Hydroteck provides technical expertise and customised sealing solutions for all your dynamic seal requirements. From machinery to cylinders we offer complete sealing solutions. All our seals are made of high-performance polymers materials like Polyurethane, Polyamide, Polyester resins, PTFE, Polyoxymethylene, NBR Rubber and etc.
Appropriate choice of seal material is very crucial in sealing systems to operate leak free and give us long uninterrupted life. Material performance and seal design are the most important factors of a system. Elastomers are one of the most widely used seal materials. They possess properties like elasticity, resilience and chemical resistance which are ideal for sealing applications.
Polyurethane has become one of the most versatile sealant products. Apart from its wear resistance characteristics in relation to other materials, it has the elastic qualities of rubber. The flexibility in TPU chemical engineering to obtain a wide range of properties, including resistance to fluids and moisture, has led to a wide acceptance of this material. Polyurethane seals offer exceptional performance in high-pressure hydraulic systems with abrasive contamination, high impact loads and associated adverse conditions as long as the temperature is below 100°C.
Nitriles are the most commonly used elastomers in the seal industry. Excellent resistance to petroleum products and its ability to be composed for serving a wide range of temperatures have made nitrile a very popular material. Nitrile is a copolymer of butadiene and acrylonitrile. Specific characteristics can be obtained by varying the proportions of these different polymers. Acrylonitrile content in Nitrile can be varied from 18% to 50% by weight. Nominal designations are 'low' (18 to 24%), 'medium' (28% to 33%), and 'high' (38% and higher) Nitrile. An increase in acrylonitrile content increases heat and chemical resistance to petroleum-based oils and fuels, but decreases flexibility at low temperatures. Nitrite provides an excellent compression set, tear resistance, cold flow, and abrasion resistance. The major limiting properties of nitrile are its low ozone and weather resistance and moderate heat resistance.
Fluorocarbon combines high temperature and chemical resistance to a broader range of fluids than any other elastomer. Low compression defined even at high temperatures makes it an appropriate selection of material under most conditions. Its operating temperature range ranges from 230ºC for high temperatures to -20ºC for low temperature applications. Three main factors make fluoroelastomers remarkably resistant to heat and fluids. Firstly, there are extremely strong bonds between the carbon atoms comprising the spine of the polymer and the attached fluorine atoms (Pendant). Second, fluoroelastomers feature a high fluorine-to-hydrogen ratio. Thirdly, the carbon's vertebral column is completely saturated. Fluorocarbons are a good choice of material for both static and dynamic applications.
POM is a high-strength engineered plastic suitable for bearings, bushings, and backup ring applications. The major molecular chain of the acetal homopolymer is the backbone of the acetal copolymer chain, where ethylene oxide is randomly added to the acetal homopolymer. The simple molecular nature of the main chain allows a very stable crystalline structure. This crystallinity leads to high heat resistance, high modulus, excellent wear resistance, and resistance to solvents.
Added ethylene bonds from acetal copolymer increase thermal stability, elongation and abrasion resistance. It also has good impact strength at low temperatures, high dimensional stability, favourable friction properties and low water absorption. It offers excellent gliding characteristics when blended with PTFE and good temperature resistance. Due to its chemical structure, POM has low moisture absorption and good chemical strength.
Glass-filled nylon turned out to be a great choice for bearing and ring applications. Its high compression module due to the strength of the fiberglass and excellent dimensional stability is very important in its functioning. GF-polyamide has a high load bearing capacity which makes it a good choice for backup rings and guide rings. It has good temperature and wears resistance as well.
PTFE is a rubber with excellent chemical, tribological and thermal properties. PTFE's reinforced shades offer excellent resistance to wear and extrusion. The bronze filler provides slightly superior properties than glass filler as far as tribological properties are concerned. PTFE is practically resistant to all hydraulic fluids. It's great for dynamic applications and pressures up to 6000 psi or 400 bar.
Hardness can be described as resistance to indentation under certain conditions. When evaluating the potential efficacy of the moulded (processed) joint, hardness is one of the most common criteria in the rubber industry. Though the elastomeric lip of most standard seals falls in the 70 to 95 Shore A range, the application in question will always govern the necessary hardness. Softer compounds with less strength can be great for low-pressure joints, but high-pressure joints will probably need a harder lip material.
Resilience (also called rebound) is the ability of a compound to regain its original size and shape after temporary deformation. While composition can improve elastomers in this area, it is essentially an inherent property. As a general rule, resilience is most critical in dynamic seals. This can be seen, for example, when a seal's elastomeric lip flexes (is distorted) to follow a shaft imperfection, and then returns to its original ("resting") position. In many cases, resilience is closely linked to flexibility.
Tear resistance (or tear strength) is the ability of a material to resist the growth of a cut or notch when tension is applied. Tear resistance is an important consideration, both as the finished item is removed from the mould and as it carries out in the actual service. Compounds with low tear resistance are at risk for installation damage, especially in designs featuring non-smooth areas (as with burrs, slots, and threads) and/or sharp, non-radiused (non-rounded) corners.
Measured as a percentage of loss based on original weight, abrasion resistance is the resistance of a material to wear through contact with a mobile abrasive surface. On the one hand, when the cutting or notching of a sealing lip is an instantaneous event, abrasive rubbing or scraping is a much more progressive phenomenon that develops over time. Seals in motion are most susceptible to abrasion. Hard compounds tend to exhibit less abrasive wear than soft compounds, but the use of a harder compound can also increase friction in dynamic seals, and increased friction generates seal-degrading heat.
The compression set is the end result of progressive stress relaxation, which is the steady decline in sealing force that results when an elastomer is compressed over a period of time. Compression adjustment tests find their widest use in the selection of materials for use as O-rings, U-cup seals and other seals that depend on an optimal degree of compression.