A dose feeder grease system is a type of centralized lubrication setup that delivers a fixed volume of grease to each lubrication point during every pump cycle. Unlike continuous-flow systems, a dose feeder meters lubricant in discrete amounts, making it ideal for bearings, gears, and sliding surfaces that need small, repeatable grease quantities at controlled intervals.
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How a Dose Feeder Works
The pump builds pressure in a main supply line. When the line reaches operating pressure, each dose feeder or metering unit opens and dispenses a calibrated volume of grease to its assigned point. After the feed is complete, pressure is relieved and the feeder resets, ready for the next cycle.
The key advantage is precision: every point receives the same amount of grease regardless of line length or back pressure, as long as the feeder is sized correctly.
Common Dose Feeder Configurations
| Type | Principle | Best For | Typical Dose Range |
|---|---|---|---|
| Piston dose feeder | Positive-displacement piston meters fixed volume | Individual bearings needing precise dosing | 0.05–2.0 ml per cycle |
| Progressive divider | Sequential pistons divide flow in fixed order | Multiple points with blocked-line detection | 0.07–2.0 ml per outlet per cycle |
| Injector feeder | Spring-return injector dispenses under line pressure | Single-line resistance systems | 0.05–0.5 ml per cycle |
Applications for Dose Feeder Grease Systems
- Machine tool bearings — spindles, slides, ball screws that need small repeated doses.
- Printing and packaging machinery — chains, cams, and rollers on continuous production lines.
- Steel and paper mills — large bearings with long supply lines and infrequent but heavy cycles.
- Wind turbines — main bearing and pitch bearing lubrication with remote monitoring.
- Mobile equipment — compact systems where reservoir size and dosing accuracy matter.
Benefits of Dose Feeder Lubrication
- Controlled grease volume prevents over-lubrication and waste
- Each point is metered independently based on its needs
- Compatible with long distribution lines and multiple outlets
- Works with timers, PLCs, and machine interlocks
- Reduces manual greasing and unplanned downtime
Dose Feeder vs. Continuous Flow Systems
| Feature | Dose Feeder Grease | Continuous Flow Oil |
|---|---|---|
| Lubricant volume per cycle | Fixed, measured dose | Continuous or variable flow |
| Primary lubricant | Grease or thick oil | Low-viscosity oil |
| Best application | Points needing periodic replenishment | High-speed bearings and gearboxes |
| Monitoring | Cycle count, pressure switch | Flow meter, temperature, oil level |
Sizing and Selecting a Dose Feeder for the Application
Choosing the right dose feeder starts with the required grease volume per point, not just the pump pressure. Begin by listing every lubrication point, the bearing or surface type, operating speed, and ambient temperature. Small bearings on machine tools may need only 0.05–0.2 ml per cycle, while large steel-mill bearings may need 1.0 ml or more. Once the per-point dose is known, select feeders whose adjustable range covers that volume at the system’s normal operating pressure.
Next, match the feeder architecture to the machine layout. Progressive dividers work well when blocked-line detection is important because a single blocked outlet stalls the entire sequence. Single-line injector systems are simpler to expand but need individual monitoring if a blocked injector must be detected. Always confirm that the feeder passages are large enough for the planned NLGI grade; stiffer greases need wider bores and stronger return springs. If the system mixes feeder brands, verify port thread types and pressure ratings match across the central lubrication system.
Monitoring and Troubleshooting Dose Feeder Systems
Dose feeder systems need feedback to confirm that grease actually reaches each point. The simplest monitor is a visual indicator pin on a progressive divider: if the pin does not move during a pump cycle, the divider has not completed its sequence. More advanced systems use cycle sensors, pressure switches, or flow sensors that report to a PLC or machine controller.
Common faults include blocked outlets, worn piston seals that allow internal bypassing, and air trapped after a refill. When one point appears under-lubricated, first verify the feeder setting, then check for a blocked line by temporarily removing the outlet fitting and cycling the pump. If grease flows freely from the feeder but not to the bearing, the restriction is downstream. Keep a log of cycle counts and alarm events to identify degrading performance before it causes a failure.
Frequently Asked Questions About dose feeder grease
Can dose feeders handle both grease and oil?
Yes, but the feeder must be selected for the lubricant viscosity. Grease feeders use larger passages and stronger springs than oil feeders. Always confirm the NLGI grade or oil viscosity with the supplier.
How do the engineer size a dose feeder for a bearing?
The required dose depends on bearing size, speed, and operating temperature. A common starting point is a small amount per cycle, then adjust based on inspection and operating hours.
What happens if one feeder is blocked?
In progressive systems, a blocked outlet stops the entire sequence, which is easy to detect. In single-line injector systems, other injectors may continue to operate, so individual monitoring is recommended.
How do the engineer calculate the required dose per cycle for a dose feeder?
Start with the bearing manufacturer’s recommended grease quantity per unit of time, then divide by the planned cycle frequency. For example, if a bearing needs 2 ml per hour and the system cycles every 15 minutes, set the feeder to deliver 0.5 ml per cycle. Fine-tune based on inspection and operating temperature.
What sensors can detect a blocked dose feeder?
Progressive dividers can use mechanical indicator pins or proximity sensors that confirm the divider completed a full cycle. Single-line injector systems may use pressure switches, cycle counters, or individual flow sensors. A pressure switch alone cannot locate a single blocked outlet, but it can signal that the system has not reached normal operating pressure.
Need Help Sizing a Dose Feeder System?
Send ISOHITECH the point count, bearing types, lubricant grade, and cycle frequency. ISOHITECH can recommend the right pump, feeder type, and tubing size for a reliable dose feeder grease system.
Related resources: oil lubrication pumps · gear lube oil pumps · central lubrication systems · grease pump working principle.
