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Newsletter "SEI NEWS" 2012

Home > Company Information > SEI WORLD > Back number > Vol.416

[Newsletter "SEI NEWS" Vol.416]

Copper Wire Rods

Copper wire rod

The history of Sumitomo Electric’s copper wire rod production dates back to the year of the Company’s founding. Since then, copper wire rods have contributed to the progress of the Sumitomo Electric Group as key products (conductors for various types of electric wires).

■ Product data
Start of production 1897
Production volume 270,000 t/y (in 2012)
Production bases Osaka (Japan), Indonesia, Thailand (start of production scheduled for 2014)

For what purposes are copper wire rods used?

The Sumitomo Electric Group uses copper wire rods to develop and produce its key products. Typical examples include ultra-high voltage, large capacity underground and submarine cables; wire harnesses that function as the nerves and veins of automobiles; magnet wires that are used for various electronic parts; residential cables used for house wiring; contact wires used for supplying electric power to trains; and ultra-thin coaxial cables consisting of wires with a diameter of 0.1 mm or less that are drawn from copper wire rods 8 mm in diameter.


Cross-linked polyethylene (XLPE) insulated cable


Magnet wire


Contact wire


The only such technology in Japan - waste electric wire recycling -

Tilting reverberatory furnace

Copper wire rods are conventionally made by continuously melting refined electrolytic copper (purity: 99.99%) in a smelting furnace called a shaft furnace. Sumitomo Electric is the only electric wire manufacturer in Japan that operates both a shaft furnace and a tilt reverberat furnace wasted electric wire recycling.

Scrapped copper wire is melted in the reverberatorying furnace at a rate of approximately 100 tons per day. Air is blown into the molten copper to remove impurities by oxidizing and floating them on the copper surface. Impurities contained in copper increase its electric resistance and softening temperature. The tiltinged reverberatorying furnace improves the purity of molten copper, thereby contributing to the production of copper wire rods having the same physical properties as wire rods made from electrolytic copper.

■ Interview with engineers in charge

Tsutomu Hirano , Electric Conductor Div.

What is the most difficult point you encounter in copper smelting?

The quality and volume of recovered copper wire vary widely. There is difficulty even before we feed the wire into the furnace. Because the temperature differs slightly according to the location in the furnace, we place copper wire containing melt-resistant material nearer the burner, so that all wires melt within a predetermined time.

Tell a story behind electric wire production difficulties you have endured

Sumitomo Electric introduced the tilting reverberatory furnace in 1981. Until then, I had been involved in rolling or casting copper products. To take advantage of the opportunity, I applied to be a furnace operator to broaden my job experience. In those days, my seniors were so proud of their work in the artisan spirit that they were reluctant to share their knowledge and techniques with their juniors. To cope with that tradition, I tried to learn skills by watching how my seniors performed their job. In recent years, I have been concentrating on teaching and training young engineers. In particular, I have developed various instruction manuals through which to hand down to these young engineers the know-how I have cultivated through my long years of experience.

■ Interview with young engineer

Daisuke Yokoyama, Electric Conductor Div.

I have been involved in smelting furnace operation for 11 years. Since the properties of the copper wires collected for recycling differ from batch to batch, we must determine the optimum way of feeding the waste wire into the furnace, furnace temperature, and air-blowing timing for each batch. There isn’t a single day when we can use the same method or procedure just as with living creatures. It is painful - but challenging - to face so many new difficulties that are not described in the manual.

2012 Index
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