Problems and solutions in the pretreatment process

2022-09-22
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Problems and solutions in the pretreatment process before coating

process links

problems

causes

solutions

oil removal

division

points

dirty oil removal

1, low oil removal concentration

1, increased concentration

2, short oil removal time

2, extended time.

3, low degreasing temperature

3, elevated temperature

4, local grease is too thick

4 Tighten the fastening screws of the load flange reliably and add pretreatment (manual)

5. The thickness of the grease floating layer on the surface of the oil removal tank

5. Skim out the oil layer

6. The nozzle is blocked in the spray treatment

6. Strengthen the cleaning of the nozzle

7. Gongji'nan new era gold Testing Instrument Co., Ltd. directly sells CDW (6) type low-temperature tank nationwide: the processing volume is large, and there is no timely addition of

7 Add chemicals in time

rust removal

parts

points

incomplete rust removal

1. The concentration of rust removal solution is low

1. Increase the concentration

2. The rust removal time is short

2. Extend the time

3. The oxide skin formed by high temperature is too thick and thick

3. Increase mechanical auxiliary rust removal

.4. The content of iron ion in derusting solution is too high. Rust prevention includes 3jing chemical, Xinyue chemical, 3ling plastic, Dongli, Sumitomo chemical Big Lu and other liquids fail

4. Replace the new tank liquid

the rust removal liquid is too acidic or the workpiece has hydrogen embrittlement or over corrosion after rust removal

1, the concentration is too high

1, add water to dilute

2, the additive is insufficient

2, add additive

3, the time is too long

3, the time is reduced

phosphorus

chemical

/p>

sub

rough crystallization of phosphating film

1, high free acidity

1 Use neutralizer to reduce free acidity

2, have residual acid

2, strengthen neutralization and water washing

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