Powder application problems

Troubleshooting Guide

A Electrostatic coating operation

A1. Fluctuations in the coating thickness

Possible cause Remedy

1. Irregular powder feed
  • 1a. Clean powder feed hoses, pump venturis and guns
  • 1b. Check humidity of the air supply which can cause powder compaction
  • 1c. Check powder free flowing properties

2. Inadequate gun distance to the workpiece

2. Readjust the distance between gun and workpiece

3. Inadequate conveyor speed in relation to the high voltage of the gun

3. Readjust the conveyor speed

4. High-voltage fluctuations

4. Systematically check electrical continuity from the voltage source to the electrode

5. Powder blown off from the workpiece
  • 5a. Powder delivery air too high. Turn down air setting
  • 5b. Move gun position further away from the workpiece

6. Pressure fluctuations in the air supply system

6. Check the air supply system

A2. Poor powder build-up and wrap on the workpiece

Possible cause Remedy

1. Poor earthing or other insulating material

1. Check the earth connections. All contact areas must be free of powder build, grease

2. Powder output too high

2. Turn down powder feed until adequate charging is obtained

3. Electrode(s) insulated by powder layer

3. Clean the electrode(s)

4. Particle size distribution not ideal

4. Too much reclaim added to the virgin powder

A3. Poor penetration into recesses and gaps (Faraday cages)

Possible cause Remedy

1. Gun voltage too high

1. Turn voltage setting down

2. Powder delivery too low

2. Turn up powder delivery air setting

3. Poor earthing

3. Check earthing connections and contact areas

4. Inadequate gun position

4. Adjust the gun position so that powder cloud has a direct path to the recess area

5. The spray pattern is too wide

5. Wrong deflector plate. Change it

6. Delivery air speed in the gun too high

6. Lower the air velocity

A4. Back-ionization – powder repelled from the workpiece in spots

Possible cause Remedy

1. Voltage too high

1. Turn down voltage setting

2. Gun too close to the workpiece

2. Relocate the gun

3. Too fine powder particle size
  • 3a. Too much reclaim added to the virgin powder
  • 3b. Originally delivered powder is too fine. Contact powder supplier

B Cured film problems

B1. Poor impact resistance

Possible cause Remedy

1. Under-cured film

1. Increase oven temperature or increase stoving time

2. Too high film thickness

2. Readjust the application equipment. Maintain recommended Dry Film Thickness (DFT)

3. Poor cleaning or pretreatment

3. Check pretreatment equipment and chemicals

4. Wrong powder selection

4. Contact powder manufacturer for right powder selection

B2. Poor adhesion

Possible cause Remedy

1. Poor cleaning or pretreatment

1. Check pretreatment equipment and chemicals

2. Under-cured film

2. Increase oven temperature or increase stoving time

B3. Poor corrosion resistance

Possible cause Remedy

1. Poor cleaning or pretreatment

1. Check pretreatment equipment and chemicals

2. Under-cured film

2. Increase oven temperature or increase stoving time

3. Wrong powder selection

3. Contact powder manufacturer for right powder selection

B4. Poor chemical resistance

Possible cause Remedy

1. Under-cured film

1. Increase oven temperature or increase stoving time

2. Wrong powder selection

2. Contact powder manufacturer for right powder selection

B5. Film hardness too low

Possible cause Remedy

1. Under-cured film

1. Increase oven temperature or increase stoving time

2. Wrong powder selection

2. Contact powder manufacturer for right powder selection

B6. Poor film flow – orange peel effect

Possible cause Remedy

1. Too low film thickness

1. Increase the film thickness

2. Too slow heating rate

2. Increase the heating rate

3. Too fast curing system

3. Contact powder manufacturer

4. Too coarse powder particles

4. Contact powder manufacturer
Home Back to Products