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Four main conditions make the seal and shaft more compatible and assist in providing optimal seal performance.
1. SHAFT HARDNESS Normally seal contact area of the shaft should be Rockwell C 45 minimum. It is and important factor to prevent excessive wear, deformation, scratches or nicks, and to control the roughness or machining surface easily.
2. SHAFT SURFACE ROUGHNESS The recommended shaft surface roughness is as follows:
Rotating: 10 to 20 µ inch AA (.25 µm to .50 µm AA).
Reciprocating: 5 to 10 µ inch AA (.13 µm to .25 µm AA).
This is very critical as greatly influence the amount of lip heat, thus this finish not be overlooked.
3. GRINDING Rotating Shift: plunge grinding is recommended.
Reciprocating shaft: centerless grinding is acceptable.
Cast iron or stainless steel shafts for rotating applications and steel shafts for reciprocating applications, we suggest using hard chrome plating. The finishing surfaces described above are required to have no machine lead, otherwise it may actually pump fluid from wider the seal lip.
4. SHAFT CHAMFER Without proper chamfer on shaft, the seal lip may be damaged or distorted resulting in dislodged garter spring. We suggest chamfer as Table EPM-3 to assist in the installations process.