finishing.com -- The Home Page of the Finishing Industry
A website for Serious Education, promoting Aloha,
& the most FUN smiley you can have in metal finishing

HomeFAQsBooksHelpWantedAdvertiseForum
topic 15043

Annealing of copper wire blackens it



A discussion started in 2002 & continuing through 2017

(2002)

Q. Dear Sir,

We are manufacturing copper uninsulated wire used for electric cable and also super enamel insulated wire. The size of the wire varies from SWG 1 to 32. We are facing a problem of having the wire oxidized/blackened soon after bringing it out from annealing Chamber. The annealing Chamber is of vacuum type having Induction coil to heat the copper wire. The Vacuum that can be applied to the Chamber is 500 mm Hg while the temperature approx.800+ centigrade. Please note the Chamber does not have any temp.meter. This is the process we are following to anneal the Copper wire. So, may I request to let me know how we can get rid of the problem of getting the wire oxidized/blackened in course of annealing.

Hope to hear soon.

Thanking you,

M.SADEK
- Dhaka, Bangladesh.


(2002)

A. Try letting the copper cool in an inert atmosphere before exposing it to air.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


(2002)

A. Alternatively let it cool in the vacuum environment used for the annealing.

Bill Reynolds
Bill Reynolds
   consultant metallurgist
Ballarat, Victoria, Australia

We sadly relate the news that Bill passed away on Jan. 29, 2010.


(2005)

Q. We are facing the same exact problem and I thought it has something to do with annealing current / voltage ... we use stainless steel cylinders for annealing (not nickel coated as usual).

Any ideas?

Amir Sharon
- Israel


(2006)

A. You have not mentioned the quantity of your batch for annealing and also the kilowatt rating of induction heating. You have to also mention the cycle time of heating, soaking and quenching. What is the sealing mechanism used during annealing to prevent outside air entering. Without temperature indicator, how did you measure the temperature of your batch during annealing continuously?

Balasubramanian Venkatraman
- Navi-Mumbai, Maharashtra, India


(2007)

Q. WE ARE MANUFACTURING COPPER TUBE, TO BE USED FOR ELECTRICAL TERMINATIONS. WE CONTINUOUSLY CAST THE TUBE , THEN DRAW THEM DOWN ON LONG HYDRAULIC BENCHES.

AFTER SEVERAL DRAWS, THE TUBES BECOME TOO HARD AND SNAP. WE LOAD THE TUBES (ON AVERAGE 2 TO 3 MTR LENGTHS) ONTO A RACK.
ROLL THE RACK INTO A ELECTRIC ELEMENT FURNACE (3.4 MTRS LONG)
WHEN THE TEMPERATURE REACHES 550 DEG C THEN THE RACK IS REMOVED,

THE TUBES ARE LIFTED OUT OF THE RACK USING CHAINS AND A HOIST AND THEN LOWERED INTO A WATER BATH TO QUENCH

WE ARE LOOKING FOR A MORE ACCURATE WAY OF ANNEALING TO IMPROVE OUR QUALITY AND PREVENT CRYSTAL REGROWTH.

ARNE HERZ
ENGINEERING - JOHANNESBURG SOUTH AFRICA


December 30, 2008

Q. We manufacture Hot dipped tin plated copper wire. After drawing the wire the elongation is about 12 to 15%.

We use vacuum annealing furnace. The heating is carried out using diesel burner & it is controlled by electrical circuitry to control the temperature.

The temperature raised and is maintained at 250 °C and the duration is about 2 Hrs. Burners are switched off automatically at this time.

The furnace is kept under vacuum containing copper wire, until the temp. drops down to ambient.

The elongation of copper wire after the process is about 25% to 28 %.

Can any one guide us to achieve more elongation Say about 35% max. ?

Sudheer Shedbalkar
mfg. hot dip tin plating - Pune, Maharashtra, India


January 8, 2009

A. Try faster cooling .

Cair Shishani
Cair Shishani
aircraft maintenance - Al Ain, United Arab Emirates


March 29, 2009

Q. We are a cable manufacturing company and want to know how copper can be annealed and to what temperature? Is there any cooling curves to follow or is there any need for a vacuum furnace to put in so to avoid oxygen contamination? Please give us useful sites for this respect ... thanks a lot

Eng.Amjad Qade
employee - Kuwait


January 14, 2011

Q. I am doing copper wire annealing in vacuum, my problem is copper loses its reddish color after annealing.
Vacuum: 760 mm of Hg
Chamber temperature: 500 °C

I also tried annealing using nitrogen instead of vacuum. But the result is same. Although annealing improves.

Can anyone suggest me how to maintain copper color during and after annealing?

How should I use nitrogen for annealing? At what temperature should I use nitrogen? And up to which temperature should I heat the copper wire.

Anuj Jain
- Delhi


March 1, 2012

A. Annealing should be done at a temperature just below melting point. I would anneal copper to glowing red hot (about 1000 ° C). The hotter the better because you're charging the metal with energy to free the particles and remove any spring tension.

After annealing run the copper through an acid bath to clean it. I use sodium bisulfate, but sulfuric should do the job. That will remove the oxide.

Samuel Erickson
student - New Zealand



October 27, 2012

Q. My problem is of annealing 0.254 mm copper wire bundles of about 5 to 6 kgs. I am annealing at 250 degree, duly monitored. This annealed copper wire is further drawn to 40 SWG and then silver plated. Silver plated copper wire is further drawn to 52 SWG, at this stage it felt that copper wire is not annealed properly or you need better annealing. Please help me by providing best possible temp of annealing copper of 0.254 mm dia. so as to get acceptable result at all level when it is further drawn to 52 or 55 SWG. Regards.

jayantilal Jain
prathamesh copper - Pune, Maharashtra, India



Copper wire remains hard after annealing

July 30, 2017

Q. I annealed cooper wire in a pot of weight 400 kg, quantity of wire of all sizes is 600 kg. temperature given is 290 °C for 5.5 hours but wire elongation is not satisfactory. Please guide me.

mayank bansal
- delhi,india



This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2017 finishing.com     -    Privacy Policy
How Google uses data when you visit this site.