tramlines and blemishes

Hello all,

I am a quality Engineer for a wire and stranding manufacturer.

we are experiencing quality issues with copper being supplied to us, we are seeing tramlines and blemishes, this occurs after performing a torsion test(twisting the wire on its axis 14 times to the left then 7 to the right)

The supplier is using a zero slip breakdown machine, we are going to help the supplier with some problem solving to try and find the root cause.

The question? Has anyone experienced the same defect modes? And what was the root cause or causes,

sizes affected 1.600mm,1.400mm and 1.000mm Copper

many thanks.

Hello Mr. Barrow,

1) What are "tramlines" on the wire? Are they say just surface marks longitudinally along the wire 's longitudinal axis or are they cracks or grooves. Please define more precisely. Take a good look at them under a microscope and advise. Can you get a micro-photograph that can be attached to the Forums?

2) Is this wire annealed at your suppliers? Electrically in line with drawing or in an annealing furnace?

3) What are these "blemishes" you refer to?. You can find out more information about surface blemish descriptions at the archived thread www.wirenet.org/forum/8-nonferrous/1357-copper-discoloration

4) Is this torsion test performed during a very short period of time and is the wire sample under test getting quite hot?

Your problem is a puzzlement for now until we receive more definitive information from you.

Thank you.

Hello Peter,

1.The tramlines are actual grooves,also scrathing is evident.

2.The wire is inlined annealed by the supplier.

3.The blemishes have alsmost a burning appearance.

4.The torsion test only takes about 25 seconds to complete and the wire is still cold.

Here are some photos of the problems being experienced.

many thanks,

Dave.

David, Peter,

I know that years ago we would run a similar test on copper rod. So we are talking about 350-357 mm vs your 1.0 to 1.6 mm. 1mm is about same as 18 awg.

My experience is that if you have a strong enough microscope and you examined a straight piece of wire you might see similar markings (note I did not say defects). We also would take a piece of bare wire and wrap it around a 1x mandrel. If there are any defects in the wire they will show up especially if you used a microscope to examine the wire.

I am not sure that what you are seeing is relevant to the quality of the finished product you are making.

Hello Richard,Peter

The quality of the copper is affecting the drawing stage. We are finding that the nickel plate is having poor adhesion to the copper. Our other supplier supplies us with copper that has no visual issues thus giving us good drawing even to fine wire 0.070mm etc

Thanks

Hello David and Richard,

Thank you for your pictures. I too came to the same conclusion that Richard advised of but because of other pressing issues, I really had no time to answer until today. Thank you Richard my friend, you beat me to the punch.

I had surmised that the grooves on the wire were from a bad die (dies) at rod breakdown.

I looked carefully at the blemishes and suspected they were due to dried annealer lubricant not properly air stripped from the wire. As I have said many times in the past, I much prefer the use of clean cooling water in an electric annealer. The only other thought that had about blemishes was that the rod breakdown drawing solution was spent and that the emulsifier was no longer doing its job. There was however no mention of dusting which is often another symptom of emulsifier failure.

Now David has brought new information to the table. I personally cannot stand these late information bulletins because the previous (limited) information often sends us in the wrong direction. Now it seems that David's employer redraws the annealed wire they receive and plate it with nickel, possibly for the aerospace market. (Perhaps plating first and then drawing and annealing.) In any event, there apparently is poor adhesion between the nickel and the copper which could be wire due to surface contamination or worse.

David, I think you should send all the bad copper back to the supplier for credit and stop using them until such time that they can clearly demonstrate they have a quality product for you. Let them solve their own problems.