Sheet Metal Services in Wilmington, NC for over 25 years.
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What
is sheet metal?
Sheet metal is simply metal formed into thin and flat
pieces. It is one of the fundamental forms used in metalworking,
and can be cut and bent into a variety of different shapes.
Countless everyday objects are constructed of the material.
Thicknesses can vary significantly, although extremely
thin pieces of sheet metal would be considered to be foil
or leaf, and pieces thicker than 1/4 inch or a centimeter
can be considered plate. Sheet metal is generally produced
in sheets less than 6 mm by reducing the thickness of
a long work piece by compressive forces applied through
a set of rolls. This process is known as rolling and began
around 1500 AD. Sheet metals are available as flat pieces
or as strip in coils. It is characterized by its thickness
or gauge of the metal. The gauge of sheet metal ranges
from 30 gauge to about 8 gauge. The higher the gauge,
the thinner the metal is. There are many different metals
that can be made into sheet metal. Aluminum, brass, copper,
cold rolled steel, mild steel, tin, nickel and titanium
are just a few examples of metal that can be made into
sheet metal. Sheet metal has applications in car bodies,
airplane wings, medical tables, roofs for building and
many other things.
We
manufacture a wide range of products for various industry
sectors and our comprehensive services includes the cutting,
punching, forming and welding of a variety of materials,
from mild and stainless steel, aluminium, brass and copper,
and perforated and mesh.
Drawing
Drawing
forms sheet metal into cylindrical or box shaped parts
by using a punch which presses the blank into a die cavity.
Drawing process can also be utilized to create arbitrary
shapes with the help of soft punch.
Deep
Drawing
Deep
Drawing is a type of Drawing process where the depth of
the part is more than half its diameter. Deep drawing
is used for making automotive fuel tanks, kitchen sinks,
2 piece aluminum cans, etc. Deep drawing is generally
done in multiple steps called draw reductions. The greater
the depth, the increased number of reductions required.
Deep drawing may also be accomplished with fewer reductions
by heating the workpiece, used in sink manufacture for
example.
In
many cases, special material that has been rolled at the
steel mill in both directions can aid in the deep drawing
process. Material that has been rolled in both directions
has a more uniform grain structure and is referred to
as "draw quality" material. Draw quality material will
often improve deep drawing (limiting tearing).
Cutting
Cutting
sheet metal can be done in various ways from hand tools
called tin snips up to very large powered shears. With
the advances in technology, sheet metal cutting has turned
to computers for precise cutting.
Most
modern sheet metal cutting operations are now based either
on CNC Lasers cutting or multi-tool CNC punch press.
CNC
laser involves moving a lens assembly carrying a beam
of laser light over the surface of the metal. Oxygen or
nitrogen or air is fed through the same nozzle from which
the laser beam exits. The metal is heated and then burnt
by the laser beam, cutting the metal sheet. The quality
of the edge can be mirror smooth, and a precision of around
0.1mm can be obtained. Cutting speeds on thin (1.2mm)
sheet can be as high as 25m a minute. Most of the laser
cutting systems use a CO2 based laser source with a wavelength
of around 10um; some more recent systems use a YAG based
laser with a wavelength of around 1um.
Punching
is performed by moving the sheet of metal between the
top and bottom tools of a punch. The top tool (punch)
mates with the bottom tool (die), cutting a simple shape
(e.g. a square, circle, or hexagon) from the sheet. An
area can be cut out by making several hundred small square
cuts around the perimeter. A punch is less flexible than
a laser for cutting compound shapes, but faster for repetitive
shapes (for example, the grille of an air-conditioning
unit). A typical CNC punch has a choice of up to 60 tools
in a "turret" that can be rotated to bring any tool to
the active punching position. A modern CNC punch can take
600 blows per minute.
A
typical component (such as the side of a computer case)
can be cut to high precision from a blank sheet in under
15 seconds by either a punch or a laser CNC machine.
Bending
and Flanging
Bending
and flanging imparts stiffness to a sheet metal part or
to form various shapes, such as 3 piece aluminum cans[1].
See Bending (metalworking).
Punching
and Shearing
During
punching or shearing, the sheet metal is cut by using
a punch and die. This process can allow many different
shapes and patterns, by a computer numerically controlled
(cnc) punch machine.
Spinning
Spinning
is used to make axis-symmetric parts by applying a work
piece to a rotating mandrel
with the help of rollers or rigid tools. Spinning is used
to make rocket motor casings and missile nose cones and
satellite dishes for example.
Press
Brake Forming
This
is a form of bending, used for long and thin sheet metal
parts. The machine that bends the metal is called a press
brake. The lower part of the press contains a V shaped
groove. This is called the die. The upper part of the
press contains a punch that will press the sheet metal
down into the v shaped die, causing it to bend. There
are several techniques used here, but the most common
modern method is "air bending". Here, the die has a sharper
angle than the required bend (typically 85 degrees for
a 90 degree bend) and the upper tool is precisely controlled
in its stroke to push the metal down the required amount
to bend it through 90 degrees. Typically, a general purpose
machine has a bending force available of around 25 tonnes
per metre of length. The opening width of the lower die
is typically 8 to 10 times the thickness of the metal
to be bent (for example, 5mm material could be bent in
a 40mm die) the inner radius of the bend formed in the
metal is determined not by the radius of the upper tool,
but by the lower die width. Typically, the inner radius
is equal to 1/6th of the V width used in the forming process.
The
press usually has some sort of back gauge to position
depth of the bend along the workpiece. The backgauge can
be computer controlled to allow the operator to make a
series of bends in a component to a high degree of accuracy.
Simple machines control only the backstop, more advanced
machines control the position and angle of the stop, its
height and the position of the two reference pegs used
to locate the material. The machine can also record the
exact position and pressure required for each bending
operation to allow the operator to achieve a perfect 90
degree bend across a variety of operations on the part.
Roll
Forming
A
continuous bending operation for producing open profiles
or welded tubes with long lengths or in large quantities,
see Roll forming.
Rollíng
-
Main
article: Rolling (metalworking)
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