At Hastings Manufacturing, we know piston rings, and we want to pass that knowledge on to you. In this video, we’re going to cover the general purpose of coatings on rings.
Basically, coatings are put on rings to improve performance in the piston. It is not required that rings have a coating, although these are typically only used for basic duty.
Chrome plate coatings are hard and wear very well. However, it has lower scuff resistance than other coatings.
Plasma sprayed molybdenum or moly is not as hard as chrome; the porosity holds lube oil and has high scuff resistance.
Nitride is wear resistant and it allows the use of steel rings in coated cylinders.
PVD is very hard, has very high scuff resistance and very low coefficient of friction. PVD is placed on hard surfaces like nitrided steel. Without a hard backing, the brittle PVD would break loose.
Flash chrome is used to reduce wear on the sides of rings and keep them from sticking.
Both manganese phosphate and black oxide coatings promote ring seating on dry start-ups and act as a mild rust preventative.
Thanks for watching. We hope this video was helpful. Feel free to leave a comment on our YouTube Page and be sure to watch our other Tough Guy Tech Tip videos to learn more.