WIRE DRAWING
The wire drawing die setup is shown in Fig. The process of
producing the wires of different
diameters is accomplished
by pulling a wire through a hardened die
usually made up carbide. However a smaller diameter wires
are drawn through a die made of diamond.
The larger diameter oriented
wire is first cleaned, pickled,
washed and then lubricated. Cleaning is essentially done to remove any
scale and rust present on the
surface, which may severely affect the die. It is normally done by acid
pickling. The hot rolled steel is de- scaled, pickled
in acid, washed
in water and coated
with lime and other lubricants. To make for an easier entrance of wire into
the die, the end of the stock is made pointed
to facilitate the entry.
A pointed
or reduced diameter at the end of wire duly
lubricated is pushed or introduced through the die which is water cooled
also. This pointing
is done by means of rotary swaging
or by simple hammering. It
is then gripped and pulled for attaching it to a power driven reel. The wire
diameter is reduced in die because of the ductility property of the material to
the smaller diameter through one set of die. However for more reduction in
diameter of the wire, various sets of dies can be used in line for subsequent
reduction in diameter at each stage as shown in Fig. The reduction in each pass through the die range
about 10% for steel and 40% for ductile
materials such as copper.
or reduced diameter at the end of wire duly
lubricated is pushed or introduced through the die which is water cooled
also. This pointing
is done by means of rotary swaging
or by simple hammering. It
is then gripped and pulled for attaching it to a power driven reel. The wire
diameter is reduced in die because of the ductility property of the material to
the smaller diameter through one set of die. However for more reduction in
diameter of the wire, various sets of dies can be used in line for subsequent
reduction in diameter at each stage as shown in Fig. The reduction in each pass through the die range
about 10% for steel and 40% for ductile
materials such as copper.
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| Wire drawing |
The drawing of the wire starts
with a rod or coil of hot rolled steel, which is 0.8 to 1.6 mm larger than the final size required. In this process,
there is no force is applied for pushing the wire into the die from the
entrance side. The material should be sufficiently ductile since it is pulled
by the tensile forces. Hence, the wire may have to be annealed properly to
provide the necessary ductility. Further, the
wire is to go through the conical portion and then pulled out through the exit by the gripper. The other aspect
of preparation needed is the cleaning
of the wire and lubricating it as it flows through the die. The
pressures acting at the interface of the die and the metal being very high, the
lubrication of the die is a serious problem. Therefore, to carry the lubricant
through the die, special methods such as gulling, coppering, phosphating and
liming are used. The wire is coated with a thin coat of ferrous hydroxide which
when combined with lime acts as filler for the lubricant. This process is
called sulling. In phosphating, a thin film of manganese, iron or zinc phosphate is applied on the wire, which
makes the lubricant to stick to the
wire, thereby reducing the friction and consequently,
the drawing load. Another lubricant vehicle that is used in wire drawing is a coating of lime. After acid pickling, lime is applied and then allowed to dry. The lime neutralizes any amount of
acid left on the surface and adsorbs the lubricant for carrying it to the die.
The lubricant normally used is the soap solution. For very thin wires,
electrolytic coating of copper is used to reduce
friction. The dies used for wire drawing are severely affected because
of high stresses and abrasion. The
various die materials that are used are chilled cast iron, tool steels,
tungsten carbide and diamond. The cast iron dies are used for small runs. For very large sizes, alloy steels are used in making the dies.
with a rod or coil of hot rolled steel, which is 0.8 to 1.6 mm larger than the final size required. In this process,
there is no force is applied for pushing the wire into the die from the
entrance side. The material should be sufficiently ductile since it is pulled
by the tensile forces. Hence, the wire may have to be annealed properly to
provide the necessary ductility. Further, the
wire is to go through the conical portion and then pulled out through the exit by the gripper. The other aspect
of preparation needed is the cleaning
of the wire and lubricating it as it flows through the die. The
pressures acting at the interface of the die and the metal being very high, the
lubrication of the die is a serious problem. Therefore, to carry the lubricant
through the die, special methods such as gulling, coppering, phosphating and
liming are used. The wire is coated with a thin coat of ferrous hydroxide which
when combined with lime acts as filler for the lubricant. This process is
called sulling. In phosphating, a thin film of manganese, iron or zinc phosphate is applied on the wire, which
makes the lubricant to stick to the
wire, thereby reducing the friction and consequently,
the drawing load. Another lubricant vehicle that is used in wire drawing is a coating of lime. After acid pickling, lime is applied and then allowed to dry. The lime neutralizes any amount of
acid left on the surface and adsorbs the lubricant for carrying it to the die.
The lubricant normally used is the soap solution. For very thin wires,
electrolytic coating of copper is used to reduce
friction. The dies used for wire drawing are severely affected because
of high stresses and abrasion. The
various die materials that are used are chilled cast iron, tool steels,
tungsten carbide and diamond. The cast iron dies are used for small runs. For very large sizes, alloy steels are used in making the dies.
 |
| Wire drawing |
The
tungsten carbide dies are used most commonly for
medium size wires and large productions. The tungsten carbide dies are
referred because of their long life that is 2 to 3 times that of alloy steel
dies. For very fine wires, diamond dies are used. Wire drawing improves the
mechanical properties because of the cold working. The material loses its ductility during the wire drawing process
and when it is to be repeatedly drawn to bring it to the final size, intermediate annealing is required
to restore the ductility.
tungsten carbide dies are used most commonly for
medium size wires and large productions. The tungsten carbide dies are
referred because of their long life that is 2 to 3 times that of alloy steel
dies. For very fine wires, diamond dies are used. Wire drawing improves the
mechanical properties because of the cold working. The material loses its ductility during the wire drawing process
and when it is to be repeatedly drawn to bring it to the final size, intermediate annealing is required
to restore the ductility.
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