Rail and screw failures are almost never sudden. They start as a 0.002 mm change in backlash, a faint discoloration on a raceway, or a wiper that has stopped touching. All three are visible long before the axis loses tolerance — if anyone looks. A maintenance schedule exists to make someone look on a fixed date rather than after a reject.
The service schedule
| Interval | Task | Failure it prevents |
|---|---|---|
| Daily | Wipe the table and check wipers for gaps | Swarf ingress into the rail raceway |
| Weekly | Wipe rails and re-grease the visible rail surface | Dry running, fretting corrosion |
| 500 h | Grease blocks and nut; check bellows for cracks | Lubricant starvation, coolant ingress |
| 2,000 h | Measure backlash; check straightness at three points | Undetected nut wear, frame settlement |
| 5,000 h | Inspect wiper lips and replace if worn; check coupling | Contamination, coupling fatigue |
| 10,000 h | Replace bellows and wipers; bearing noise check | End-of-life seals, bearing failure |
The 2,000-hour measurement is the one that matters most. Backlash doubles before a nut fails, and a doubling between two checks means the nut is at the end of its preload life. Replacing a nut on schedule costs a fraction of replacing a screw and a nut after a seizure.
Lubrication: quantity and type both matter
Lithium-based grease with a base oil viscosity around 100 cSt is the default for a standard slide table. A block that is over-greased churns and heats; a block that is under-greased films and wears. The correct quantity is the one that shows a thin bead at the wiper after a stroke — no bead means dry, a heavy extrusion means too much.
Never mix grease types. Lithium and calcium-thickened greases are incompatible and produce a soap that hardens in the block. If you change supplier, purge the block completely rather than topping up.
Contamination is the number one killer
In a machining environment, more slide tables fail from swarf and coolant than from load. A wiper that has lost its lip still looks like a wiper. Check it by running a fingernail along the lip: if the lip does not spring back, it is no longer sealing.
Wiper check
Two minutes, once a month, prevents the most common failure mode on a wet machine.
- Lip condition
- Springs back, no flat spot
- Contact
- Touches rail full width
- Debris behind lip
- None visible
- Action if failed
- Replace wiper, clean rail, re-grease
Measuring backlash in two minutes
Mount a 0.001 mm indicator on the table, command a 0.1 mm move in one direction, zero the indicator, then command 0.1 mm in the reverse direction and read the lost motion. Do it at the centre of travel and at both ends, because a nut wears unevenly if the axis works in a narrow band.
Record the number. A trend is more useful than a single reading: 0.004 mm steady over a year is fine, 0.004 to 0.008 in three months is a nut on its way out.
Common failures and what they mean
- Tight spot mid-travel — rail is bent or the mounting surface is not flat. Re-shim; do not increase motor torque.
- Noise at one end of travel — coupling misalignment or screw bearing wear. Check coupling runout first.
- Growing backlash — nut preload relaxed or wiper failure allowing contamination. Measure, then inspect the raceway.
- Position drift through the shift — thermal growth, not wear. Add warm-up cycles or a scale; do not re-tune the servo.
- Chatter at extended travel — moment load or carriage stiffness, not lubrication. Check the load offset before rebuilding.
What to keep on the shelf
For a machine in production, stock one wiper set, one bellows and one coupling per axis type. Those three parts cover the failures that stop a machine for a day. A spare nut is worth holding if the axis runs continuously, because preload life is finite and predictable from the backlash trend.
Every TEBAK shipment includes the lubrication and maintenance sheet with the part numbers of the wear items for that specific assembly. If a slide has been in service long enough that the sheet is lost, send us the model and serial from the plate and we will reissue it with current part numbers.
Common questions
Every 500 hours of operation, or monthly, whichever comes first. Coolant washes grease out faster than clean operation, so the interval shortens by roughly half in a wet environment.