Mechanical face seals Created by ttv for extreme usage conditions
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 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.
The standard type consists of two identical metallic sliding rings and two elastomer O-rings arranged on the profile of the metal seal. The seals from ttv 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 approx. 25% volumetric pressure, which is crucial for the proper functioning of the sealing system.
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. In the past, numerous drive seal designs have been developed based on a wide variety of application requirements. ttv has some unique designs that are ideally suited for demanding applications and adverse operating conditions.</div>Standard type The standard type consists of two identical metallic sliding rings and two elastomer O-rings arranged on the profile of the metal seal. The seals from ttv are available in two material versions: alloy cast iron and alloy forged steel. However, the O-ring materials differ depending on the application requirement.
Special type X, Y-type
ttv doesn't just offer "standard" designs - so 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 develop, produce, test and take these concepts through to production.
We stock all standard dimensions for these drive seals and can also convince with short delivery times of any desired drive seal for your application. Special contours and special materials of our drive seals are also available on request. A detailed list of dimensions for all types of drive seals can be found under this download.
What you can expect from mechanical drive seals:
Must be able to withstand circumferential 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 bearings, wet brake discs, gears, shafts and axles must be perfectly protected from contamination by destructive media.
ttv's mechanical face seals are designed to open from the seal faces towards the centre axis to form a tapered gap which has the following advantages:
Due to the capillary action in the gap and the centrifugal force, the lubricant easily reaches 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.
Importance 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
DThe sealing surfaces of the metal rings are hardened and precisely lapped, while the elastomers are selected according to the conditions of use.
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.
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 ist das Alleinstellungsmerkmal von ttv. Dies ist einer unserer Grundwerte der in unserer Philosophie gelebt, und in unserem täglichen Handeln und somit in allen Geschäftsbereichen aktiv umgesetzt wird.
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
Friction management in our sealing solutions is already given importance 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 layer, making our seals suitable for harsh working environments. The result is a range of new products for PTO, axle and drive motor applications.
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.
Whether agricultural machinery, construction machinery, forestry technology, drive technology, mechanical engineering, automotive or aerospace, we are ready for your challenges. With our engineering solutions, we manage to offer added value in all decisive product parameters through solutions developed specifically for customers and applications. Get to know our competence and best examples in the most diverse markets.