Summary of common problems and solutions in powder spray production

1.

A) The workpiece is not powdered, or powdered very little, or has poor adsorption force, and it is easy to fall off

Possible Causes:

1.

2.

3.

4.

5.

6.

Suggested solutions:

1.

2.

3.

4.

5.

6.

B) The dead corners and grooves of the workpiece are not powdered or powdered very little
.

Possible Causes:

1.
The spraying parameters of the spray gun, such as voltage, current, powder size, etc.
do not match the type of workpiece;

2.
The performance of the spray gun is not good enough
.

Suggested solutions:

1.
Adjust the appropriate spraying parameters, such as voltage, current, powder output, etc.
, test the best spraying parameters and store them, and call up the best parameters for this kind of workpiece
.

2.
Replace the spray gun with better performance
.

C) Uneven powder on workpiece automatic spray gun

Possible Causes:

1.
The hanging direction of the workpiece is not uniform, resulting in different powder application of the automatic spray gun at the same position of the workpiece
.

2.
The sprayed powder mist type or powder output does not match the workpiece
.

3.
The arrangement angle, quantity or position of spray guns need to be changed
.

Suggested solutions:

1.
The hanger needs to be adjusted, and the same type of workpiece hangs the same, so that the powder uniformity of the automatic spray gun is consistent
.

2.
Reduce the powder output, or change it to a suitable nozzle
.

3.
Adjust the number, position and installation angle of spray guns
.

D) The powder is not evenly discharged from the spray gun, or spit out powder
.

Possible Causes:

1.
The compressed air pressure is too small or the air volume is not enough;

2.
The powder is not fluidized well or not fluidized;

3.
The powder pipe channel is blocked with foreign matter;

4.
The powder pump is faulty;

5.
The secondary air pressure regulating valve of the controller is faulty;

6.
The powder is too moist or agglomerated, or there are too many impurities in the powder
.

Suggested solutions:

1.
Spray guns with program storage function generally require compressed air at 6 atmospheres;

2.
Solve the problem of powder fluidization;

3.
Carefully clean the powder passage from the powder pipe to the spray gun;

4.
The atomizing gas connector on the powder pump is not ventilated or leaking, and needs to be replaced or cleaned up;

5.
The failure of the pressure regulating valve causes little atomization gas to be output to the powder pump
.

6.
Improve powder quality
.

E) No powder from the spray gun

Possible Causes:

1.
The controller is faulty;

2.
The powder pump problem;

3.
If the automatic gun is equipped with gap control and is enabled, it may be that the encoder for measuring chain speed has no signal input or the grating is faulty
.

Suggested solutions:

1.
Check whether the solenoid valve in the controller is damaged;

2.
Check the powder pump, such as whether its connector is connected correctly, whether the spray gun and the powder pump are connected incorrectly, etc.
;

3, the encoder checks whether loose or broken cable, to check whether the raster damaged
.
Restart the test machine after connecting
.

F) The powder output of the spray gun is not large

Possible Causes:

1.
The venturi tube in the powder pump is worn out;

2.
The powder pump joint or base is leaking or damaged;

3.
The primary air valve is faulty;

Suggested solutions:

1.
Replace with a new venturi;

2.
Replace the powder pump connector, etc.
, or clean the base or replace with a new sealing ring to maintain a good seal
.

3.
Check whether the primary air valve in the controller is broken or blocked by impurities in the compressed air
.

G) The powder spraying isolates the indoor ground and air everywhere, causing pollution and waste
.

Possible Causes:

1.
The design or quality of the spray booth and powder recovery system is not good, the air extraction volume actually required by the spray booth is not reached, or the design structure is wrong, which causes the powder to float out of the spray booth;

2.
Failure of the recovery system, such as powder discharged from the exhaust vent;

3.
The powder brought out by the fluidized gas of the powder bucket falls outside;

4.
When changing colors and cleaning the spray booth, use compressed air to blow randomly;

5.
The powder that floats when the powder is manually sieved, the powder that floats when the powder is added, and so on
.

6.
The air permeability of the filter element is clogged and the air permeability is greatly reduced, resulting in insufficient ventilation, and the powder floats out of the spray booth
.

Suggested solutions:

1.
Transform the spray booth or recovery system;

2.
The reasons for the leakage of powder, such as broken filter element, broken sealing strip, peeling off sealant, incorrect installation of filter element, etc.
, need to be carefully inspected and repaired or the powder recovery system should be reformed;

3.
Replace or repair the powder bucket;

4.
Pay attention to the correct operation when changing colors and cleaning;

5.
It is best to use a fully automatic powder recovery and sieving device to avoid the problems, errors and waste of manual powder sieving
.

6.
Replace the good filter element
.

H) The color change and cleaning time of the spray booth is too long or it is difficult to clean up

Possible Causes:

1.
The design of the spray booth is unreasonable, the volume is large or there are many dead corners, and it is difficult to clean up;

2.
The operator is unskilled or the tools are inappropriate;

3.
Many automatic spray guns
.

Suggested solutions:

1.
Improve the unreasonable structure of the spray booth;

2.
Train operators to be proficient in cleaning the spray booth system, and be sure to choose appropriate cleaning tools;

3.
Improve the automation level of the spray booth, such as installing a powder center with automatic cleaning function
.
Or equip more parts that are easy to change colors, such as one more powder tube per spray gun, more powder buckets, etc.
, try to achieve a special color powder bucket
.

I) A lot of waste powder generated by the post filter recycling, wasting powder

Possible Causes:

1.
The small cyclone or large cyclone recovery system itself has low separation and recovery efficiency, and the equipment itself is of poor quality;

2.
The automatic conveying device for recycled powder does not work, and the recycled powder under the small cyclone or large cyclone device accumulates too much, and then it is directly sucked to the post filter;

3.
The automatic powder sieving machine is blocked, causing excessive accumulation of recycled powder under the small cyclone or large cyclone device, which is then directly sucked into the post filter
.

Suggested solutions:

1.
Modification or replacement of the recovery system of the small cyclone or the large cyclone;

2.
Check the automatic conveying device for recycled powder and solve the existing faults;

3.
Check the sieving machine and solve the existing faults
.

Second, the problems of the coating after powder curing

A) Serious orange peel

Possible Causes:

1.
The powder coating is too thick;

2.
The temperature and time of the oven do not match the powder;

3.
The problem of powder leveling itself;

4.
Anti-ion effect of spray gun;

Suggested solutions:

1.
Adjust spraying parameters to reduce coating thickness;

2.
Adjust the oven temperature, chain speed, etc.
, contact the powder supplier and request data;

3.
Contact the powder supplier and request guidance data;

4.
Lower the static parameters or increase the distribution halo

B) The gloss of high-gloss powder is low or the gloss of low-gloss powder is too high

Possible Causes:

1.
The thickness of the powder coating is large, or there is contamination of different powders;

2.
Whether the oven temperature parameter or curing time is appropriate;

3.
Other pollution, or high water content in compressed air;

Suggested solution: contact the flour mill and ask it to provide guidance;

C) Variety appears in the coating

Possible Causes:

1.
Incomplete cleaning when changing powder;

2.
The design defects of the spray booth lead to the blind spots that cannot be cleaned up
.

Suggested solution

1.
Thoroughly clean the spray booth and the channels, containers and equipment through which the powder is recovered;

2.
Renovate defective equipment
.

D) Uneven film thickness

Possible Causes:

1.
There is too little powder in dead corners and recesses, and the automatic spray gun parameter adjustment does not match;

2.
Manual spraying is uneven;

3.
The hanging of workpieces is not neat and uniform;

4.
The turning point of the elevator does not match the height of the workpiece
.

Suggested solution

1.
Contact the flour mill and ask it to provide guidance;

2.
Increase the level of supplementary spraying or pre-spraying;

3.
Rectify the hanger, the same kind of workpiece should be hanged neatly and uniformly;

4.
If the top or bottom is too thin or too thick, it means raising or lowering the lift's reciprocating point position
.

E) The coating has irregularities such as zebra patterns at regular intervals

Possible cause: The elevator speed does not match the chain speed, too slow or too fast

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1.
Change to a spray gun with good performance;

2.
Adjust the appropriate spraying parameters, such as adjusting the current to 20 microamperes or even lower, and the voltage to 60KV or lower, and the operator needs to have good spraying skills and experience;

3.
Reduce the powder output of the spray gun
.

N) Poor film adhesion

Possible Causes:

1.
The pretreatment is not done well, for example, the quality of the phosphating film is not good, etc.
;

2.
Oxides or solvents remain on the surface;

3.
The coating is too thick or the curing time is not enough;

Suggested solution

1.
Ask the pre-processing supplier for solutions;

2.
Same as above;

3.
Seek powder suppliers to provide reference data
.

Three, concluding remarks

During the powder spraying process, various equipment production problems, equipment structure and design problems, equipment parts damage problems, powder coating problems, pre-treatment problems, environmental pollution problems, etc.
will be encountered.
Long-term professional training, long-term on-site problem solving work experience and Service experience, and must be good at thinking and learning to accumulate advanced ability to solve practical problems
.