%),trisodium phosphate(8%) in 10-15 min.
b) swirling-then the material is dippedunder pure water and
swirled so that by centrifugal force the remaining dirt is
washed away.
c) derusting-the remaining dirt is washed away by dippingin
orthophospharicacid at normal temperature.
d) swirling-once again swirled under pure water.
e)phosphating-two types of phosphatingis done mainly iron
phosphatingand zinc phosphatingat 60-700
C..
f)swirling-finallyonce again swirled.
g)sealing-after rinsing the coating should be sealed
immediately.
h)drying-the components shall be dried thoroughly in air
dryer.

2. Powder coating:-
The most common way of applyingthe powder coating to
metal objects is to spray the powder using an electrostatic
gun.The gun imparts a positive electric charge to the
powder, which is then sprayed towards the grounded object
by mechanicalor compressed air spraying and then
accelerated towards the workpiece by the powerful
electrostatic charge.
Then the objects are dried in baking oven(70-800
C) by
bllowingof air for a duration of 15-30min.
Powder coating