Leak Testing - O-ring installation in the groove of Bore ID

GURU SDI

Involved In Discussions
Hello All,

I have received a customer complaint in a brake assembly in which leak is observed. After doing analysis on field samples, it is found that the leak is due to improper O-ring installation. Actually an O-ring is installed in a groove in the bore ID & piston is assembled in the Bore ID. This is done by manually.

Any improper placement of O-ring in the groove making the leak in the process. Now we would like to ensure the proper O-ring installation in the bore. Kindly suggest any process improvements to automate the O-ring installation in the groove of Bore ID. Kindly suggest

Thank you
 

Steve Prevette

Deming Disciple
Leader
Super Moderator
Re: Leak testing - O ring

Would really need to know what is the failure. Is the o-ring rolled or twisted? Not in the groove properly? Are you sure there is no defect with the groove or the o-ring itself? Is the o-ring lubricated? Why do you believe automation would solve the problem? Is this an immediate failure when put on service?
 

GURU SDI

Involved In Discussions
Hello Steve,

The complaint is Oil leak from the assembly.

The O-ring got twisted, it got deformed when we opened the assembly for analysis.

The groove corner radius, entry chamfer are measured and found okay.

The O-rings are not lubrictaed.

The O-ring material is FFKM.

Since the manual process is possible for making a improper assembly in the groove.
 

Steve Prevette

Deming Disciple
Leader
Super Moderator
Of course there is always a possibility of creating an automated robot of some sort. Other options include:

1. Is the worker able to lay the O-ring into place with the grooves horizontal?
2. Does the work have to push the O-ring into the cylinder a ways before getting to the groove (you mention this being a Bore Inner Diameter?). That could cause unequal twisting.
3. Is there a way to visually tell that the O-ring has gotten twisted during installation? Could the surface be marked or chalked to make it visible that the O-ring is twisted?
4. Is it possible that the O-ring is being installed properly, but is getting twisted during assembly?
5. Would adding a second person as an inspector help? That may depend upon answer to question 3.
6. Has this problem always existed or did it start recently? Related - is this a new design? Any changes in manufacturing or manufacturer? Any experience with a similar assembly that had no problems?
 
Z

zancky

in my past experience with FKM oring we have found very useful dry self-lubricating o-ring (i.e. fkm oring with a thin shell, few micrometers, of a mix of ptfe and fkm)
they work as standard FKM for temperature glass transition and performances and as lubricated orings for the operator assembly.
one big advantage was we were able to make a reliable tightness test as there was no oil
 
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