Linear guideway running resistance is the force required to keep a guide block or moving table traveling along its rail after motion has started.
It is not determined by the rolling friction coefficient alone. The measured force also includes resistance from preload, seals, lubricant, ball or roller circulation, mounting error, contamination, temperature and other components connected to the moving table.
A linear guideway can therefore have a very low theoretical rolling-friction force but still require a noticeably higher pull force in the assembled machine. To judge whether the resistance is normal, the guide type, block quantity, preload, sealing arrangement, lubrication condition and installation structure must all be known.
What Is Included in Linear Guideway Running Resistance?
The term "running resistance" is sometimes used as if it were identical to the coefficient of friction. They are related, but they are not the same parameter.
| Term | Meaning | Typical Unit |
|---|---|---|
| Friction coefficient μ | A dimensionless reference describing the load-dependent rolling-friction relationship | No unit |
| Starting resistance | Peak force required to begin moving the block or table from rest | N or kgf |
| Running resistance | Force required to maintain movement at a defined constant speed | N or kgf |
| Resistance fluctuation | Difference between the maximum and minimum force measured through the stroke | N or percentage |
| Complete-axis resistance | Total resistance from guide blocks, seals, drive system, cable chain, covers and other moving components | N, motor torque or motor current |
Starting resistance and steady running resistance should be recorded separately. A block may require a higher force to begin moving because the grease and seals have remained stationary, but its force may decrease after movement starts.
Resistance fluctuation is often more useful than one average value. A guide that requires a consistent force through the entire stroke may be normal for its preload and sealing arrangement. A sharp force peak at one position is more likely to indicate a local installation or damage problem.
The measured pull force of a guide block includes rolling contact, preload, lubricant, internal circulation and seal resistance.
How to Estimate Linear Guideway Running Resistance
A commonly used preliminary calculation is:
| Symbol | Meaning | Unit |
|---|---|---|
| F | Estimated total running resistance | N or kN |
| μ | Reference coefficient of rolling friction | No unit |
| W | Normal load supported by the guide block or guide system | N or kN |
| S | Additional resistance from seals, lubricant, rolling-element circulation and other approximately load-independent effects | N or kN |
For preliminary reference, ball-type profile linear guideways are often calculated using a rolling-friction coefficient of approximately 0.004, while roller-type guideways may use approximately 0.003.
Example: Rolling-Friction Component of a 100 kg Table
Consider a horizontal moving table with a total mass of 100 kg supported by ball-type linear guides.
The approximate normal load is:
Using μ = 0.004, the load-dependent rolling component is:
This does not mean the complete table should require only 3.9 N to move. The seals, grease, preload and block circulation resistance must still be added.
In a lightly loaded guide system, these additional components may represent a larger proportion of the measured pull force than the load-dependent rolling friction.
Total Resistance with Multiple Guide Blocks
If a table uses several guide blocks, the resistance of all blocks contributes to the total pull force.
If four blocks support a balanced table, the total normal load is distributed among the four blocks. The load-dependent term remains related to the total supported load, but the seal and internal resistance of four separate blocks are added together.
Adding more blocks can improve load distribution and moment rigidity, but it does not automatically reduce total running resistance. It may increase total seal resistance and make the system more sensitive to rail alignment and table flatness.
In a multi-block system, the load is shared, but the sealing and internal resistance of each block contribute to the total pull force.
Why Low Load Does Not Always Mean Very Low Resistance
When the external load is small relative to the guideway's static load capacity, the μW portion of the equation is also small. The measured resistance may then be dominated by grease viscosity, seals and rolling-element circulation.
This explains why a large guide block carrying a very light table may feel tighter than expected. The guide has been selected far above the required load, but its larger seals, greater lubricant volume and selected preload still create resistance.
| Operating Condition | Main Resistance Source | Selection Implication |
|---|---|---|
| Light load with oversized blocks | Seals, grease and preload may dominate | Do not select guide size from load capacity alone |
| Higher external load | Rolling-contact force becomes a larger part of total resistance | Calculate actual block load and required service life |
| High preload with light load | Internal preload can exceed the useful external load effect | Select preload from rigidity requirements rather than assuming higher is better |
| Dust-proof or double-seal configuration | Additional contact between seal lips and rail surfaces | Balance contamination protection against the permitted drive force |
Main Factors That Change Linear Guideway Running Resistance
1. Preload
Preload applies an internal force between the rolling elements and raceways before the guideway carries the external machine load.
Increasing preload can reduce clearance, increase rigidity and improve resistance to vibration or elastic displacement. It also increases contact force and generally raises running resistance, drive torque and heat generation.
A light and fast automation axis should not automatically use heavy preload. A machine-tool axis exposed to cutting force may accept higher resistance because rigidity is more important.
For preload selection, see What Is Linear Guide Preload and How Should It Be Selected?
2. Seal Type and Quantity
End seals, bottom seals, double seals and scrapers help prevent dust, chips and coolant from entering the block. These accessories normally contact the rail and create additional resistance.
A block fitted with double seals and a scraper should not be expected to have the same pull force as the same block with standard sealing.
Seal resistance may also change when the seal is dry, damaged, incorrectly assembled, swollen by an incompatible chemical or pressed unevenly against the rail.
3. Lubricant Type and Quantity
Grease viscosity, base oil, consistency and additive system affect running resistance. A lubricant designed for heavy load may create a different force from one intended for high-speed or low-temperature operation.
Insufficient lubricant can increase metal-to-metal contact, noise and wear. Excessive grease can also raise resistance because the rolling elements must repeatedly push and shear the excess lubricant inside the circulation path.
A newly lubricated block may initially feel tighter. The force should be evaluated after several full strokes have distributed the lubricant rather than immediately after a large amount of grease has been injected.
4. Temperature
At lower temperature, grease and oil become more viscous and can increase running resistance. As the guide warms, the lubricant may flow more easily and the measured force may decrease.
However, resistance that continues increasing as the machine warms can indicate thermal misalignment, excessive preload, table deformation, bearing problems or insufficient thermal clearance elsewhere in the axis.
5. Speed
Running resistance should be measured at a defined speed because lubricant shear, seal behavior and circulation conditions can change with velocity.
A hand-pull test is useful for detecting tight spots, but it cannot completely predict the resistance or temperature of a continuously operating high-speed axis.
6. Mounting Accuracy
Incorrect rail parallelism, uneven mounting surfaces, burrs, debris under the rail and improper bolt tightening can force the blocks to operate with an unintended side load.
In a dual-rail system, even if each individual rail and block meets its manufacturing specification, the assembled table can become tight when the two rails are not aligned to each other.
Higher-preload guideways are less able to absorb mounting error. The installation accuracy must therefore be matched to the selected preload.
For the complete installation procedure, see How to Install Linear Motion Guides .
7. Worktable Rigidity
Tightening a thin or distorted worktable onto four guide blocks can pull the blocks away from their natural alignment.
If the blocks move smoothly before the table plate is tightened but become stiff afterward, the problem may come from the table mounting surface, block-height variation or tightening sequence rather than from the rail itself.
8. Contamination and Damage
Dust, metal chips, dried coolant or damaged raceways can create local peaks in resistance. Contamination mixed with grease can also produce a gradual increase across the full stroke.
Adding fresh grease on top of contaminated lubricant may hide the symptom temporarily without removing the abrasive particles.
Ball Guide vs Roller Guide: Which Has Lower Running Resistance?
A roller-type guideway may use a slightly lower reference rolling-friction coefficient than a ball-type guideway. This does not mean every roller guide has a lower measured pull force.
| Characteristic | Ball-Type Guideway | Roller-Type Guideway |
|---|---|---|
| Rolling element | Steel balls | Cylindrical rollers |
| Reference friction coefficient | Approximately 0.004 | Approximately 0.003 |
| Main advantage | Smooth movement, versatile performance and suitability for high-speed automation | Higher rigidity and lower elastic deformation under heavy load |
| Actual pull force | Depends on size, preload, seals, grease and mounting | Also depends on size, preload, seals, grease and mounting |
| Selection priority | Balanced load, speed, smoothness, size and cost | Heavy load, high moment and high rigidity requirements |
How to Measure Linear Guideway Running Resistance
A pull-force test is more reliable than judging the block only by hand feel. The test procedure must be controlled so that results can be compared before and after installation or maintenance.
Equipment Required
- Digital force gauge, pull-force gauge or load cell
- Rigid pulling cable, rod or fixture aligned with the travel direction
- Controlled low-speed drive where a constant-speed test is required
- Temperature measuring device
- Data recorder or inspection sheet for force and position
Step 1: Define What Is Being Measured
Decide whether the test is intended to measure:
- One block on one rail
- A complete rail with multiple blocks
- A dual-rail moving table
- The complete machine axis including drive and cable chain
These results cannot be compared directly. A guide-only pull test and a motor-current test of the complete axis measure different combinations of resistance.
Step 2: Isolate the Guide System Where Possible
Disconnect the ball screw, belt, coupling, cylinder or other drive component if the objective is to measure only the guide system.
If the drive cannot be disconnected, record the result as complete-axis resistance rather than linear guideway resistance.
Step 3: Stabilize the Lubrication Condition
Confirm that the guideway contains the specified lubricant and that no large amount of excess grease has just been added.
After relubrication, move the blocks through several complete strokes to distribute the grease before recording the final running-resistance value.
Step 4: Align the Pulling Force
The force gauge should pull parallel to the guide rail and as close as practical to the intended drive-force line.
Pulling upward, downward or from one side introduces an additional moment and can make the measured force higher or less stable.
Step 5: Record Starting and Running Force Separately
Increase the force gradually until the block or table starts moving. Record this peak as the starting resistance.
Continue moving at a controlled, approximately constant speed. Record the steady force through the usable stroke as the running resistance.
Step 6: Test Both Directions
Measure the force from left to right and then from right to left. A substantial directional difference may indicate:
- Uneven seal contact
- Cable-chain force
- Rail inclination
- Drive or coupling misalignment
- An asymmetric external load or table deformation
Step 7: Record Force by Position
Do not record only one force at the center of the rail. Measure or continuously record the force through the entire usable stroke.
The inspection record should include:
- Maximum starting force
- Average steady running force
- Maximum running force
- Minimum running force
- Locations of any force peaks
- Movement direction
- Test speed
- Guide and ambient temperature
- Lubricant and lubrication date
- Block model, quantity, preload and sealing configuration
How to Interpret the Pull-Force Pattern
The shape and location of the resistance change often provide more diagnostic information than the average force alone.
| Resistance Pattern | Possible Cause | First Check |
|---|---|---|
| Uniformly high through the full stroke | High preload, strong seals, excessive grease or oversized blocks | Model, preload, seal code and lubrication quantity |
| Sharp peak at one rail position | Local burr, rail dent, damaged raceway, debris or uneven bolt tightening | Rail and mounting surface near the peak position |
| Resistance gradually rises toward one end | Dual-rail parallelism error, rail straightness error or table distortion | Rail spacing and parallelism through the complete travel |
| High only immediately after greasing | Excess or undistributed grease | Grease quantity and force after several full strokes |
| Lower after the guide warms up | Lubricant viscosity decreasing with temperature | Cold and stabilized operating temperatures |
| Higher after the machine warms up | Thermal misalignment, structural expansion, excessive preload or bearing heat | Rail alignment, base temperature and complete axis structure |
| Different in opposite directions | Seal orientation, slope, cable-chain force or asymmetric loading | Test setup and external components connected to the table |
| Sudden increase after normal operation | Contamination, seal damage, lubrication failure or internal damage | Stop and inspect before continued high-speed operation |
How Running Resistance Affects Motor Selection
Linear guide resistance is one part of the force that the motor must overcome. It should be added to acceleration force, process force, gravity on a vertical axis and resistance from other moving components.
Ball Screw Drive Torque
The torque required only to overcome guide running resistance through a ball screw can be estimated as:
- T = drive torque in N·m
- F = linear resistance in N
- p = ball screw lead in meters per revolution
- η = transmission efficiency
For example, if the measured linear resistance is 80 N, the ball screw lead is 10 mm and the transmission efficiency is 0.90:
This is only the torque required to overcome the measured running resistance. Acceleration, cutting force, gravity, bearing resistance and safety margin must still be included in the complete motor calculation.
Drive Power
The mechanical power used to overcome running resistance is:
Where P is power in watts, F is resistance in newtons and v is linear velocity in meters per second.
A resistance of 100 N at 1 m/s requires 100 W of mechanical power before other machine loads and drive losses are added.
Is There a Normal Running-Resistance Value?
There is no single normal pull-force value that applies to every linear guideway.
A valid acceptance limit must specify:
- Guideway series and size
- Block length and block quantity
- Preload grade
- Seal and scraper configuration
- Lubricant type and quantity
- Applied load
- Test speed
- Temperature
- Mounting orientation
- Whether the test covers one block, one rail or the complete axis
For production equipment, the most useful method is often to establish a baseline after correct installation and commissioning. Later tests can then be compared under the same load, speed, temperature and lubrication condition.
A stable force that is slightly higher than expected may be acceptable for a preloaded and well-sealed guide. A new localized peak, increasing directional difference or continuing upward trend is more likely to require inspection.
DLY Linear Guideway Selection by Resistance and Rigidity
| DLY Series | Guide Type | Selection Direction |
|---|---|---|
| HD Series | Heavy-load ball guideway | General CNC and automation axes requiring balanced load capacity, rigidity, speed and smooth motion |
| ED Series | Low-profile ball guideway | Compact and high-speed equipment where reduced assembly height and lower moving structure are important |
| RD Series | High-rigidity roller guideway | Heavy-load machine tools, high moment loads and applications where low elastic deformation is more important than minimum pull force |
| MD Series | Miniature ball guideway | Compact instruments and light moving mechanisms where size and moving mass are limited |
View the complete DLY linear guideway product range for HD ball guideways, ED low-profile guideways, RD roller guideways and other rail-and-block structures.
Information Needed to Evaluate Running Resistance
If an application has a strict pull-force, motor-current or low-speed smoothness requirement, provide the complete operating and assembly conditions rather than only the rail size.
- Linear guideway series and model
- Rail length
- Block type and quantity
- Preload grade
- Accuracy grade
- Seal, double-seal or scraper requirement
- Lubricant type
- Moving mass and external load
- Rail and block arrangement
- Horizontal, vertical, side or inverted mounting
- Required speed and acceleration
- Ambient and operating temperature
- Dust, chips, coolant or cleanroom conditions
- Maximum permitted pull force or motor-current limit
Frequently Asked Questions
Does a larger linear guideway always have lower resistance?
No. A larger guideway may carry the same load at a lower load ratio, but it also has larger rolling elements, seals and lubricant volume. In a lightly loaded application, these additional resistance sources may dominate.
Does higher preload improve running smoothness?
Suitable preload can improve rigidity and motion stability under load. Excessive preload increases resistance and installation sensitivity and may make low-speed movement feel tighter rather than smoother.
Why is a new guide block difficult to move by hand?
The block may have preload, new seals and concentrated grease that has not yet been distributed through the circulation path. Move it through several full strokes and compare the force again. Persistent local tightness should still be inspected.
Can motor current be used to measure guide resistance?
Motor current is useful for trend monitoring, but it represents the resistance of the complete driven axis. Support bearings, ball screw or belt transmission, coupling, cable chain and motor characteristics are included. A force gauge is more suitable when the guide-only resistance must be isolated.
Why does resistance increase after the worktable is installed?
The table may be forcing the blocks out of alignment because of mounting-surface error, block-height variation, incorrect tightening sequence or insufficient table rigidity. Check whether the blocks move smoothly before and after the table bolts are tightened.
Is a roller guideway always easier to move than a ball guideway?
No. Roller guideways may have a lower reference rolling-friction coefficient, but their actual pull force depends on preload, block size, seals, lubricant and installation. They are mainly selected for load capacity and rigidity.
Contact DLY
Send DLY your linear guide model, rail length, block quantity, preload, seal structure, moving load, speed, mounting orientation and permitted drive force. We can help review the suitable HD, ED, RD or MD guideway structure and identify the operating conditions that may affect running resistance.
Email: export@dlybearing.com
