Before you travel, do your homework: request the ISO 9001 certificate, customer references, order backlog and, where available, audited financials. Define an audit matrix that scores documentation, manufacturing, quality and service so the visit produces comparable evidence rather than impressions.
On the production floor, look beyond the brochures. Note the age and brand of the machine park, spindle run-hours and maintenance logs, housekeeping discipline, calibration stickers on gauges, and where in-process inspection actually happens. A clean, organized floor is a strong proxy for process control.
Check metrology capability: does the shop own a CMM, laser interferometer, ballbar and surface testers, or only outsource them? Are calibration certificates current? Can it demonstrate ISO 230 accuracy testing in-house? Precision claims are only as good as the measurement equipment behind them.
People matter as much as machines. Look at engineer headcount and turnover, language ability, and who handles export documentation and overseas commissioning. Ask to meet the after-sales team rather than only the sales staff - you are buying service as much as hardware.
Trace one part from incoming material through sub-assembly, final run-in and packing, and confirm that the run-in test matches your specification. Place a first-article sample order for independent dimensional verification, issue a written corrective-action plan, and link audit sign-off to the payment schedule.