Start with the assembly
Collect drawings, material specifications, joint geometry and the functional requirements for the weld. Identify product variants and note which requirements are still provisional.
Map the machine boundaries
Assign ownership for the laser, motion, fixtures, enclosure, utilities and machine sequence. A subsystem can only be designed sensibly when its interfaces with the parent machine are understood.
Agree on the evidence
Define representative samples and evaluation methods. Record the tested conditions so later machine decisions can be traced to the application review.