How to Get Rid of Shearing Defects?

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How to Get Rid of Shearing Defects?
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Shearing is a fabricating process used to cut
metal sheets. The Shear blade machine consists
of a shear table, blank holders, upper and lower
blades. A back gauge is used to make sure that
the cutting process is streamlined. When it comes
to a perfect cut of the metal you need a high
quality shear blade like Amada shear blades
which reduces the effects of variable sheet metal
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characteristics, internal stress, geometry to
reduce the possible defects in the shear
blades. In this case, you need to take care of
these natural effects. As they can make your
shear blades defected and may reduce the final
cutting quality of the product. If you work at
the metal forming factory you must know that it
is important to maintain your shear blades
timeto time. In this article, we have a list
of variables used in this process along the
solutions to get rid of possible shearing
defects. Cutting Angle It is the cuttingedge
angle of the blade. With two square edge blades,
it requires higher cutting force than the upper
blade. It is at an angle of 87. And the lower
blade is always at 90. These are the
fouredge blades. Angled blades are called
twoedge blades.
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Shearing Angle
This angle has a great effect on the shearing
force. When you shear thin strips, this angle has
an important effect on twisting. The shearing
angle is less than 3.
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Blade Clearance Its the perpendicular distance
between the shearing blades. The quality of
results depends on plate thickness and material
strength. If the cutting clearance is too small,
the costs will be higher. If its too large, the
result will be precise and large plastic
deformation. Clearing Angle The clearing angle
is fixed and set to 1.5. The Blade ram is not
perfectly vertical but is tilted pointing
towards the backside to facilitate the piece
separation.
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The Shearing Defects and Solutions Twisting In
shear blades, this defect twists the plate with
its axis. When shear narrow down the strips, it
results in twisting. Other responsible shearing
conditions are related to metal geometry.
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For example, high thickness and short length
reduce the width, material characteristics like
the soft material, uneven stress distribution
and cutting parameters like high rake angle,
high cutting speed etc. To get rid of this
defect it is recommended to lower the rank
angle. This way, it would become useful to add
an antitwist device. Also, this option consists
of a series of cylinders that push the plate
against the top blade. This force applies when
it corresponds to the plate thickness. Poor Edge
Quality During the shearing process, the material
initially deforms in a very small area, with a
residual deformation. Then the upper blade
penetrates the material where cutting is neat
and clear. At the end of the shearing process,
the material would give up. Because of that, the
material cracks with a rough and irregular
surface known as the
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fractured zone. This is often not perpendicular
to the plate but a variable angle. You can
improve edge quality by adjusting blade
clearance, and keeping blade wear under
control. Crooking In this defect, the surface
stays flat, and a plate is curved along its
plane. The responsible conditions include strip
width, thickness, material strength, and
previous cold rolling direction. The best way to
reduce crooking is to use a smaller shearing
angle and performedcuts along rolling
direction. Guillotine shear is another condition
where blade ram supports its ends instead of the
entire length. Even during the shearing process
the blade will become crooked because of the
cutting force and will tend to open in the
center. The best solution is to choose a shear
with adjustable blade pads to keep it perfectly
liner. You can opt for Amada shear blades as
they come with these specifications.
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Bowing
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In such a situation, the metal is no longer flat
as this effect results in bowed sheet
metal. Generally, it is related to cutting angle
and plate strength. The best way to reduce this
is by using a smaller shearing angle and hold
the sheet metal with back support. Does your
shearing blades have experienced such defects?
Amada Replacement Parts help you to avoid such
types of defects for a period of time with their
high tech functionalities. Although the regular
maintenance and abovementioned steps would help
you to eliminate the shearing deficiencies.
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