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KCW

KCW
KCW_image_3d_v1
KCW_image_3d_v2

Description

The KCW profile is a shaft seal composed of a single metal cage with rubber grooves on the outside of the cage, a primary sealing lip without a spring and an additional anti-pollution sealing lip.

Advantages

Very good static sealing
Very good thermal expansion compensation
Greater roughness is allowed in the housing
Reduced risk of corrosion
Easy to assemble with very limited bounce-back effect
Sealing for high viscosity fluids
Primary sealing lip generating low levels of friction and heat
Protection against undesirable air contaminants

Technical data

Applications

All types of rotative applications
Machine tools
Agriculture
Construction
Transmission
Gear boxes
Motors
Pumps

Materials

Rubber

ACM 70 - 75 Shore A
EPDM 70 - 75 Shore A
FKM 70 - 75 Shore A
HNBR 70 - 75 Shore A
NBR 70 - 75 Shore A

Metal cage

Steel - AISI 1010

Dimensions
Materials
Conditions
for use
Seal design
Shaft design
Housing design

Dimensions

Installation drawingLogement pour bague d'étanchéité - Housing Groove for shaft seal

Materials

Metal cage

The table below shows the materials that we can offer for metal cages.

Application Material Standard Characteristics
Metal cage Non-alloy standard steel AISI 1010
(DIN 1624)
Cold rolled steel
Metal cage Nickel chrome steel AISI 304
(DIN 1.4301 - V2A)
Standard stainless steel
Metal cage Chrome-nickel-molybdenum steel AISI 316
(DIN 1.4401 - V4A)
Stainless steel highly resistant to corrosion

Rubbers

ACM (Polyacrylate)

Polymers containing ethyl acrylate (or butyl acrylate) have a small amount of monomer, which is necessary for cross-linking; ACM is a material with better heat resistance than NBR. It is often used for automatic gearboxes.

Chemical resistance Mineral oils (motor oils, gear box oils, ATF oils)
Atmospheric and ozone agents
Compatibility issue Glycol-based brake fluids (Dot 3 & 4)
Aromatic and chlorinated hydrocarbons
Water and steam
Acids, alkalis and amines
Temperature range -25°C to + 150°C (short-term peak at +160°C)
-35°C / +150°C with particular ACMs
AEM (ethylene acrylate rubber)

As a methyl acrylate and ethylene copolymer, AEM is considered to be more resistant to heat than ACM. Its characteristics make it an intermediary between ACM and FKM.

Chemical resistance Cooling fluids
Aggressive mineral oils
Atmospheric agents
Water
Compatibility issue Aromatic solvents
Strong acids
Brake fluids
Gearbox oils
ATF oils
Temperature range - 40°C to + 150°C
CR (Polychloroprene)

This CR-based rubber is used in the refrigeration industry and for ventilation systems. This chloroprene was the first synthetic rubber to be developed and marketed.

Chemical resistance Paraffinic mineral oils
Silicone oils and greases
Water and water-based solvents for use at low temperatures
Refrigerant fluids
Ammoniac
Carbon dioxide
Atmospheric and ozone agents
Limited chemical resistance Naphthenic mineral oils
Aliphatic hydrocarbons (propane, butane, petroleum)
Glycol-based brake fluids
Compatibility issue Aromatic hydrocarbons (benzene)
Chlorinated hydrocarbons (trichlorethylene)
Polar solvents (ketone, acetone, acetic acid, ethylene-ester)
Temperature range -40°C / +100°C (short-term peak at +120°C)
EPDM (Ethylene Propylene Diene Monomer rubber)

As an Ethylene Propylene Diene Monomer copolymer, EPDM is commonly used for hot water taps, cooling systems, brake systems, dishwashers and washing machines.

Chemical resistance Hot water and steam up to +150°C
Glycol-based brake fluids (Dot 3 & 4) and silicone-based brake fluids (Dot 5)
Organic and inorganic acids
Cleaning agents, sodium and potassium alkalis
Hydraulic fluids (HFD-R)
Silicone oils and greases
Polar solvents (alcohols, ketones and esters)
Atmospheric and ozone agents
Compatibility issue Mineral oils and greases
Hydrocarbons
Low impermeability to gas
Temperature range -45°C / +150°C (short-term peak at +175°C)
FFKM (perfluorinated rubber)

FFKM has the best characteristics for resistance to high temperatures, with an excellent chemical inertia. This FKM-based rubber is very often used for high-temperature hydraulic and pneumatic systems, industrial valves, injection/fuel systems, motor seals and high-vacuum systems.

Chemical resistance Aliphatic and aromatic hydrocarbons
Polar solvents (ketones, esters and ethers)
Organic and inorganic acids
Water and steam
High-vacuum system
Compatibility issue Coolants (R11, R12, R13, R113, R114, etc.)
PFPE
Temperature range -15°C/+320°C
FKM (fluorinated rubber)

Depending on their structure and fluorine content, the chemical resistance and resistance to the cold in fluororubbers can vary. This FKM-based rubber is very often used for high-temperature hydraulics and pneumatics, for industrial valves, injection/fuel systems, motor seals and high-vacuum systems.

Chemical resistance Mineral oils and greases, ASTM n°1, IRM 902 and IRM 903 oils.
Fire-resistant liquids (HFD)
Silicone oils and greases
Mineral and vegetable oils and greases
Aliphatic hydrocarbons (propane, butane, petroleum)
Aromatic hydrocarbons (benzene, toluene)
Chlorinated hydrocarbons (trichlorethylene)
Fuel (including high alcohol content)
Atmospheric and ozone agents
Compatibility issue Glycol-based brake fluids
Ammonia gas
Organic acids with a low molecular weight (formic and acetic acids)
Temperature range -20°C / +200°C (short-term peak at +230°C)
-40°C / +200°C with particular FKMs
FVMQ (fluorosilicone rubber)

The FVMQ has mechanical and physical properties that are very similar to those of the VMQ. However, the FVMQ offers better resistance to fuels and mineral oils. However, resistance to hot air is not as good as that of the VMQ.

Chemical resistance Aromatic mineral oils (IRM 903 oil)
Fuels
Aromatic hydrocarbons with low molecular weights
(benzene, toluene)
Temperature range -70°C/+175°C
HNBR (Hydrogenated Nitrile Butadiene Rubber)

This HNBR-based rubber is obtained through selective hydrogenation of the NBR's butadiene groups. It is commonly used for power-assisted steering and for air conditioning.

Chemical resistance Aliphatic hydrocarbons
Mineral and vegetable oils and greases
Fire-resistant fluids (HFA, HFB and HFC)
Diluted acids, saline solutions and bases for operation at an average temperature
Water and steam up to +150°C
Atmospheric and ozone agents
Compatibility issue Chlorinated hydrocarbons
Polar solvents (ketones, esters and ethers)
Strong acids
Temperature range -30°C / +150°C (short-term peak at +160°C)
-40°C / +150°C with particular HNBRs
NBR (Nitrile Butadiene Rubber)

Nitrile rubber (NBR) is the general term for acrylonitrile-butadiene copolymer. The ACN content can vary between 18% and 50%. While the acrylonitrile content is important, the resistance to oil and fuel is more so. Conversely, the elasticity and compression set are not as good. The NBR has good mechanical properties and good wear resistance. However, its resistance to atmospheric agents and the ozone is relatively low.

Chemical resistance Aliphatic hydrocarbons (propane, butane, petroleum, diesel fuel)
Mineral oils and greases
Fire-resistant fluids (HFA, HFB and HFC)
Diluted acids, low-temperature alkaline and saline solutions
Water (up to +100°C max)
Compatibility issue Fuels with high aromatic content
Aromatic hydrocarbons (benzene)
Chlorinated hydrocarbons (trichlorethylene)
Polar solvents (ketone, acetone, acetic acid, ethylene-ester)
Strong acids
Glycol-based brake fluids
Atmospheric and ozone agents
Temperature range -30°C / +100°C (short-term peak at +120°C)
-40°C / +100°C with particular NBRs
VMQ (silicone rubber: methyl vinyl polysiloxane)

This FVMQ-based rubber is very often used in fuel systems.

Chemical resistance Animal and vegetable oils and greases
Water for operation at an average temperature
Diluted saline solutions
Atmospheric and ozone agents
Compatibility issue Superheated steam up to +120°C
Chlorinated hydrocarbons with a low molecular weight (trichlorethylene)
Aromatic hydrocarbons (benzene, toluene)
Temperature range -60°C / +200°C (short-term peak at +230°C)

The table below gives an overview of the physical, chemical and mechanical characteristics for each of the materials.

Characteristics/Materials ACM AEM CR EPDM FFKM FKM FVMQ HNBR NBR VMQ
Abrasion resistant 2 3 2 2 4 2 4 2 2 4
Resistance to acids 4 3 2 2 1 1 3 1 3 3
Chemical resistance 4 2 2 1 1 1 1 2 2 2
Resistance to cold 4 2 2 2 3 4 2 2 2 2
Dynamic properties 3 3 3 2 3 2 4 1 2 4
Electrical properties 3 3 3 2 1 4 1 3 3 1
Flame resistant 4 4 2 4 1 1 2 4 4 3
Heat resistant 1 1 2 2 1 1 1 1 2 1
Sealing water 1 1 2 2 2 2 4 2 2 4
Oil resistant 1 3 2 4 1 1 2 1 1 2
Ozone resistant 1 1 2 1 1 1 1 2 4 1
Tearing resistant 2 3 3 1 4 3 4 2 2 4
Traction resistant 3 2 2 1 2 1 3 1 2 4
Water/vapour resistant 4 4 3 1 2 3 3 1 2 3
Resistance to atmospheric agents 1 1 1 1 1 1 1 2 3 1

1. Excellent properties 2. Good properties 3. Average properties 4. Poor properties

Chemical compatibility

A "Chemical compatibility guide" catalogue can be downloaded from the Documentation section. You can also use our online "Chemical compatibility" tool free of charge.

These two tools give you the option of measuring the behaviour of our materials that come into contact with the majority of existing fluids. The data displayed is the result of rigorous testing of the ambient temperature and in consultation with previous publications. Test results are not fully representative due to the specific features of your application. The tests performed actually do not consider additives and impurities that may exist under the actual conditions of use, nor the potential elevation of temperatures. Other parameters can also alter the behaviour of our materials, such as the hardness, persistence, abrasion, etc. We therefore recommend performing your own tests to verify the compatibility of our materials according to your specific application. Our technical team can provide you with any additional information.

Conditions for use

Speed

The table below indicates the relationships between the linear speed, the rotation speed and the recommended material.

Maximum speed for standard shaft seals without spring

Linear speed calculation:

s (m/s) = [Ø shaft (mm) x speed (rpm) x π] / 60,000

Pressure

Standard shaft seals with a primary sealing lip and no spring are used only in unpressurised environments.

We recommend using shaft seals with springs for use in pressurised environments between 0.02 and 0.05 MPa (max).

For even higher pressures, we recommend using high-pressure SCHP - TCHP shaft seals which, because of their specific design (shorter sealing lip, thicker rubber membrane, metal cage closer to the shaft), can support pressures of up to 1.0 MPa with speeds reduced to 0.3 m/s.

Temperature

The table below indicates the temperature limits, depending on the materials and fluids used.

Media Maximum temperature, depending on the materials
ACM AEM EPDM FKM HNBR NBR VMQ
Mineral oils Oils for motors +130°C +130°C - +170°C +130°C +100°C +150°C
Oils for gearboxes +120°C +130°C - +150°C +110°C +80°C +130°C
Oils for hypoid gears +120°C +130°C - +150°C +110°C +80°C -
ATF oils +120°C +130°C - +170°C +130°C +100°C -
Hydraulic oils +120°C +130°C +150°C +130°C +90°C -
Greases - +130°C - - +100°C +90°C -
Fire-resistant
fluids
HFA group - Emulsion with more than 80% water - - - - +70°C +70°C +60°C
HFB group - Opposite solution (water in oil) - - - - +70°C +70°C +60°C
HFC group - Polymer aqueous solution - - +60°C - +70°C +70°C -
HFD group - Water-free synthetic fluids - - - +150°C - - -
Other fluids EL + L heating oil - - - - +100°C +90°C -
Air +150°C +150°C +150°C +200°C +130°C +90°C +200°C
Water - - +150°C +100°C +100°C +90°C -
Water for washing - - +130°C +100°C +100°C +100°C -
Temperature range Min. -25°C -40°C -45°C -20°C -30°C -30°C -60°C
Max. +150°C +150°C +150°C +200°C +150°C +100°C +200°C

The sealing lip of the shaft seal endures a higher temperature due to shaft rotation, and the significant pressure and friction on the mechanical parts. Good lubrication is therefore necessary to allow for a better release of heat and thus limits the temperature rise in the parts subjected to friction.

By definition, the temperature at the edge of the seal is raised when the rotation speed (and thus the linear speed) as well as the shaft diameter increases. The graph below gives an overview of the increase in temperature (in °C) at the point of contact on the sealing lip.

Under sealing lip for rotary seals 2

Under sealing lip for rotary seals 1

Fluids

Greases

Greases are generally applied to bearings etc. and require specific adaptation to provide favourable operating conditions for the shaft seal. To prevent the lip of the seal from sustaining more significant pressures than planned, we recommend positioning the lip seal on one side of the bearing in such a way so that the lip is not prematurely destroyed. We also recommend reducing the rotation speed by 50% when lubricated, to ensure that less heat escapes during friction.

Seal design

Tolerance for the outside diameter of the seal (ØD)

The table below indicates the pre-tightening for shaft seals on the housing diameter according to standard ISO 6194-1.

Bore diameter
ØD1 (mm)
Tolerances on the outside diameter ØD of the ring Roundness tolerance
Apparent metal cage Rubber coating Coating with grooves Apparent metal cage Rubber coating
ØD1 ≤ 50.0 +0.10 / +0.20 +0.15 / +0.30 +0.20 / +0.40 0.18 0.25
50.0 < ØD1 ≤ 80.0 +0.13 / +0.23 +0.20 / +0.35 +0.25 / +0.45 0.25 0.35
80.0 < ØD1 ≤ 120.0 +0.15 / +0.25 +0.20 / +0.35 +0.25 / +0.45 0.30 0.50
120.0 < ØD1 ≤ 180.0 +0.18 / +0.28 +0.25 / +0.45 +0.30 / +0.55 0.40 0.65
180.0 < ØD1 ≤ 300.0 +0.20 / +0.30 +0.25 / +0.45 +0.30 / +0.55 0.25% of ØD 0.80
300.0 < ØD1 ≤ 500.0 +0.23 / +0.35 +0.30 / +0.55 +0.35 / +0.65 0.25% of ØD 1.00
500.0 < ØD1 ≤ 630.0 +0.23 / +0.35 +0.35 / +0.65 +0.40 / +0.75 - -
630.0 < ØD1 ≤ 800.0 +0.28 / +0.43 +0.40 / +0.75 +0.45 / +0.85 - -

Tolerance for the inside diameter of the seal (Ød)

Free and without constraint, the inside diameter of the sealing lip is always smaller than the diameter of the shaft. The pre-tightening or interference denotes the difference between these two values. Depending on the shaft diameter, the diameter of the sealing lip is generally considered to be less, between 0.8 and 3.5 mm.

Shaft design

Shaft installation for the shaft seal

Shaft material

Suitable materials are:

  • ordinary C35 and C45 steels used in mechanical construction
  • 1.4300 and 1.4112 stainless steels for sealing water
  • sprayed carbide coatings
  • graphite
  • malleable cast iron
  • materials with a CVD and PVD coating

Not appropriate:

  • chrome coatings solidified through non-uniform wear
  • plastic materials resulting from low thermal conductivity, which can lead to a disturbance in the transport of heat, an increase in temperature in friction areas with the shaft seal, as well as a potential softening

Shaft hardness

Shaft hardness will depend on the linear speed (in m/s) and the level of pollution.

Rotation speed Hardness in HRC
s ≤ 4.0 m/s 45 HRC
4.0 < s ≤ 10.0 m/s 55 HRC
s > 10.0 m/s 60 HRC

Surface roughness

The recommendations below must be considered for the quality of the shaft surface area.

Standard conditions:

  • Ra = 0.2 to 0.8 µm and 0.1 for demanding applications
  • Rz = 1.0 to 4.0 µm
  • Rmax ≤ 6.3 µm

Shaft tolerance

The shaft must have a tolerance of h11, in line with standard ISO 286-2

Shaft diameter
Ød1 (mm)
Tolerance
h11 (mm)
Ød1 ≤ 3.0 -0.060 / 0
3.0 < Ød1 ≤ 6.0 -0.075 / 0
6.0 < Ød1 ≤ 10.0 -0.090 / 0
10.0 < Ød1 ≤ 18.0 -0.110 / 0
18.0 < Ød1 ≤ 30.0 -0.130 / 0
30.0 < Ød1 ≤ 50.0 -0.160 / 0
50.0 < Ød1 ≤ 80.0 -0.190 / 0
80.0 < Ød1 ≤ 120.0 -0.220 / 0
120.0 < Ød1 ≤ 180.0 -0.250 / 0
180.0 < Ød1 ≤ 250.0 -0.290 / 0
250.0 < Ød1 ≤ 315.0 -0.320 / 0
315.0 < Ød1 ≤ 400.0 -0.360 / 0
400.0 < Ød1 ≤ 500.0 -0.400 / 0

Chamfer and radius

You are strongly advised to install a chamfer on the shaft so as not to alter the primary sealing sealing lip of the shaft seal during assembly. Please refer to the table below.

Shaft diameter
Ød1 (mm)
Chamfer diameter
Ød3 (mm)
Radius
R (mm)
Ød1 ≤ 10.0 Ød1 - 1.50 2.00
10.0 < Ød1 ≤ 20.0 Ød1 - 2.00 2.00
20.0 < Ød1 ≤ 30.0 Ød1 - 2.50 3.00
30.0 < Ød1 ≤ 40.0 Ød1 - 3.00 3.00
40.0 < Ød1 ≤ 50.0 Ød1 - 3.50 4.00
50.0 < Ød1 ≤ 70.0 Ød1 - 4.00 4.00
70.0 < Ød1 ≤ 95.0 Ød1 - 4.50 5.00
95.0 < Ød1 ≤ 130.0 Ød1 - 5.50 6.00
130.0 < Ød1 ≤ 240.0 Ød1 - 7.00 8.00
240.0 < Ød1 ≤ 500.0 Ød1 - 11.00 12.00

Shaft run out and eccentricity

The shaft run out is a deviation between the current shaft axis and the theoretical rotation axis. It is important to reduce the shaft run out as much as possible by positioning the shaft seal as close as possible to the bearing.

The shaft and housing must be assembled centred on one another in order to remove any unilateral radial load at the sealing lip of the ring.

Shaft run-out + Eccentricity for shaft seals without spring

Shaft machining

Correct shaft machining is essential to the proper operation of the sealing system.

  • Plunge grinding: preferred machining method that ensures the absence of striations on the shaft (0 +/- 0.05°)
  • Turning: suitable for shafts used with a unidirectional sense of rotation

Machining guidelines for surface adjustments

Parameters Requirements
Speed of the part to be machined 30 to 300 rpm
Wheel speed 1500 to 1700 rpm
Surfacing feed < 0.02 mm/turn
Dressing tool multi-grain dressing diamond, single drain dressing diamond
Grinding rate feed approximately 0.02 mm
Spark duration full spark, min. 30 secs
Passing depth > Rmax of the old machining operation
Eccentricity of the tool and part to be machined the best possible

Housing design

Housing installation for the shaft seals

Surface roughness

The recommendations below must be considered for the quality of the housing surface area.

Standard conditions for shaft seals with a rubber coating:

  • Ra = 1.6 to 6.3 µm
  • Rz = 10.0 to 25.0 µm
  • Rmax ≤ 25.0 µm

Tolerance of the bore diameter of the housing

The bore diameter of the housing must have a tolerance of H8, in line with standard ISO 286-2

Bore diameter
ØD1 (mm)

Tolerance
H8 (mm)

3.0 < ØD1 ≤ 6.0 0 / +0.018
6.0 < ØD1 ≤ 10.0 0 / +0.022
10.0 < ØD1 ≤ 18.0 0 / +0.027
18.0 < ØD1 ≤ 30.0 0 / +0.033
30.0 < ØD1 ≤ 50.0 0 / +0.039
50.0 < ØD1 ≤ 80.0 0 / +0.046
80.0 < ØD1 ≤ 120.0 0 / +0.054
120.0 < ØD1 ≤ 180.0 0 / +0.063
180.0 < ØD1 ≤ 250.0 0 / +0.072
250.0 < ØD1 ≤ 315.0 0 / +0.081
315.0 < ØD1 ≤ 400.0 0 / +0.089
400.0 < ØD1 ≤ 500.0 0 / +0.097
500.0 < ØD1 ≤ 630.0 0 / +0.110

Groove width dimensions

The table below provides information on the width of the groove and the recommended radius.

Height
H1
Width Radius
Max R2
L2min (H1 x 0.85) L1min (H1 x +0.3)
7.00 5.95 7.30 0.50
8.00 6.80 8.30
10.00 8.50 10.30
12.00 10.30 12.30 0.70
15.00 12.75 15.30
20.00 17.00 20.30

Only on request