RIKEN CORPORATION

Piston Ring Museum

Technologies that Assure Ring Function

C-7 Serving a Broad Range of Applications

Engines come in a variety of shapes and sizes depending on the application. There are applications requiring enormous engine output as well as applications needing engines that can be hand carried. A piston ring designer must take the specific nature of the particular application into account when deciding upon ring characteristics.

Piston Ring Size

Piston rings are manufactured in all sizes from finger ring size to larger than 1 meter in diameter. Used for lawn & garden equipment and marine engines respectively, these sizes represent the extreme ends of the piston ring size range. The greatest numbers of rings are produced for automobile and light truck engines with diameter sizes ranging from 70mm to 100mm in diameter.

Piston Ring Siz

Piston Ring Cross-Sectional Shapes

The cross-sectional shape of the ring will vary and is determined by such factors as which ring it is (i.e., top, second, oil), which functions it has to perform, what material and/or surface coating is called for and by the particular engine application.

Piston Ring Cross-Sectional Shapes

Working Face Profile

The working or running face of the upper and lower compression rings will show one of the following configurations:

orking Face Profile

Gap Shape

The ring gap creates a possible gas leakage path. In certain applications, special gap shapes are designed to minimize the gap clearance in order to decreases unwanted gas leakage.

Gap Shape

Surface Treatments

A number of different surface treatments are applied, depending upon the engine's particular application and the design concept of the power cylinder system. It must be emphasized that the inter-related power system components, the cylinder, the piston, and the piston rings, must all be optimized for the specific application and bring similar qualities of high performance and long service life.

Typical Surface Treatment Tchnology for Piston Ring
Type of Surface Treatment Application Applicable Engine
Surface treatment Symbol Hardness(HmV) Rust
prevention
used
together
with
rust
preventives
Initial-
break-
in
Wearresis-
tance
Side
wear
prevention
Side
stick
prevention
Aluminum
alloy
cylinder
Inner
grove
wear
prevention
Gasoline
engine
Diesel
engines
Unleaded Leaded
Electro-plating Hard chromium plating (Sinding faces) Cr 800~1100        
Side chromium plating   800~1100            
Circumferential chromium plating   800~1100              
Copper plating Cu 90~620                
Nitriding Gas Nitriding GN 700<        
Deposition Ion plating IP 850<            
Composite electro-plating Nickel base CPN 800~1100          
Spraying Metal spraying RF 700<              
Ceramic spraying RF 700<              
Spray coating Tough-RIK                  
Compound processing Phosphoric zing film RPK-10 -            
RPK-11 -            
RPK-12 -              
Phosphoric manganese film RPK-25 -          
RPK-26 -          
RPK-27 -          
RPK-28 -          
Ferox treatment RPK-30 -              
Electro-plating+Reverse current treatment QB chromium plating QBC 800~1100