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Composite polyurethane seals for hydraulic cylinders



The hydraulic cylinders work in the presence of high pressures that allow, for example, to move the arms of earth-moving machines or large presses used for metal forging, as well as for ceramic production. The seals used in these applications must therefore meet both the need for load resistance and wear resistance


A customer, a well-known manufacturer of special hydraulic cylinders, commissioned us to study a custom sealing system capable of replacing the oring-energized PTFE pad solutions used up to that moment, with a solution able to improve the life of the seal while keeping the same guarantees of operation in difficult conditions.


For the development of this solution, the team of the ATP design office started from the analysis of the technical parameters of the application:

  • Fluid used: Mineral oil
  • Working pressure: approximately 460 bar (possible peaks at 550 bar)
  • Inbound working pressure: approximately 300 bar
  • Work environment: marine with the presence of humidity and high salt concentration (highly corrosive)
  • Stroke 700 mm
  • Prolonged exposure of the shaft to climatic agents
  • Thermal range: -10 ° C / + 70 ° C

Analyzing the conditions of use, the SINTEK D55, a polyurethane characterized by high resistance to abrasion, even in the presence of high loads, and high resistance to chemical and atmospheric agents, was found to be the most suitable material for the application. With the aid of FEM analysis, the profile of the pads was studied so that they could guarantee excellent sealing and extreme resistance to wear and extrusion. A classic geometry (AA101) has been optimized for the scraper, able to guarantee effective cleaning of the surface and prevent harmful infiltration of brackish water and impurities inside the cylinder.


The performances in terms of sealing, resistance to wear and extrusion, the possibility of use in high pressure and the practicality of assembly have led the customer to adopt the SINTEK D55 for this solution and to replace other cylinders previously equipped with traditional PTFE-based materials.

Consulta sul nostro catalogo generale i materiali consigliati a seconda delle condizioni operative.

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