Fluid Power - NAK Sealing · PDF file3 Chapter 1 Application Guide 1.1 Introduction Nowadays,the different operation conditions andcritical requirements are found in hydraulic and

Fluid Power Handbook

Dated 2005

1

Table of Contents Chapter

1. Application Guide… … … .… … … … … … … … … … … 3

1.1 Introduction … … … … … … … … … … … … … … 3

1.2 Classifications of Rod Seals and Piston Seals … 4

1.3 Characteristics of seal … … … … … … … … … … … 10

1.4 Examples of Applications .… … … … … … … … 12

2. Sealing Mechanism … … … … … … … … … … … … … . 15

2.1 Seal Theory … … … … … … … … … … … … … … 15

2.1.1 Coefficient of Friction … … … … … … … … 18

2.1.2 Stribeck-Curve … … … … … … … … … … … 19

2.2 Seal Life … … … … … … … … … … … … ..… … … … 20

2.2.1 Service Life … … … … … … … … … … … … … … 20

2.2.2 Shelf Life … … … … … … … … … … … … … … 21

3. Selection of Seals … … … … … … ...… … … … … … … . 22

3.1 Seal Types … … … … … … … … … … … … … … 22

3.1.1 Rod Seal … … … … … … … … … … … … … … 22

3.1.2 Piston Seal … … … … … … … … … … … … … 24

3.1.3 Symmetric Seal … … … … … … … … … … … . 27

3.1.4 Wiper … … … … … … … … … … … … … … … 28

3.1.5 U-Packing + Ring … … … … … … … … … … . 33

3.1.6 Static Seal … … … … … … … … … … … … … . 34

3.2 How to Select the Correct Seal … … … … … … 35

4. Materials … … … … … … … … … … … … … … … … … 37

4.1 Material Compounds … … … … … … … … … … … . 37

4.2 Classification of Material … … … … … … … … 40

4.3 Materials & Fluid Compatibility … … … … … … 43

5. Installation of Seals … … … … … … … … … … … … 45

5.1 Caution when installing the Seal … … … … … … … 45

2

5.2 How to Install the Seal … … … … … … … … … 47

6. Cylinder Design Parameters .… … … … … 52

6.1 Tolerance of Bore and Shaft … … … … … … … … 54

Appendix:

1. Product Information … … … … … … … … … … … … … … … … … 56

2. Packing Design Sheet … … … … … … … … … … … … … … … … . 120

3

Chapter 1 Application Guide

1.1 Introduction

Nowadays, the different operation conditions and critical

requirements are found in hydraulic and pneumatic systems and

equipments. As a result, a large variety of different seal types are

needed and the sealing elements are required with long service life and

perfect reliability. The critical factors that influence the sealing

performance, therefore, should be noticed, such as speed of stroke,

temperature, system pressure and media. In addition, low friction, no

leakage to atmosphere, and low price/performance ratio should also be

considered.

Both U-rings and wipers are important sealing elements used in

hydraulic and pneumatic systems and equipments. Their main function is

to avoid the medium escaping from the cylinder piston and rod ensuring

the cylinder function whether in a pressured or un-pressured state.

Type Application conditions Piston seal Characteristic Rod seal Characteristic

0 ~ 20 Mpa-30 ~ 100℃

UOP has excellent wearresistance and sealing ability.

UIP has an asymmetrical profileof the sealing lips.WP3 protects cylinders againstingress of dirt and maintainssealing performance of packings.

Heat-resistant0 ~ 14 Mpa-25 ~ 200℃

UNR has a symmetrical profileof the sealing lips, and theheight of both sealing lip isequal.

UNR has a symmetrical profile ofthe sealing lip, and the height ofboth sealing lip is equal.WP4 protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, WP4 canprevent oil from scraping off.

Cold-resistant0 ~ 14 Mpa-40 ~ 100℃


UNR has a symmetrical profile ofthe sealing lip, and the height ofboth sealing lip is equal.WP3 protects cylinders againstingress of dirt and maintainssealing performance of packings.

1.2 Classification of Rod seals and Piston seals

UIP WP3(PU 90) (PU 90)

UNR WP4(PU 90)(FKM 90)

UNR WP3(PU 90)(NBR 90)

UOP(PU 90)

UNR(NBR 90)

(FKM 90)UNR

4


0 ~ 14 Mpa-40 ~ 100℃


UNR has a symmetrical profile ofthe sealing lip, and the height ofboth sealing lip is equal.WPK protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, WPK canprevent oil from scraping off.

0 ~ 14 Mpa-40 ~ 100℃


UNR has a symmetrical profile ofthe sealing lip, and the height ofboth sealing lip is equal.WP4 protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, WP4 canprevent oil from scraping off.

0 ~ 20 Mpa-30 ~ 100℃


UIP has an asymmetrical profileof the sealing lips.WP4 protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, it can preventoil from scraping off.

UNR WPK(NBR 90) (NBR 90)



UOP(PU 90)

UNR(NBR 90)

UNR(NBR 90)

5


0 ~ 14 Mpa-40 ~ 100℃



0 ~ 20 Mpa-30 ~ 100℃


UNP has a symmetrical profile ofthe sealing lip, excellent wearresistance, and sealing ability.WPK protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, WPK canprevent oil from scraping off.

0 ~ 14 Mpa-40 ~ 100℃


UNR has a symmetrical profile ofthe sealing lip,the height of bothsealing lip is equal.WP4 protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, it can preventoil from scraping off.

UNP WPK(PU 90) (NBR 90)

UOP(PU 90)

UNR(NBR 90)

UNR(NBR 90)



6


0 ~ 14 Mpa-30 ~ 100℃


UNP has a symmetrical profile ofthe sealing lip, excellent wearresistance, and sealing ability.WP4 protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, WP4 canprevent oil from scraping off.

0 ~ 14 Mpa-40 ~ 100℃



0 ~ 20 Mpa-30 ~ 100℃


UIP has an asymmetrical profileof the sealing lips.WP3 protects cylinders againstingress of dirt and maintainssealing performance of packings.

UNR(NBR 90)

UNP WP4(PU 90) (PU 90)


UOP(PU 90)

UOP(PU 90)


7


0 ~ 14 Mpa-40 ~ 100℃



0 ~ 14 Mpa-30 ~ 100℃


UIP has an asymmetrical profileof the sealing lips.WP5 protects cylinders againstingress of dirt and maintainssealing performance of packings.WP5 has high dustproofperformance.

0 ~ 20 Mpa-30 ~ 100℃


UIP has an asymmetrical profileof the sealing lips.WP4 protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, WP4 canprevent oil from scraping off.

UIP WP5(PU 90)(NBR 90)

UOP(PU 90)

UNR(NBR 90)

UNR(NBR 90)



8


0 ~ 20 Mpa-30 ~ 100℃


UIP has an asymmetrical profileof the sealing lips.WP4 protects cylinders againstingress of dirt and maintainssealing performance of packings.Having a double lip, WP4 canprevent oil from scraping off.

0 ~ 16 Mpa-30 ~ 100℃

_ _UIP has an asymmetrical profileof the sealing lips.

UIP(PU 90)

UOP(PU 90)


9

10

1.3 Characteristics of seal

The characteristics of U-rings are described as following:

1. Have long service life.

2. Avoid leakage.

3. Easily remove and install.

4. Be compatible with the fluid at operating temperature and pressure.

5. Not pollute the hydraulic fluid with compounding factors.

6. Avoid foreign materials entering.

The function of different packing types used in the cylinder are described

as Table1.1 (See Fig. 1 to Fig. 3):

Table 1.1 Function of packing types

Type FUNCTION

(1) Piston Seal Prevent air bypass between the piston head and cylinder bore.

(2) Wear Ring Prevent metal-to-metal contact.

(3) Rod Seal Eliminate leakage along the static and dynamic surfaces.

(4) Wiper Exclude contaminants from entering the system, therefore extending equipment life.

(5) Cushion Seal Absorb shocks at the end of a cylinder stroke and prevent damage and impact noise.

11

Cushion Seal Cushion Seal

Cushion Seal Wiper

Piston Seal Rod Seal

Wear Ring

Fig. 1

Cushion Seal

Piston Seal

Wear Ring

Cushion Seal

Rod Seal

Wiper

Fig. 2 Fig. 3

12

1.4 Examples of application

The seal is commonly used in: tooling machines (e.g. injection

molding machine、 compression molding machine etc.), engineering

machines (e.g. excavator, bulldozer, backhoe etc.), transportation (e.g. car,

diesel engine, bicycle etc.), conveyances (e.g. crane, forklifts etc.),

agricultural machines (tractors、combines etc.), and others (hydraulic

elevator, plunger pump etc.). During machine operation, the oil seal

must be able to adopt all kinds of different application environment. In

order to prevent the contaminants from entering the system and extend

equipment life, the seal is necessary to be used in the transportation

system.

Hydraulic and Pneumatic seals can be used in these areas: 1. Tooling machines:

These seals need to resist higher temperature and pressure.

2. Engineering machines:

These seals must be used in outdoor dirty environment, which may

include contamination such as dust, mud, dirt, rocks, rain, and other

13

materials.

3. Transportation:

These seals can be used from low to medium pressures in a relatively

clean or indoor environment. Application range is from light to medium

duty.

4. Conveyances:

These seals must have low leakage, little or no stick-slip, low friction,

which can see a diverse range of temperatures and contamination.

14

5. Agricultural machines:

These seals often require working in a variety of temperature and

atmospheric conditions, which can seal a great deal of pollution.

15

Figure 1

Chapter 2 Sealing Mechanism 2.1 Seal Theory

During the reciprocating motion, the seal and sliding surface will be

separated by the thickness of the lubricating film. That is able to avoid

oil leakage and decrease frictional force and continual wear on the sliding

surface. During the motion of the contact pressure distribution and the

frictional force in the interface, the micro-asperities will be produced.

This will cause the pumping effect to prevent oil leakage (Figure 1).

By using the given contact pressure distribution due to the initial

compression and continued pressure, the thickness of the lubricating film

and leakage volume can be calculated by applying Reynolds equation

(equation 1) described as follows:

36

hhh

UdxdP −

= η … … … … … … … … … … … … (1)

pressureimummaxofpositiontheatheightfilmthe:h

heightfilmiablevar:hstoketheonrodofvelocity:U

gaptheinsideitycosviskinematic:filmtheinpressureiablevar:P

η

When hydraulic cylinder piston stop rod is on the forward stoke, the

maximum of contact pressure must higher than the hydraulic

pressure . Based on the contact pressure distribution, we can find the

)( max1P

)( 1P

16

Figure 2

film thickness of the outstroke depends on the maximum pressure

gradient on the fluid side . (See Figure 2)

When hydraulic cylinder piston stop rod is on the return stoke, the

maximum of contact pressure must higher than the hydraulic

pressure . Based on the contact pressure distribution, we can find

that the film thickness of the instroke depends on the maximum

pressure gradient on the atmospheric side . ( See Figure 3)

)( Ph

PdxdP max,)/(

)( max2P

)( 2P

)( Mh

MdxdP max,)/(

axial position

contact pressure

Maximum Pressure Gradient

17

Figure 2

axial position

contact pressure Figure 3

The major factors that affect the nature of the fluid film are viscosity

of the fluid at operating temperature, the relative velocity between the

seal and the sliding surface, and the maximum contact pressure gradient.

Equation (2) shows the relationship between these factors.

max/9

8dxdPU

hη

= … … … … … … … … … (2)

gradientpressurecontactimummaxofvalueabsolute:dx/dP

stoketheonrodofvelocity:Ufluidofitycosviskinematic:

max

η

Maximum Pressure Gradient

18

In addition, the film thickness )( Ph of the outstroke and the film

thickness )( Mh on the instroke can be calculated by equation 2 shown as

equation 3.

P

PP dxdP

Uh

max,/9

8η=

M

MM dxdP

Uh

max,/9

8η= … … … … … … … … (3)

stokereturntheongradientpressurecontactimummaxofvalueabsolute:dx/dP

stokeforwardtheongradientpressurecontactimummaxofvalueabsolute:dx/dP

stokereturntheonvelocity:Ustokeforwardtheonvelocity:U

Mmax,

Pmax,

M

P

During the cylinder’s reciprocating motion, the leakage between the

seal and the sliding surface per cycle can be calculated by equation 4.

)(21

MP hhDLQ −= π … … … … … … … … … … … (4)

lengthstokeLdiameterrodD

cyclepervolumeleakagenetQ

:::

Therefore, the seal’s qualification must correspond to the

leakage . Equation 4 shows that the dynamic sealing mechanism

is .

2.1.1 Coefficient of friction

Equation 5 presents the relation between the frictional force (F),

viscosity of the fluid (U), and contact area (A).

UAF η∝ … … … … … … … … … … … … ...… … . (5)

areacontact:Astoketheonrodofvelocity:U

gaptheinsideitycosviskinematic:forcefrictional:F

η

0≤Q

MP hh ≤

f

19

friction coefficient

Ⅰ Ⅱ Ⅲ

PUη

f PN

Figure 4

Frictional force divided by radial load equals coefficient of friction.

Thus, equation (6) divided by radial load ( ), the results are as

follows.

PP NUA

NF η

∝ … … … … … … … … … … … … (6)

Here, represents frictional coefficient ( ). In addition, are the

reciprocal of contact stress , so equation (6) can be the

PU

fη

∝ … … … … … … .… … … … … … .... (7)

The above-mentioned are the friction equation of the sliding surface.

takes into a non-dimensional parameter.

2.1.2 Stribeck-Curve

Figure (4) shows the lubricating situation during the different

operating environment and conditions. The Stribeck-Curve can be

divided into three frictional conditions as follows.

1. I: static friction (dry solid-body friction), the thickness of the

lubricating film is close to Zero.

PUη

h

PNF

PNAf

P1

20

Leakage v.s. Friction Force

Speed

Friction Force

Friction ForceLeakage Rate

Figure 5

2. II: mixed friction (solid-body friction and fluid friction), the

thickness of the lubricating film is close to the surface roughness

( ).

3. III: fluid friction (no solid-body contact), the thickness of the

lubricating film is greater than the surface roughness.

High frictional force can cause over-heat and over-wear. Thus, the

frictional force is an critical factor that can affect the efficiency of the

seals installed in cylinder mechanism. The ideal design for seals is to

reach the mixed friction region. The goal is to decrease the frictional

force and continual wear during the reciprocating and make the seals

have the best properties and long service life.

2.2 Seal Life

2.2.1 Service Life

For a seal, to provide reliable service and long life, the balance

between the friction behavior and the leakage must be achieved. (See

figure 5)

h

aR

h

Lea

kage

Rat

e

21

2.2.2 Shelf Life

a. Storage Conditions

In order to maintain the chemical and physical properties of the

seal’s material for a long time, the factors that have the influence on the

material should be noticed, such as the temperature, humidity, direct

sunlight, radiation, oxygen, ozone, deformation, and contact with fluids.

b. Storage Procedures

(1) Maintain packings in the suitable temperature (21℃~25℃ ) after

packings are packaged by NAK in a box.

(2) Protect packings from dust sticking after opening the packings.

Meantime, Keep the packings in their original conditions in the

storage until the time of delivery date.

(3) Be careful to avoid rust developing in the product with metal rings and

humidity (≦65% r.h.) affecting polyurethane products.

(4) Protect packings from direct lights while in storage.

(5) Confirm that no foreign contaminates will pollute original packings

while in storage.

c. Expiring date of keeping packings in storage

Material Expiring date of keeping in storage (years)

NBR 10

FKM 10

PU 10

Chapter 3 Selection of Seals 3.1 Seal Types

Pressure(MPa) Max. Speed(m/s) Temp(℃)

Hydraulic UIRNK961VN901

15 0.5-35~100-25~200

Seal designed with asymmetric lips. Usuallyused for rod hydraulic application.

●Standard cylinder●Cylinders for constructionand industrial vehicles●Cylinders for robots

page 56

Hydraulic/Pneumatic CIR

NK961VN901

10 0.5-35~100-25~200

Seal designed with asymmetric lips. Thelip seal may easily be snapped into thegrooves. The seal should be takencarefully and not be pulld over sharpedges.

●Standard cylinders page 57

Hydraulic LIR

NK961VN901

4 0.5 -30~100Flange packings are single-acting non-symmetrica lip-type rod seals ●Standard cylinders page 58

Hydraulic UIP

UB903UB904UK905

40 0.5 -40~100Seal designed with asymmetric lips.Usually used for rod hydraulic application. ●Standard cylinders page 59

Hydraulic UIP2

UB903UB904UK905

40 0.5 -40~100

Seal designed with asymmetric lips. Thesecondary edge can reduceleakage,friction, and dirt ingression .Usually used for rod hydraulic application.


Hydraulic UNP2UB903UB904UK905

40 1 -40~100Seal designed with symmetric lips can beused for piston and rod application. ●Standard cylinderpage 61

3.1.1 Rod Seal

MaterialProductName

Service rangeService Application Cross SectionStandard Material Speification

Characteristics Main usageProduct

Information

22

Hydraulic CIP

UB903UB904UK905

40 0.5 -40~100

Seal designed with asymmetric lips. Thelip seal may easily be snapped into thegrooves. The seal should be takencarefully and not be pulled over sharpedges.


Hydraulic LIP

UB903UB904UK905

40 0.5 -40~100Flange packings are single-acting non-symmetrica lip-type rod seals ●Standard cylinders page 63

23

Pressure(MPa) Max. Speed(m/s) Temp(℃ )

Pneumatic PPNKC61VNC25

1 1-40~100

-25~200

Seal designed with the asymmetric lips.

Usually used for pneumatic piston

application.


Pneumatic PDVNK761VN761

1.2 1-40~100

-25~200

Seal designed with a case body and rubber

lips. Usually used for larger pressure

condition than standard seal.


Hydraulic PDCNK961VN901

6 0.5-35~100

-25~200

Seal designed with a case body, spring and

rubber lip. Seals feature is stable for high

pressure and slower speed.


Hydraulic PDHNK961VN901

6 0.5-35~100

-25~200





Pneumatic PDV1NK761VN761

1.2 1-40~100

-25~200





Hydraulic PSCNK961VN901

6 0.5-35~100

-25~200





ProductInformationMaterial

3.1.2 Piston Seal

Service rangeProductName

Service Application Cross SectionStandard Material Speification

Characteristics Main usage

24

Pneumatic PSVNK761VN761

1.2 1-40~100

-25~200





Pneumatic PSV1NK761VN761

1.2 1-40~100

-25~200




●Standard cylinders page71

Pneumatic PSV2NK761VN761

1.2 1-40~100

-25~200





Hydraulic/Pneumatic CORNK961VN901

10 0.5-35~100

-25~200

Seal designed with asymmetric lips. The lip

seal may easily be snapped into the grooves.

The seal should be taken carefully and not be

pul d over sharp edges.


Hydraulic LORNK961VN901

4 0.5 -30~100Flange packings are single-acting non-

symmetrica lip-type piston seals●Standard cylinders page 74

Hydraulic UOP

UB903

UB904

UK905

40 0.5 -40~100Seal designed with asymmetric lips. Usually

used for rod hydraulic application.●Standard cylinders page 75

Hydraulic COP

UB903

UB904

UK905

40 0.5 -40~100

Seal designed with asymmetric lips. The lip

seal may easily be snapped into the grooves.

The seal should be taken carefully and not be

pulled over sharp edges.


25

Hydraulic LOP

UB903

UB904

UK905

40 0.5 -40~100Flange packings are single-acting non-

symmetrica lip-type piston seals●Standard cylinders page 77

26


Hydraulic UNRNK961VN901

14 0.5-35~100-25~200

Seal designed with symmetric lips can beused for piston and rod application. ●Standard cylinderpage 78

Hydraulic CNRNK961VN901

10 0.5-35~100-25~200

Seal designed with symmetric lips can beused for piston and rod application. ●Standard cylinderpage 79

Hydraulic UNPUB903UB904UK905


Hydraulic UNP1UB903UB904UK905


Hydraulic CNPUB903UB904UK905

20 0.5 -40~100Seal designed with symmetric lips can beused for piston and rod application. ●Standard cylinderpage 82

Hydraulic UP1UB903UB904UK905



3.1.3 Symmetric



Characteristics Main usage

27


Hydraulic/Pneumatic WP1UB903UB904UK905

- 1 -40~100Popular dust seals. Used for heavy dutyapplication.

●Standard cylinder●Heavy-duty cylinders

page 84


- 2 -40~100 Popular dust seals. ●Standard cylinderpage 85


- 1 -40~100Popular dust seals. Add the steel caseclad. Used for heavy duty application.


page 86




page 87




page 88




page 89

Main usageProduct

InformationMaterial

3.1.4 Wiper



Characteristics

28

Pressure(MPa) Max. Speed(m/s) Temp(℃)Main usage


3.1.4 Wiper



Characteristics


- 2 -40~100Popular dust seals. Add the steel caseskeleton. Used for heavy duty application.


page 90


- 2 -40~100Popular dust seals. Add an indentation forspecial application. ●Standard cylinderpage 91


- 1 -40~100Popular dust seals. Add an indentation forspecial application. ●Standard cylinderpage 92




page 93


- 2 -40~100Popular dust seals. Add the steel caseskeleton. Used for heavy duty application.


page 94


- 1 -40~100Popular dust seals. Used for heavy dutyapplication.


page 95

29



3.1.4 Wiper



Characteristics


- 1 -40~100Popular dust seals. Add an indentation forspecial application. Used for heavy dutyapplication.


page 96

Hydraulic/Pneumatic WPB NK961VN901

- 1-35~100-25~200

Popular dust seals. Add the steel caseclad. Used for heavy duty application.


page 97

Hydraulic/Pneumatic WPC NK961VN901

2-35~100-25~200

Popular dust seals. Add the steel caseskeleton. Used for heavy duty application.


page 98

Hydraulic/Pneumatic WPK NK961VN901

- 1-35~100-25~200



page 99

Hydraulic/Pneumatic WPM NK961VN901

- 1-35~100-25~200



page 100

Hydraulic/Pneumatic WPR NK961VN901

- 2-35~100-25~200



page 101

30



3.1.4 Wiper



Characteristics

Hydraulic/Pneumatic WPV NK961VN901

- 1-35~100-25~200



page 102

Hydraulic/Pneumatic WP12 NK961VN901

- 2-35~100-25~200

Popular dust seals. ●Standard cylinderpage 103


- 1-35~100-25~200



page 104


- 1-35~100-25~200



- 2-35~100-25~200

Popular dust seals. Add an indentation forspecial application. ●Standard cylinderpage 106


- 1-35~100-25~200


31



3.1.4 Wiper



Characteristics


1-35~100-25~200



- 1-35~100-25~200


32


Hydraulic HBU-Packing: PUO-Ring:NBR

35 0.5 -30~100A loaded U-packing with a fitted O-ring,and the O-ring provids extreme loads foreffective sealing at low or zero pressure.

●Standard cylinderpage 110

Hydraulic HDU-Packing: PUO-Ring:NBR



Hydraulic HSU-Packing: PUO-Ring:NBR



Hydraulic HBXU-Packing: PUO-Ring:NBR

35 0.5 -30~100

A loaded U-packing with a fitted X-ring,and the X-Ring under the U-packingprovides positive wiping for effectivesealing at low or zero pressure.


Hydraulic HDXU-Packing: PUO-Ring:NBR

35 0.5 -30~100



Hydraulic HSXU-Packing: PUO-Ring:NBR

35 0.5 -30~100



Main usageProduct

InformationMaterial

3.1.5 U-Packing+Ring



Characteristics

33

Product Name Pressure(MPa) Max. Speed(m/s) Temp(℃)

Pneumatic/Hydraulic O-ringNK761VNC25

10 --40~100-25~200

A popular round shape makes it be the mostwidely used ring in static. ●Standard cylinderpage 116

Pneumatic/Hydraulic X-ringNK761VNC25

10 --40~100-25~200

The special four-lipped design makes it betterthan O- ring in some aspects, especially less proneto twist in dynamic applications.


Pneumatic/Hydraulic SQ-ringNK761VNC25

10 --40~100-25~200

The simple square cross section makes it a goodreplacement for O-ring in high pressure staticapplications. Low cost is another factor why it isused.


Pneumatic/Hydraulic D-ringNK761VNC25

10 --40~100-25~200

The customized D-shape design can meet specialneeds with a better groove support. ●Standard cylinderpage 119

Note: 1 MPa=10 bar

MaterialService range

3.1.6 Static Seal


Characteristics Main usageProduct

Information

34

35

3.2 How to Select the Correct Seal

The following introduces the factors that have influences on the type

of Hydraulic and Pneumatic seals when choosing the seals.

1. Application

What applications are suitable, hydraulic or pneumatic? What

application location are suitable, Piston or Rod? How about

condition of your application, as the roughness, is suitable?

2. Size

What size is fit? Please consult the specification at the appendix.

If there is no specification, please fill out the seal design sheet and

send to us. That will help us to design the seal for “You.”

3. Temperature:

The two critical factors, the media and working temperature, needs to

be determined in selecting the correct seal. Moreover, the possible

and continuous working temperatures should be determined, and

their maximum values should be noticed. The temperature affects

to choice the seal’s material. (Please see chapter 3.1)

4. Pressure:

Greater pressure will make the lip wear to increase while operating,

and then influence sealing function. This is why the system

pressure is the important factor needed to be made sure when

choosing the seal type. (Please see chapter 3.1)

5. Linear Velocity:

In the hydraulic and pneumatic systems, understanding the number

of movements per minute of cylinder strokes and calculating the

velocity are the two important elements. (Please see chapter 3.1)

6. Media:

The type of the media used is very important in choosing the

material for the sealing element. If the media not matches the seal

36

material, the sealing function will decrease. Moreover, the value of

the media fill is also important. The application is for running dry,

lubricant, no lubricant, etc.

Temperature Pressure

Linear Velocity

Media

Size

Application

37

Chapter 4 Materials

4.1 Material Compounds

NBR

NBR is the most generally used material in all areas of seal

technology due to its good physical and mechanical characteristics. It is

a polymer of butadiene and acrylonitrile. The acrylonitrile (ACN)

content is between 18% and 50% (see table 4.1). Contents ranging from

28% to 38% are commonplace. It is most frequently used in hydraulic

and pneumatic system due to it is highly resistant to mineral oils,

vegetable oils and many acids. It is commonly attacked by ozone,

ketones, esters, aldehydes, chlorinated and nitro hydrocarbons.

Table 4.1 ACN content changed affect physical property Bond ACN Content 18% ←→ 50% Properties

→ Hardness increase → Tensile strength increase → Oils resistance increase → Heat resistance increase → Antifriction ability increase → Chemicals resistance increase

← Elasticity increase ← Plasicizers compatibility increase ← Low temperature property increase

Fig 4.1 the structure of NBR

38

FKM

VITON® Rubber is one of the most promising elastomer family in

the world. FKM has various composition and fluorine contents from 65

to 71%. It has high resistance to temperature, weathering, ozone, and

chemicals. The thermal operating range is up to 220℃. It also has

good tensile strength, resilience, low compression set. Moreover, it is

highly resistant to almost all mineral oil based and synthetic-based

hydraulic fluids. In contrast, it is not resistant to polar solvents, ketones,

and brake fluid.

Fig 4.2 the structure of FKM

39

PU

Polyurethane is one of the groups of elastic thermoplastic materials.

PU has been used in seal technology for many years because of their

physical characteristics. It is an organic material of high molecular

weight whose chemical composition is characterized by a large number of

urethane groups. In addition, it is characterized by extremely good

mechanical properties such as high tensile strength, abrasive resistance,

tear strength, and extrusion strength. The temperature range is between

-40℃ and 100℃ . However, it is not resistant to polar solvents,

chlorinated hydrocarbons, aromatics, brake fluids, acids, and alkalis.

Fig 4.3 the structure of PU

40

4.2 Classification of Material

Table 4.2 the coded meaning of material

N K 7 0 1

1st Digit ─ Material 3rd Digit ─ Hardness 2nd Digit ─ Color 4th & 5th Digit ─ Property (Sequential Number)

Table 4.3 Test condition follow ASTM D2000 standard Test Standard Properties Measured Notice

D2240 Hardness Test methods for rubber property

D412 Tensile strength Test methods for vulcanized rubber and thermoplastic rubbers and thermoplastic elastomers

D412 Elongation Test methods for vulcanized rubber and thermoplastic rubbers and thermoplastic elastomers

D624 Tear strength Test method for tear strength of conventional vulcanized rubber and thermoplastic elastomers

D395 Compression set Test methods for rubber property

D1329 TR10 Test methods for evaluating rubber property

D573 Heat resistance Test methods for rubber

1st Digit 2nd Digit 3rd Digit Material Color Hardness

Symbol Meaning Symbol Meaning Symbol Meaning N NBR K Black 9 90±5 U PU B Blue 8 80±5 V FKM N Brown C 75±5 - - - - 7 70±5

1st Digit

2nd Digit

3rd Digit

4th & 5th Digit

41

Table 4.4 Material and characteristic introduction

Physical Property

Material Code Hardness (Shore A)

Tensile strength MPa (psi)

Elongation (%)

Tear strength (Kg/cm)

Temperature Range (℃) Characteristic

NK701 68 16.13 (2339) 453 67 -40~100 For resistant oils and good adhesion with iron

NK761 71 17.21 (2497) 392 65 -40~100 For resistant oils and friction

NKC61 75 16.02 (2324) 342 77 -40~100 For low temperature and resistant oils

NK861 79 16.52 (2397) 308 69 -40~100 For low temperature and resistant oils

NK901 87 19.97 (2896) 211 49 -40~100 For high hardness and good adhesion with iron

NBR

NK961 87 17.57 (2549) 197 45 -35~100 For high hardness and high pressure

VN761 71 14.61 (2119) 285 46 -25~200 For high temperature condition

VNC25 75 16.88 (2449) 220 44 -25~200 For reciprocating action and high temperature FKM

VN901 88 14.50 (2104) 138 39 -25~200 For high hardness and high temperature

UB903 94 48.32 (7010) 547 209 -40~100 For high pressure and friction

UB904 94 47.73 (6921) 500 177 -40~100 For high pressure and friction PU

UK905 95 44.83 (6500) 457 189 -30~100 For high pressure and friction

42

Heat Resistance

Hardness change (points)

Tensile strength change (%)

Elongation change (%)

Compression Set (%)

Test condition Material Code

A：100℃，70hours B：250℃，70hours C：100℃，24hours D：200℃，22hours E：100℃，22hours

TR10 (℃) Suitable Types

NK701 +1 (A) +9 (A) -9 (A) +10 (E) -34 PDV

NK761 +5 (A) +11 (A) -17 (A) +7 (E) -29

NKC61 +6 (A) +10 (A) -30 (A) +7 (E) -29 PP

NK861 +5 (A) +12 (A) -8 (A) +10 (E) -29

NK901 +7 (A) +7 (A) -10 (A) +8 (E) -33 PDC

NBR

NK961 +6 (A) +15 (A) -7 (A) +12 (E) -30 UIR, UNR, PDC, WP14, WP17, WP19, WP20

VN761 +3 (B) -3 (B) -22 (B) +12 (D) -18 PDV

VNC25 +1 (B) -11 (B) -17 (B) +7 (D) -16 PP FKM

VN901 +2 (B) -3 (B) -20 (B) +9 (D) -16 UIR, UNR, PDC, WP14, WP17, WP19, WP20

UB903 0 (A) +5 (A) +1 (A) +54 (C) -35 WP21, WP22, WP1

UB904 0 (A) -6 (A) -2 (A) +58 (C) -33 WP21, WP22, WP1 PU

UK905 0 (A) +8 (A) +12 (A) +66(C) -26 WP21, WP22, WP1

43

4.3 Materials & Fluid Compatibility

Table 4.5 Material and fluids compatibility

Material Code Motor oils Automatic

transmission fluid

Hypoid gear oils

Silicon based greases Water Air Brake fluids

Temperature range (℃) -40~150 -50~160 -40~150 -50~250 0~100 -15~200 -50~130

Maximum used temperature in fluids (℃)

NK701

NK761

NKC61

NK861

NK901

NBR

NK961

100 100 90 100 80 100 NS

VN761

VNC25 FKM

VN901

150 160 150 200 100 200 NS

UB903

UB904 PU

UK905

100 100 100 100 40 40 NS

44

Material Code ASTM

NO.1 Oil ASTM

IRM 903 Oil Isooctane (100%)

Isooctane (70%)

Toluene (30%)

Diesel fuel Fuel for gasoline

and petrol engines

Temperature range (℃)

＜150 ＜150 Room temp. Room temp. Room temp. Room temp.

Maximum used temperature in fluids (℃)

NK701

NK761

NKC61

NK861

NK901

NBR

NK961

100 100 Room temp. Room temp. Room temp NS

VN761

VNC25 FKM

VN901

150 150 Room temp. Room temp. Room temp Room temp.

UB903

UB904 PU

UK905

100 100 Room temp. Room temp. Room temp NS

NS：Denotes that the elastomer is not suitable

45

Chapter 5 Installation of Seals

5.1 Caution when installing the seal

To avoid damage when installing the seal, the following precautions

should always be taken.

² Correct direction

Make sure the installation of the seal must take place with the

prestressed side facing the direction of pressure. See Fig 5.1.

² Lead in chamfer

The lead in chamfers on the cylinder (see Fig. 5.2) and piston rod

(see Fig. 5.3) are necessary, since it can prevent the seal from damage

when installing.

² Protective devices

The protective devices should be used when installing. The seal

should not be pushed over the sharp edges, drillings, gaps, or rough

surfaces. See Fig. 5.4.

Pressure Pressure Fig. 5.1

Fig. 5.2 Fig. 5.3

46

² Installation tools

To avoid damage, the installation tools should be used with soft

material and not have any sharp edges. See Fig. 5.5.

² Cleanliness

To prevent damaging the sealing function, dust, dirt, metal ship and

any foreign particles must be carefully removed. See Fig. 5.6.

² The groove and associated metal areas

The groove and associated metal areas will contact the seal should

not be any sharp edges.

Fig. 5.4

Fig. 5.5

Fig. 5.6

47

² Lubrication

The seal, cylinders, rods and installation tools must be lightly

lubricated before installation.

5.2 How to install the seal

Rod and Symmetrical packing installation

² Split installations

Method A

To be used for “heel first” installation into open grooves.

(1) Installation procedure

U packing can be installed “heel first” into open grooves without

difficulty. See Fig. 5.7.

Fig. 5.7

Method B

To be used for “lip first” installation into open grooves.

(1) Installation tools

a. Assembly bushing: The main function is to protect the U packing

from threads, shoulders, any metal or plastic may be used.

Meantime, it must be smooth and lubricated.

b. Pusher plug (see Fig. 5.8). Soft metal or plastic be used.


U packing can be installed “lip first” into open grooves without

difficulty by using assembly bushing to protect the U packing during

installation of the piston into the cylinder. See Fig. 5.8.

48

Fig. 5.8

Rod and Symmetrical packing installation

² Snap-in installations

Method A

To be used for installing small as well as large U packing.


a. Groove alignment plug; curvature of plug (see Fig. 5.9) not critical.

Therefore, in order to be flush with groove edge, the installation

tools (such as, any metal or plastic) must be smooth and lubricated.

b. Pusher plug or rod (see Fig. 5.9). Soft metal or plastic be used.


Squeeze U packing together and feed end into bore first, until lower

end is engaged in installation groove. Release U packing and force

upper end of U packing downward using pusher rod until U packing

snaps into groove.

Fig. 5.9

Method B

To be used for installing large U packing.

a. Assembly bushing

b. Pusher plug

b. Pusher plug

a. Groove alignment plug

49


The body of the installation tool (see Fig. 5.10).

a. Part 1 may be made from any soft metal or hard plastic machined

smooth and free of burrs.

b. Part 2 inserted into the body of the installation tool is a fixed steel

pin.

c. Part 3 and 4 are two movable pins.


a. Slip the U packing over part 2 fixed pin and bend it over part 3

movable pin. See Fig. 5.11.

b. Continue bending U packing until part 4 movable pin can be

pushed through the U packing loop which locks U packing in

position. See Fig. 5.11.

c. Withdraw part 4 movable pin so that U packing loop snap in

installation groove. See Fig. 5.12.

d. Withdraw part 3 movable pin and U packing will completely

snap into the groove. See Fig. 5.13.

e. Withdraw installation tool.

Part 2

Part 3

Part 4

Part 1 Part 2

Part 3

Part 4

Part 4

Part 3

Fig. 5.10 Fig. 5.11

Fig. 5.12 Fig. 5.13

50

Piston and Symmetrical packing installation

² Split installations

Method A

To be used for “heel first” installation into open grooves.


U packing can be installed “heel first” into open grooves without

difficulty. See Fig. 5.14.

Fig. 5.14

Method B

To be used for “lip first” installation into open grooves.


Assembly bushing: The main function is to protect the U packing

from threads, shoulders, any metal or plastic may be used.

Meantime, it must be smooth and lubricated. See Fig. 5.15.


U packing to be installed “lip first”, using assembly bushing to

protect the U packing during installation of the piston into the

cylinder. See Fig. 5.15.

Piston and Symmetrical packing installation

² Snap-in installations

To be used for installing large U packing.

Assembly bushing

Fig. 5.15

51


The installation tool consists of a circular pivot with an arm inserted

through it. The circular pivot is sized so as to fit in the position

guide hole. The installation tool may be made of steel. See Fig.

5.17. Cone-shaped installation tools should not be used to install

snap-in type piston seals, as this will cause the U packing to be

stretched to a much larger diameter that will require a very high

assembly force.


Installation will be facilitated if piston can be clamped to a vise

during U packing installation. Lubrication of U packing for this

type of installation is mandatory. (1) Snap one side of the U

packing into the installation groove in piston (see Fig. 5.16). (2)

Hold U packing in installation groove with thumb while inserting

tool (see Fig. 5.17) in guide hole. (3) Apply a downward force on

installation tool while rotating handle 3600 (see Fig. 5.18). (4)This

will snap U packing into groove (see Fig. 5.19).

Fig. 5.16 Fig. 5.17

Fig. 5.18 Fig. 5.19

52

Chapter 6 Cylinder Design Parameters Packing is one of the critical factors that can affect the performance

and durability of a cylinder. As a result, since packings of a cylinder are

made of the material that is soft and easy to be hurt, the installing portion

and its peripheral part must be designed carefully. The following table

shows the defects and problems that should be noticed.

1. Cylinder Walls

Material: Common structure steel or better

Tolerance: H 8-H 11, dependent on seal

Peak-to-valley-height: R max=< 2.5 µm R a= < 0.05-0.3 µm

Machining process: Honing and roller burnishing (rolling). Material should be removed at the concluding process stage, rather there ought to be a reshaping. Scratches, scores, machine scoring running

Cylinder Walls

Housing Rod

53

concentrically or spirally are not permitted.

2. Rods

Material: JIS(S45C) 、 SAE 1045 、 DIN CK45 or better

Tolerance: Is determined by individual application and sealing component

Peak-to-valley-height: R max=< 2.5 µm R a= < 0.05-0.3 µm

Machining process: Non-oriented, ground or roller burnishing (rolling)

Corrosion protection: Hard chrome with coating thickness 30-50 µm

Severe true stress: Hardening (55-60 HRC) and hard chroming. Re-work (finishing, grinding among others) to required surface quality after hard chroming. In doing so, developing scratches, scores, machine scoring running concentrically or spirally are not permitted.

3. Housings

Material: St, cast steel (free of cavities/blow-holes)

Tolerance: Can be taken from respective groove drawings.

Peak-to-valley-height: Base of groove: R max=< 6.3 µm R a=< 1.6 µm Sides of groove: R max=< 15.0 µm Some types allow a rougher groove base

Machining process: Turning and grinding

Comment: Phosphated and nitrated surfaces (bonding, chemical nickel plating) are not suitable as contact surfaces for seals without mechanical re-work.

54

6.1 Tolerance of Bore and Shaft

Drawing of Bore&Shaft marked dimension

Standard series of roughness Symbol of surface

Ra Rmax Rz ▽▽▽▽ 0.2a 0.8S 0.8Z ▽▽▽ 1.6a 6.3S 6.3Z ▽▽ 6.3a 25S 25Z ▽ 25a 100S 100Z

~ Specific regulation

more less E7 E8 E9 F6 F7 F8 G6 G7 H5 H6 H7 H8 H9 H10+24 +28 +39+12+16+20+8 +12+4 +6 +10+14+25+40

+32+38+50+18+22+28+12+16+5 +8 +12+18+30+48

+40+47+61+22+28+35+14+20+6 +9 +15+22+36+58

Dimension(mm)

─ 3

3 6

6 10

10 14

14 18

18 24

24 30

30 40

40 50

50 65

65 80

80 100

100120

120140

140160

160180

180200

200225

225250

250280

280315

315355

355400

400450

450500

tolerance of bore (unit：µm )E F G H

+14 +6 +2 0

+20 +10 +4 0

+25 +13 +5 0

+50+59+75+27+34+43+17+24 +43+70

+32 +16 +6 0

+8 +11+18+27

+61+73+92+33+41+53+20+28 +52+84

+40 +20 +7 0

+9 +13+21+33

+75+89+112+41+50+64+25+34 +62+100

+50 +25 +9 0

+11+16+25+39

+90+106+134+49+60+76+29+40 +74+120

+60 +30 +10 0

+13+19+30+46

+107+125+159+58+71+90+34+47 +87+140

+72 +36 +12 0

+15+22+35+54

+108+137+49+69+162+191+240+88

+106+39+54+18+148+185+68+83 +160

+85 +73 +14 0

+25+40+63+100+125

+146+172+215+79 +122+44 +20+61 +185

+100 +50 +15 0

+29+46+72+115+96

+210+52

+110 +56 +17 0

+23+32 +81+130

+182+214+265+98+119+151+54+75 +140+230

+125 +62 +18 0

+25+36+57+89

+198+232+290+108+131+165+60+83 +155+250

+135 +68 +20 0

+27+40+63+97

55

56

Product Information NAK Type：UIR

Description：Rod seal

1. Features

Having an asymmetrical profile

of the sealing lips.

2. Material

Rubber: NBR or FKM with a

hardness of 90 Shore A.

3. Application

Generally for hydraulic cylinders,

used for rod application. Rod

seal for light applications,

preferably for use only as a

replacement part.

Example:

(1) Agricultural equipment

(2) Heavy mobile hydraulics

(3) Loading platforms

(4) Cranes

(5) General cylinders

4. Operating conditions

Media Mineral Oils, Hydraulic Fluids

Temperature NK961: -35℃~100℃

VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 15 MPa

5. Groove and Machining

Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

57

Product Information NAK Type：CIR


1. Features



2. Material



3. Application


used for rod application.

Rod seal for light applications,


replacement part.

Example:




(4) Cranes





VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 10 Mpa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

58

Product Information NAK Type：LIR


1. Features

Rod seal with sealing lip.

2. Material



3. Application

Rod seal preferably for use only

as a replacement part and

secondary applications.

Example:








VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 4 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

59

Product Information NAK Type：UIP


1. Features



2. Material

PU material with a hardness of

90 Shore A.

3. Application

Generally for standard hydraulic

cylinders, they can be used for all

cylinder design.

Example:


(2) Bulldozers

(3) Cranes

(4) Construction equipment


(6) Forklifts

(7) Mobile lifts

(8) Mobile arm truck


Media

Mineral oil based Lubricating oils, hydraulic oils, non-flammable hydraulic fluids.

Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦40 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

60

Product Information NAK Type：UIP2


1. Features


of the sealing lips. The secondary

edge provides axial stability to

reduce tilting problem.

2. Material


90 Shore A.

3. Application



cylinder design.

Example:


(2) Earth moving equipment

(3) Support cylinders


(5) Hydraulic jacks


Media Mineral oil based hydraulic fluids.

Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 40 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

61

Product Information NAK Type：UNP2

Description：Symmetric seal

1. Features

Having a symmetrical profile of

the sealing lip and the height of

both sealing lips is equal.

Especially, it adds the second lip

at the rod side to provide axial

stability to reduce tilting

problem.

2. Material


90 Shore A.

3. Application


both used for piston and rod

application.

Example:






Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦1 m/sec

Working Pressure

≦40 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

62

Product Information NAK Type：CIP


1. Features



2. Material


90 Shore A.

3. Application



cylinder design.

Example:


(2) Bulldozers

(3) Cranes



(6) Forklifts

(7) Mobile lifts



Media


Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 40 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

63

Product Information NAK Type：LIP


1. Features

Rod seal with sealing lip.

2. Material


90 Shore A.

3. Application

Rod seal for secondary

applications and replacement

parts.

Example:


(2) Bulldozers

(3) Cranes



(6) Forklifts

(7) Mobile lifts



Media Mineral oil, hydraulic fluids.

Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 40 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

64

Product Information NAK Type：PP

Description：Piston seal

1. Features

Designed especially for

pneumatic cylinders with its

dynamic sealing lips (external

sealing lips) having shorter

height. It provides a safe

static sealing when its internal

sealing lips are installed in

housing.

2. Material



3. Application

Generally for pneumatic

cylinders, used for piston

application.

Example:

(1) Pneumatic application


Media Prepared, dirt and lubrication free compressed air.

Temperature NKC61: -40℃~100℃

VNC25: -25℃~200℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 1 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

65

Product Information NAK Type：PDV


1. Features

Designed for larger pressure


Complete piston with steel case

bonded to sealing lips with

special pneumatic edge.

2. Material



Spring: SAE 1070

Case: SAE 1008

3. Application



application.

Example:

(1) Pneumatic applications

(2) Complete piston assembly




VN761: -25℃~200℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 1.2 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

66

Product Information NAK Type：PDC


1. Features

Seals feature is suitable for high


Designed in such a way that

piston with steel case bonded to

spring loaded sealing lips.

2. Material



Spring: SAE 1070

Case: SAE 1008

3. Application

Generally for Hydraulic


application. (Also be used for rod

seal).

Example:

(1) Hydraulic application



Media Mineral oils, Hydraulic Fluids.


VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 6 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

67

Product Information NAK Type：PDH


1. Features






2. Material



Spring: SAE 1070

Case: SAE 1008

3. Application



application. (Also be used for rod

seal).

Example:






VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 6 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

68

Product Information NAK Type：PDV1


1. Features



Complete piston with steel case

bonded to sealing lips with

special pneumatic edge.

2. Material



Spring: SAE 1070

Case: SAE 1008

3. Application



application.

Example:






VN761: -25℃~200℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 1.2 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

69

Product Information NAK Type：PSC


1. Features






2. Material



Spring: SAE 1070

Case: SAE 1008

3. Application



application.

(Also be used for rod seal).

Example:





VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 6 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

70

Product Information NAK Type：PSV


1. Features



Piston with steel case bonded to

sealing lips with special

pneumatic edge.

2. Material



Spring: SAE 1070

Case: SAE 1008

3. Application



application.

Example:





VN761: -25℃~200℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 1.2 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

71

Product Information NAK Type：PSV1


1. Features





pneumatic edge.

2. Material



Spring: SAE 1070

Case: SAE 1008

3. Application



application.

Example:





VN761: -25℃~200℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 1.2 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

72

Product Information NAK Type：PSV2


1. Features





pneumatic edge.

2. Material



Spring: SAE 1070

Case: SAE 1008

3. Application



application.

Example:





VN761: -25℃~200℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 1.2 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

73

Product Information NAK Type：COR


1. Features


of the sealing lips

2. Material



3. Application


used for rod application.

Piston seal for light applications,


replacement part.

Example:




(4) Cranes





VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 10 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

74

Product Information NAK Type：LOR


1. Features

Piston seal with sealing lip.

2. Material



3. Application

Piston seal preferably for use

only as a replacement part and

secondary applications.

Example:








VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 4 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

75

Product Information NAK Type：UOP


1. Features


of the sealing lips

2. Material


90 Shore A.

3. Application



cylinder design.

Example:


(2) Bulldozers

(3) Cranes



(6) Forklifts

(7) Mobile lifts



Media


Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 40 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

76

Product Information NAK Type：COP


1. Features



2. Material


90 Shore A.

3. Application



cylinder design.

Example:


(2) Bulldozers

(3) Cranes



(6) Forklifts



Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 40 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

77

Product Information NAK Type：LOP


1. Features

Piston seal with sealing lip.

2. Material


90 Shore A.

3. Application

Piston seal for secondary

applications and replacement

parts.

Example:


(2) Bulldozers

(3) Cranes



(6) Forklifts

(7) Mobile lifts



Media Mineral oil, hydraulic fluids.

Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 40 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

78

Product Information NAK Type：UNR


1. Features


the sealing lip. The height of


2. Material



3. Application



application.

Example:




(4) Cranes





VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 14 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

79

Product Information NAK Type：CNR


1. Features



both sealing lip is equal.

2. Material



3. Application



application.

Example:




(4) Cranes





VN901: -25℃~200℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 10 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

80

Product Information NAK Type：UNP


1. Features




2. Material


90 Shore A.

3. Application



application.

Example:




(4) Cranes




Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 30 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

81

Product Information NAK Type：UNP1


1. Features




2. Material


90 Shore A.

3. Application



application.

Example:




(4) Cranes




Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 35 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

82

Product Information NAK Type：CNP


1. Features




2. Material


90 Shore A.

3. Application



application.

Example:




(4) Cranes




Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 0.5 m/sec

Working Pressure

≦ 20 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

83

Product Information NAK Type：UP1


1. Features




2. Material


90 Shore A.

3. Application



application.

Example:




(4) Cranes




Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec

Working Pressure

≦ 45 MPa


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

84

Product Information NAK Type：WP1

Description：PU Wiper

1. Features

Having a double lip and all

rubber part. This can prevent

oil scraping off.

2. Material


90 Shore A.

3. Application

Generally for heavy-duty


cylinder design.

Example:

(1) Bulldozers


(3) Forklifts

(4) Mobile lifts


(6) Injection molding machines

(7) Mobile arm trucks


Media Dirt, Dust, etc.

Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

85



1. Features

Having a single lip and all PU

part. It’s a single acting wiper

for protection of cylinders against

ingress of dirt.

2. Material


90 Shore A.

3. Application


cylinders, used for all cylinder

design.

Example:


(2) Bulldozers


(4) Cranes




Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 2 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

86



1. Features

Having a single lip with steel

case clad and PU part. It’s a

single acting wiper for protection

of cylinders against ingress of

dirt.

2. Material


90 Shore A.

3. Application



design.

Example:


(2) Bulldozers


(4) Cranes

(5) Forklifts



Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

87



1. Features

Having a double lip with steel

case skeleton and PU part.

It’s a single acting wiper for

protection of cylinders against

ingress of dirt.

2. Material


90 Shore A.

3. Application



design.

Example:


(2) Bulldozers

(3) CNC machines


(5) Cranes



Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

88



1. Features





dirt.

2. Material


90 Shore A.

3. Application



design.

Example:


(2) Compression molding

(3) Cranes


(5) Fork lift trucks



Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

89



1. Features





dirt.

2. Material


90 Shore A.

3. Application



design.

Example:



(3) Cranes





Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

90



1. Features


case skeleton and PU part. It’s

a single acting wiper for


ingress of dirt.

2. Material


90 Shore A.

3. Application



design.

Example:


(2) Bulldozers


(4) Cranes




Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 2 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

91



1. Features




ingress of dirt.

2. Material


90 Shore A.

3. Application



design.

Example:


(2) Bulldozers


(4) Cranes




Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 2 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

92



1. Features



oil scraping off.

2. Material


90 Shore A.

3. Application



cylinder design.

Example:

(1) Bulldozers


(3) Forklifts

(4) Mobile lifts






Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

93



1. Features





dirt.

2. Material


90 Shore A.

3. Application



design.

Example:


(2) Bulldozers


(4) Cranes

(5) Forklifts



Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

94



1. Features


case skeleton and PU part.



ingress of dirt.

2. Material


90 Shore A.

3. Application



design.

Example:


(2) Cranes





Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 2 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

95



1. Features




ingress of dirt.

2. Material


90 Shore A.

3. Application



design.

Example:





(5) Hydraulic jacks

(6) Mining hydraulics



Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

96



1. Features




ingress of dirt.

2. Material


90 Shore A.

3. Application



design.

Example:





(5) Hydraulic jacks




Temperature

UB903: -40℃~100℃

UB904: -40℃~100℃

UK905: -40℃~100℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

97

Product Information NAK Type：WPB

Description：Rubber Wiper

1. Features


case clad and rubber part. It’s a



dirt.

2. Material


hardness of 90 Shore A

3. Application



design.

Example:


(2) Bulldozers


(4) Cranes

(5) Forklifts




VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

98

Product Information NAK Type：WPC


1. Features


case skeleton and Rubber part.



ingress of dirt.

2. Material



3. Application



design.

Example:


(2) Cranes






VN901: -25℃~200℃

Linear velocity

≦ 2 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

99

Product Information NAK Type：WPK


1. Features


case skeleton and rubber part.



ingress of dirt.

2. Material



3. Application



design.

Example:


(2) Bulldozers

(3) CNC machines


(5) Cranes




VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

100

Product Information NAK Type：WPM


1. Features





dirt.

2. Material



3. Application



design.

Example:



(3) Cranes






VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

101

Product Information NAK Type：WPR


1. Features





ingress of dirt.

2. Material



3. Application



design.

Example:


(2) Cranes






VN901: -25℃~200℃

Linear velocity

≦ 2 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

102

Product Information NAK Type：WPV


1. Features





dirt.

2. Material



3. Application



design.

Example:



(3) Cranes






VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

103



1. Features

Having a single lip and all rubber



ingress of dirt.

2. Material



3. Application



design.

Example:


(2) Bulldozers


(4) Cranes





VN901: -25℃~200℃

Linear velocity

≦ 2 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

104



1. Features



The wiper O.D. with groove is

easily to be installed and used

for the cylinder with high swell

factor.

2. Material



3. Application



design.

Example:


(2) Bulldozers

(3) CNC machines





VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

105



1. Features



oil scraping off.

2. Material



3. Application

Generally for standard cylinders,

used for all applications.

Example:

(1) Bulldozers


(3) Forklifts

(4) Mobile lifts








VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

106



1. Features




ingress of dirt.

2. Material



3. Application



design.

Example:


(2) Bulldozers


(4) Cranes





VN901: -25℃~200℃

Linear velocity

≦ 2 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

107



1. Features



oil scraping off.

2. Material



3. Application



Example:

(1) Bulldozers


(3) Forklifts

(4) Mobile lifts








VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

108



1. Features




ingress of dirt.

2. Material



3. Application



Example:





(5) Hydraulic jacks


(7) Hydraulic presses




VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

109



1. Features




ingress of dirt.

2. Material



3. Application



Example:





(5) Hydraulic jacks





VN901: -25℃~200℃

Linear velocity

≦ 1 m/sec


Criteria

Rmax ≦ 2.5 µm

Ra ≦ 0.05-0.3 µm

110

Product Information NAK Type：HB

Description：U-Packing + Ring

1. Features

With a fitted O-ring under the

U-packing, provide extreme

loads for effective sealing at low

or zero pressure.

2. Material

U-Packing：PU with a hardness

of 95 Shore A.

O-Ring：NBR with a hardness of

70 Shore A.

3. Application

Generally for hydraulics,

reciprocating movements and

high loads.

Example:

(1) Agricultural machines

(2) Earth moving machines

(3) Forklifts

(4) Mobile arms


Media Hydraulic oils

Temperature UK905: -30℃~100℃

NK761: -40℃~100℃

Linear velocity

≦0.5 m/sec

Working Pressure

≦35 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.1-0.4 µm

111

Product Information NAK Type：HD

Description：U-Packing+Ring

1. Features




or zero pressure.

2. Material


of 95 Shore A.


70 Shore A.

3. Application



high loads.

Example:



(3) Forklifts




NK761: -40℃~100℃

Linear velocity

≦0.5 m/sec

Working Pressure

≦35 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.1-0.4 µm

112

Product Information NAK Type：HS


1. Features




or zero pressure.

2. Material


of 95 Shore A.


70 Shore A.

3. Application



high loads.

Example:



(3) Forklifts

(4) Mobile arms




NK761: -40℃~100℃

Linear velocity

≦0.5 m/sec

Working Pressure

≦35 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.1-0.4 µm

113

Product Information NAK Type：HBX


1. Features

With a fitted X-ring under the

U-packing, provide positive

wiping for effective sealing at

low or zero pressure.

2. Material


of 95 Shore A.

X-Ring：NBR with a hardness of

70 Shore A.

3. Application



high loads.

Example:



(3) Forklifts





NK761: -40℃~100℃

Linear velocity

≦0.5 m/sec

Working Pressure

≦35 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.1-0.4 µm

114

Product Information NAK Type：HDX


1. Features





2. Material


of 95 Shore A.


70 Shore A.

3. Application



application.

Example:

(1) Agricultural machines.

(2) Earth moving machines.

(3) Forklifts.

(4) Mobile arms




NK761: -40℃~100℃

Linear velocity

≦0.5 m/sec

Working Pressure

≦35 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.1-0.4 µm

115

Product Information NAK Type：HSX


1. Features





2. Material


of 95 Shore A.


70 Shore A.

3. Application



high loads.

Example:



(3) Forklifts





NK761: -40℃~100℃

Linear velocity

≦0.5 m/sec

Working Pressure

≦35 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.1-0.4 µm

116

Product Information NAK Type：O ring

Description：Static seal

1. Features

A popular round shape makes it

to be the most widely used ring

in static or even low duty

dynamic applications.

2. Material



3. Application

O-ring can be used in almost all

general industrial machines for

different sealing function types.

Mainly be used for static

applications, like axial seals and

radial seals. Both pneumatics and

hydraulics are well suited.

Example:

(1) Machine tools


Media

Mineral oil, grease, water, air, diesel fuels,.. et al. Depending on the rubber used.


VNC25: -25℃~200℃

Working Pressure

≦ 5~10 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.05-1.6 µm

117

Product Information NAK Type：X ring


1. Features

The special four-lipped design

makes it better than O-ring in

some aspects. Especially, this

type can avoid twisting in the

groove.

2. Material



3. Application

Primarily used in dynamic

applications and some in static

applications. Both pneumatics

and hydraulics are applicable.

For example, reciprocating

piston seal (dynamic) and flanges

seal (static).

Example:

(1) Agricultural machinery


Media

Mineral oil, grease, water, air, diesel fuels. (Depend on the rubber used.)


VNC25: -25℃~200℃

Working Pressure

≦ 5~10 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.05-1.6 µm

118

Product Information NAK Type：SQ ring


1. Features

The simple square cross section

makes it to be good replacements

for O ring in high-pressure static

applications. Low cost is another

factor why it is used.

2. Material



3. Application

Mostly used in static applications

like rod seal, bore seal, face seal

with internal pressure, face seal

with external pressure et al.

Example:



(3) Bulldozers



Media



VNC25: -25℃~200℃

Working Pressure

≦ 5~12 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.05-1.6 µm

119

Product Information NAK Type：D ring


1. Features

The customized D-shape design

can meets your special needs

with a better groove support.

2. Material



3. Application

Mainly be used for static

applications, like axial seals and

radial seals. Both pneumatics and

hydraulics are well suited.

Example:



(3) Bulldozers


(5) Forklifts

(6) Mobile lifts


Media



VNC25: -25℃~200℃

Working Pressure

≦ 5~10 MPa


Criteria

Rmax ≦ 16 µm

Ra ≦ 0.05-1.6 µm

120

Packing Design Sheet NO.336 INDUSTRIAL ROAD., NANKANG INDUSTRIAL ZONE, NANTOU CITY,54012 TAIWAN, R.O.C. TEL: 886-49-2255011, FAX: 886-49-2250035, E-Mail: [email protected]

Customer & Division Cycles/Min. Stroke Length Average Speed

Speed

Customer P/N Min. Normal Max.

Temperature

Contact

Application

City/State/Zip Media to be sealed Viscosity

Telephone Pressure Min. Normal Max.

Address Size

Type of Equipment

OEM Date Required NAK Standard (ASTM)

Aftermarket Material

Customer Standard

Annual Usage Peak Month NAK Standard (AQL 4.0,C=0)

Q.C.

Customer Standard

Special Operating Conditions NAK standard

ODM

Customer Sample

Design by

Customer Drawing

b

a

c

a

b

c

Documents

Fluid Power - NAK Sealing · PDF file3 Chapter 1 Application Guide 1.1 Introduction Nowadays,the different operation conditions andcritical requirements are found in hydraulic and