Definition
Hold time is the amount of time programmed into the weld controller,
typically between the end of weld time and the command to open the electrodes
(see figure).
Description
Hold time allows the weld to solidify before the electrodes are removed.
If the cooled electrodes are kept in contact with the workpiece for
too long, an unacceptable weld may result in some materials, a condition
termed Hold Time Sensitivity. This is sometimes seen in hardenable
metals, in which the excessive quenching effect of the extended hold
time can create brittle phases in the cooling weld.
Typical Weld Schedule
Detection
Detectable evidence may include:
Significance
Quality, Workplace Issues, Cost, Downtime, Maintenance, Throughput (cycle
time; PPH), are all potentially affected by this condition. Special
considerations are noted below:
Quality: Brittle welds may be produced in hold
time sensitive materials.
Throughput: Long hold times affect the overall weld
time, potentially increasing station cycle time, thereby lowering
throughput.
Subordinate Causes
- Improper hold time value programmed in weld schedule
- Faulty weld cylinder
- Faulty gun closing valve operation
WeldHelp: To Issue/Cause
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