Industrial seal self study guide - SKF.com

Seal Applications (cont.)
+ Handles high surface speeds
+ Some blends are food grade compatible
+ Can accept high pressure
+ Service life capability can exceed rubber compounds
Disadvantages
- Higher initial cost
- Normally non-stock
- Mechanical properties must be engineered in (Virgin PTFE
has low mechanical strength)
- Extra care is required during assembly
- Difficult to install
- Generally requires higher shaft hardness
Operating Ranges
Thermoplastic PTFE seals handle a wide temperature range, from
–400°F to 500°F (240°C to 260°C).
Identification
Red, white, gray, blue, green or brown.
Once the most popular seal
material, leather is now being
replaced by less expensive
synthetic materials (fig. 4k).
LEATHER SEALS
Before synthetic materials were developed, leather was the sealing
element commonly found in most early seals. Leather is tough, resists
abrasion and works well even today in many dirt exclusion applications.
However, it is expensive and can usually be replaced with another lip
material (fig. 4k). SKF stocks very few leather seals.
Advantages
+ Good tensile strength and abrasion resistance
+ Performs well with minimal lubrication
+ Tends to smooth rough shaft surfaces
+ Compatible with most lubes and solvents
+ Good dry running performance
+ Good in very cold temperature operation
+ Tough
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