MFA > Materials
Choosing materials is one of the important tasks which require a lot of investigations, experiences and compromises between different desirable properties. At Mohandesi Farapardaz Arvand (Seal Jet Iran) we have great expertise in this area. We are well prepared to help you choosing the right material for your application.
For a given application there may be a number of different materials that are well suited, but our job is to find the best solution for you. This is often a combination between material properties and price. However, looking at the procurement price only is often very misleading, as this does not consider actual life-cycle cost for a given product. Downtime, equipment failure and repair cost due to a faulty seal is many times higher than the cost of the seal, even in cases when some of the more expensive materials are chosen.
Mohandesi Farapardaz Arvand (Seal Jet Iran) is dedicated to find the best overall sealing solutions and materials with special attention to functionality, reliability and low overall life-cycle cost.
Seals are faced with an ever increasing demand for higher pressure, temperature, functionality and longevity. This means that some of the more “traditional” materials no longer are as well suited as they used to be. Advances in material science are resulting in new and improved materials, suited to meet the increased demands.
Classification of sealing materials
In sealing technology, mainly two groups of macromolecular (polymer) substances are used: elastomers and thermoplastics. Macromolecular substances are organic compounds; its molecules consist of several thousands, often even millions of atoms, known as macro, giant, string or chain molecules. They can be created either by modification of highly molecular natural materials (e.g. natural rubber) or by depositing low-molecular elements (so called monomers) through various chemical reactions (synthetic materials, plastics).
Elastomers are materials that can be highly expanded by exerting relatively little power. Because of their structure, elastomers have a high retractibility, which means the compression set is very limited. There are two main groups of elastomers; rubber materials and thermoplastic elastomers. The rubber materials are polymers, which are formed by chemically cross-linked macromolecules with various vulcanization additives. Due to their chemical bonds they do not melt but rather begin to decompose at high temperatures. The cross-links also results in that the rubber materials don’t dissolve or, depending on the medium, swell or shrink.
The Thermoplastic Elastomers demonstrate the characteristic properties of elastomers over a wide temperature range, but with the processing behavior of thermoplastics. They can be melted at high temperature and can be processed with traditional thermoplastic processing techniques. Thermo plastic elastomers are soluble and they generally swell less in comparison to their chemically crosslinked equivalents. Engineering Thermoplastics are e.g. POM, PA, PTFE and Peek.
Thermoplastics can be melted. They are polymer materials, which are essentially harder and rigid at their application temperature compared to elastomers. Depending on the chemical structure, the properties vary from hard, to stiff, to ductile and flexible. Due to the morphological structure, extensive stretching is non-reversible and moulded parts remain in the deformed state. Thermoplastics are therefore called Plastomers. Engineering Thermoplastics are applied in the sealing technology for back-up rings and guide rings, bearing bushes, etc.
Thermoplastic elastomers belong to the elastomer family of materials. The elastomer family consists of materials that can be highly expanded by exerting relatively little power. Because of their structure, elastomers have a high retractability, which means the remaining deformation is very small.
Unlike elastomers (rubber), thermoplastic elastomers are physically but not chemically cross-linked. Therefore they can be melted at higher temperature and can be processed with traditional thermoplastic processing techniques. Thermoplastic elastomers are soluble; generally they swell less in comparison to their chemically cross-linked equivalents.
The thermoplastic elastomers of Mohandesi Farapardaz Arvand (Seal Jet Iran) are various types of polyurethanes from the company SKF (Economos). We are proud to be the only manufacturer of machined seals in Iran by using injection molded semi-finished polyurethane material.
Polyurethanes (TPU: Thermoplastic Polyurethane) have superior mechanical properties compared to elastomers (rubbers) and with the variety of different polyurethanes presented below, polyurethane will be the preferred material for many sealing systems.
H-ECOPUR is a hydrolysis-resistant thermoplastic polyurethane elastomer. It combines the engineering properties of ECOPUR with a high resistance to hydrolysis which is otherwise rarely found in polyurethanes. It is stable in water up to +90°C and has an outstanding stability in mineral oil. Because of its resistance to hydrolysis H-ECOPUR can be used for water hydraulic and for applications in steel plants, mining, tunneling and presses. H-ECOPUR is particularly recommended for the use in pure and seawater, for HFA and HFB fluids and biologically degradable hydraulic fluids (vegetable oils and synthetic esters) and food articles. H-ECOPUR is KTW approved and meets the FDA standards.
Temperature range from -20 ºC to 110 ºC
ECOPUR is a thermoplastic polyurethane elastomer (TPU), which has an unusually high abrasive resistance, low compression set, high physical properties and tear strength. In sealing technology ECOPUR is mostly used for U-cups, lip seals, wipers and packings, but it may also be used for dampers and other machined parts. Products made from this material can be used in mineral oil, in water up to 40°C and in bio-degradable hydraulic oils like vegetable oils and synthetic esters up to 60°C. Depending on the seal design and the housing conditions seals made of ECOPUR can be used up to 400 bar (for high pressure demands, experts from SKF recommend to use anti-extrusion-rings).
Temperature range from -30 ºC to 110 ºC
S-ECOPUR has been optimized with regard to the tribological characteristics friction and wear. This was achieved by the addition of a synergetic combination of solid lubricants. This special material is therefore best suitable for most severe applications in the water hydraulics and oil-free pneumatics.
Chemical properties are similar to H-ECOPUR.
Temperature range from -20 ºC to 110 ºC
T-ECOPUR is modified for low temperature applications. The properties of T-ECOPUR are similar those of ECOPUR, but the minimum service temperature is extended to -50°C. For that reason T-ECOPUR is most suitable for applications in severe climatic conditions and processes for frozen goods. T-ECOPUR has an unusually high abrasive resistance, low compression set, high physical properties and tear strength. Products made from this material can be used in mineral oil and in bio-degradable hydraulic oils like vegetable oils and synthetic esters.
Temperature range from -50 ºC to 110 ºC
G-ECOPUR is a casted hydrolysis-resistant polyurethane with similar properties to H-ECOPUR, especially regarding its chemical stability. G-ECOPUR can be used in the same hydraulic fluids as H-ECOPUR. Generally, G-ECOPUR is used for seals with a diameter from 540 mm up to 4000 mm as one piece and larger using our special welding technique.
Temperature range from -30 ºC to 110 ºC.
The composition of X-ECOPUR provides outstanding friction and wear properties as well as high pressure resistance. Therefore the material is well suited for the use as a composite seal, for wipers working in heavy-duty applications as well as for engineered plastic parts that require high elasticity and superior resilience.
Due to the exceptional extrusion resistance, seals made of this material work at higher pressure leve