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A ball screw can be accurate, but the machine will not hold that accuracy if its support bearing arrangement has the wrong stiffness, preload or mounting condition. Problems at the fixed end may appear as axial movement, heat, noise, unstable positioning or poor repeatability. Replacing the bearing by dimensions alone does not address those risks.
The correct choice starts with the complete designation and the screw-drive arrangement. This guide explains the main checks for replacement and new-build projects, using INA ZKLF1560-2RS-XL as a practical product example from the FONKIN BEARING range.
The fixed-end bearing locates the screw axially and helps the drive resist thrust in both directions. It also influences axial rigidity and positioning accuracy. Depending on the machine design, the opposite end may use a simpler support that allows thermal movement.
Axial angular contact ball bearings are commonly used at the locating end because their contact geometry is designed for axial load and rigidity. Some arrangements use matched individual bearings. Others use a compact double-row unit with mounting holes, seals and a defined internal setting.
Do not change from one arrangement to another simply because the boundary dimensions fit. Housing geometry, shoulder locations, clamping method, shaft accuracy and the machine builder's preload concept must also agree.
Begin with the complete bearing marking. Suffixes can identify seals, shields, design generation, preload, accuracy or other features. A basic number without its suffix may not describe the product installed in the machine.
For a useful technical review, collect:
Complete bearing designation and photographs of the marking
Machine maker, model and axis position
Ball screw diameter and support drawing
Maximum and normal screw speed
Axial load, duty cycle and acceleration, when known
Mounting orientation and lubrication condition
Required positioning accuracy and axial runout
Quantity, destination and required delivery date
If a bearing failed early, also record temperature, noise, lubricant condition and visible damage. That evidence may show that the original problem was caused by installation, contamination or alignment rather than product selection alone.
Schaeffler identifies ZKLF1560-2RS-XL as an X-life, double-row axial angular contact ball bearing for screw drives with fixing holes. It is a compact locating unit that can support axial loads in both directions as well as radial load.
The verified catalogue dimensions are:
| Item | INA ZKLF1560-2RS-XL |
|---|---|
| Bore diameter | 15 mm |
| Outside diameter | 60 mm |
| Width | 25 mm |
| Shoulder diameter d1 | 28 mm |
| Approximate mass | 0.43 kg |
The designation should be kept complete in the RFQ. ZKLF1560, ZKLF1560-2RS and ZKLF1560-2RS-XL should not be treated as interchangeable wording without checking the applicable catalogue and supplied product.
In this product designation, 2RS identifies a sealed version. Seals help retain lubricant and limit the entry of contaminants, but their friction and speed behaviour differ from a shielded version. The correct closure should therefore be selected from the application requirements rather than price or availability alone.
XL identifies Schaeffler's X-life design generation for this product. It is part of the complete designation and should remain on the purchase order when that exact product is required.
Suffix meanings are manufacturer- and product-family-specific. Never apply the meaning of a suffix from one brand to another without checking the correct technical source.
The Schaeffler technical publication lists the following performance data for ZKLF1560-2RS-XL:
| Performance item | Catalogue value |
|---|---|
| Basic dynamic axial load rating Ca | 19,600 N |
| Basic static axial load rating C0a | 28,000 N |
| Fatigue limit load Cu | 1,650 N |
| Limiting speed with grease nG | 8,200 min⁻¹ |
| Thermally safe operating speed nθr | 3,500 min⁻¹ |
| Bearing frictional torque MR | 0.2 Nm |
These values are not a promise that the bearing can run at one stated speed in every machine. Actual suitability depends on load, preload, lubrication, heat transfer, fit, adjacent components and duty cycle. The thermally safe speed and limiting speed also describe different constraints; buyers should not select from the larger number alone.
For a new design, use the manufacturer's calculation method and machine requirements. For replacement work, preserve the original arrangement unless an engineer has approved a change.
Not automatically. Schaeffler lists both sealed 2RS and shielded 2Z versions in this size, but their published speed and friction values differ. For ZKLF1560, the 2Z version has higher published speed values and lower listed frictional torque than the 2RS version. That does not make it a universal upgrade.
The closure also affects contamination protection and lubrication behaviour. Before changing from 2RS to 2Z, confirm the machine environment, lubrication plan, speed, temperature and the equipment manufacturer's approval.
A precision support bearing cannot correct an inaccurate housing or shaft. Dirt under a mounting face, damaged shoulders, uneven screw tightening or incorrect clamping can change alignment and load distribution. Excessive clamping can also create heat or affect the internal setting.
Before installation, check the bearing seat, shoulder, nut, housing face and fixing holes. Keep the bearing in its packaging until the work area is clean. Apply mounting force through the correct ring or mounting face, and follow the bearing and machine manufacturer's tightening procedure.
After assembly, rotate the screw through its travel and establish baseline temperature, noise and positioning data. A controlled test at increasing speed is more informative than starting immediately at full operating conditions.
A clear request can be short. It should still identify the exact product and the machine requirement:
Please quote INA ZKLF1560-2RS-XL, quantity __ pieces, for the fixed end of a CNC ball screw. Destination: __. Please confirm the complete designation, closure type, availability and documentation. The existing bearing marking and machine information are attached.
If alternatives are acceptable, ask the supplier to state every difference rather than quoting an unnamed “equivalent.” Compare dimensions, bearing arrangement, closure, accuracy, internal setting, load ratings, speed data and mounting features.
It is an axial angular contact ball bearing unit designed for screw drives. Its double-row arrangement and fixing holes distinguish it from a general-purpose single-row angular contact bearing.
The catalogue dimensions are 15 mm bore, 60 mm outside diameter and 25 mm width. The approximate mass is 0.43 kg.
No universal maintenance claim should be made from the suffix alone. The sealed design is supplied for defined lubrication and protection conditions, but service decisions still depend on the manufacturer guidance, machine design and operating environment.
An alternative can be evaluated, but matching 15 × 60 × 25 mm dimensions is not enough. The arrangement, mounting holes, closure, accuracy, preload or internal setting, load ratings and speed capability must also be compared.
Selecting a ball screw support bearing requires more than finding the same bore, outside diameter and width. The bearing arrangement, suffixes, closure, load, speed, mounting accuracy and machine design all affect the result. INA ZKLF1560-2RS-XL is a useful example because its complete designation identifies a specific sealed, double-row screw-drive bearing unit.
FONKIN BEARING can review complete designations, marking photographs and bearing lists for CNC and industrial screw-drive applications. New customers may send the quantity, destination and application information by WhatsApp at +86-187-5155-1686 or email fonkin-industries@188.com.
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