First, O ring permanent deformation, loss of sealing effect related factors
1/ permanent deformation and medium working pressure
In all kinds of factors causing permanent deformation of the sealing ring, the pressure of the working medium is the main reason for the permanent deformation of the O ring. Normally, the higher the work pressure, the higher the hardness of the sealing material. In order to meet the requirements of different working conditions, especially high requirements are particularly high, the general should be considered in the new formula, in order to increase the elasticity of the material (especially increase the elasticity of the material at low temperature), reduce the material compression permanent deformation.
2/ permanent deformation, compression ratio and tensile strength
O ring seals are sealed by compression and tension under the condition of compression or tension. It has been proved that the longer the use time, the greater the compression ratio and the amount of tensile, the greater the stress drop, and eventually lead to the lack of elasticity of the O ring, thus the greater the probability of losing the sealing effect. At present, in the design and use, we will try to increase the size of the O ring section and try to use low hardness material, thereby reducing the compression ratio, to prevent the occurrence of permanent deformation.
3/ permanent deformation and temperature
Temperature not only is one of the important reasons to accelerate the aging of rubber materials, but also is an important factor affecting the permanent deformation of O rings.
The initial stress due to compressive deformation will gradually decrease with the relaxation of the O coil and the decrease of temperature, so as to disappear. And the higher the operating temperature, the greater the permanent deformation of the O ring. When the permanent deformation is greater than 40%, the leakage is lost and the sealing capacity is lost. Similarly, at very low temperatures, such as working below zero, the initial compression may decrease or completely disappear due to a sharp decrease in temperature. Therefore, in the design and use, we must try to ensure that the seal has a suitable working temperature, the corresponding selection of materials, such as the use of high temperature and low temperature O ring material, to extend service life.
Two, what is the O ring?
Is a kind of rely on seal elastic deformation and sealing o-ring. A sealing element originally used as a cylinder for a steam engine. Because of its cross section is O, often called O-ring, the Taiwanese and Japanese companies, also known as o-ring. Because of its simple structure and very practical, it is one of the most widely used seals in hydraulic and pneumatic systems. According to whether the movement can be divided into static and dynamic two forms of seal. Not only can be used alone, but also in many combinations of sealing devices in the basic component.
Three. Introduction of star shaped ring
1) the star ring (X-ring) is also a standard piece, and the cross section is a X type sealing ring. For machinery, valves, cylinders, pumps, etc.. The main specifications to American Standard AS568 as the standard, the diameter of 1.78, 2.62, 3.53, 5.33, 6.99; the spot mainly use NBR and fluorine rubber and other non-standard specifications can also be customized mold. The star ring is a four lip cross section seal. The same as it o ring has the advantages of convenience, economy and wide application field etc.. Compared with O-Ring, it improves distortions, extrusion and other issues. In reciprocating, rotary motion and spiral motion in the sealing system, can better reflect its advantages. It has good interchangeability with the groove of AS 568A standard series O-Ring. The ring is applied in a dynamic or static situation in gas and liquid, and is suitable for reciprocating piston, piston rod and plunger, and can also be applied to shafts and spindles under the condition of swinging, spiral and rotating.
2) X type sealing ring working pressure: static without retaining ring, up to 5MPA; when there is retaining ring, up to 40MPA.
Dynamic, reciprocating movement, without retaining ring, up to 5MPA; reciprocating movement of the retaining ring, up to 30MPA; rotating movement with retaining ring, up to 15MPA;
3) movement speed: reciprocating movement, up to 0.5M/S; rotation movement can reach 2M/S.
4) temperature: general and the selected material decision, Ding rubber NBR limit temperature is -40~120 degrees; fluorine rubber VITON limit temperature is -40~240 degrees centigrade.
5) star shaped ring features:
A, anti distortion and extrusion resistance is better; B, double sealing lip; C, no rolling phenomenon; D, small friction;
E, dynamic sealing performance is excellent.
Four, O ring and other rubber seals, incoming inspection procedures
O ring and other rubber products in inquiry, order, delivery, delivery, use and a series of processes, including the receiving link is also very important part. It actually checks the products ordered before use. Here, Taiwan Asahi Meike seal XOK, suggestions from the following aspects:
1) visually inspect the packing for damage so as to avoid damage to the sealing ring;
2) check the label, size, material, hardness, quantity and color indicated on the outer packing ring, and agree with the sales order;
3) inspect the sealing ring for burr, bad edge, bump and breakage;
Check the number: 4) if for large size, the number is not much, can be used in the form of points; if the small size, and the number is more, recommend the use of electronic scales weighing the nuclear to check the number of each package of the sealing ring;
5) size and tolerance confirm: you can use vernier caliper to measure the size of the sealing ring, in the form of sampling. Sampling rules suggest: quantity 500~1000, sampling 5%; quantity 1000~5000; sampling 3%; quantity 5000~10000; sampling 2%; quantity 10000; sampling 1%.
If you have any questions, please contact the supplier in time