Lubrication interval: count the kilometres, not the months

2026-11-06

# Lubrication interval: count the kilometres, not the months

Most maintenance schedules say "re-grease quarterly". That is a guess dressed as a procedure, and it fails in both directions: the axis that runs eight hours a day is under-lubricated, the one that moves twice a week is over-lubricated and quietly collecting debris.

The correct unit is distance, and the number you need is the travel distance since the last grease, not the date.

Why distance is the right unit

Grease is displaced by every pass of every ball. The failure mode is not evaporation, it is the film being pushed off the raceway and not returning. That happens per kilometre of travel, not per month of calendar.

A rough working schedule for a clean, indoor, normal-load application:

The first interval is shorter on purpose. The initial grease charge settles and the block seats against the rail in the first tens of kilometres.

How to work out the distance

Distance is not the stroke multiplied by the cycle count — it is the stroke plus any overtravel, times the number of cycles.

km per month = (stroke_mm + overtravel_mm) × cycles_per_month / 1,000,000

A 500 mm stroke reciprocating 20,000 times a month:

500 × 20,000 / 1,000,000 = 10 km per month

At 10 km a month and a 1,000 km interval, the honest answer is every 8 years — which explains why some machines never need greasing and their operators conclude that lubrication does not matter.

Now the same machine at 400,000 cycles a month: 200 km a month, so a re-grease every five months. Same guide, same calendar, twenty times the wear.

What to do when the distance is high

Above roughly 1,000 km a month, manual greasing stops being practical. Three options:

1. An automatic lubricator feeding the block through the side or end port. This is what our E2 self-lubricating type is for — but note it solves the "nobody remembers" problem, not the "contamination" problem.
2. A centralised lubrication system if the machine already has one, taken off the same pump with a metering valve.
3. A larger block size run at lower relative load, which tolerates longer intervals.

The two things people get wrong

Over-greasing is not free. Excess grease pushes out past the wiper carrying dust with it, and on a vertical axis it can run down and pool at the bottom of the stroke. Follow the specified fill volume, not "until it comes out".

The wiper matters more than the grease. A worn wiper lets abrasive into the block, and no lubrication interval will save it. When you service, look at the lip of the wiper: once it is cut or hardened, replace it before it starts grinding.

What to send with an enquiry

If you want us to size the lubrication interval rather than guess:

1. Stroke, and whether there is overtravel
2. Cycles per hour, and hours per day
3. Environment: clean, dust, coolant, washdown
4. Mounting orientation — vertical axes are more sensitive to over-greasing

Three of those four you can read off the machine, and they turn a guess into a schedule you can put in a maintenance manual.