Mechanical Face Seals

Mechanical Face Seals

Why SAP PARTS Seals

Corrosion Resistant.

Higher operational life.

Precision Lapped seals.

No micro-fine scratches.

Wear Re-countering Design.

Minimum face load variations.

Self-renewing sealing surfaces.

Special Seal and O - Ring materials.

Suitable for Heavy Duty Applications.

PageContent

1 Mechanical Face Seals............................................................................................ 2

2 Application Requirement ...................................................................................... 3

3 Sealing Function ........................................................................................................... 4

4 Lubrication ....................................................................................................................... 5

5 Seal Design ..................................................................................................................... 6

6 Special Seal Design................................................................................................... 10

7 Innovations....................................................................................................................... 11

8 Sealing System Clearance..................................................................................... 13

9 Materials ............................................................................................................................ 15

11 Mechanical Face Seal Design Input Data.................................................. 18

10


© SAP PARTS India. 1

O ring ................................................................................................................................... 16


Mechanical face Seals are designed to be employed in most abusing working conditions, accepted worldwide to use in extremely harsh environments under enormous stresses, sand, dirt, mud, dust and earth material. Sealing technology for Static and Dynamic Applications is mainly concerned with providing sealing solutions for machinery and applications in which conventional sealsfail or lack the necessary durability.

For Years together, SAP PARTS™ branded Mechanical Face Seals have been used by OEMs and Users of Seals with outstanding s u c c e s s i n C o n s t r u c t i o n E q u i p m e n t s , Transmission Drives, axles, Rollers and Argo machineries. The Special Alloy Cast iron materials Provided by SAP PARTS ™ are having extraordinary capacity for wear resistance, for a verity of demanding applications, such as mining machinery, agriculture equipments, undercarriage vehicles, track rollers and many other applications.

Continuous technological research in SAP PARTS™ sealing solutions guarantee our esteemed customers a long lasting, highly durable service life and maximum productivity of equipments using SAP PARTS™ Seals.

© SAP PARTS India.2

Application Requirements

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Machines operating in abrasive media like dirt, dust,sand, mud and stone demands extreme wear resistance of the sealing system. A high quality comopnet sets like Bearing, wet brake discs, gears, spindles, axles need to be perfectly protected against contamination of destructive media.

Must withstand to a Circumferencial Speed of up to 10 m/sec

The Sealing faces must continuously lubricated as to prevent any cold welding due to excessive heat generated in rubbing.

Wear rate of Sealing Surfaces must be proportional to the face load within the sealing system.

The static as well as dynamic leakage prevention must be guaranteed.

The heat generated at sealing faces due to friction must be despised with adequate oil flow in the sealing system.

The pressures pipe in the application must be handled by the sealing system.

3


Sealing Function

The alloy cast iron seal rings are preloaded by Torric rings or O - Rings. As a result, the axial load closes the gap between the seal faces, which leads to the sealing function. The relative movement in circumferential direction is only taken place between the seal faces.

Axial load experienced by the metal sealing faces.

Transmission of the friction torque to the housing components.

Static sealing between each seal ring and its housing. The seal faces of the metallic rings are precision lapped.

The Load distribution by O rings is combinition of various Load vectors as below -

The Seals are designed in such a way that they open out from the seal faces towards the centre axis, forming a cone-shaped gap which has the following benefits:

Due to capillary action in the Gap and centrifugal force , lubricant admits easily in to the seal faces.

Potential cold welding of the seal faces is avoided since Adequate lubrication and cooling are assured.

As wear goes on , sealing band increases and it can virtually only end when the seal collar will completely worn out.

This sealing system retains a continuous oil film on the sealing surfaces.


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Lubrication

Absolute Lubrication is Most necessary for the function of the mechanical face seal.

The use of oil lubrication considerably increases with the field of applications and with respect to peripheral speed. This is because of the heat description properties of the oils. As a standard Transmission oils, grade SAE 80 and SAE 90, found to be quite suitable for typical face seal operation. The oil level after flling should be between the axis center line and 2/3 of the seal diameter.................................................

When filled to the correct level, the oil will generally is sufficient for the lifetime of the seal. The face seal requires no additional maintenance.

Oil lubrication

When the applications are with low sliding speeds al low as 1m/sec, grease is the right consideration as a permanent lubrication. Seal Face Gap is vital consideration however in this selection. The maintenance care needs to be taken while filling grease, is that if the gun pressures is increased chances of dislodging of O - rings can result.

Grease lubrication

5


Seal Design

Mechanical Face Seal DO- Type

The DO type Mechanical Face Seal consists of two identical metal face seals and two rubber O - rings placed on the Ramp profile of the metal seal. The SAP PARTS ™ Seals comes in two material versions - Alloy cast iron and Alloy Forged Steel grades. The O- ring material s however are of 4 types based on the application requirements

At Seal assembly the o-rings are compressed between the tapered contact surfaces of the seal ring and housing. The o-rings undergo a calculated compression as per SAP PARTS ™ standards it is around 25% volumetric compression, which is critical for proper operation of the sealing system Also the overall system Cleanliness of the o-rings and housing free of oil and dirt is of primary importance. Lubrication of the o-rings with oil or grease is not permitted during the installation process

There are most comman Two Types of Mechanical Faces Seals. That is with O Ring ( DO Type) and with Trapezoidal Torric Rings (DF Type) .


Design - DO Type

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Installed condition

retaining lip

seal face

Housing Boregripping taper

shoulder

seal ring

deformed o-ring

O-RING

A

BSEAL RINGS WITH O-RING

TI

seal face

land

land surface

gripping taper

seal face taper

throat radius

retaining lip

HOUSING BORE

A

R3

T1

T2

T3

R1R2

T4

0D

5

0D

3

0D

4

0D

1

0D

2

7


Seal Design

Mechanical Face Seal DF- Type

The Mechanical Face Seal of DF Type consists of two metallic angular seal rings with identical geometrical profiles. The seal rings are assembled with trapezoid rubber rings which are placed in the particular housing bore. The geometry of the housing profile is comparatively easier to produce and the seal installation does not require an installation tool. As compared to the DO type Mechanical face seals, the resilience of the trapezoid rubber ring is normally stiffer. This limits the permitted axial movement and tolerance.

Historically a numerous mechanical face seal designs

were developed based the verity of application needs.

SAP has few unique designs extremely suitable for

demanding applications and adverse operating

condition. The Design of one of the seal in the group

is Inverted wrt to the other seal. This provides

considerable advantage of manufacturing process

of the sealing system mating components.


Housing bore

A

Rz 25-40

t2

t1

t3

RS

Řd

Řd

f

β

Installed conditionseal face

bore Ø

shoulder

deformedbelleville washer

seal ring

Trapezoid ring

bŘ

d1

h

Seal rings with trapezoid ring

seal facelandland surface

seal face taper

ŘD

a

ŘD

i

H

Designs - DF Type



Special Seal Design

SAP PARTS not only offers “off-the-shelf” designs – its engineering team is also available to work with your engineers to design ‘non-standard’ metal face seals. Whether developing a new seal size or type to fit your application, or utilizing a new metal seal or O-Ring material, SAP PARTS engineers have the experience necessary to design, procure and test these concepts and follow them to production.


© SAP PARTS India.

Innovations

At SAP Parts, we continuously effort to pioneer developments that create competitive advantage with our parts. Our innovation plan and actions are in close collaboration with our suppliers, customers and human resources in order to meet the variable needs of customers, from time to time.

Innovation is the USP of SAP Parts. Moreover it is our core value and we intend to proactively employee innovative thinking culture in all our opertions.

The Sealing Solutions Delivered by SAP Parts Involves ahigh end research and patented technology warrantingthe highest performance and application sustainabilityof Mechanical Face Seals at -

Max 10 M/s Surface speed.

Most Severe Environmental Situations.

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BEARINGCAVITYPRESSURE

SAP Parts Seals Come with most advance and innovative anti corrosive surface treatment called CED. CED is an Extremely high corrosion protection. A 20 micron dry film of coating thickness can withstand as much as 1000 hours salt spray test ASTM B117.Able to coat complex shapes with a very high degree of accuracy and repeatability. This is an environment friendly, Water - based technology eliminates risk of fire and reduces air and water pollution.


Technological Developments

Seal Design for Differential Load applications.

Model for Contact Surface Wear Life Prediction.

Elastomeric Variable Load Stress Relaxation Modeling.

Innovative Surface Treatments for Demanding Applications.

Functional Conformance of Metallurgical Properties of Ni-Hard

Cast Alloys & Sealing Surface Asperities in Abrasive Environment.

Finite Element Model Details

Axial constraint (Y-direction)

Representative Insertion tool

Innovations

TIME = 5UX (AVG)RSYS = 0PowerGraphicsEFACET = 1AVRES = MatDMX = 10. 406SMN = 3. 3936SMX = 2. 72519 -3. 3936 -2. 71374 -2. 03387 -1. 354 - .674138 . 005728 . 685595 1. 36546 2. 04533 2. 72519

© SAP PARTS India.

O - Ring CrossSection d1

d1 < 8.0

8 < d1 < 12.7

d1 > 12.7

Gap 'S'

4

5

6

Ra < 6.5 μm

Rz < 10.0 μm

Rmax < 16.0 μm

The axial gap "S"in the housing is vital, and is such that it meets the demands of the construction equipments and off highway Vehicle industry. For high sliding speeds it may be necessary to reduce the axial compression, thus reducing the load of the seal faces and the heat generation in the seal face. This is achieved by increasing the axial gap ''S". The following gaps are possible, depending on the O-Ring cross section.

SAP Parts recommend that tests be carried out to find the most appropriate setting. Since the O-Ring is always oversized to the housing, the edges of the housing must be rounded. Surfaces Under pressure, elastomers adapt themselves to irregular surfaces. However, for liquid-tight conditions, certain minimum requirements have to be made on the surface finish of the faces to be sealed. Scores, scratches, pores and concentric or spiral machining scores are not permissible. For the surface of the seal installation chamber we recommend a machining quality of Mechanical Face Seals.

Installed condition

retaining lip

seal face

Housing Boregripping taper

shoulder

seal ring

deformed o-ring

TM

13

Sealing System Clearance


X

Y Z

Contact Forces, Contact Surface & Torque Capability

Load v/s Circumferential Speed Characteristics

Linear Speed [ m/s]

0

0

50

100

150

200

250

3001)

350

400

450

50025 50 75 100 125 N=150 N=200 N=300 N=400

N=500

N=750

N=1000

N=2000

N=4000

1 2 3 4 5 6 7 8 9 10 11 12

Se

al O

uts

ide

Dia

m [

mm

]

Ask for Seal Housing Gap “S’’

N is RPM


© SAP PARTS India.

Materials

Material

Chemical

Composition

c

Si

Ni

Cr

Mo

Co

V

W

P

s

Microstructure

Hardness

SAE-52100

Forged Steel

0.93 - 1.05

0.15 - 0.35

0.25 Max

1.35 - 1.60

0.10 Max

-

-

-

0.025 Max

0.015 Max

Fine

Tempered

Martensite

59 - 65 HRc

FC15CR3MO

( ASTM-A

531-ll Class

B) Cast Iron

3.2 - 3.6

1.1 - 1.6

1 - 2.0

14 - 16

2.0 - 4.0

0.2 max

0.2 Max

0.2 max

-

-

Cementite

Microstructure

64 - 75 HRc

Ni-Hard

Cast Iron

3.0 - 3.6

0.4 - 0.7

3.5 -4.3

1.2 - 1.7

0.4 Max

-

0.3 -0.6

-

0.3 Max

0.1 Max

Eutectic Carbide

M7C3 in the

Matrix of

Martensite

57 - 64 HRc

SAE-52100

FC15CR3MO

Ni-Hard

Magnification

To address the main potential failure threats of a sealing system it is needed, the Wear and corrosion resistance to be adequate in the material of a seal ring. Specifically for mining machines, agriculture machinery. SAP Seals uses Alloy Steels of various Grades, following various Manufacturing Processes like Forging, and Investment Casting etc. Most preferably used are the forged Alloy Steel of Grade SAE:52100 also called as Bearing steel and Special Alloy Steel Castings, detail Specifications of these Seal Ring materials are as below:"

Seal Ring Materials

SAP PARTS ™ offers different coatings which provide a considerable good sealing solutions for harsh environmental conditions, and enhanced corrosion resistance for demanding environments and applications.If any special requirements SAP PARTS™ provides customized solutions on coating for which a contact to the SAP PARTS™ Engineering is needed

15


Nitrile

-25

100

Excellent

Good

Excellent

Excellent

Low

LT Nitrile

-50

105

Excellent

Good

Excellent

Excellent

Low

Viton

-10

190

Good

Good

Fair

Excellent

High

HNBR

-40

135

Excellent

Good

Excellent

Excellent

High

Silicone

-60

165

Poor

Poor

Excellent

Poor

Medium

Service Temp (-) C

Service Temp (+) C

Abrasion Resistance

Tear Resistance

Water Resistance

Oil Resistance

Cost

O Rings

SAP PARTS ™ uses several materials for its Torric rings are available to meet a variety of application requirements. The most common materials are nitrile (NBR) and silicone. Viton and highly saturated nitrile (HNBR) are available for more specialized applications. The table listed below gives a brief comparison between available O- ring options

The elastomers of various hardness are served depending upon the application requirements. Below is the comman materials and their applicability wrt service temperature conditions for reference.

Elastomer properties for O/T -Ring selection


O-Ring Deformation

NODAL SOLUTIONSTEP = 5SUB = 20TIME = 5CONTPRES (AVG )DMX = 5.08001SMX = 1.89639 0 .21071 .421419 .632129 .842838 1.05355 1.26426 1.47497 1.68568 1.89639

X

Y Z

NODAL SOLUTIONSTEP = 5SUB = 20TIME = 5UYRSYS = 0DMX = 5.08001SMN = -.533E-05SMX = 5.08001 -.56444 1.12889 1. 69333 2.25778 2.82222 3.38667 3.95111 4.51556 5.08001X

Y Z



Mechanical Face Seal Design Input Data Form

Contact Information Seal Housing Groove Parameters

Company Name :...........................................................................

Date: ..............................................................................................

Contact Person's Name: ...............................................................

Email ID: ........................................................................................

Phone No.1: ....................................................................................

Phone No.2: ...................................................................................

S Housing Flange Gap

D Groove Diameter - Max

D1 Groove Corner Diameter

D2 Housing Inside Diameter

a Ramp Angle

r Groove Radius

L4 Distance of Groove from Face

h Seal Group Width

Do Outer Diameter of Seal

DI Inner Diameter of Seal

Horizontal VerticalHousing Position

Material / grade

Hardness

Surface Finish

Dynamic Run Out

Offset

Motion - Direction of Rotation

Clockwise Counter- Clockwise Both

Normal RPM Max RPM

Assembly

Removal Frequency

Rare Offten

Space Restrictionss Yes No

If Yes - Extenet of Ristriction

Operating Temperature

Oil Sump

Environment Max Min

Contamination

Partical Type

% Exposed

% Submerged

Application Load

Extent in Kg/Cm2

Fluid / Lubrication

Grade

Viscosity

Sump Level

Application Description

Type Axial Radial

Oil Grease

© SAP PARTS India.

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Mechanical Face Seals