Wear starts before the noise
Oil wear debris monitoring detects the ferrous particles a gearbox, engine or hydraulic system sheds as it wears, while the machine is running. WearDetect captures that debris magnetically and reports how much fine and coarse debris has been caught, plus water presence and oil temperature, so maintenance can follow condition rather than the calendar.
How does oil debris monitoring detect wear early?
Gears and bearings shed metal into the oil as they wear, often days or weeks before vibration, temperature or noise changes. An online debris sensor such as Gill WearDetect counts ferrous particles in the oil continuously and reports the trend to the machine’s control or monitoring system, so maintenance can be planned around the condition of the machine.
Gears and bearings do not fail all at once. They wear, and as they wear they shed metal into the oil.
That debris is the earliest physical evidence of a developing fault. It is there days or weeks before vibration changes, temperatures rise or a noise appears.
Scheduled maintenance works on averages. Two identical gearboxes on the same duty can wear very differently, and a fixed interval treats them the same.
Watching the debris in the oil, continuously, turns an interval into a decision based on the machine in front of you.
The evidence is inside the machine
Condition monitoring is only useful if it sees the change early enough to act and reports it somewhere someone will look. Sampling, access, timing and interpretation all decide whether it does.
An oil sample sent to a laboratory is detailed but occasional. A magnetic plug is simple but has to be removed and inspected by hand. Online debris sensing sits between the two: continuous, in the machine, reporting into the system that already watches it.
A sample is a snapshot
Laboratory oil analysis tells you a great deal about one moment. Wear keeps developing between samples.
Fine and coarse mean different things
A steady rise in fine debris is normal wear. Coarse debris is the signal that the wear has changed. Telling them apart is the point.
Fine and coarse ferrous debris
Water does its own damage
Water in oil attacks bearings and breaks down the lubricant. Detecting its presence is part of the same job.
Water presence | Oil temperature
The reading has to reach the control system
A sensor nobody reads is an ornament. The output has to arrive in the PLC, SCADA or vehicle system already in use.
0-10 V | 4-20 mA | CANbus | Modbus RTU
Four ways to watch wear
These methods complement each other. Most mature condition monitoring programmes use more than one.
| Consideration | Laboratory oil analysis | Vibration monitoring | Magnetic plug inspection |  Online debris sensing, WearDetect |
|---|---|---|---|---|
| What it detects | Wear metals, contamination and oil condition in detail | Changes in the machine’s dynamic behaviour | Ferrous debris caught on the plug | Fine and coarse ferrous debris, water presence, oil temperature |
| How often | Each time a sample is taken | Continuous or periodic | Each time the plug is removed | Continuous, in real time |
| Human effort | Sampling, shipping, reading reports | Analysis of vibration data | Manual removal and inspection | Reports into existing monitoring systems |
| Limits | Delay between sample and result | Some faults show late in vibration | Relies on inspection intervals | Targets ferrous wear, not non-ferrous debris |
| Best for | Detailed diagnosis and oil health | Rotating machinery faults such as imbalance and misalignment | Low-cost periodic checks | Early warning of ferrous wear between inspections |
WearDetect complements oil analysis and vibration monitoring rather than replacing them. It is the continuous early warning that tells you when a sample or an inspection is worth doing.
Debris sensing has limits too
Ferrous wear only
WearDetect detects ferrous, magnetic debris. Non-ferrous wear is outside its target, which is one reason it sits alongside oil analysis.
Water needs to be free water
Water presence detection needs around 10 per cent free water. It is an alert for significant contamination, not a moisture analyser.
Fitting shapes the result
The sensor fits as a smart sump-plug replacement or in a bypass circuit. Where it sits in the oil path affects what it captures.
A trend beats a threshold
The value is in how the debris count changes over time. Alarms work best once a baseline for that machine is known.
Debris counted as it happens
WearDetect uses a powerful magnet to capture ferrous wear particles suspended in the oil, then reports the quantity of fine and coarse debris captured. It suits oils, fuels and coolants, and fits a wide range of fittings.
WearDetect
Oil debris sensor
The oil debris sensor with a separate electronics enclosure for mounting flexibility, fitted as a smart sump-plug replacement or in a bypass circuit.
WearDetect with Display
Oil debris sensor with local readout
The same sensor with an integrated display, for machines where the reading needs to be visible at the equipment as well as in the data system.
Level sensing
Capacitive oil and fluid level
Oil level and oil condition are two halves of the same question. Capacitive level sensors report how much oil there is, continuously, with no moving parts.
insight
Watch the coarse count
Every oil-lubricated machine sheds some fine ferrous debris as it runs. That is normal wear, and on its own it says the machine is working.
Coarse debris is different. Larger particles come from surface fatigue, pitting and spalling on gears and bearings, the damage that precedes a failure. A rising coarse count is the machine reporting that its condition has changed.
That is why WearDetect reports fine and coarse separately. The ratio and the rate of change tell a maintenance team far more than a single total would.
The practical result is a planned intervention. A gearbox that is starting to fail can be scheduled for work at a convenient time, instead of stopping a line or a vehicle when it chooses.
Drives that cannot stop
KnowledgeCommon causes of bearing failure in gearboxes
The failure modes that oil debris monitoring is designed to catch early.
ApplicationGearbox wear monitoring on cranes
Debris monitoring on lifting equipment where downtime is expensive.
ApplicationConveyor drive condition monitoring
Continuous monitoring on drives that run all day.
ApplicationDrivetrain and machinery condition
Condition monitoring for renewable energy drivetrains.
Speak to our team
Tell us what you need to measure, where and under what conditions. We’ll help you work out the appropriate approach.
Wear monitoring questions
An oil debris sensor detects wear particles suspended in lubricating oil. WearDetect uses a magnet to capture ferrous particles and reports the quantity of fine and coarse debris captured. It also reports water presence and oil temperature.
Laboratory oil analysis gives a detailed picture of wear metals, contamination and oil health at the moment a sample is taken. Online debris monitoring, such as WearDetect, reports ferrous wear debris continuously while the machine runs. The two are complementary: online monitoring gives early warning, and oil analysis gives the detailed diagnosis.
Gearbox bearing failure commonly follows lubrication problems, contamination, water ingress, misalignment and overload, which lead to surface fatigue and spalling. As that damage develops, the bearing sheds ferrous debris into the oil, which is why debris monitoring can detect it early.
WearDetect is available with analogue 0-10 V or 4-20 mA outputs, or digital CANbus or Modbus RTU outputs. The output model is chosen to match the PLC, SCADA or vehicle system that will read it.
Yes. WearDetect can report water presence as well as ferrous debris and oil temperature. The datasheet notes a minimum of around 10 per cent free water for detection, so it is an alert for significant contamination rather than a precise moisture measurement.
WearDetect is fitted as a smart sump-plug replacement or in an oil bypass circuit, and a wide range of fittings is available. It is used on gearboxes, engines and hydraulic systems across industrial processes, power generation, transport and mining.