Piston ring and method for manufacturing a piston ring
AssigneeMahle International GmbH
InventorsThomas J. SMITH, Thomas STONG, Andrea C. PAUL, Alexander S. COOPER
Life of this patent
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Abstract
An unchamfered piston ring that is pre-treated by grit blasting to a defined roughness, followed by PVD coating with a metal nitride to a thickness of at least 10 μm, leaving peaks and valleys in the coated piston ring. The coated piston ring is then lapped to remove the peaks without penetrating the coating, so that valleys and plateaus remain in the coated surface. The resulting piston ring exhibits superior coating retention due to the increased surface area created by the grit blasting, and yet also superior performance, as the cavities remaining increase the porosity of the coating and thus enhance the lubrication of the ring.
Claims12
A method for manufacturing a piston ring, comprising;
- providing a piston ring base having an unchamfered face surface, and a gap between two gap surfaces of the ring;
- grit blasting the face surface to create a roughened texture having an average surface roughness Ra of 1.02-1.99 and Rz 6.28 to 9.05;
- depositing a coating on the roughened face surface and chamfer surface via physical vapor deposition, wherein the coating is applied at a thickness of at least 10 μm;
- and
- lapping the coating to remove peaks in the surfaces without penetrating the coating, so that the coated surfaces contain plateaus and valleys.
A piston ring comprising:
- a ring formed of a base material and having an unchamfered face surface that is surface roughened to a roughness average of between Ra of 1.02-1.99 and Rz 6.28-9.05;
- a coating disposed on at least the face surface, the coating being deposited by physical vapor deposition and then lapped to remove peaks without penetrating the coating, so that the surface of the piston ring contains plateaus and valleys, wherein the coating has a thickness of at least 10 μm.
Dependencies are inferred from the claim text.