Selection Of Hydraulic Cylinder Seal Support Material

   Hydraulic cylinders are main executive parts of construction machinery, and many actions are 

done by the cylinder. The supporting bushing material has a great influence on the quality of the 

cylinder, and the non-metallic materials commonly used as the supporting bushing are nylon 1010 

and polyoxymethylene.

   First, support the assembly of the bushing and assembly gap

   1.The supporting bushing is set in the groove of the guide sleeve (the material is ductile 

iron), and the piston rod is guided and supported. The optimum design clearance of the inner 

diameter and the outer diameter of the piston rod is 0.08-0.16mm. Less than 0.08mm, the piston 

rod movement resistance, the tank tremble, support the bushing wear to speed, with severe 

abnormal sound, loss of support, gap more than 0.16mm, it is easy with the piston rod partial 

grinding, slide force, result in fuel tank leakage, piston rod with oil.

   2.The outer diameter of the supporting bushing is in contact with the inner diameter of the 

cylinder. The optimum design gap is 0.1-0.19mm. Less than 0.1mm, the piston rod movement 

resistance increases, can not maintain uniform motion, oil temperature is more obvious.Bushing 

does not support the role of the piston rod on the baffle or piston outer edge easy to scratch 

the cylinder wall, serious lead to cylinder scrapped.

   It can be seen that the assembly gap is critical to the quality of the cylinder. Assembly gap 

should be adjusted to support the bushing, supporting the adjustment of the sie of the assembly 

gap is B, the tolenrance requirement of mm.

    Second, the performance characteristics of the two material

    Nylon 1010 strength, rigidity, heat resistance are good, forming process is also good, water 

absorption and shrinkage is large, poor dimensional stability, by the temperature range of 

-30~80℃.

     POM is a high melting point, high density, cryatalline linear polymer, with good overall 

performance, tensile strength, impact toughness, stiffness, fatigue strength, creep resistance 

and dimensional stability are good, small water absorption. Very good chemical resistance and 

solvent resistance, especially organic solvents and oils. Even at high temperatures, the change

in weight of polyoxymethylene in general organic solvents is only 0.3% to 3%, and the dimensional change is only 0.1% to 1%. The working temperature is generally -40℃~140℃. The disadvantage is 

easy to decompose heat, forming difficult than nylon.

    Third, the application of two kinds of materials and processing methods

    1.Nylon 1010 has a high hardness, stiffness, processing technology is better, but by the 

temperature greater impact.Applicable to engineering machinery, machine tools and other places 

affected by the temperature less.

     2.POM has excellent mechanical properties, coupled with the use of thermoplastic molding 

methods can be used to shape, so that in the automotive industry, machinery industry, electronic 

machinery, buliding materials and other industries are widely uesd. POM can also replace copper, 

zinc, aluminum and other non-ferrous metal production of structural parts. Particularly suitable 

for the production of friction and bear the high load parts.

     3.Both materials have good practicality and ease of processing. With the original material 

into a bar or a pipe, with ordinary lathe can be processed, after molding ca also be scraping and 

other processing. Therefore, not only for machine manufacturing, but also for equipment 

maintenance.