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Inspection of Contaminants in the Space Expander of a Piston Ring

Piston ring
An example of a space expander


The oil ring portion of a piston ring distributes the required layer of oil that enables a piston to slide easily inside a cylinder. If a foreign object or material is attached to the surface of the space expander on the oil ring, the oil layer will no longer be adequate, and the piston will not move smoothly. Exclusion of such contaminants is, therefore, critical to piston performance.


Accurate analysis of foreign objects on the surface of space expanders plays an important role in maintaining and improving engine efficiency. It is important to select inspection equipment that is well-suited for this purpose.


The inverted design of the Olympus DSX digital microscope enables nondestructive observation of a piston of any size. Its 3D image acquisition function provides a detailed display of foreign material through a profile measurement that includes width, height, or other dimensions. The microscope can be used to identify foreign material, which helps highlight any manufacturing processes that may be the source of this commingled foreign material.


Piston ring SE_ob20X_3D
A foreign object on the surface of a space expander, as observed with a 20x objective lens

Piston ring SE_ob5X_3D
The surface of a space expander, as observed with a 5x objective lens

Olympus IMS
Products used for this application

Better images and results. DSX1000 digital microscopes enable faster failure analysis with accuracy and repeatability.

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