Unitek Peco PHASEMASTER 6, Руководство пользователя

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CHAPTER 3: OPERATING INSTRUCTIONS
PHASEMASTER™ 6 DIRECT ENERGY WELDING CONTROL
3-18 990-083
Electrode Force and %CURRENT
The heat of resistance welding is produced, in part, by the resistance of the interface between the work pieces
to the flow of electricity (the contact resistance).
Sufficient electrode force is required to contain the molten material produced during the weld. However, as the
force is increased, the contact resistance decreases.
Lower contact resistance requires additional energy to produce the heat required to form a weld.
The higher the electrode force, the greater the energy (current and/or time) required to produce a given weld.
Low force usually results in lower bond strength. Increased force requires higher energy but usually results in a
stronger bond. Energy is proportional to time and the square of the welding current.
Causes of Imperfect Welds
Table 3-2 lists the effects of the basic welding parameters on weld quality.
Table 3-2. Causes of Imperfect Welds
Electrode
Problem
Current or
Energy
Force Size
Time
Weak Weld Too Low Too High Too Large Too Short
Blow Holes.
Expulsion. Too High Too Low Too Small Too Long
Burned, Pitted
or Cracked
Electrodes Too High Too Low.
Requires
Maintenance Poor
Maintenance Too Short
Polarity
Users of Half-Cycle Welders have found that the direction of current flow can have a marked effect on the weld
characteristics of some material combinations. This effect occurs when welding:
•
Materials with large differences in resistivity, such as copper and nickel.
•
Identical materials with thickness ratios greater than 4 to 1.