Piston Rings

A piston ring must have both spring-like tension and the properties to become a true circle when closed. In the combustion chamber of engine, NPR’s piston rings serve to seal combustion gas, control lubricating oil, dissipate heat, and prevent wear and seizure under the severe conditions of operation. Now that engines are required to be more compact, lighter, and more sophisticated in performance, the choice of piston ring materials has been widened to include steel in addition to the traditional cast iron. Moreover, in order to enhance their wear resistance and durability, they also undergo various surface treatments including nitriding and PVD treatment.

For Gasoline Engines

1st ring : Steel + Cr
2nd ring : Cast iron
Oil ring : Nifflex-S (3 piece type)

1st ring : Steel + Cr
2nd ring : Steel + Nitriding
Oil ring : Nifflex-H (3 piece type)

1st ring : Steel + PVD
2nd ring : Cast iron
Oil ring : 2 piece type with high traceability + PVD

In these environmentally aware times, progress is being made in the introduction of low-emission cars for NOX and HC reductions and in the control of fuel consumption for CO2 reduction. To achieve these purposes, the following techniques have been developed and incorporated in the design of piston rings.

• Piston ring combination for low-friction
• Thinner width compression-and oil control rings
• Advanced surface treatments, and high-durability, low-cost materials
• Optimum design through tuning techniques

For Diesel Engines

For Passener Car Diesel Engines

This is a ring set to meet high speed use and high durability. Steel material is adopted on 1st ring and 2 piece oil ring. Nitriding or PVD treatment is made on 1st ring and oil ring.

For Middle/large Vehicle : diesel engines(3 ring pack)
For large vehicle diesel engines

This is a set of all steel piston rings to meet the high output and emission regulation. For the 1st (2nd) rings, keystone shape for prevention of sticking are approved, and PVD treatment is made so as to enhance wear resistance and scuffing resistance. Narrow width and weight reduction enabled with production by steel.

For Motor Cycle Engines

For Two-stroke Motorcycle Engines/for Four-stroke Motorcycle Engines
Steel ring pack for high speed engines: Both of Compression/Oil rings are made of steel. Oil ring is NX95F type applicable for ultra thinning design.

A chromium plated cast iron 1st ring of proven stability is included along with a chromium plated cast iron two piece oil ring or a steel 3 piece oil ring(Nifflex-S).