Peeling, rust recurrence or coating flaking requires a review of the complete substrate-preparation and coating process. Surface preparation may be involved, but coating selection, application, curing and service conditions can also contribute. Do not decide that a new shot blasting machine is the solution before investigating the failure.
Record the Failure and Process History
Identify the substrate, coating system, affected locations, time in service and exposure conditions. Preserve inspection findings and relevant preparation, application and curing records. Compare affected and unaffected areas where practical.
The appearance of a failure is a starting point, not a complete diagnosis. Review the evidence with the responsible coating and engineering specialists before selecting corrective work.
Check Surface Preparation Requirements
| Characteristic | Review question |
|---|---|
| Visual cleanliness | Was the required preparation condition achieved and inspected? |
| Surface profile | Was the specified parameter measured by the required method? |
| Dust and contamination | Were relevant residues assessed and removed? |
| Geometry | Were edges, welds, recesses and protected areas addressed? |
| Post-cleaning condition | Was the surface protected from recontamination before coating? |
ISO 8501-1 concerns visual assessment of applicable steel surface cleanliness. Profile is a separate property. ISO 8503-5 addresses a replica-tape profile method; its result should not be treated as interchangeable with every Ra or Rz value.
Review the Abrasive and Incoming Surface
Check the approved media, working mix, contamination and the incoming rust or scale. Oil and grease may require removal before abrasive treatment. Soluble contamination may require a separate assessment and treatment route.
Media that removes scale can also alter texture or damage sensitive material. Select the abrasive and settings through the actual substrate and coating requirements. Do not assume that a recovery system removes every contaminant from circulating media.
Inspect Coverage and Handling
Review the part orientation, fixture, blast direction and residence time. Shadowed areas and contact points may need reorientation or another defined operation. An enclosed wheel-blast machine does not automatically clean every corner equally.
Check residual abrasive after unloading, particularly in cavities and pockets. Handling, storage and the interval before coating can introduce new contamination or corrosion. These steps belong in the preparation procedure.
Assess Equipment Condition and Controls
Inspect relevant wear parts, seals, media delivery and extraction through the approved maintenance procedure. For air blasting, review the specified nozzle supply conditions; for wheel blasting, review the actual wheel and feed arrangement. A generic blast-pressure statement does not describe every machine.
Recipes, monitoring and records can help control a qualified process. Confirm what each signal measures and how faults are handled. Automation does not independently verify cleanliness, profile or coating adhesion.
Review Coating Application and Service Conditions
Check the coating supplier's requirements for surface condition, environmental conditions, mixing, application, thickness and curing. Confirm compatibility with the intended exposure. Preparation quality cannot compensate for an unsuitable coating or an application deviation.
Use the required inspection and testing methods to establish acceptance. Do not replace a technical investigation with an assumed adhesion-success percentage or a generic equipment-upgrade ROI table.
Validate the Corrective Action
Define the diagnosed cause, proposed change and trial criteria. Use representative substrates and the specified coating process, documenting preparation and application together. Inspect the result and complete any required performance testing before wider release.
Select maintenance, process adjustment or equipment changes according to the evidence. A supported corrective plan explains what will change and how success will be measured, without promising that a machine alone will eliminate every coating failure.
Contact Hitech-China with the application information to discuss a configuration-specific proposal.
