"knurling" on stainless steel

[cervantes]

Hello,

any tips on how this kind of "knurling" was made on this stainless steel pipe?
1) pipe was not deformed during this proces
2) it is not additionaly welded (however it looks like this) - this surface is "torned out" from pipe material
3) anyone knows machines which can do this type of surface ? (if not - I need to do some R&D'ing on my own)

thanks in advance

M

 

[Pud]

Could be chemical etching?
It also looks like a bit like a very heavy spark eroded finish.




www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.

 

[MikeHalloran]

Maybe electropolishing gone out of control...
or corrosion in some aggressive environment.

Wait; you _want_ a surface like that?
Be aware that it may have greatly reduced fatigue resistance, not ordinarily a desirable thing in pipe or anything else.




Mike Halloran
Pembroke Pines, FL, USA

 

[JStephen]

Could it possibly the this? The pictures on this website aren't close-up enough to tell.

http://www.slipnot.com/products/ladder-rungs/stainless-steel/

 

[MikeHalloran]

Those are pretty, er, slick.


Mike Halloran
Pembroke Pines, FL, USA

 

[cervantes]

JStephen & MikeHalloran:

this is the purpose, it is used in chairs as a shoes slip-protector
but it is made only on a small part of pipe, not fully around

thanks for a link to this ladder company

 

[MintJulep]

Thermal spray.

https://en.m.wikipedia.org/wiki/Thermal_spraying

 

[berkshire]

Could this be spark deposition , then electro polished after buffing?
B.E.

You are judged not by what you know, but by what you can do.

 

[MintJulep]

Possibly "sweeping" the surface with a plasma-arc cutter.

 

[Compositepro]

I looks tome that the pattern is embossed (pressed into the surface). To do this you need to have an embossing roller made with your desired pattern.

 

[someguy79]

I don't have any certain answers, but I'll throw out a few reasons and guess.

The surface appears to have small nodules of material. I can't think of a material removal process that creates this type of shape. Though I'm not familiar with spark erosion or many plasma techniques.

I don't see much regularity/pattern in the textured surface. Therefore I suspect it's not an embossed or rolled surface.

Some kind of deposition might make that sort of texture, and could be done on only part of the surface.

As for chemical etching, the boundary between polished and textured surface is not a nice line that I would expect if you masked and etched.

Another clue is shown on the edge of the textured-polished boundary. There appear to be voids there. It looks to me like the high points in this area are ground and/or polished down, leaving only the low spots. Material deposition on one side followed by grinding/polishing could do this.

Is there much variation in thickness on the polished side vs. the textured side?

 

[MikeHalloran]

Next, I'll guess that the extra texture was arc/flame sprayed, which is the only _fast_ process I know of that's capable of producing such a surface.



Mike Halloran
Pembroke Pines, FL, USA

 

[gerhardl]

New or used pipes? Used: In what environment and process conditions? If new: impurities before (if any) surface treatment?

 

[gerhardl]

Looked once more at the pictures. Guess that the clue is something wrong during the manufacturing process, for instance false heating/cooling combination at the end of the process? Try a moere metallurgic orientated forum?

 

[cervantes]

thanks for all feedbacks
this surface is a desired surface - I mean manufacturer wanted to do that and he did it nice way

this is of course a new pipe and material is homogenous
see attachment for an evidence