AIRCUT
-101
I
,161
IW
,200
IW Inverter Plasma Cutting Machine
WARPP ENGINEERS PVT LTD
25
the open circuit voltage may be lower, while it is higher by using air, nitrogen, hydrogen.
8) Cutting speed
The cutting speed is related with many parameters. The main parameters
determining cutting speed include work-piece thickness, cutting current, air flux and
nozzle aperture. A proper drag is allowed during cutting. The cutting speed should be
increased as much as possible, but the incision quality must be guaranteed.
2
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Eliminate the cutting burr
9) The characteristics of the incision burr
The ordinary cutting surface is smooth and clean, but if the parameter
selection is not suitable, and electrode centering is not good, then burr may be
formed on the cutting surface.
Slag is formed by molten metal and its oxide which is adhesive to the bottom
edge of incision and solidified. The reason for forming this slag is that the molten
metal adhesive strength is bigger than the gravity and blow strength of metal oxide.
When cutting the alloy steel, the molten metal is difficult to be blown away
because of its bad fluidity, in addition, the alloy steel have bad thermal conductivity,
the incision bottom is over-heated easily, the left molten metal and incision bottom
melts into one, thereby the irremovable and tough burr is formed.
On the contrary, the incision bottom is difficult to be melted together with
molten metal, and the burr formed under incision is come off easily.
10) The factors affecting the forming of burr
The fluidity of the molten metal is not good, when the power is too small or the
plasma arc compression effect is not good, the temperature of molten metal during
the cutting process is low, fluidity is weak, even if the air current blow force is
strong, it is still difficult to blow away the metal completely, so the burr is formed.
When cutting the thick plate, the burr is caused by the drag of overlarge cutting
seam. During the cutting process, the heat received by different parts of metal is
different, the heat on the upper incision is larger than that of the lower incision, so
the upper part melting speed is faster than that of lower part, thereby a distance
between them is formed, it is called drag L of cutting seam. The drag size is related
to plasma arc shape and cutting speed. When the flame is short while the cutting
speed is too fast, drag L increases, so the vertical and horizontal blow force of the
arc is formed, the vertical one helps to blow away the molten metal, while the
horizontal one makes the molten metal flow backward along with incision bottom,
this over-heated metal will melt parts of the bottom metal again, then the burr is
formed when they cool down and melt together.
The burr is caused by overheat bottom. When the cutting speed is too slow, but
the incision bottom is so over-heated that it melts, the liquid metal flows to bottom
metal and combines into one which makes the difficulty to blow away molten
metal by air current, and then the burr is formed.
The air current blow force is not enough. When cutting with plasma, the arc
blow forceconsists of the air current blow force and the arc electromagnetic force,
the air current blow force acts the main function. If the air current blow force is not
strong enough, it cannot ensure all the burr is flown away,then the burr is formed.
11) The measurement to eliminate burr
