What to Know Before Choosing Sealing Elements
The use of high-performance and long-term use sealing elements depends on the conditions in the system. The correct selection of seals will increase machine maintenance intervals while reducing downtime and spare parts costs. It is therefore important to correctly determine the following information before selecting a sealing element.
Operating pressures, sudden pressure changes and shocks in the system have an important influence on the selection of sealing elements. Especially in high-pressure systems, the extrusion gap value becomes even more critical. If the extrusion gap cannot be reduced, products with support rings should be preferred. In hydraulic systems, where temperatures can rise above 60°C and pressures can exceed 250 bar, materials with high extrusion strength and well-designed products should be selected. Negative effects of pressure on sealing elements due to deformation or leakage can lead to material extrusion. In low pressure situations, it is recommended that nut type sealing elements made of low hardness are preferred.
The minimum and maximum operating temperatures and the duration of the effects of these temperatures are important. Fluid temperature is another important factor in hydraulic cylinders.
However, the temperature on the sealing element reaches higher values as a result of the pressure. Temperature seriously affects the wear and crush resistance, chemical resistance, and compression permanent deformation properties of the sealing elements.
Especially at high temperatures (60°C and above), even at low pressures, this may lead to the extrusion of sealing elements produced from low hardness, rapid corrosion, and deterioration of the grain structure of the material. At negative temperature values, changes that adversely affect the sealing performance, such as shrinkage, hardening, and loss of preload, may be observed in sealing elements made from materials that are not suitable for cold operating conditions.
Therefore, the temperature values given in the catalog should be noted when selecting sealing elements.
Fluid type (medium)
The choice of sealing element for the type of liquid or gaseous fluid with which the sealing element will come into contact is important for system life and performance. Fluids with high lubricating properties are recommended to reduce system wear and to obtain a quiet and long service life. Fluids may also interact with sealing elements, causing them to expand and contract, increase and decrease in size or damage the chemical structure of the sealing element. For the use of special fluids, please contact our sales department.
Hydraulic cylinder dimensions
Seal element recess dimensions bore and rod diameters and their tolerances, the surface roughness of the working surface, and hydraulic cylinder stroke are values that should be considered during the design and production phase. When designing a cylinder, consideration should be given to the fact that bores with thin wall thicknesses may expand and lose dimensional stability and that long rods with small diameters may bend under load. The dimensional tolerances of these elements in their recesses should be checked prior to mounting the sealing elements to see what their surface quality will be after machining, honing, and grinding. It is important to consider the chamfer dimensions, cross-sections, and diameter ratios that will be mentioned in the mounting section for design purposes.