ZUFEK
Identify the surfaces that control fit
Mark the shoulder, thread, bearing face and any bore that interfaces with another component. Explain whether coating is required, permitted or excluded on each functional area. An all-over finish note may conflict with a fit that the drawing defines without considering the surface system.
Specify the actual coating system
Name the relevant finish requirement and thickness controls rather than using color alone. Different systems can have different dimensional and friction effects. The manufacturer needs the agreed system to propose appropriate preparation and finishing allowances for the specific geometry.
Resolve the inspection stage
State whether dimensions refer to the pre-coating or final condition. If both stages matter, identify their separate limits and checks. Do not assume that a shoulder accepted before finishing or a thread accepted before coating will automatically meet the final assembly requirement.
Include local finish restrictions
Masking, selective treatment or post-finish operations may be relevant, but must be reviewed for feasibility and function. Agree any permitted bare surfaces and protection requirements. A route change intended to rescue a fit should not silently change the approved surface condition.
Specification example
For a locating shoulder with a coated thread, distinguish the two surface requirements on the drawing. This allows the manufacturer to review whether one uniform treatment is appropriate.
RFQ checklist
- Functional coated surfaces
- Finish system and thickness requirements
- Pre-finish versus final dimensions
- Selective coating restrictions
- Final thread and shoulder checks
Use the RFQ preparation checklist, then submit your drawing for review. For acceptance requirements, see quality planning.
General guidance only. Material properties, tolerances, standards and manufacturing feasibility must be verified for the actual specification. This article does not establish a product performance guarantee.