Materials and Coatings

LPR Rings are manufactured from a particular raw material whose composition, hardness and micro-structure are thoroughly tested to ensure the highest standards of quality.

GREY CAST IRON - A Pearlitic medium Phosphorous Grey Iron, because of its inherent wear resistance, good machinability and relatively low cost is the most common basic material being used for normal engine application, intermediate and oil control rings.

For top rings, ALLOYED CAST IRON duly heat treated with better physical properties, proper & uniform hardness and microstructure is also being used. It posses high bending strength & is recommended for heavy duty engines.

For high RPM engines and automotive applications rings are also being made from NODULAR IRON (S.G./DUCTILE IRON) being one of the highest tensile strength material. High strength ductile material is best suited for rings which are subjected to heavy thermal loads & high dynamic stresses. These rings have high resistance against bending , wear & breakage.

Wear resistance coatings as CHROME PLATING & MOLYBDENUM SPRAY are being used for enhancing the life and working conditions of Piston Rings. For some specific applications COPPER COATING on the periphery by spray is also applied.

MANGANESE PHOSPHATE, a chemical etching of the surface and TIN PLATING are two types of surface treatments to assist the initial run-in of the ring and to protect it from rusting.

 

Chemical Composition

ELEMENT
UNIT
VALUE
GCI
VALUE
ACI
VALUE
S.G
TOTAL CARBON % 3.35 TO 3.70 3.30 TO 3.80 3.50 TO 4.00
SILICON % 2.25 TO 2.70 2.40 TO 3.00 2.10 TO 2.50
MANGANESE % 0.60 TO 0.90 0.60 TO 0.80 0.20 TO 0.50
CHROMIUM % 0.20 TO 0.40 0.20 TO 0.40 MAX 0.20
PHOSPHOROUS % 0.20 TO 0.35 0.15 TO 0.35 MAX 0.30
SULPHUR % MAX 0.10 MAX 0.10 MAX 0.05
COPPER % MAX 0.35 0.35 TO 0.60 -
MOLY % - 0.45 TO 0.60 -

Note:- Wide range in the above mentioned values is for different sizes & different applications of rings.

Micro structure
Graphite
  • Magnification*100

  • For Grey Cast Iron & Alloyed Cast Iron-
    Uniformly distributed graphite with random orientation.
    Size fine to medium 4 to 6
    Predominately type A & B

  • For S.G.Iron
    Uniformly distributed Spheroidical 
    Graphite
    Size 5 to 6

Matrix

  • The Matrix is essentially pearlitic and is free of ferrite and cementite and is uniformly distributed. In  GCI & ACI ferrite does not exceed 5%, if at all present . 

  •  For S.G.Iron Matrix is tempered martensite

Phosphide

  • Fine and uniformly distributed , not
    forming a network . 

Hardness
  • The hardness of the Piston rings is 205 
    to 325HB

                                                    | HOME  | PROFILE  | QUALITY  | PRODUCTS  | 
                                                     | MATERIALS & COATINGS | RANGE | CONTACT US |