mechanical face selas

requirements

Mechanical face Seals are designed to be employed in most exhaustive worhing conditions, accepted worldwide to use in extremely harsh environments under enormous stresses, sand, dirt,mud, dust and earth material.

In the fields of agricultural and construction machinery technology, as well as in the area of renewable energy in wind power plants, neither standard shaft sealing rings nor cassette seals are usually able to achieve the desired service life.

For this reason our technicians have collaborated with a number of different customers to develop new mechanical face seals for static or dynamic applications that offer major benefits in terms of service life and functionality.

the benefits

  • High abrasion-resistance
  • Free of maintenance
  • No infiltration of aggressive or abrasive media

design

The ttv mechanical face seals are fitted inside a split housing, with their lapped running surfaces pressed against each other. An O-ring (NBR / FPM / etc.) is usually used as a pre-load element to fix and align the seal correctly in place inside the housing.


Typs

Standard-Type

L-Type

X, Y-Type

dimensons

All standard dimensions are available, and we can also provide quick delivery whatever your field of application. Special contours and special materials are also available on request. You can find a detailed overview of all types and dimensions here.

STANDARD-TYPE
The standard type consists of two identical metallic seal rings and two elastomer O-rings arranged on the profile of the metal seal. ttv's seals are available in two material versions: alloy cast iron and alloy forged steel. However, the O-ring materials differ depending on the application requirement.

In the area of cast iron alloys, ttv offers two material compositions, the selection of which depends on the requirements of the applications.

In the sealing arrangement, the O-rings are pressed together between the conical contact surfaces of the sealing ring and the housing. The O-rings are subjected to a pressure calculated according to ttv's standards, which is approximately 25% volumetric pressure, which is crucial for the proper functioning of the sealing system.

L-TYPE
The drive seal type MRTZ consists of two metal rectangular sealing rings with identical geometric profiles. The sealing rings are mounted with trapezoidal rubber profiles placed in the respective housing bore. The geometry of the housing profile is comparatively easier to manufacture and the seal installation requires a simple assembly tool. Compared to the ANTN type mechanical seals, the elasticity of the trapezoidal rubber ring is usually stiffer, which limits the permissible axial movement and tolerance.
Numerous drive seal designs have been developed in the past based on a wide variety of application requirements. ttv has some unique designs that are ideally suited for demanding applications and adverse operating conditions.

SPECIAL DESIGN X, Y-TYPE
ttv does not only offer "standard" designs - we are also available to work with your engineers to develop "non-standard" drive seals. Whether you are developing a new seal size or type for your application, or using a new metal or elastomer material, ttv's Engineering Solution Team has the experience to design, produce, test and bring these concepts through to production.

 

What you can expect from mechanical drive seals:

  • Must withstand peripheral speeds of up to 10 m/sec.
  • Sealing surfaces must be continuously lubricated to prevent cold welding due to excessive heat generated by friction.
  • The sealing surfaces should be in constant contact to prevent leakage.
  • The same applies to the elastomer contact within the sealing system. Both static and dynamic tightness must be ensured.
  • The heat generated by friction at the sealing surfaces must be dissipated by a sufficient flow of oil in the sealing system.


Machines used in abrasive media such as dirt, dust, sand, mud and stone require extreme wear resistance of the sealing system. High-quality components such as bushings, wet brake discs, gears, shafts and axles must be perfectly protected from contamination by destructive media.

ttv's drive seals are designed to open from the seal faces towards the centre axis, forming a conical gap which has the following advantages:

  • The capillary action in the gap and the centrifugal force allow the lubricant to easily reach the sealing surfaces.
  • Possible cold welding of the sealing surfaces is avoided as sufficient lubrication and cooling is ensured.
  • This sealing system maintains a continuous oil film on the sealing surfaces.

The sealing rings made of alloyed cast iron are pretensioned by trapezoidal rings or O-rings. The axial force thus closes the gap between the sealing surfaces, resulting in the sealing function. The relative movement in the circumferential direction only takes place between the sealing surfaces.

Significance of elastomer O-rings in the sealing unit:

  • The axial load on the sealing surfaces is caused by the pressure of the O-ring, or the trapezoidal rings.
  • The frictional torque is transmitted via the O-rings and housing parts.
  • The static seal between each seal and the housing is ensured by an O-ring.

The sealing surfaces of the metal rings are hardened and precisely lapped, while the elastomers are selected according to the conditions of use.

OIL LUBRICATION
The use of oil lubrication significantly increases the life of the seal due to better cooling. However, it is selected taking into account the application area, the arrangement available in the system for the oil circuit and circumferential speed. Normally, applications with higher speeds require oil lubrication.

Standard SAE 80 and SAE 90 gear oils are suitable for typical mechanical seal operation.

The oil level after filling should be 2/3 of the available oil volume of the oil housing and above the seal axis. When filled correctly, this is usually sufficient for the life of the seal and thus the seal faces are maintenance free.

GREASE LUBRICATION
For applications with low sliding speeds up to an order of magnitude of 1 m/s, grease lubrication as permanent lubrication of the sealing system is the right choice. For this option, the gap of the sealing surface is an important design feature. During maintenance work, when filling with grease, it should be noted that with increased grease pressure there is a risk of the elastomer round cord rings loosening from their position.

Adequate lubrication of the sealing surfaces is of utmost importance for the proper functioning of the mechanical seal.

Engineering solution is the unique selling point of ttv. This is one of our core values, which is lived in our philosophy and actively implemented in our daily activities and thus in all business areas.

The sealing solution delivered by ttv incorporates research and technologies that ensure the highest performance and application sustainability of drive seals

at max. 10 m/s surface speed and
under the most severe operating conditions.
operating conditions.

Friction management in our sealing solutions is already taken into account in the development of proprietary materials, the introduction of innovative process engineering technologies, the understanding of the tribology of wear parts and the special thermal barrier coating, making our seals suitable for harsh working environments. The result is a range of new products for PTO, axle and drive motor applications.

Technological developments:

Seal design for a wide range of applications.
Model for life prediction of contact surface wear.
FKM analysis to determine O-ring deformation.
Innovative surface treatments for demanding applications.
Functional conformity of metallurgical properties of chilled cast alloys and sealing surface irregularities in abrasive environments.
ttv seals feature the most advanced and innovative corrosion resistant surface treatments.

TSB (thermal protection coating) - a unique surface coating technology introduced by ttv for seals in high temperature operating conditions (>250°C). TSB isolates the seal from ambient heat and allows it to dissipate from the friction surfaces through the heat sinks on the inside of the seal. This innovative product development is used under the toughest applications.

To minimise the potential risks of failure for the sealing system, the wear and corrosion resistance of the metal surfaces must be adequate. ttv uses alloy steel of various grades for its cast design.

The steel commonly referred to as SAE 52100 grade bushing steel is offered for metal gaskets in steel design.

Our seals can be used specifically for applications in mining, dredging and rice cultivation, some of the most demanding environments where the material composition of the drive seals plays an important role. ttv has developed its own special cast iron materials with high chromium/nickel content and free graphite in the secondary matrix of the microstructure, which ensure high abrasion and corrosion resistance as well as higher heat dissipation.

Based on customer needs and knowledge of applications, many other casting designs are offered. These very solid castings are produced by lost wax and centrifugal casting processes, among others, for products with an outer diameter of 50 mm to 1300 mm.

ttv offers various coatings that provide extremely good sealing solutions for harsh environments and improved corrosion resistance for demanding environments and applications. Under special requirements, ttv offers customised coating solutions for which contact with our Engineering Solution Team is required.

ttv uses different materials for round cord rings for a variety of application requirements. The most common materials are NBR and FKM/FPM. Silicone and HNBR are available for special applications. The table below gives a brief comparison of the available O-ring options.

Elastomers of varying hardness are available for seal designs depending on application requirements.

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