THK Linear Bushing User manual

Instruction Manual
No. 1030-T34670
Linear Bushing
THK Linear Motion System
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Table of Contents
i
Linear Bushing
1. Introduction 1-1
1-1 Foreword 1-1
1-2 About This Manual 1-1
1-3 Applying This Product  1-2
1-4 Product Support 1-2
1-5 Product Information and THK Information 1-2
2. Precautions on Use 2-1
2-1 Safety Related Warning Displays  2-1
2-2 Handling  2-1
2-3 Precautions on Use  2-2
2-4 Lubrication  2-3
2-5 Storage  2-3
2-6 Disposal  2-3
3. Assembly 3-1
3-1 Mounting the Outer Cylinder  3-2
3-2 Mounting the Shaft Support 3-5
3-3 Mounting the Linear Bushing  3-5
3-4 Attaching FLM Felt Seal  3-7
4. Lubrication 4-1
4-1 Lubrication Interval  4-1
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1-1
Linear Bushing
1. Introduction
1.
Introduction
1-1 Foreword
Thank you for purchasing this THK product. This manual describes the precautions on use,
assembly method, and lubrication method that apply to a Linear Bushing.
1-2 About This Manual
1-2-1 Intended Audience
Persons in charge of product mounting design, installation, wiring, and maintenance, and
persons actually using the product.
1-2-2 Using This Manual
This manual describes the correct handling of this product and precautions on its use.
For maximum product performance and long-term use, read this manual carefully and
understand its contents so that you use this product safely and properly.
When printing this manual for reading, store it in a place where the intended audience can read it
when necessary.
1-2-3 Notice and Attention
zDo not handle or use this product in any way other than as described in this manual.
zNo part of this manual may be duplicated, reproduced, or loaned without permission.
zDue to a continuing process of product improvement, information contained herein is subject
to change without notice.
zEfforts have been made to ensure the accuracy of the information contained herein. If,
however, you notice an error or have a concern, notify THK.
zThe diagrams contained herein are representative examples and may vary from the actual
product.
zTHK will not be liable for the effects resulting from the use of this manual for any reason
whatsoever.
zThis manual also applies to special products, but content specified on the Delivery
 
*Special products are products that differ from standard products listed in the catalog, in

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1-2
Linear Bushing
1. Introduction
1-3 Applying This Product
zDo not use this product for equipment or systems used in life-threatening situations.
zConsult THK beforehand when considering using this product for special applications such as
in passenger vehicles or in medical, aviation and space, nuclear power, or electrical power
equipment or systems.
zThis product was manufactured under strict quality control, but this does not completely rule
out product failure. When using this product in equipment where failure of this product could
cause a severe accident or damage, install a safety device or backup device to prevent the
occurrence of severe accidents or damage.
1-4 Product Support
Efforts have been made to ensure the accuracy of the information contained herein. If, however,
you have a concern, notify THK.
1-5 Product Information and THK Information
For the latest product information and company information, we recommend that you regularly
access and view the THK website.
zWebsite URL: https://www.thk.com/eng/
zTechnical support site URL: https://tech.thk.com/
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2-1
2. Precautions
Linear Bushing
2.
Precautions on Use
2-1 Safety Related Warning Displays
This manual uses the following safety related warning displays. Descriptions containing safety
related warning displays are serious and must be followed. The Linear Bushing is a precision
part, to be handled with care based on the following information.
Warning "A matter which, if mishandled, could result in
death or serious injury."
Caution "A matter which, if mishandled, could result in
physical injury or material damage."
"Prohibited (never do this)"
"Required (always do this)"
2-2 Handling
CAUTION
Do not disassemble
zDisassembling components may cause dust to enter the system or degrade mounting
accuracy of parts. Do not disassemble the product.
Falling objects
zTake care not to drop or strike the Linear Bushing. This could cause injury and damage the
product. If the product receives an impact, it could impair the product's functions, even if the
product looks intact.
Handle with care
zWhen handling the product, wear safety gloves and safety boots, etc., as appropriate to
ensure safety.
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2-2
2. Precautions
2.
Precautions on Use
Linear Bushing
2-3 Precautions on Use
CAUTION
Prevent dust
zPrevent foreign materials, such as cutting chips or coolant, from entering the product. Failure
to do so could damage the product.
zPrevent foreign materials, such as cutting chips, coolant, corrosive solvents or water from
getting in the product by using a bellows or cover when the product is used in an environment
where such a thing is likely.
zIf foreign materials such as cutting chips adhere to the product, clean the product and then
replenish the lubricant.
zSmall strokes can inhibit the formation of an oil film between the raceway and the area of
contact for rolling elements, resulting in fretting. Therefore, be sure to use a type of grease
with high fretting resistance properties. We recommend periodically adding stroke movement

raceway and the rolling elements.
Maximum temperature
80°C
Max
zDo not use this product if the external temperature exceeds 80 °C. If used in excess of this
temperature, there is a risk that the resin and rubber parts may deform or become damaged
(except the heat-resistant type).
Handle with care
zDo not forcibly drive a pin, key, or other positioning device into the product. This could create
indentations on the raceway and impair the product's functions.
zInserting the shaft while tilted risks foreign material entering, internal parts being damaged,
󰀨
zUsing while the rolling elements are removed may cause early damage.
zA lack of rigidity and accuracy of mounting components may cause the bearing load to

the rigidity and accuracy of the housing and base, and the strength of the securing bolts.
Falling objects
zIf any of the rolling elements fall, discontinue use and contact THK.
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2-3
2. Precautions
2.
Precautions on Use
Linear Bushing
2-4 Lubrication
CAUTION
Check lubricant
zThoroughly remove anti-rust oil and feed lubricant before using the product.
zDo not mix different lubricants. Even grease containing the same type of thickening agent
may, if mixed, interact in an adverse manner due to disparate additives or other ingredients.
zWhen using the product in locations subject to constant vibrations or in special environments
such as in clean rooms, vacuums, and under low or high temperatures, be sure to use a

zWhen lubricating products, directly coat the raceway surface with lubricant and perform
several warm-up strokes to ensure that the grease permeates the interior.
zGrease consistency can vary depending on the temperature. Keep in mind that the Linear
󰀨
zFollowing greasing, the stirring resistance of the grease can cause the Linear Bushing to
exhibit increased sliding resistance. Before commencing operations, be sure to run the unit
through several warm-up cycles to ensure that the grease is adequately integrated and
dispersed.
zExcess grease may spatter immediately after lubrication. Wipe off spattered grease as
necessary.
zThe properties of the grease deteriorate over time, thereby degrading the lubricity. It is
necessary to inspect and apply the grease in accordance with the usage frequency.
zHow often grease should be replenished varies depending on the usage conditions and
environment. Final greasing interval/amount should be set at an actual machine.
2-5 Storage
Linear Bushings should be stored in their original packaging in an indoor location where they are
not exposed to abnormally high or low temperatures or high humidity.
2-6 Disposal
The product should be disposed of appropriately as industrial waste.
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3-1
3. Assembly
Linear Bushing
3.
Assembly
Housing Inner Diameter
Table 3-1 shows recommended housing inner-diameter tolerance for the Linear Bushing. When


Table 3-1 Housing Inner-diameter Tolerance
Type Housing
Model No. Accuracy Loose fit Transition fit
LM
High accuracy grade
(no symbol) H7 J7
Precision grade (P) H6 J6
LME H7 K6, J6
LMF
High accuracy grade
(no symbol) H7 J7
LMK
LMH
LM-L
LMF-L
LMK-L
LMH-L
LMIF
LMIK
LMIH
LMIF-L
LMIK-L
LMIH-L
LMCF-L
LMCK-L
LMCH-L
Clearance between the Outer Cylinder and LM Shaft
When using the Linear Bushing in combination with an LM shaft, use normal clearance in
ordinary use and a small gap if the clearance is to be minimized.
Note 1: If the clearance after installation is to be negative, it is preferable not to exceed the radial clearance

Note 2: The shaft tolerance for case unit models SC, SL, SH, and SH-L falls under the high accuracy grade (no
symbol).
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3-2
3. Assembly
3.
Assembly
Linear Bushing
Table 3-2 Shaft Outer-Diameter Tolerance
Type LM Shaft
Model No. Accuracy Normal clearance Small gap
LM
High accuracy grade
(no symbol) f6, g6 h6
Precision grade (P) f5, g5 h5
LME h7 k6
LMF
High accuracy grade
(no symbol) f6, g6 h6
LMK
LMH
LM-L
LMF-L
LMK-L
LMH-L
LMIF
LMIK
LMIH
LMIF-L
LMIK-L
LMIH-L
LMCF-L
LMCK-L
LMCH-L
3-1 Mounting the Outer Cylinder
Although the Linear Bushing does not require a large amount of strength for securing it in the LM
shaft direction, do not rely only on a press fit to support the nut. For the housing inner-diameter
tolerance, see Table 3-1.
zMounting a Standard Linear Bushing
Figure 3-1 and Figure 3-2 show mounting examples.
Use snap rings or stopper plates when securing Linear Bushings.
Figure 3-1 Secured by a
Snap Ring
Figure 3-2 Secured by a
Stopper Plate
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3-3
3. Assembly
3.
Assembly
Linear Bushing
Snap Ring for Mounting
See Table 3-3 for the models of snap rings to use for securing the Linear Bushing model LM.
Note 1: For models indicated in parentheses, use C-shape concentric snap rings.
Note 2: Table 3-3 commonly applies to models LM, LM-GA, LM-MG, and LM-L.
Table 3-3 Types of Snap Rings
Snap ring
Model No.
For outer diameter For inner diameter
Needle
snap ring
C-shape
snap ring
Needle
snap ring
C-shape
snap ring
LM 3   AR 7 
LM 4   8
LM 5 WR 10 10 10 10
LM 6 12 12 12 12
LM 8 15 15 15
LM 8S 15 15 15
LM 10 19 19 19 19
LM 12 21 21 21 21
LM 13 23 22 23 
LM 16 28 28 28
LM 20 32 32 32
LM 25 40 40 40 40
LM 30 45 45 45 45
LM 35 52 52 52 52
LM 38   57 
LM 40 60 60 60
LM 50 80 80 80
LM 60 90 90 90
LM 80A 120 120 120
LM 100A (150) 150 
LM 120A (180) 180 
Set Screws Not Allowed
As shown in 3-3, avoid securing the nut by using one
set screw to press against the outer surface of the outer
cylinder, because this will cause deformation to the
outer cylinder.
Figure 3-3 Set Screws Not Allowed
Outer
cylinder
Set screw
Housing
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3-4
3. Assembly
3.
Assembly
Linear Bushing
zMounting a Flanged Type
With models LMF, LMK, LMH, LMIF, LMCF, LMIK, LMCK, LMIH, and LMCH, the flange is

Mounting outer cylinder spigot and socket jointMounting by only the flange
zMounting a Clearance-Adjustable Type
To adjust the clearance of a Clearance-Adjustable type
(-AJ), use a housing that allows adjustment of the outer
diameter to facilitate adjustment of the clearance
between the Linear Bushing and the LM shaft.
Positioning the Linear Bushing slit at a 90° angle to the
housing slit will apply uniform deformation in the
circumferential direction. (Figure 3-4)
zMounting an Open Type
For an Open type (-OP), also use a housing that allows
clearance adjustment, as shown in Figure 3-5.
Open types are normally used with a light preload.
Be sure not to provide an excessive preload.
Figure 3-4 Mounting a
Clearance-Adjustable Type
Rotation
stopper plate
Rotation
stopper plate
Housing
Adjustment
bolt
Figure 3-5 Mounting an Open Type
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3-5
3. Assembly
3.
Assembly
Linear Bushing
3-2 Mounting the Shaft Support
Shaft Support model SK can easily be secured to the
table using mounting bolts and the LM shaft can be

3-3 Mounting the Linear Bushing
zMounting Model SC (SL)
Since models SC and SL can be attached from the top or bottom by simply tightening the bolts,
the installation time can be shortened. (Figure 3-6)
Figure 3-6 Mounting Model SC (SL)
zMounting Model SH (SH-L)
Since models SH and SH-L can be attached from the top or bottom by simply tightening the
bolts, the installation time can be shortened. (Figure 3-7)
Alternative mounting
Basic mounting
Figure 3-7 Mounting Model SH (SH-L)
Fastening bolt
Mounting bolt
Washer
Reference
surface
THK
SK30
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3-6
3. Assembly
3.
Assembly
Linear Bushing
Installing the Outer Cylinder
When incorporating the standard Linear Bushing into a
housing, do not directly hit the seal or side plate. Use a

on the nut and gently hit that. (Figure 3-8)
Inserting the LM Shaft
When inserting the LM shaft into the Linear Bushing,
align the center of the shaft and gently insert the shaft
straight into the nut. If the shaft is slanted while it is
inserted, balls may fall out or the retainer may be
deformed. (Figure 3-9)
Under Moment Load
When using the Linear Bushing, make sure the load is evenly distributed across the entire ball
raceway. In particular, if a moment load is to be applied, use two or more Linear Bushing units on
the same LM shaft and secure an adequately large distance between the Linear Bushings.
Also, when using with a moment load, calculate the equivalent radial load and check the model
number.
Rotational Use Not Allowed
The Linear Bushing is structurally not suited for
rotational operation. (Figure 3-10)
Forcibly rotating it may cause an unexpected accident.
D: outer cylinder
outer diameter
dr: bore diameter
D-0.3
dr-0.3
Figure 3-8 Installing the Outer
Cylinder
Figure 3-9 Inserting the LM Shaft
Figure 3-10 Rotational Use Not
Allowed
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3-7
3. Assembly
3.
Assembly
Linear Bushing
Precautions on Installing an Open Three-Ball-Row Type Linear Bushing
When mounting an Open Three-Ball-Row type Linear
Bushing, mount it as shown in Figure 3-11, while taking
into account the load distribution.
3-4 Attaching FLM Felt Seal

H7, but cannot be used as a stopper for preventing the
Linear Bushing from detaching. Be sure to attach the
felt seal as shown in Figure 3-12.
Also make sure to impregnate the felt with sufficient
lubricant before attaching it.
Load
LM12
13
Figure 3-11 Precautions on Installing
an Open Three-Ball-Row
Type Linear Bushing
Figure 3-12 Attaching FLM Felt Seal
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4-1
4. Lubrication
Linear Bushing
4.
Lubrication
It is necessary to use a good quality lubricant when using Linear Bushings. Usage with no
lubrication may increase wear on the rolling elements and shorten the service life.
A lubricant has the following effects.
(1) Minimizes friction in moving elements to prevent seizure and reduce wear.
(2) Forms an oil film on the raceway to decrease stress acting on the surface and extend rolling
fatigue life.
(3) Covers the metal surface in an oil film to prevent rust formation.
To optimize Linear Bushing functions, provide lubrication appropriate to the usage conditions.
Grease Lubrication
When installing onto an LM shaft, apply grease to the rows of balls in the Linear Bushing.
Then, depending on the usage state, either apply as described above when appropriate, provide
a housing as shown in Figure 4-1, or apply grease to the LM shaft.
We recommend using high-quality lithium-soap group grease No. 2.
Oil Lubrication
Either drip oil onto the LM shaft when appropriate, or provide a
housing as shown in Figure 4-1 like for grease lubrication.
Turbine oil, machine oil and spindle oil are commonly used as a
lubricant.
In addition to the above, an oil hole or a grease nipple could be
used. Contact THK for details.
4-1 Lubrication Interval
4-1-1 Grease Lubrication
How often grease should be replenished varies depending on the usage conditions and
environment. We recommend greasing the system approximately every 100 km traveled (three
to six months). Final greasing interval/amount should be set at an actual machine.
Housing
Spacer
Figure 4-1
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4-2
4. Lubrication
4.
Lubrication
Linear Bushing
Normally, relubricate using the same grease type and through the lubrication hole or grease
nipple provided on the Linear Bushing. Mixing different types of grease may deteriorate the
system’s performance due to increased consistency or other such factor.
Lubricant Type Brand name
Grease
Lithium-Based Grease
Urea-Based Grease
Calcium-Based Grease
AFA Grease (THK)
AFB-LF Grease (THK)
AFC Grease (THK)
AFE-CA Grease (THK)
AFF Grease (THK)
AFG Grease (THK)
AFJ Grease (THK)
L100 Grease (THK)
L450 Grease (THK)
L500 Grease (THK)
L700 Grease (THK)
Alvania Grease S No.2 (Showa Shell Sekiyu)
Eponex Grease No.2 (Idemitsu Kosan)
or equivalent
*The recommended grease will vary according to the usage conditions and environment.
4-1-2 Oil Lubrication
LM systems that require oil lubrication are shipped with only anti-rust oil applied. When placing
an order, specify the required lubricant oil.
zThe amount of oil to be applied varies depending on the stroke length. For a long stroke,
increase the lubrication frequency or the amount of oil applied so that an oil film is able to form
in the stroke end of the raceway.
zIn environments where coolant may spatter, the lubricant may become mixed with the coolant.
This could result in the lubricant being emulsified or washed away, causing significantly
degraded lubrication performance. In such locations, apply a lubricant with high viscosity
(kinematic viscosity: approx. 68 cst) and high emulsification resistance, and adjust the
lubrication frequency or the amount of the applied lubricant accordingly.
zFor machine tools and similar devices that are subject to heavy loads, require high rigidity, and
operate at high speed, oil lubrication is recommended.
zMake sure that lubrication oil discharges normally from the ends of the lubrication piping; that
is, the oiling ports that connect to your linear motion system.
Lubricant Type Brand name
Oil Raceway Oil or Turbine Oil
ISOVG32 to 68
Daphne Super Multi Oil (Idemitsu Kosan)
Mobil DTE Oil Series (Exxon Mobil)
Shell Tonna S3 M (Showa Shell Sekiyu)
Mobil Vactra Numbered Series (Exxon Mobil)
Mobil Vactra No. 2 SLC (Exxon Mobil)
or equivalent
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Appendix
Revision History
The instruction manual number is on the back cover.
Publication Date Instruction Manual No. Revisions
December 2017 No. 1030-T34670 First edition
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No. 1030-T34670
Inquiries
Website URL: https://www.thk.com/eng/
Technical support site URL: https://tech.thk.com/
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