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| FAQ's |
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- F.A.Q: General Topics
- General technical issues.
- 1. Shaft Preparation
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- 1. Shaft Preparation - Top
- Q. What is the recommended shaft hardness?
A. Seals perform best on medium to high carbon steel (SAE 1035, 1045) or Stainless Steel. Shafts, should be hardened to Rockwell C30 or higher mainly to avoid handling damage.
Q. What is shaft to bore misalignment?
A. Shaft to bore misalignment (STBM) is the amount by which the shaft centerline is off center with respect to the bore’s centerline. The RMA recommends no more than .010”. The closer to .000 the better for seal life.
Q. What is shaft lead?
A. Spiral machining grooves or inclined scratches, known as machine lead, can auger or pump the oil out from under the lip, resulting in early leakage.
Q. What is the recommended shaft configuration?
A. A 15° - 30° burr-free chamfer or a smooth radius is required for the seal lead in. No burrs or sharp corners are allowed. 45° chamfers are not recommended.
Q. What is the recommended method to obtain a proper surface finish?
A. The best known method of obtaining the proper surface finish is plunge grinding. Shafts should be ground with mixed number RPM ratios between the workpiece and grinding wheel. The grinding wheel should be allowed to spark out to insure all shaft lead is eliminated.
Q. What is the recommended Ra value for surface finish?
A. The specification is 8 to 17 min. (micro inch) Ra, using a .010” cutoff, with no machine lead. No machine lead is defined as 0°±0.05° lead angle.
Click here for further information:
457010 Shaft Requirements - Updated: April 24, 2003
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