Successful Conversion from Manual to Robotic Welding

by Rich Shive
Panasonic Factory Solutions Company

Situation:

Productivity Welding Inc. (PWI), a systems integrator, reveals how to successfully convert from manual to robotic welding. A chief design requirement was achieving true dimensional repeatability.

Solution:
 
Designing for true dimensional repeatability was the key in converting to a robotic welding system.  There were a series of steps involved: weldment component and weld joint repeatability, weldment fixtures and tooling, and system feasibility and cost justification.

How to determine true dimensional repeatability:

1. Choose the three to six key weldments with the greatest potential for improving welding cycle time.
2. Collect a representative sample of these weldments from a day's production output.
3. Measure and record the true dimensional repeatability of each weldment by analyzing and documenting each weld joint and the variability in location, gap and configuration.

Weldment Fixtures and Tooling:

Robotic welding systems fail due to poorly designed fixtures.  Proper fixtures must:

1. Position or deflect weldment components to a repeatable location.
2. Hold that location securely throughout the welding cycle.
3. Operate without hindering robotic arm or torch movements during the welding sequence.
4. Enable the operator to load/unload weldment components safely.
5. Allow for simple replacement for critical tooling or wear components.
6. Provide for effective fixture removal and replacement in the system.

Prior to the systems integrator designing and building the fixtures, the following should be provided: 

1. Final weldment drawings
2. Critical dimensions
3. Completed reference weldments
4. Several sets of components for each key weldment to be completed

System Feasibility and Cost Justification:

After the systems integrator analyzes the key weldments, collects actual weld production data, and reviews the true dimensional repeatability information, a welding cycle time study for each of the key weldments should be performed.