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Design Reference of Electric
Contact Rivets
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In general, F type is designed for fixed
contact while R type is for movable contact.
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Please refer to the table of ¡°Common Sizes of
Contact Rivets¡± for dimension design.
The
tolerance of R figure of contact rivet is ¡À2R.
Tolerance for brazed rivet is the
same with
that for contact tip and depends on the contact
dimensions .
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(1) |
Head Diameter (D) Dimension:
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(D) should be the multiple of 0.5mm , e.g.
¦Õ1.5, ¦Õ2.0¡. ¦µ5.5,etc.(except the unit is by
inch) Don't design the half moon shape for (D)
as it takes high tooling charge and easily
causes the defects such lase burrs, bad
concentricity of contacts(due to asymmetric) and
rough surface(because it's hard to polished).
All of these defects will block the auto-feeding
and aiming-at during auto-bonding process.
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(D) ¨Q 2.4mm, solid type is more suitable than
bimetal type. For heavy current test, we suggest
to use brazed rivets with (D)>6.5mm.
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The maximum range of (D) could be the
multiple of (d) by 1.7 ~ 2.3 times. Please note
the multiple relation of (D) and (d) with above
table. |
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(2) |
Tolerance of (D):
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¡À0.1mm in general. While (D) ¨Q 2.4mm, it
could be ¡À0.075mm. |
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(1) |
Head Thickness (T):
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The beteer design of head thickness is over
0.5mm for solid rivet, and over 0.7mm for
bimetal rivet. Too thick or too thin design
increases the difficulty of producing. If
possible, make the T thicker in view of
increasing heat-dissipation area and reducing
the temperature rising. |
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(T) could be 20%~40% of (D) for special
design. For example, (D) = 3mm, then (T) =
0.6~1.2mm. |
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(2) |
Tolerance of (T):
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¡À0.05mm in general. When (D) ¨R 6.0mm., it
could be widened to ¡À 0.1mm. After bonding
process, (T) will be thinner under the press of
riveting and squeezing operation. Besides,
after the using of switch, the gap will be
enlarged to lessen the spring press. Thus,
it's better to take the upper limit.
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(1) |
Shank Diameter (d) Dimension:
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Bimetal Rivet: Please assure
to design (d) as the multiple of 0.5mm standard
shank dimension, e.g. ¦µ1.5mm, ¦Õ2.0mm, ¦Õ2.5mm or
¦Õ3.0mm, otherwise, it requires new molds, new
blades as well as irregular diameter, Ag wire
and copper wire. It might cause unstable
quality,higher producing cost and longer
delivery. |
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Solid Rivet: The design
principle could be the same with bimetal rivet.
Tre head diameter is better to be smaller than
2mm. Normal shank diameters are ¦Õ0.8, ¦Õ1.0 and
¦Õ1.2. |
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Chamfered Shank: It's better
not to use the chamfered shank, if the design of
copper hole diameter and rivet shank diameter is
suitable. If the chamfered shank is a
must, we suggest to design the chamfered shank
taper as 20¡ã with the standard taper length by
0.6mm. (Please see below left sketch.)
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Concave Shank: General
¡°conical angle¡± of concave shank is 120¡ã. The
min. conical angle should not be smaller than
90¡ã.(Please see blow right sketch.)
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(2) |
Tolerance of (d):
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Upper limit: +0. Lower limit: -0.1mm The
upper limit of its tolerance is set at zero to
prevent the rivet from being unable to inserted
into the corresponding hole in the support plate
when the hole is formed with the smallest
allowable hole diameter. |
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The corresponding hole in the support plate
should be produced larger than shank diameter by
0.05~0.10mm. In order to have a better
bonding force between rivet and plate, flat
surface and no-burr on plate is required,
otherwise the poor bonding will effect the
contact life. |
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(1) |
Shank Length (L):
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The shank length is normally thicker than
support plate by 0.8~1.5mm(depend on the plate
thickness and tolerance). It should carry
to the multiple of 0.5mm. For example. The
plate thickness is 1.0mm, we calculate the
suitable shank length as follows: |
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(a). (L) ¡ú 1.0 +0.8 = 1.8mm,
carry to the multiple of 0.5mm ¡ú 2.0mm
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(b). (L) could be lengthen
to 2.5mm(1+1.5 =2.5mm) if there is enough space
inside the switching appliance, especially while
the dimension of corresponding hole tend to
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the upper limit. It is because the
longer shank could be riveted tightly
with support |
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plate than the shorter shank does.
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(2) |
Tolerance of (L):
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in general, it's +0.15/-0mm or ¡À0.1mm
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