Laser Marking effects on the Fatigue Strength of Alloys

[elsatercool]

During reviewing my technical file class III , reviewer asked issued CAR :

[FONT=&quot]The laser marking drawing indicated markings in the highly stressed zone of the stem: it is known that laser marking can affect the fatigue strength of alloys and therefore should be restricted to low stress regions and be minimised in extent [/FONT]


Attached the Drawing , Please HELP ME

 

[Mikishots]

During reviewing my technical file class III , reviewer asked issued CAR :

[FONT=&quot]The laser marking drawing indicated markings in the highly stressed zone of the stem: it is known that laser marking can affect the fatigue strength of alloys and therefore should be restricted to low stress regions and be minimised in extent [/FONT]


Attached the Drawing , Please HELP ME

Not sure what you're asking as there doesn't seem to be a question here. Can you clarify?

If I was to go out on a limb, I'd suggest to follow the advice from the CAR issuer, unless you have reason or proof to contest it.

 

[pkost]

You laser marking does appear to be rather large, I would follow the advice of the reviewer - move it to an area of lower stress and make it much smaller!

Also keep it away from areas of significant wear

 

[John Broomfield]

During reviewing my technical file class III , reviewer asked issued CAR :

[FONT=&quot]The laser marking drawing indicated markings in the highly stressed zone of the stem: it is known that laser marking can affect the fatigue strength of alloys and therefore should be restricted to low stress regions and be minimised in extent [/FONT]


Attached the Drawing , Please HELP ME

elsatercool,

It is time to request a design change of EMED.

The design will either be changed or the designer will explain why the laser marking is benign.

Either way you have closed the CAR.

John

 

[elsatercool]

I asked about the reply on the reviewer comment , Means "The influence of laser marking on the material CO Cr "

 

[Miner]

Can you have an FEA (Finite Element Analysis) run on the part? This could simulate the laser etch and show the effect on stress concentration.

 

[pkost]

The effect of the laser will to be a very localised heating of the material that will change it's structure. This will affect the material properties although only to a very localised extent. The problem is that you need to understand the effect of that localised change on the performance of the stem as a whole

Miner - there are more things to consider here than just stress - effect on fatigue, wear properties and characterisation of the wear particles that may be produced. This then follows on to the potential for these factors to exacerbate other risks that are known to be present in hip joints