Problems and solutions in the pre-painting process (Baoji Leiden Chemical Co., Ltd.)

Problems and solutions in the pre-painting process

Baoji Leiden Chemical Co., Ltd.

Process link

problem

the reason

Solution

except

oil

unit

Minute

Degreasing is not clean

1, low concentration of oil removal

1, increase the concentration

2, short degreasing time

2, extend the time

3, low oil removal temperature

3, the temperature rises

4, the local grease is too thick

4, increase pretreatment (manual)

5, the grease floating layer thickness on the surface of the oil tank

5, the oil layer

6. Nozzle blockage during spray treatment

6, strengthen the cleaning nozzle

7, the workpiece processing capacity is large, no timely addition

7, add drugs in time

except

rust

unit

Minute

Rust removal is not complete

1. Low concentration of descaling solution

1, increase the concentration

2, the derusting time is short

2, extend the time

3, the scale formed by high temperature is too thick, too thick

3. Increase mechanical auxiliary rust removal

4. The iron ion content in the derusting liquid is too high, and the anti-rust liquid is invalid.

4, replace the new bath

Derusting liquid is too large or there is hydrogen embrittlement or over corrosion after the workpiece is rusted

1, the concentration is too high

1, add water to dilute

2, insufficient additives

2, add additives

3, the time is too long

3, time reduction

phosphorus

Chemical

unit

Minute

Phosphating film crystal roughness

1, high free acidity

1. Reduce the free acidity with a neutralizer

2, there is residual acid

2, strengthen the neutral wash

3, the surface of the workpiece is too corroded

3. Control concentration and time

Phosphating film is too thin, no obvious crystallization

1, low free acidity

1. Add phosphating solution and then adjust the neutralizer

2, the total acidity is high

2, diluted with water

3, the surface of the workpiece has a hardened layer

3, strengthen pickling

4, the temperature is too low

4, increase the temperature

5, the ferrous ion content is too low

5, increase ferrous ions

The phosphating film has poor corrosion resistance and rusting occurs during the drying process.

1, phosphating film coarse

1, reduce free acidity

2, the total acidity is low

2. Increase the phosphating solution

3. There is residual liquid on the surface of the workpiece.

3. Strengthen neutralization and washing

4, low phosphating temperature

4, increase the temperature

5, the phosphating time is short

5, increase the time

6, the workpiece overlaps during the drying process

6, separate monomer placement

7. There is water accumulation in the workpiece.

7, change the workpiece placement angle

After phosphating, the workpiece has ashing phenomenon

1, the free acidity is too low

1, increase free acidity

2, the water is not clean

2, strengthen the wash

Phosphating film is uneven

1, the oil is not clean

1. Strengthen degreasing

2, the surface of the workpiece has a hardened layer

2, strengthen pickling

3. Uneven material after heat treatment

3, strengthen pickling

1, the ferrous ion content is too high

1, treated with hydrogen peroxide

2. The pickling bath is brought into the phosphating solution.

2. Strengthen the neutralization and washing, pay attention to the operation process