ZUFEK
Identify the susceptible condition
Strength, hardness, material condition and tensile stress influence susceptibility. Cleaning, pickling and electroplating can be hydrogen sources. Property class alone is not a complete risk assessment.
Define a coating system
Specify the substrate, process, coating thickness, friction and acceptance requirements. Zinc-flake deposition can avoid electrolytic deposition, but pretreatment and other steps must still be reviewed.
Understand the limit of baking
Hydrogen-relief baking can reduce risk under a controlled specification. It is not a guarantee that every fastener is free from embrittlement. Define any required process controls and verification with the responsible technical team.
Write a useful RFQ
Include grade, final properties, coating specification, functional fits, documentation and application requirements. Avoid a blanket rule that every zinc finish is forbidden or that every coating requires the same baking cycle.
Map potential exposure through the full route
Review cleaning and pretreatment alongside deposition. A non-electrolytic coating does not remove every possible hydrogen source elsewhere in the sequence. Relate the process to the specified material condition and application stress. Avoid treating either a coating trade name or a property-class label as a complete risk assessment.
Define evidence before the order
The responsible technical review should establish the applicable process controls, any relief requirement, verification and records. A generic statement that parts were baked omits the conditions that made the process applicable. Risk reduction is not a guarantee of elimination; decide the acceptance scope under the actual specification rather than substituting a blanket zinc ban or blanket bake instruction.
Keep corrosion, friction and fit in the same review
Changing a coating to address one concern can alter thread allowance, friction or the bearing surface. Reassess the assembly and dimensional requirements when the surface system changes. A corrosion test result under stated conditions does not prove field life or the absence of embrittlement. These are different acceptance questions.
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.