Strategically located in the flow stream to collect a representative sample of wear debris circulating in the system: for example, engine swarf, bearing flakes, and fatigue chunks. The rate of buildup of wear debris reflects degradation of critical surfaces.



Related Terms

FATIGUE CHUNKS

Thick three-dimensional particles exceeding 50 microns indicating severe wear of gear teeth.

CUTOFF POINT

  1. The point at which there is a transition from spiral flow in the housing of a centrifugal fan to straight-line flow in the connected duct. 2. The point on the stroke of a steam engine where admission of steam is stopped.

FATIGUE PLATELETS

Normal particles between 20 and 40 microns found in gear box and rolling element bearing oil samples observed by analytical ferrography. A sudden increase in the size and quantity of these particles indicates excessive wear.

OIL GROOVE

A channel or channels in a bearing to improve oil flow through the bearing.

SCUFFING

Abnormal engine wear due to localized welding and fracture. It can be prevented through the use of anti-wear, extreme-pressure and friction modifier additives.

BOTTOM END BEARING

A bearing at the larger (crankshaft) end of a connecting rod in an engine.
Made of cast steel and each consist of an upper and lower part secured to the connecting rod by means of fitting bolts, the nuts of which are secured. Compression shims are provided between the bottom end bearing and the palm of the connecting rod.
The bearings have white metal bearing surfaces provided with lubrication grooves for the necessary supply of lubricating and cooling oil. Shims of different thickness are inserted between the shells to enable adjustment of the bearing clearances (approx. 0.20-0.30mm).

BIG END BEARING

A bearing at the larger (crankshaft) end of a connecting rod in an engine.
The bearings are made of cast steel and each consist of an upper and lower part secured to the connecting rod by means of fitting bolts, the nuts of which are secured. Compression shims are provided between the bottom end bearing and the palm of the connecting rod.
The bearings have white metal bearing surfaces provided with lubrication grooves for the necessary supply of lubricating and cooling oil. Shims of different thickness are inserted between the shells to enable adjustment of the bearing clearances (approx. 0.20-0.30mm).

ANALYTICAL FERROGRAPHY

The magnetic precipitation and subsequent analysis of wear debris from a fluid sample .This approach involves passing a volume of fluid over a chemically treated microscope slide which is supported over a magnetic field. Permanent magnets are arranged in such a way as to create a varying field strength over the length of the substrate. This varying strength causes wear debris to precipitate in a distribution with respect to size and mass over the Ferrogram. Once rinsed and fixed to the substrate, this debris deposit serves as an excellent media for optical analysis of the composite wear particulates.

GALLING

A form of wear in which seizing or tearing of the gear or bearing surface occurs.

TURBO CHARGER

The blades of a turbine in the outlet exhaust flow of an engine are driven by the gases flowing over them. Compressor blades at the other end of the same axle are spun in the inlet flow, drawing large volumes of air into the cylinders. This enables faster combustion than naturally aspirated engines and increases power of the engine.

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