PTFE oil seal installation method

When installing PTFE oil seals, it is important to be careful to avoid damaging the sealing lip. If the seal is installed from behind, the end of the shaft must be rounded or chamfered. At the same time, there must be no burrs, sharp angles, or rough machining lines, as shown in Figure 1.

When installing the seal with the lip facing the shaft end, it is required that the minimum diameter of the chamfer introduced is less than the unstressed diameter of the sealing lip, as shown in Figure 2.

 Table 1 gives guidance values for the introduction angle, and it is recommended that shallow angles should be used in practice within the range given.  

The preferred option is to use a mounting taper sleeve, as shown in Figure 3, where the seal can be mounted on the taper sleeve before being loaded into the shaft, ensuring proper positioning of the sealing lip.

Installation should be swift to reduce the time it takes for the sealing lip to deform on the cone sleeve and thus the time for the lip to recover.

Single and small batches of PTFE oil seals will be supplied in blister packs with a dedicated shipping mandrel that will pre-form the element beyond its free diameter, but smaller than the shaft diameter to be used, which is advantageous at the time of installation and also guarantees that the element will not be deformed or damaged during transport.

PTFE oil seals do not require any special storage conditions, unlike elastomer seals that must be kept away from sunlight and high temperatures to avoid rubber degradation.

Investigations of premature failures have shown that a significant proportion is due to inappropriate installation methods. However, following the following guidelines for installation can avoid such failures. - Fixtures and installation tools should be inspected regularly. - Do not remove the mandrel supplied with the goods until before installation. When removing the tapered mandrel, pay attention to the direction of the removal and do not increase the deformation diameter of the lip. - PTFE oil seals should be installed on shafts under non-lubricated (thousand-type) conditions to avoid contamination by dynamic pressure characteristics, if present. - Care should be taken not to damage the outer diameter surface of the seal. ——The seal should be pressed-in installed, and attention should be paid to the requirement that the circumference of the press-in stress point should be evenly distributed and as close to the outer diameter of the seal as possible. - If the seal has dynamic pressure characteristics on the sealing lip, ensure that the lip is introduced in the direction of rotation of the shaft. - The usual operation is to place the lip of the seal towards the medium to be sealed. (The seal is installed in reverse only if the exclusion medium is more important than the retention medium). - In harsh applications or where a secure seal is required, special sealants or adhesives can be used to improve the outer diameter seal.

Regarding the fixation of seals under pressure conditions, the following diagram gives installation recommendations.

If painting, be sure to block the seals, avoid getting the paint on the lip or the shaft where the lip is placed, and also block any vents or leaks so that they don't get clogged. Remember to remove the lid before the unit is working. If the paint has been baked, or in other words the mechanism is heated, the seals cannot be heated to a temperature higher than their material can allow. Do not allow the seal to come into contact with any non-specified fluid or subjected to a non-specified pressure during cleaning or testing. Pull-out items such as taper, internal threads, or simple grooves can be included in custom PDR designs.

Carsten Holm A / S

Since 1979, Carsten Holm A/S has been manufacturing and selling seals for a wide range of applications and harsh conditions such as hydraulics, pneumatics, static and rotary, and has been marketed to numerous industries in Northern Europe and abroad. Carsten Holm A/S is a market leader in seals and gaskets and is committed to adding value to its customers and providing outstanding solutions. We have the largest inventory of O-rings, rotary oil seals in Northern Europe. We have a team of professionals, documented processes and a high level of attention to quality. Our excellent service makes the difference! We offer a wide range of solutions that are adapted to the needs of our customers.

Carsten Holm A/S guarantees all of the following:

• Fast and reliable delivery • Competitive price • Excellent technical support • High quality products