19 Design Consideration In Sheet Metal | Machine Design

17 Design Consideration In Sheet Metal | Machine Design

Following are some basic sheet metal design, Thump rules  for Sheet metal Design

1. Bends

  •  For the ease of manufacturing,
    multiple bends on the same plane should
    occur in the same direction.
  • Avoid large sheet metal parts with
    small bent flanges.
  • In low carbon steel sheet metal,
    the minimum radius of a bend should be
    one- half the material thickness or
    0.80 mm (0.03 inch), whichever is
    larger.
  • Bends specified as angles may
    be tolerance at plus or minus
    one-half degree at a location adjacent
    to the bends.
Edge Flange Design Consideration
Edge Flange Design Consideration

2. Curls

  • The minimum radius is two times
    the material thickness with an
    opening to a minimum of one material
    thickness.
  • The minimum distance between a curl
    and the edge of a hole is the radius
    of the curl plus the material
    thickness.
  • The minimum distance a curl should
    be from an internal bend is six times
    the material thickness plus the
    radius of the curl.
  • The minimum distance a curl should
    be from an external bend is nine
    times the material thickness plus the
    radius of the curl.
Sheet metal design -curls
Sheet metal design-curls

3. Dimples

  • The maximum diameter should be six times the
    material thickness, and a maximum depth of one-half
    the inside diameter.
  • The minimum distance that a dimple should
    be from a hole is three times the material
    thickness plus the radius of the dimple.
  • The minimum distance that a dimple should
    be from the edge is four times the material
    thickness plus the inside radius of the
    dimple.
  • The minimum distance that a dimple should be
    from a bend is two times the material thickness
    plus the inside radius of the dimple plus the
    radius of the bend.
  • The minimum distance between one dimple and
    another is four times the material thickness plus
    the inside radius of each dimple.

 

Dimple -Sheet metal Design 

4. Embossments

  • The maximum depth is
    proportional to the internal radius or material
    thickness.
  • The maximum depth for a
    flat embossment is equal to the internal radius
    plus the external radius.
  • The maximum depth for a V
    embossment is equal to three times the material
    thickness.
Embossments
  • The minimum distance between two
    extruded holes is six times the material
    thickness.
  • The minimum distance from an extruded
    hole to an edge is three times the material
    thickness.
  • The minimum distance from an extruded
    hole to a bend is three times the material
    thickness plus the bend radius.
Extrude Cut ,Holes Extrude Cut ,Holes
Extrude Cut,Holes 

6. Flanges gap

  • The minimum height of a bent flange
    is

    directly related to the
    material thickness, bend

    radius, and length of bend.

  • The minimum width of a bend relief is
    one

    material thickness or 1.50 mm
    (0.06 inch),

flange gap
Flange Gap

7. Gussets

  • The width and
    depth,

    recommended
    at an
    angle of
    45

    degrees,
    is
    directly
    proportional
    to

    the
    radius
    and
    meterial
    thickness.

  • The minimum
    distance that a

    gusset
    should be
    from the
    edge
    of

    a hole
    in a
    parallel
    plane is
    eight

    times the
    material
    thickness
    plus

    the
    radius of
    the
    gusset.

Gussets
Gussets 

8. Hems

  • The minimum diameter
    of a teardrop hem is
    equal to the material
    thickness, with a
    return flange height
    equal to or greater
    than four times the
    material thickness,
    and a minimum opening
    of 1/4 of the
    material thickness.

  • The minimum diameter
    of an open hem is
    equal to the material
    thickness with a
    return flange height
    equal to or greater
    than four times the
    material thickness.

  • The minimum return
    flange height of a
    closed hem is equal
    to or greater than
    four times the
    material thickness
    (the diameter is
    zero).
    NOTE:
    Closed hems tend to
    fracture at the bend
    and cause entrapment
    of solutions during
    the finishing
    process.

  • The minimum distance
    from a hole to a hem
    is two times the
    material thickness
    plus the radius of
    the hem.

  • The minimum distance
    a hem should be from
    an internal bend is
    five times the
    material thickness.

  • The minimum distance
    a hem should be from
    an external bend is
    eight times the
    material thickness.

Hem Design
Hem
Design 

9. Holes

  • The minimum
    diameter of a
    hole should
    be equal to
    the materials
    thickness or
    1.00 mm (0.04
    inch),
    whichever is
    greater.

  • The minimum
    distance
    between holes
    is directly
    proportional
    to the size
    and shape fo
    the hole
    feature and
    the material
    thickness

  • The minimum
    distance the
    edge of a
    hole should
    be from a
    form is three
    times the
    material
    thickness
    plus the form
    radius.

  • The minimum
    distance the
    edge of a
    hole should
    be from a
    bend is two
    times the
    material
    thickness
    plus the bend
    radius.

  • The minimum
    distance
    between a
    hole and the
    edge of the
    material is
    directly
    proportional
    to the size
    and shap of
    the hole and
    the material
    thickness.

  • The minimum
    distance
    between the
    leading edge
    of a hole
    through a
    bend should
    be equal to
    the thickness
    of material
    plus the bend
    radius or two
    times the
    material
    thickness,
    whichever is
    greater.

  • The
    minimum
    width of
    an open
    lance is
    two times
    the
    material
    thickness
    or 3.00
    mm (0.125
    inch),
    whichever
    is
    greater,
    with a
    maximum
    length of
    five
    times the
    width.

  • The
    minimum
    width of
    a closed
    lance is
    two times
    the
    material
    thickness
    or 1.60
    mm (0.06
    inch),
    whichever
    is
    greater,
    and a
    maximum
    height of
    five
    times the
    material
    thickness
    at a
    45-degree
    angle.

  • The
    minimum
    distance
    from a
    lance to
    a bend in
    a
    parallel
    plane is
    eight
    times the
    material
    thickness
    plus the
    radius of
    the bend.

  • The
    minimum
    width
    is
    equal
    to
    the
    material
    thickness or
    1.00
    mm
    (0.04
    inch),
    whichever
    is
    greater.

  • The
    maximum
    length
    for a
    straight/radius
    end
    notch
    is
    equal
    to
    five
    times
    the
    width.

  • The
    maximum
    length
    for a
    V
    notch
    is
    equal
    to
    two
    times
    the
    width.

  • The
    minimum
    distance
    between
    a
    hole
    and
    the
    edge
    of a
    notch
    is
    directly
    proportional
    to
    the
    size/shape
    of
    the
    hole
    and
    the
    material
    thickness.

  • The
    minimum
    distance
    from
    a
    notch
    to a
    bend
    in a
    parallel
    plane
    is
    eight
    times
    the
    material
    thickness
    plus
    the
    radius
    of
    the
    bend.

  • The
    minimum
    distance
    from
    a
    notch
    to a
    bend
    in a
    perpendicular
    plane
    is
    three
    times
    the
    material
    thickness
    plus
    the
    radius
    of
    the
    bend.

  • The
    minimum
    distance
    beyond
    the
    bend
    on
    the
    side
    edge
    is
    equal
    to
    the
    thickness
    of
    the
    material
    plus
    the
    bend
    radius,
    or
    two
    times
    the
    material
    thickness,
    whichever
    is
    greater.

Notches and Relief Cut
Notches and
Relief
Cut 
  • The
    maximum
    inside
    radius
    is
    equal
    to
    three
    times
    the
    material
    thickness,
    with
    a
    maximum
    depth
    of
    the
    inside
    radius.

  • The
    minimum
    distance
    from
    a
    center
    line
    of
    a
    rib
    to
    the
    edge
    of
    a
    hole
    is
    three
    times
    the
    material
    thickness
    plus
    the
    radius
    of
    the
    rib.

  • The
    minimum
    distance
    a
    rib
    should
    be
    from
    an
    edge
    in
    a
    perpendicular
    plane
    is
    four
    times
    the
    material
    thickness
    plus
    the
    radius
    of
    the
    rib.

  • The
    minimum
    distance
    a
    rib
    should
    be
    from
    an
    edge
    in
    a
    parallel
    plane
    is
    eight
    times
    the
    material
    thickness
    plus
    the
    radius
    of
    the
    rib.

  • The
    minimum
    distance
    a
    rib
    should
    be
    from
    a
    bend
    perpendicular
    to
    the
    rib
    is
    two
    times
    the
    material
    thickness,
    plus
    the
    radius
    of
    the
    rib,
    plus
    the
    radius
    of
    the
    bend.

  • The minimum distance
    from a semi-pierced hole
    and a form is three times
    the material thickness
    plust the form radius.
  • The minimum distance
    from a semi-pierced hole
    and a bend is two times
    the material thickness
    plus the bend radius.
  • The minimum distance
    between semi-pierced
    holes is eight times the
    material
    thickness.

14.
Slots

  • The minimum width of
    a slot is equal to the
    material thickness or
    1.00 mm (0.04 inch),
    whichever is greater.
  • The minimum distance
    from the inside surface
    of a bend to the edge of
    a slot is directly
    proportional to the
    length of the slot,
    material thickness, and
    radius of the bend.
  • When using slots and
    tabs the maximum width of
    the slot must be greater
    than the thickness of the
    tab and the tab length
    should equal the material
    thickness.

15.
Tabs

  • The minimum width is
    equal to two times the
    material thickness or
    3.200 mm, whichever is
    greater, while the
    maximum length is five
    times the width.
  • The minimum distance
    between tabs is equal to
    the material thickness or
    1.00 mm (0.04 inch),
    whichever is greater.

16.
Counterbores

  • The minimum distance
    between two counterbores
    is eight times the
    material thickness.
  • The minimum distance
    from a counterbore to an
    edge is four times the
    material thickness.
  • The minimum distance
    from a counterbore to a
    bend is four times the
    material thickness plus
    the bend radius.

17.Countersinks

  •  The maximum
    depth is 3.5 times the
    material thickness at an
    angle of the hardware.
  • A minimum of 50%
    contact between the
    hardware and the
    countersink is required.
  • The minimum distance
    between two countersinks
    is eight times the
    material thickness.
  • The minimum distance
    from one countersink and
    an edge is four times the
    material thickness.
  • The minimum distance
    from a countersink and a
    bend is four times the
    material thickness plus
    the bend radius.

18.Welding

  • Spot welding should
    be restricted to joining
    coplanar surfaces.
  • The minimum distance
    between welds is 10 times
    the material thickness.
    Using 20 times the
    material thickness is
    ideal.
  • The minimum distance
    between a weld and the
    edge is two times the
    diameter of the spot
    weld.
  • The minimum distance
    from a weld to a form is
    the spot diameter plus
    the bend radius.
  • Use PEMs instead of
    threaded inserts.

19.
Plating

  • Outside sharp corners
    receive twice as much
    plating as flat surfaces.
  • Allow for pitch
    diameters for screw
    threads, which can
    increase four times the
    plating thickness.
  • Tapped holes may need
    to be re-tapped after
    plating to ensure
    accuracy.
  • Projections
    accumulate more plating
    than other areas.
  • Recessed areas may be
    difficult to plate,
    resulting in little or no
    coverage.
  • Lap-welded joints
    trap plating solutions.
    One solution is to raise
    welds on embossed areas
    by 0.015 in. (0.3 mm) to
    allow for flushing and
    blow drying between the
    surfaces.
  • Maskings of stampings
    and fabrications to
    anodize certain areas is
    not recommended.
  • Design drain
    holes/vent holes for
    plating solutions and
    rinsing.
  • Design tabs/holes for
    attachment to part racks.

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