Nitrided Hydraulic Cylinder Rods
Liquid
Nitriding is a surface treatment process that produces a black in
color finish that is very hard and corrosion resistant. It combines
a high surface hardness with increased corrosion resistance. The
process begins with the cleaning and super-polishing of the material to
a surface roughness of 6 to 10 Ra. The steel bars or components
are then fixed vertically, and submerged into an electrically controlled
liquid tank.
Salt Bath Nitriding Steps - ARCOR Process
-
1
MECHANICAL FINISHING
Smooth component surface to requirements, improve friction properties -
2
DEGREASING / RINSING
Remove all oils and other particulates from the components surface -
3
PREHEATING
Maintain a stable temperature in the process -
4
NITROCARBURIZING
Surface structure conversion -
5
OXIDIZING
The nitride layer is oxidized to increase corrosion resistance producing the black finish -
6
COOLING/CLEANING
Remove salt from the component surface, wipe clean with oiled rag
This process; through thermochemistry nitrocarburizes
the steel at temperatures within the range of 930 to 1150 degrees
Farenheit in a specially formulated Nitrogen-bearing salt bath.
The Nitrogen diffuses into, and chemically combines with the nitride
forming elements in the metal. The steel's surface is thus converted
to iron nitride to a typical depth of up to .001", based on product
requirements. This surface is very uniform, increasing the surface
hardness above 55 Rc. Beneath the iron nitride layer is a nitrogen-enriched,
hardened diffusion zone. The diffusion zone functions as a lightly
hardened case with a hardness ranging from around 55 Rc just below
the iron nitride layer to approximately 40 Rc at a depth of approximately.010".
Results vary depending on the base material being used as there
are many types of metal that can be nitrocarburized. Oxidizing is
employed to produce the black, corrosion resistant surface film.
Nitrided hydraulic cylinder rods offer the following benefits over conventional hard chrome:
- Surface hardness above 55Rc
- Surface finish 16 Ra or better
- 0.001" thickness per side (0.0254mm)
- Improved corrosion resistance
- Salt spray tested (ASTM B117) to 100 hours min. with zero corrosion
- Improved wear & dent resistance
- Improved oil retention (longer seal life)
- No surface pitting, flaking or micro-cracking
- Environmentally friendly process compared to chrome plating
Once the cylinder shaft or rod is assembled
into a cylinder and put into service the hydraulic fluid on the
surface provides additional corrosion resistance which is normally
sufficient to protect the shaft during its entire life. However,
there are occasions when the shaft is not being worked and when
the surface is exposed to a corrosive environment. For example,
brand new equipment may be stored outside for a considerable period
of time at a manufacturer's plant, or an equipment dealer may
hold inventory before it is sold. In these instances it is best
to provide some additional corrosion protection. An inexpensive
application of a rust preventative mixture can be applied to prevent
corrosion and thereby preserve the quality of the nitride and
the life of the cylinder.