Capability match
Confirm geometry, size, heat-treatment route, finishing process and accuracy. Ask what is in-house and how external processes are controlled.
Choose a manufacturer that can show a controlled route for your gear type, material, heat treatment, accuracy and volume. Review metrology, traceability, change control and repeat-batch evidence; a certificate or machine list alone is not enough.
Use this precision gear manufacturer evaluation framework to compare suppliers on the same evidence.

Confirm geometry, size, heat-treatment route, finishing process and accuracy. Ask what is in-house and how external processes are controlled.
Review calibrated equipment, sample reports, hardness or metallography records and the reaction plan near specification limits.
Check revision control, lot traceability, tool life, first-off checks, nonconformance handling and notification before process changes.

Agree the inspection pack before sampling, then compare a later repeat lot against the same critical characteristics. The PairGears buyer checklist helps structure this review.