First, the process: degreasing → washing → phosphating → washing → drying → coating.
Second, the preparation of bath solution (calculated by 1M2 tank)
1, degreasing tank: add design volume of water in the tank, heated to about 45 °C above, and then open the spray pump to add 20 ~ 25Kg PA30-SM degreaser, test free alkalinity, heating to about 50 ~ 65 °C Put into use.
2, washed: ordinary tap water.
3. Phosphating bath: Add water with design volume in the tank, turn on the spray pump to add PA-27-400 phosphating solution 16~20Kg, appropriate amount of liquid caustic soda. The free acidity of the test should be within the process range, and heat up to about 35~50°C. Put into use.
4, washing: ordinary tap water.
5, drying:
6, coating:
Third, the bath management
1, degreasing tank
Periodical tests for free alkalinity should be greater than 11 points (generally at 11 to 18 o'clock the best, according to the actual plate oil pollution, free alkalinity can be lower), when low should be added degreasing agent, when it is 1M3 tank plus Kg Free base rose 3 to 4 points. Adhere to regular process change slots.
Free Alkalineity Test: Take 10ml bath, add 50ml distilled water, 1~2 drops of phenolphthalein indicator, 0.1N HCL standard drop, red → colorless as end point, consume the ml of HCL standard as free alkalinity point .
2, phosphate tank
Periodical tests of free acidity should be in the range of -1.0 to 0.5 points. Phosphating solution should be added when it is low. When it is a 1M3 tank, 5Kg of free acidity is increased by about 0.2 points. It is usually recommended to take consecutive drops after experience. This saves and stabilizes quality. Adhere to regular process change slots.
Free acidity test: Take 50ml bath, 3~5 drops of bromophenol blue indicator, 0.1N NaOH standard drop, yellow to purple as the end point, the number of milliliters of NaOH standard consumed is the free acidity point (when adding bromine When the phenol blue indicator is purple, it is titrated with 0.1N HCL standard solution, the endpoint is purple to yellow, and the number of ml of HCL standard consumed is the negative number of free acidity).
Fourth, the process parameter table
Workstation name
Processing temperature
Processing time
Control parameters
Test frequency
Degreasing
45~60°C
90~180 seconds
Free Alkalinity: 11~18 points
One time/class
Washing
Normal temperature
30~150 seconds
Overflow wash
Phosphating
35~50°C
90~180 seconds
Free acidity: -1.0~0.5 points
Once / 2 hours
Washing
Normal temperature
30~150 seconds
Overflow wash
V. Maintenance item list
Workstation name
Maintenance item
frequency
Maintenance
Degreasing
conventional
1 time/day
Check the liquid level and remove impurities
Nozzle
1 time/week
Remove cleaning
Bath solution
1 time/quarter (or according to pollution)
Clean the tank, change the bath
Washing
conventional
1 time/day
Check the liquid level and remove impurities
Nozzle
1 time/week
Remove cleaning
Bath solution
1 time/day (or according to pollution)
Clean the tank, change the bath
Phosphating
conventional
1 time/day
Check the liquid level and remove impurities
Nozzle
1 time/week
Remove cleaning
Bath solution
1 time/quarter
Clean the tank, change the bath
Heat exchanger
1 time/quarter
2~5% dilute nitric acid cleaning
Washing
conventional
1 time/day
Check the liquid level and remove impurities
Nozzle
1 time/week
Remove cleaning
Bath solution
1 time/day
Clean the tank, change the bath
Six, common faults and exclusion
6.1 Degreasing tank
Common malfunctions
cause
Method of exclusion
Poor oil removal capacity
Low concentration
Add degreasing agent
Low temperature
increase temperature
Solid grease can not be removed
Low temperature
Raise the temperature or pre-erase
Bath fluid turns black, liquid slick
Excessive oil in bath
Change the bath
6.2 phosphate bath
Common malfunctions
cause
Method of exclusion
Phosphate film is uniformly yellowed
Low concentration
Phosphating agent
Low temperature
increase temperature
Stop line
Reduce stoppages
Phosphate film is too thick, hang gray
Low concentration
Naturally consumed or diluted with water
Free acidity is too high
Alkali neutralization
High temperature
Reduce the temperature
Stop line
Reduce stoppages
Membrane difference in normal parameters
Bath aging
Change the bath