WCA March 2015

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56 Wire & Cable ASIA – March/April 2015
Water lubricating
application in wire and
coaxial cable drawing
process with nano-dies
By Zhang Wenhua, Guo Songshou, Zhang Zhiming and Shen Hesheng, Shanghai Jiaoyou Diamond Coating Co Ltd, and
Shen Bin, Sun Fanghong and Wang Xinchang, Shanghai Jiaotong University, China
❍
❍ Figure 1: Illustration showing the appearance of the bias
enhancement hot filament CVD fabricating apparatus for
nanocrystalline diamond composite coatings drawing dies
Abstract
An extremely effective new type of wire drawing, cable
compacting and tube drawing die is capable of providing
dramatic benefits over PCD and tungsten carbide
dies in particular applications. This paper introduces
nanocrystalline diamond composite coatings technology
applied to dies (nano-dies) and discusses applications
in aluminium wire drawing and coaxial cable drawing.
The benefits of using nano-dies include significant price/
performance improvements, better surface finish, higher
productivity and a most attractive green element – water
lubricating.
1 Introduction
There are many aluminium drawing processes in the
electric cable industry and metal wire and tube industries,
including aluminium wire, copper clad aluminium wire
(CCA), aluminium enamelled wire, aluminium coaxial
cable and aluminium-plastics compound pipe. Among
these applications, one key factor is preparation of a kind
of drawing die suitable for aluminium drawing, with high
production efficiency and product quality.
Conventional drawing dies for these applications
include tungsten carbide (WC-Co) drawing dies (TC
dies) and several kinds of diamond drawings dies, such
as single-crystal diamond and polycrystalline diamond
(PCD) drawing dies. Although diamond drawing dies have
the advantages of high hardness and wear resistance,
low friction coefficient and good thermal conductivity,
it remains impossible to fabricate traditional diamond
drawing dies with large bore diameter at costs that would
make them easy or attractive to purchase.
Furthermore, these types of dies are easily broken when
drawing, especially at high speed and for high strength
material. TC drawing dies can be manufactured very
economically in a wide range of bore diameters (from 0.4
to 60mm or even larger) and they are used in a wide range
of applications (due to their low cost), but they also have
serious disadvantages of short working lifetime (easily
worn and lose tolerance quickly) and this translates to low
1 Filament
power source
2 DC source
3 Electrode
holder
4 Reaction
gas inlet
5 Drawing die
6 Hot filament
7 Support
8 High
temperature
spring
9 Gas outlet