Choose the function first
Conversion coatings chemically modify the aluminum surface and may serve as pretreatment, corrosion protection or part of an electrically conductive interface. These functions are not interchangeable. Define whether the part will be painted afterward and whether contact resistance or standalone corrosion performance controls acceptance.
Make the system unambiguous
Specify the applicable process requirement, chemistry restrictions and finish class or type when the governing specification uses them. Terms such as clear treatment or passivation are not enough to select a controlled process. Review the casting alloy and local surface preparation with the proposed finisher.
Preserve the intended interfaces
Masking, cleaning, storage and handling can affect the surface presented to the next operation. Identify grounding points and adhesive or paint zones on the drawing. If electrical performance matters, agree where and how it is measured on the finished component.
Review checklist
| Review item | Define before release | Evidence to retain |
|---|---|---|
| Role | Paint base, corrosion barrier or contact surface | Specified functional requirement |
| System | Process specification and chemistry restrictions | Finishing record |
| Interface | Masking and handling conditions | Finished-state verification |
Worked review example
An enclosure requiring both paint adhesion and an electrical ground needs separately defined zones. A visually similar clear treatment is not sufficient evidence of contact performance.
Apply the review to your drawing
Identify the affected features on the current drawing and attach the material, finish and operating requirements that control them. Agree the proposed route and acceptance evidence before releasing a change. Send the controlled files for a project review.