Marking on Bolt

[paramathma]

Hi,

We need to manufacture a custom bolt and also we need to mark the part number on it. Previously we were etching the part number on the bolt shank. But analysis & testing showed that etching reduced the fatigue life of the bolt. The bolt has a very thin shank. Laser marking is not an alternative as the cost of marking will be very high.
Is there any cost effective marking methods?
Example of part marking "5555-0123".
Please advice.

Attached is bolt drawing

 

[rb1957]

ink ?

wire locking a tag ?

 

[bf109g]

rb is right. Ink works, but if the part is too small to be marked, 14CFR45.15(b) gives you an out:

(b) If the Administrator finds that a part is too small or that it is otherwise impractical to mark a part with any of the information required by paragraph (a) of this section, a tag attached to the part or its container must include the information that could not be marked on the part. If the marking required by paragraph (a)(4) of this section is so extensive that to mark it on a tag is impractical, the tag attached to the part or the container may refer to a specific readily available manual or catalog for part eligibility information.

 

[CoryPad]

For marking, try Videojet:

http://www.videojet.com

 

[RPstress]

Ink stamp is still widely used, but it does tend to wear off if the part is in an 'active' area like a nacelle or gear bay.

Having the mark on the shank might protect it or might damage it on insertion/removal or vibration in service. Are you sure it's ok to obscure it in this way?

Our titanium nacelle primary structure parts used to be electro-etched without compromising their fatigue life.

PS: that *is* a small shank!

 

[IRstuff]

I'm not sure what your cost margins are, but there are electronic components that sell for pennies that are laser-marked.

TTFN

FAQ731-376

 

[WKTaylor]

How about dot-peening, vibro-peening or engraving, the OD [not top] of the head?

Regards, Wil Taylor

 

[Neubaten]

For fatigue sensitive parts, airgrit marking and laser bonding are suitable methods.

Airgrit still leaves an impression onto the part, although it is not deep and the radii are high, thus making the mark less of a stress raiser.

Laser bonding leaves the part virtually as it is. It shall not change its fatigue properties. It consists of a ceramic label cured by laser onto the surface of the part.

 

[seniorja]

What about heat-shrink materials? As long as hole clearance isn't a factor with regards to the diameter of the shank - this would also provide a thin barrier between any dissimilar metals providing added protection against corrosion.

 

[monkeywrencher]

Not sure if this would work rule-wise, but I have seen it used before.


Mark the head with a colored dot. In whatever parts breakdown, bulletin, maintenance instructions can refer to this dot. 'Ensure that bolt is replaced with colored head. If no marking is visisble, discard and replace'

Reading the 1st couple of lines, laser etching popped into my head. But then I read the cost effectiveness part. I think this would be the cheapest solution....

 

[BobMeister]

You didn't mention the type of driver for the bolt. Assuming that you're using a hex head then condider stamping the head face with a number or dots (less stamping force).

You could try a single stamped dot, then painted (colour coded). The indentation will hold the paint and it will then not wear off. I have seen these on hex head and socket head cap screws and bolts.

 

[mfgenggear]

in addition to what was suggested.

when parts are to small or not economically feasible

Bag & Tag