Final answer:
Proper tip size selection depends on the base metal's thickness, welding process, thermal conductivity, and expansion rates.
Step-by-step explanation:
The selection of the proper tip size for base metal applications depends on several factors, including the thickness of the base metal, the type of welding process being used, and the characteristics of the base metal itself, such as its thermal conductivity and expansion properties. For instance, thicker metals require larger tips to deliver more heat, while materials with high thermal conductivity may require a tip with a higher heat output to achieve the same welding effectiveness. In addition, the expansion rates of metals when heated also play a role—some metals expand more than others under the same temperature increase, as illustrated by the behavior of bimetallic strips. This knowledge helps in choosing the right size and type of tip for effective welding results.