Plating that blisters or peels is the most common quality complaint in metal finishing, and it is almost always the same root cause wearing different clothes.
The causes
- Incomplete pretreatment. Residual oil, oxide, or scale between the substrate and the deposit. The plating bonds to the contamination, not to the metal. This is the cause in most cases we see.
- Insufficient activation. The surface passivates between pretreatment and plating and the deposit never keys in.
- Substrate problems. Porous castings, contaminated weld joints, or a surface that was never going to hold a coating.
- Process parameters out of range. Wrong current density, bath temperature, or chemistry drifting out of spec.
Why it appears late
This is what makes peeling expensive. A marginally adhered coating often looks fine at inspection and fails weeks later, after thermal cycling, handling, or humidity. By then the parts are with your customer. The defect was created in the pretreatment tank; it just took a month to become visible.
Prevention
- Rigorous pretreatment: degrease, pickle, activate, with controlled times and chemistry
- Bath and current parameters held in range, not "roughly right"
- Racking and handling that don't recontaminate a clean surface
- Adhesion testing on production parts, not just on a coupon
None of this is clever. It is just discipline, which is why the supplier you choose matters more than the process you specify. See the electroplating process.
FAQ
Can peeling be repaired?
Not really. The part has to be stripped and re-processed from pretreatment.
How do I avoid it?
Specify an adhesion test, and choose a plater with a pretreatment process they can describe in detail.
How do you control it?
Controlled pretreatment and inspection at every stage. Request a quote.