O-ring for sealing reciprocating piston

[454Casull]

Parker recommends the use of a hard chrome plating on the bore for a reciprocating piston sealed with an O-ring. What are the qualities of hard chrome, besides hardness if any, that make it so suitable as a counter-wearing surface? Are newer coatings like TiN superior?

 

[hydtools]

Hardness and corrosion resistance.

Ted

 

[MikeHalloran]

Also, just the right friction coefficient and a little microporosity to retain a tiny bit of oil and carry it under/through the seal line to lubricate the o-ring.

Mating surfaces that are too smooth will rub the o-ring to death very quickly.

Be aware that you also need some axial clearance in the gland in a reciprocating application, to allow the o-ring to roll a little bit, again to carry oil under/through the seal line.



Mike Halloran
Pembroke Pines, FL, USA