Previous in Forum: Aluminized Coating   Next in Forum: What's the Best Way to Clean Dielectric Oil from a Stator Winding?
Close
Close
Close
24 comments
Active Contributor

Join Date: May 2007
Location: BUFFALO NY UNITED STATES
Posts: 19

Can Tin Coated Copper Wire Be Magnetic?

06/25/2007 4:08 PM

We make a part of small quantity for a costumer. The part is tin coated copper wire it weighs .008 oz per piece very light.well they claim the last batch we made for them is magnetic .We have a strong earth magnet to see if this is true and nothing we can't see any magnetic pull.They claim they put the part on a string and with a large earth magnet are able to pull the part,is this even possible and why or how is this possible.any info will help so we could address the problem.

thank you

__________________
Help me with the things i don`t know . I`ll try to help you with the things i do know and we`ll both get smarter
Register to Reply
Pathfinder Tags: Copper Magnets wire
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16499
Good Answers: 662
#1

Re: Can Tin Coated Copper Wire Be Magnetic?

06/25/2007 4:55 PM

I was under the impression that all metals have some magnetic susceptibilty.

Suggest you google magnetic susceptibility of tin..copper etc.

__________________
health warning: These posts may contain traces of nut.
Register to Reply
Power-User

Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 381
Good Answers: 1
#2

Re: Can Tin Coated Copper Wire Be Magnetic?

06/25/2007 6:10 PM

I am afraid the Dell the Cat is very right. The part is made of wire, coated or not wire will be subject to a magnetic field.

Perhaps they are trying to bamboozle you and get the work for free??

As in a Motor / armature effect

Register to Reply
Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
Posts: 1950
Good Answers: 109
#3

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 1:57 AM

Hi,

if they claim that the piece is magnetic they should disclose how they measured and what field strength and which direction of field strength. (Some measure flux density that can be converted to field strength in air by B=ยต.H)

I experienced once a magnetisation of nonmagnetic stainless steel by cold deformation.

Another possibility may be some iron or iron-oxide content inside the copper or tin.

And there exist some strange magnetic alloys, may be you discovered a new one.

RHABE

Register to Reply
Guru
Belgium - Member - New Member APIX Pilot Plant Design Project - Member - New Member

Join Date: Aug 2006
Location: Glabbeek, Belgium
Posts: 1480
Good Answers: 28
#4
In reply to #3

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 2:37 AM

The part of the magnetic stainless steel I get, but copper and tin forming a magnetic alloy with nobody noticing it before?

I would assume that they did an after treatment which deposited some ferro metal on the part.

Did you check on what they send back or on your own stock?

Start asking the parts back and check it.

A copper wire in a magnetic field will have some induced current when it forms a closed circuit, this could be what happened.

__________________
"Here we are now, entertain us"
Register to Reply
Anonymous Poster
#5

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 5:57 AM

I would think not unless there was current flowing through it.

I would get the exact sample they tested. Either something has been inadvertantly switched or the copper is contaminated with iron.

Register to Reply
Power-User

Join Date: Nov 2006
Location: Near Rochester, New York
Posts: 156
Good Answers: 2
#6

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 7:23 AM

MAD:

If they are moving their magnet, they're setting up eddy currents in the wire (a conductor) which produce magnetic fields. Any motion of the wire, then, could be the result of the magnetic fields interacting. If there is attraction when everything is still, then there must be real ferromagnetism.

DickL

Register to Reply
Active Contributor

Join Date: May 2007
Location: BUFFALO NY UNITED STATES
Posts: 19
#7

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 8:32 AM

So this morning i got material off the spoil the wire come form and bent a piece and put it on a pivot point and brought a earth magnet to it and presto the wire rotated from magnetism.

The wire is .032 diameter material is OFHC 102 COPPER ALLOY specifications is ASTMB 3 the chemical properties are CU 99.95%

So is this material reject able or is it saying .05% can be iron .I'm searching the net now please advise any info that may help me with this.

thank you

__________________
Help me with the things i don`t know . I`ll try to help you with the things i do know and we`ll both get smarter
Register to Reply
Guru
Belgium - Member - New Member APIX Pilot Plant Design Project - Member - New Member

Join Date: Aug 2006
Location: Glabbeek, Belgium
Posts: 1480
Good Answers: 28
#8
In reply to #7

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 8:54 AM

Does it follow the magnet or just starts to move when the magnet passes by?

It can contain up to 4ppm Fe and 4ppm Ni (copper 102 = oxygen free copper)

Will these contents invoke magnetism? Start with a chemical analysis and when nothing is wrong there the final customer has to accept it. (if he did not specified it better)

http://www.copper.org/resources/properties/144_8/144_8.html

__________________
"Here we are now, entertain us"
Register to Reply
Power-User

Join Date: Nov 2006
Location: Near Rochester, New York
Posts: 156
Good Answers: 2
#9
In reply to #7

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 8:55 AM

MAD:

My question is, still, did it rotate only when the "earth magnet" was moving, or did it rotate while the magnet was still?

DickL

Register to Reply
Power-User

Join Date: Nov 2006
Location: Near Rochester, New York
Posts: 156
Good Answers: 2
#15
In reply to #7

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 10:48 AM

MAD:

From out of left field, could this possibly be electrostatic repulsion? I still get sparks when leaving my car in this dry weather. Check by touching the magnet to the wire and seeing if the movement still takes place afterward.

DickL

Register to Reply
Guru
Technical Fields - Architecture - New Member Popular Science - Weaponology - New Member Engineering Fields - Control Engineering - New Member Engineering Fields - Electrical Engineering - New Member Engineering Fields - Electromechanical Engineering - New Member Hobbies - Fishing - New Member Hobbies - Target Shooting - New Member Hobbies - Hunting - New Member

Join Date: Dec 2005
Location: Clemson, South Carolina
Posts: 1722
Good Answers: 18
#10

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 9:19 AM

Check out Lorentz Force. Bassically, when a permanent magnet is moved relative to a conductor, it causes a current to flow in the conductor, which, in turn creates a magnetic field in the opposite direction.

In the case of a conductor which is not a loop, the current will be a transient which quickly dissipates due to its inability to continue past the end of a suspended wire, for example, and the only way it can exist at all is due to the inductance of the wire itself.

If the customer is making a loop of the wire, then they are messin' with you, 'cause in that case, the current has a complete path.

__________________
We have met the enemy and he is us . . . Walt Kelly
Register to Reply
Guru

Join Date: Jun 2007
Posts: 1035
Good Answers: 40
#12
In reply to #10

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 9:44 AM

I have to agree with the responses that lean toward this explanation. Pure Silver, Copper & Gold (the best conductors of electricity, in order) are actually DIAMagnetic, and are actually slightly repelled by a magnetic field. Tin (like magnesium, lithium, tantalum and molybdenum) is slightly PARAMagnetic, meaning it exhibits only a slight tendency to concentrate lines of magnetic field within itself.

Between the slight induction taking place when the magnetic field is brought into proximity with the wire (at which time, current {or charge} is occuring in the wire ONLY while the lines of magnetic force are MOVING thru it) ... and the 'ever-so-slight' magnetic field associated with that induction (which will always be in opposition TO the field inducing it) ... I believe that a miniscule, though measurable, effect is in fact taking place.

Register to Reply
Guru
Belgium - Member - New Member APIX Pilot Plant Design Project - Member - New Member

Join Date: Aug 2006
Location: Glabbeek, Belgium
Posts: 1480
Good Answers: 28
#13
In reply to #12

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 9:51 AM

But I assume that the effect is never noticed before.

OR the customer changed the WOW in the assembly. (which is in most cased the reason for such trouble)

OR there is something different with the actual alloy that was not present before.

Mad to answer.

__________________
"Here we are now, entertain us"
Register to Reply
Guru
Australia - Member - New Member Fans of Old Computers - H316 - New Member Hobbies - Model Rocketry - New Member

Join Date: Jun 2006
Location: Port Noarlunga, South Australia, AUSTRALIA (South of Adelaide)
Posts: 3048
Good Answers: 75
#11

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 9:32 AM

Hi MADMACHINE,

First off since I haven't corresponded with you before welcome to CR4, the best site on the internet for us engineer types to show we really do know what we are talking about and can solve all the world's problems if only people would listen to us.

I think DickL has hit the nail on the head. When you have a moving magnetic field interacting with a conducting medium it will try and induce a current in that medium that in turn produces a magnetic field that will oppose the existing magnetic field. Now the thing is you don't need a complete circuit as the you can get what is called eddy currents. These are like little whirlpools of electric current flowing within the material and when you add them all up they tend to cancel out in the centre of the material and add together forming a current that flows around the surface of the conductor.

The performance of transformers and electric motors can be severely impacted by eddy current and commonly employ various techniques to limit them. The most common and effective way is to laminate the core so that the distance the currents can flow before they hit a non conductive layer is limited. This is the main reason the magnetic core of transformers and electric motors are constructed of layers of thin sheets rather than a solid piece of metal.

The other thing to remember is that materials fall under one of two magnetic categories, magnetic or diamagnetic. You will no doubt be familiar with magnetic materials. These are the materials that are attracted to a magnet like iron and cobalt. Diamagnetic materials are the exact opposite and are repelled by magnetic fields. Most people never know about the diamagnetic properties of materials as the diamagnetic effect is several orders of magnitude less than the magnetic properties people are familiar with, so, if you don't specifically look for them and use very powerful magnets and highly sensitive equipment you would never see them. The photograph on the right is of a frog, which is primarily diamagnetic, being levitated within an extremely intense magnetic field. The filed repelling the frog from all sides and is creating a force strong enough to cancel out gravity.

Since you are talking about something that has very little mass and has its weight supported by a string there is a possibility that what you are seeing is actually a diamagnetic property rather than a magnetic property.

__________________
An elephant is a mouse built to government specifications.
Register to Reply
Member

Join Date: Jun 2007
Posts: 6
#14

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 10:12 AM

Run a magnetic test on the Sn and Cu materials first, to determine if one or both are magnetic, if one or both are magnetic, run a chemistry on the Sn and Cu separately, you may not have the proper material to begin with. Sometimes you could also create magnetism by cold working the materials to some extent...

Register to Reply
Active Contributor

Join Date: May 2007
Location: BUFFALO NY UNITED STATES
Posts: 19
#16
In reply to #14

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 2:09 PM

Thank you all for your replies your all very intelligent .anyhow I'm not making a closed loop i moved the magnet to the part in a straight motion and saw the affect and after this and your comments i took a part and removed the tin coating from half the part and the side without tin had no movement at all ,the same part with tin coating on it the magnet pulled so it has something to do with the tin coating .i called the supplier and got the plating certification on the tin coating i got back MATERIAL OFHC PLATING TIN THICKNESS .0002 the WIRE company gave us the certification earlier and seem correct.is there a standard allowably magnetic material level for tin coatings. By the way they asked for a solderable tin coated copper wire ofhc 102 copper alloy. please reply with anymore info so i can close this chapter

thank you all

__________________
Help me with the things i don`t know . I`ll try to help you with the things i do know and we`ll both get smarter
Register to Reply
Guru

Join Date: Jun 2007
Posts: 1035
Good Answers: 40
#20
In reply to #16

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 7:03 PM

You have confirmed the tin (which is paramagnetic) to be the culprit. The paramagnetism is a quality of the element itself. I know of no way to negate it (short of elevating it to its Curie temperature... and keeping it there!). The denser the lines of magnetic field to which it is subjected, the greater will be the effect upon it. Tho the effect will always be much less than the effect on a ferromagnetic material, it will remain measurable nonetheless. This might well be one of those CLASSIC cases of either "The Spec is Wrong", or the original "Design Didn't Take Everything Into Consideration". IF the miniscule paramagnetic effect of the tin truly affects the end-product in an adverse way, then perhaps a different means of soldering/brazing the (O2_pure) copper should be sought.

Register to Reply
Anonymous Poster
#17

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 2:54 PM

Only alloys made with the following metal composition

Register to Reply
Guru

Join Date: Nov 2006
Location: KnoxTN
Posts: 1485
Good Answers: 6
#18

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 3:05 PM

A test was made using an 8" length of 0,023" tinned coper wire. Mil. spec stuff from 1950's surplus. A series stack of 2-1" spneres and 3 odd shape 3/8" thick rare earth magnets had NO effect on a hair pin shaped piece supported by a small loop in another piece of the same wire.

Any possibility that there are traces of iron or something else in either the wire or the tin coating? Have analytical tests been done by the lab?

__________________
Do Nothing Simply When a Way Can be Found to Make it Complex and Wonderful
Register to Reply
Active Contributor

Join Date: Mar 2007
Location: pennsylvania
Posts: 12
#19

Re: Can Tin Coated Copper Wire Be Magnetic?

06/26/2007 3:34 PM

Perhaps nickel in plating?

Register to Reply
Guru
Australia - Member - New Member Fans of Old Computers - H316 - New Member Hobbies - Model Rocketry - New Member

Join Date: Jun 2006
Location: Port Noarlunga, South Australia, AUSTRALIA (South of Adelaide)
Posts: 3048
Good Answers: 75
#21

Re: Can Tin Coated Copper Wire Be Magnetic?

06/27/2007 7:16 AM

If you follow the link in post #18 there are some interesting compounds that contain copper oxide and are magnetic so maybe there is something happening between the tin and copper that is causing an oxide layer to build up. As rbwhite101 stated perhaps the tin plating is contaminated with small amounts of nickel, chrome or cobalt.

__________________
An elephant is a mouse built to government specifications.
Register to Reply
Guru
Belgium - Member - New Member APIX Pilot Plant Design Project - Member - New Member

Join Date: Aug 2006
Location: Glabbeek, Belgium
Posts: 1480
Good Answers: 28
#22
In reply to #21

Re: Can Tin Coated Copper Wire Be Magnetic?

06/27/2007 8:45 AM

Or Manganese

__________________
"Here we are now, entertain us"
Register to Reply
Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
Posts: 1950
Good Answers: 109
#23

Re: Can Tin Coated Copper Wire Be Magnetic?

06/27/2007 5:44 PM

Hi Gwen,

I think you are right, manganese will give together with copper and tin one of the alloys that are called Heusler-alloys, magnetic alloys in a composition that show no magnetic property as individual materials.

Magnetism is meant here as ferro- or antiferro-magnetic both looking to the outside investigator as ferromagnetic.

RHABE

Register to Reply
Active Contributor

Join Date: Jun 2007
Posts: 24
#24
In reply to #23

Re: Can Tin Coated Copper Wire Be Magnetic?

06/30/2007 12:04 AM

I think most of the last many posts are on the right track. I have a little different take on it but along the same lines. Did he say mono-crystaline 99.99% pure copper? As a conductor it can definitely have eddy currents induced in it which will then create a magnetic field, when there is a moving magnetic field around it. Also the thin and uniform skin of tin around it being paramagnetic has a tendency to react to the extremely high magnetic field even when the field is stationary. then there are a couple of other factors.... was the copper cleaned with Chromic acid? ( Chromium is "Ferro"magnetic) or was the tin applied in some other solution such as stanous flouride?,... ( the mention of copper oxide in super conductors,... but a very thin layer of stanous flouride could have a similar effect,... also is the tin plate extremely thin and uniform. The conjoining of dissimilar metals especially with mono crystaline copper may effect some rectification of any electromagnetically induced eddy currents in the copper. This could be from ambient light (a photo electric effect) or just ambient Radio Frequency fields or perhaps the slightest motion of the rare-earth magnet, or cell phone background radiation or whatever. A tube of very thin tin around a column of mono chrystaline copper may then have unequal forces axially, versus radially.

I'm guessing annealing the copper, which is done the opposite of steel ( by sudden heating and cooling, and possibly adding a thicker and less uniform, coating of tin, not by plating but by immersing in molten tin, will eliminate this effect. I think it has to do with the tin being so thin it acts as a rectifier with the copper, and the copper is carrying the eddy currents so it is acting sort of like a maglev train, or an induction motor. If the tin is a lot thicker (like several thousands of an inch), the eddy current within the tin will reduce this magnetic compass needle effect, if I am correct about the interaction between the two metals.

I have found that brass connectors (tin and copper) for audio electronics often will rectify radio frequency broadcasts, creating interference in audio electronics. Off course I also remember a physics class demonstration of the effect of a strong magnetic field, slowing the movement of a sheet of aluminum or copper, through it. I'm also remembering how a loop of copper with low voltage, high current of a soldering gun, reacts to a neodymium speaker magnet even when several inches away.

Geoffrey Reed

Register to Reply
Register to Reply 24 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Copy to Clipboard

Users who posted comments:

Anonymous Poster (2); BIG KAHUNA (1); Bill (1); dbdwoods (1); Del the cat (1); DickL (3); GeoffreyReed (1); Gwen.Stouthuysen (4); MADMACHINE (2); masu (2); ndt-tom (2); rbwhite101 (1); RHABE (2); Stirling Stan (1)

Previous in Forum: Aluminized Coating   Next in Forum: What's the Best Way to Clean Dielectric Oil from a Stator Winding?

Advertisement