APPENDIX D: DEFINING THE OPTIMUM PROCESS
UB25 LINEAR DC RESISTANCE WELDING CONTROL
990-665
D-3
Consider the Material Properties
The important material properties to be considered in the resistance welding process are as follows:
•
Electrical and thermal conductivity
•
Melting point
•
Hardness
It is also important to consider the surface properties of each material such as plating, coatings, and oxides.
The figure below gives an idea of the variance in resistivity and melting point for some of the more
common materials used today in micro resistance welding. The materials can be grouped into three
common catagories.
The types of joints achievable within each of the main groups are as follows:
•
Group I – Conductive Metals
−
Conductive metals dissipate heat and it can also be difficult to focus heat at the interface. A
solid-state joint is therefore preferred. Typically resistive electrode materials are used to
provide additional heating.
500
1000
1500
2000
2500
3000
3500
200
400
600
800
Al
Cu
Ni
Mo
Nb
Pt
Ag
Ta
Ti
W
Inconel
Ti-6Al-4V
Pt-Ir
Nichrome
Bro
Br
G
Steel
Resistivity
(nano-ohm)
Melting Point (C)
Stainless Steels
(304, 316, etc.)
Group I
OFF Scale
Group II
Group III
