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The Effect Of Grommets Compression Rate On Sealing Performance

Doit Rubber Products Co.,Ltd | Updated: Sep 04, 2017



The effect of Grommets compression rate on sealing performance

Characteristics of Grommets:

1. Working medium and working conditions

In the specific selection of Grommets materials, the compatibility with the working medium should be considered first. The pressure, temperature, continuous working time and operating cycle of the seal shall be considered. If used in rotation, the temperature rise caused by friction heat should be considered. Different sealing material, its physical properties and chemical properties are different, see the rubber sealing parts raw material characteristics table.

2. Sealing form

The load type can be divided into static seal and dynamic seal; The sealing USES can be divided into hole seal, shaft seal and rotary shaft seal. The installation can be divided into radial installation and axial installation. In the radial installation, the deviation of the Grommets inside diameter and the diameter of the sealed diameter d2 should be as small as possible for the axial seal. For hole seal, the inner diameter of the hole should be equal to or slightly less than the diameter of the groove d1.

When the shaft is installed, consider the pressure direction. When internal pressure, the outer diameter of the Grommets should be about 1 ~ 2% of the outer diameter of the groove. When external pressure, the inner diameter of O type Grommets should be 1 ~ 3% smaller than that of groove diameter.

The above contents are sent out by rubber and plastic sealing parts co., LTD. Please indicate the source seal and the characteristics of Grommets. Thank you.

The effect of Grommets compression rate on sealing performance

O - type Grommets material selection has great significance for its sealing performance and service life. The properties of the material directly affect the performance of the Grommets. In addition to the general requirements of Grommets materials, the o-type Grommets should also pay attention to the following conditions:

(1) flexibility and resilience;

(2) appropriate mechanical strength, including expansion strength, elongation and tensile strength, etc.

(3) the performance is stable, it is not easy to melt in the medium, and the thermal contraction effect (joule effect) is small.

(4) easy to process molding and maintain precise dimensions.

(5) non-corrosive contact surfaces, non-polluting media etc.

The most suitable and most commonly used materials to meet the above requirements are rubber, so the Grommetss are mostly made of rubber. There are many kinds of rubber, and there are always new rubber varieties. When designing and choosing, we should understand the characteristics of various kinds of rubber and make reasonable choices.

Second, silica gel is also used in rubber, which is also used to make the o-type Grommets (silicone Grommets), for example, the box washer with a button, and a Grommets on the lid. High quality silicone Grommetss are not only smooth, non-stick glass, but also highly scalable. It's nontoxic and tasteless.

The compression ratio and tensile strength of Grommets are closely related. The longer the Grommets is used, the greater the compression ratio and the tensile strength, the greater the stress resulting from the rubber stress relaxation, so that the washer is less elastic and the sealing capacity is lost. The rubber of the various formulations used to make Grommetss will produce compressive stress relaxation under compression. At this time, compressive stress decreases with time.

When the compression ratio is calculated, it tends to ignore the decrease of the section height caused by the stretching of the Grommets during assembly. The change of the area of the Grommets area is inversely proportional to the change of its circumference. At the same time, because of the force of tension, the shape of the section of the Grommets will also change, which will show its height decrease. In addition, under the action of surface tension, the outer surface of the washer becomes more flat, i.e. the section height is reduced slightly. Increasing the section size of the Grommets is the simplest way to reduce the compression rate, but it will increase the size of the structure.

When the Grommets is in the same amount of stretching, the stiffened Grommets and its cross-section height decrease more. From this point, the material should be selected as low hardness as possible in accordance with the conditions of use. Under the action of liquid pressure and tension, the o-Grommets of rubber material will gradually become plastic deformation and its cross section height will be reduced accordingly.

When choosing a Grommets, you should pay attention to the contrast between compression ratio and tensile strength, so that you can choose a good Grommets to extend the use time without causing leakage in advance.