Common Sizes and Design Reference of Electric Contact Rivets in LML Metal Products Ltd.

Common Sizes of Electric Contact Rivets in LML Metal Products Ltd.

NOTE:
F stands flat head ,flat head contact rivet is usually for stationary contact
R stands round head,round head contact rivet is usually for moving contact
Other dimensions could be supplied on customers' request.

 

          

 

           


Design Reference of Electric Contact Rivets     
1.About Head type,use F OR R

Usually,type F is designed for fixed contact and type is for movable contact.
  
 
Please refer to the table of “Common Sizes of Contact Rivets” for dimension design.
2.About Head Diameter D and tolerance

  (D) should be the multiple of 0.5mm, e.g. φ1.5, φ2.0…. φ5.5,etc.(except the unit is by inch) Don’t design the half crescent for (D)
 as it takes high tooling charge and easily causes the defects such like 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)≦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.   
   
 The tolerance of D is ?span lang="EN-US">0.1mm in general. While (D)≦2.4mm, it could be ?span lang="EN-US">0.075mm.

3. About Head Thickness (T) and tolerance

  The good 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 reduce the temperature rising.
       
(T) could be 20%~40% of (D) for special design.  For example, (D) = 3mm, then (T) = 0.6~1.2mm.
  
The tolerance of  T is span lang="EN-US">0.05mm in general. When (D) ≧6.0mm., it could be widened to span lang="EN-US"> 0.1mm.
 After bonding process, (T) will be thinner under the press of riveting and squeezing operation.  Besides, after  using of switch,
the gap will be enlarged to lessen the spring press.  Thus, it’s better to take the upper limit.

4. About Shank(foot) Diameter (d) Dimension and tolerance:

 Bimetal Rivet: Please assure to design (d) as the multiple of 0.5mm standard shank dimension, eg.  φ1.5mm, φ2.0mm, φ2.5mm or φ3.0mm, 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 above bimetal rivet. It’s better for   head diameter smaller than 2mm. Normal shank diameters are  φ0.8, φ1.0 and φ1.2.    
      　
  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?/span> with the standard taper length by  0.6mm. (Please see below left sketch.)   
      
  Concave Shank: General “conical angle” of concave shank is 120?span lang="EN-US">. The min. conical angle should not be smaller than 90?span lang="EN-US">.(Please see blow right sketch.) 
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 be 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 longerity of contact.

5. About Shank Length (L) and tolerance:
 

  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. E.g. 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    
   
  
 theupper limit.  It is because the longer shank could be riveted tightly with support   
  
 plate than the shorter shank does.   
      
  Tolerance of (L):    

  In general, it’s +0.15/-0mm or  /font>0.1mm
Dear customer,if have more questions for contact rivet design,please kindly contact sales@lmlmetalproducts.com ,LML provide assistance at any time.