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Electric Contact Rivets Electrical Contact Tips Recommended Contact Materials for Various Switches

     Contact Rivet Materials      Common types of Contact Rivets
     Commonsizes of Contact Rivets      Design Reference of Contact Rivets

Design Reference of Electric Contact Rivets          

 

  

In general, F type is designed for fixed contact while R type is for movable contact.

Please refer to the table of Common Sizes of Contact Rivets for dimension design.
The tolerance of R figure of contact rivet is 2R. Tolerance for brazed rivet is the
same with that for contact tip and depends on the contact dimensions .

(1)

Head Diameter (D) Dimension:

(D) should be the multiple of 0.5mm , e.g. 1.5, 2.0. 5.5,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.

(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.

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.

(2)

Tolerance of (D):

0.1mm in general. While (D) Q 2.4mm, it could be 0.075mm.

(1)

Head Thickness (T):

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.

(T) could be 20%~40% of (D) for special design.  For example, (D) = 3mm, then (T) = 0.6~1.2mm.

(2)

Tolerance of (T):

0.05mm in general. When (D) R 6.0mm., it could be widened to 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.

(1)

Shank Diameter (d) Dimension:

Bimetal Rivet: Please assure to design (d) as the multiple of 0.5mm standard shank dimension, e.g. 1.5mm, 2.0mm, 2.5mm or 3.0mm, 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.

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 0.8, 1.0 and 1.2.

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 with the standard taper length by 0.6mm. (Please see below left sketch.)

Concave Shank: General conical angle of concave shank is 120. The min. conical angle should not be smaller than 90.(Please see blow right sketch.)

(2)

Tolerance of (d):

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.

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.

(1)

Shank Length (L):

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:

(a). (L) 1.0 +0.8 = 1.8mm, carry to the multiple of 0.5mm 2.0mm

(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

  

the upper limit.  It is because the longer shank could be riveted tightly with support

plate than the shorter shank does.

(2)

Tolerance of (L):

in general, it's +0.15/-0mm or 0.1mm





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