Cause 1: Improper pH Value. Improper pH can damage the passivation layer on metal surfaces. Solution: Use neutral pH (7-8) for aluminum alloy, and weakly alkaline (8.5-10) for steel.
Cause 2: Delayed Drying After Cleaning. Prolonged water film presence triggers electrochemical corrosion. Solution: Immediately blow dry with compressed air or proceed to the drying process.
Cause 3: Insufficient Rinsing. Residual cleaning agent absorbs moisture, creating a corrosive environment. Solution: Ensure rinse tank water is clean and replace rinse water regularly.
Cause 4: Water Quality Issues. Calcium and magnesium ions in hard water react to form insoluble salts. Solution: Use pure or softened water for rinsing.
Cause 5: Extended Inter-Process Storage. Solution: Use cleaning agents with rust prevention function (such as TS-W300), or apply short-term rust preventive oil.