Determining inductive sensor wear debris limits for rolling contact fatigue of bearings

Abstract

A relatively recent development for the condition monitoring of oil-wetted machinery has been the in-line full-flow inductive wear debris sensor (hereafter referred to as inductive wear debris sensors). These sensors detect a disturbance to a magnetic field caused by metallic wear debris shed from deteriorating dynamic components that is entrained in the lubricant. Applications for these sensors currently include (but are not limited to) aviation machinery, wind-turbine generators, marine propulsion systems, and locomotives. Inductive wear debris sensors can distinguish between ferromagnetic and nonferromagnetic particles as well as providing size and other related information. One of the primary advantages of this sensor type is that the detectable size range is broad and may be used to track the progress of an incipient failure such as the rolling contact fatigue of a bearing or gear as it occurs. One aspect that has received little attention in the literature is the methodology for determining a suitable limit for a particular application. Limits are a critically important aspect of machinery condition monitoring and need to be established by a robust and reliable method otherwise unnecessary maintenance can occur or an incipient fault may be missed. This paper describes a generic method for determining a physically meaningful debris limit for a deteriorating rolling element bearing when utilizing an inductive wear debris sensor.

On the impact of fine filtration on spectrometric oil analysis and inductive wear debris sensors

“…The data from the IWDS were constantly monitored for each test and the rig was stopped when a predetermined limit was reached. 18 The lubricant used for these tests was a MIL-PRF-23699 synthetic turbine oil (polyol ester). Oil samples (25 ml) were taken from a sampling point fitted to the scavenge line immediately prior to the reservoir (Figures 3 and 4) approximately every 3 h of running time.…”

Health indicator metrics applicable to inductive wear debris sensors

“…A series of accelerated seeded fault tests were conducted in a bearing test rig ( Figure 4) to produce RCF damage in an angular contact ball bearing (NTN 7006UCGD2/GNP4) under axial loading. The primary purpose of the experiments was to compare a calculated cumulative limit and predicted spall area with the actual inner race damage area 4 ; however, the data were also used to validate the HI and subordinate CI metrics. The test rig incorporated a MetalSCAN 7.6 mm bore IWDS in the lubricant scavenge line to detect liberated metallic debris from the test bearing.…”

“…The data from the IWDS were constantly monitored for each test and the rig was stopped when a predetermined limit was reached. 4 The lubricant used for these tests was a MIL-PRF-23699 synthetic turbine oil (polyol ester). A total of six bearings were tested and comparable RCF damage areas were observed in each case (Table 1 and Figure 5).…”

“…Previous work described a method for determining a cumulative wear debris limit for rolling element bearings where an IWDS is employed. 4 One of the issues identified was how to prevent particles not associated with incipient damage distorting a cumulative count (e.g. short bursts of residual overhaul particles sometimes observed).…”

Multichannel Inductive Sensor Based on Phase Division Multiplexing for Wear Debris Detection

“…Many methods have been developed for real time wear debris detection, such as bulk measurement, capacitance, inductance, acoustic, and optical/imaging detection [1,2,3,4,5]. Among these methods [6,7,8,9,10], an inductive sensor is proved to be the most practical method for the following reasons. Inductance detection could differentiate between ferrous and nonferrous debris [11,12], and it is insensitive to air bubbles and water droplets [13,14].…”