Platinum Iridium Piping issues

We have recently encountered piping issues on our Platinum Iridium rods. there's no process change, what are the possible root causes?
thanks for the help.
Mandy

Hello;
This seems to me as if it is a central burst defect (AKA a Cup-cone fracture or chevroning.) Often this is the result of putting a die in backwards in a drawing machine.

Please see www.metalforming-inc.com/publications/bo.../chapter_3/3-5-5.pdf

Any recommneded equipments where we can detect piping without breaking up the wires at this fine size(0.098")? We use Ultrasound, but at wire size of 0.5".

I do not know of any instrumentation that can see inside the wire at diameters less than 1/10 inches.

Fortunately central burst failures are very rare in common metal (copper and aluminum) drawing practice. One of the indications you get on the surface of the conductor is chevroning which is often called "Crows Feet" which actually describes what the chevrons look like. Please see this web site for more information:
books.google.ca/books?id=YXp6zao0HqgC&pg...%20in%20wire&f=false

Thus there may be chevrons on the surface of your wire when central bursting occurs. The chevrons point in the direction that the wire was drawn. Thus you may be able to see the chevrons on the surface of the wire. The other indication of central bursting is that; "If you bend a piece of central burst wire between your fingers, it usually breaks like a dry twig."

Presumably central burst failures are very rare for you as well. If this is true, I very much doubt that you really need on-line scanning instruments. ( I of course know nothing of the drawing process and drawing failures in platinum Iridium wire but I am assuming that the wire drawing problems are similar. I am also assuming that there was no internal defects in the platinum Iridium to start with Before it was drawn).

Here are the typical reasons for chevron formation: (WAI Nonferrous Handbook Volume 2: Bare Wire Processing)

• - Misaligned wire entering a drawing die.
• - An improper die contour such as;: badly blended angles inside the die, too short or no bearing on the die, wrong entrance or reduction angle (Such as putting a die in backwards.)
• - Improper or insufficient lubrication.

I'm sorry but that is essentially all I can tell you from afar.