The stick-slip phenomenon, also known as the slip-stick phenomenon or simply stick-slip, is "the spontaneous jerking motion that can occur while two objects are sliding over each other."
In the area of seals and cylinders, Stick-slip is characterized by a distinct stop-start movement of the cylinder, and may be so rapid that it resembles severe vibration, high pitched noise or chatter. Seals are often thought to be the source of the stick-slip, but other components or hardware can create this issue.
Causes for stick-slip
The causes for stick-slip may include
- Swelling of wear rings or back-up rings
- Extreme side-loading
- Valve pulsation
- Poor fluid lubricity
- External sliding surfaces
- Seal pressure trapping
Tips for stick-slip trouble-shooting
The following are tips for trouble-shooting and solving stick-slip.
|Possible Cause||Trouble-shooting Tip|
|Surface finish out of specification||Verify surface is neither too smooth or too rough|
|Poor fluid lubricity||Change fluid or use oil treatments or friction reducers|
|Binding wear rings||Check gland dimensions, check for thermal or chemical swell|
|Side loading||Review cylinder alignment, incorporate adequate bearing area|
|Seal friction||Use material with lower coefficient of friction|
|Cycle speed||Slow movement increases the likelihood of stick-slip|
|External hardware||Review system for harmonic resonance|
|Valve pulsation||Ensure valves are properly sized and adjusted|
|Temperature||High temperature softens seals, expands wear rings, and can cause thermal expansion difference within hardware|
Download more frequently asked questions supplied by Parker's Engineered Polymer Division for further help.
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