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Powder Supply Problems

 

1. Fluidized Bed Operation

What is the problem you are facing?

Dusting - Powder blowing out of hopper

Possible Causes Possible Solutions
1. Air pressure to high 1. Adjust air regulator to lower pressure to fluid bed.
2. Powder too fine 2a. Too much reclaim added to virgin powder.
2b. Virgin powder pulverised too fine by manufacturer.

 

No air-precolaitng through powder surface

Possible Causes Possible Solutions
1. Insufficient air pressure. 1a. Check air supply, Increase air regulator pressure.
1b. Check air line size to equipment.
2. Plugged membrane. 2. Check membrane for plugged pores dirty air supply.
3. Obstructed membrane. 3. Check bottom of bed for plastic, cardboard or other large obstructions.
4. Compacted powder. 4. Manually loosen powder and fluidize well with clean, dry air.

 

Rat holing - air blowing large jet holes through power surface

Possible Causes Possible Solutions
1. Powder level too low. 1. Add powder until hopper is 2/3 full when fluidized.
2. Packed or moist powder. 2a. Manually loosen powder and fluidize well with clean, dry air.
2b. Check compressed air and booth air for high humidity.
3. Obstructed membrane. 3. Check bottom of bed for plastics, cardboard or other large obstructions.
4. Plugged or broken membrane. 4. Check membrane for plugged pores from dirty air supply, cracks or holes.

 

Stratification - powder separating into layers of fine and coarse particles.

Possible Causes Possible Solutions
1. Powder level too high. 1. Remove powder until 2/3 full when fluidized.
2. Powder too fine. 2a. Too much reclaim added to virgin powder.
2b. Virgin powder pulverized too fine by manufacturer.

 

 

2. Hoses and Pumps - Venturi Operation

What is the problem you are facing?

Plugged from impact fusion hard build-up.

Possible Causes Possible Solutions
1. Normal build-up. 1. Clean or replace parts.
2. Air pressure too high. 2. Turn down air settings on pumps and guns.
3. Moisture in air supply. 3. Check air supply for clean, dry air.
4. Composition of powder feed hoses. 4.Check hoses.
5. Worn venturies and wear parts. 5. Replace worn parts.
6. Powder too fine. 6a. Too much reclaim added to virgin powder.
6b. Virgin powder type pulverized too fine by manufacturer.
7. Powder type of formula. 7. Some resin types tend to have more impact fusion. Check with your powder supplier.

 

Insufficient powder feed.

Possible Causes Possible Solutions
1. Powder not fulidizing. 1. See fluidized bed section.
2. Obstruction from contaminated powder supply. 2a. Clean out venturies and hoses.
2b. Check powder supply for contamination.
2c. Sieve all reclaim before using.
3. Kinked or flatened hoses. 3a. Replace if permanently deformed.
3b. Avoid sharp bends. Use hose saddles for reciprocators.
3c. Run hoses in covered trenches across traffic aisles.
4. Worn pump venturies. 4. Replace worn parts.
5. Low air pressure. 5. Check air supply. Adjust all setting to pumps and guns.

 

 

4. Collection and Reclamation Operation

What is the problem you are facing?

Contamination in reclaim powder.

Possible Causes Possible Solutions
1. Reclaim in-line sieve torn, missing or inoperable. 1. Replace sieve or repair as necessary.
2. Powder or dirt falling in spray booth from conveyor or hangers. 2. Clean conveyor regularly (or continuously) before entering powder spray booth. Strip hangers as needed.
3. Contamination from parts entering spray booth. 3. Check cleaning pre-treatment equipment and ensure proper part drainage before spray booth.
4. Contamination from plant air circulated through spray booth. 4. Isolate spray booth area. Preferably enclose in a room filtered, humidity controlled air.

 

Spray booth dusting inadequate air flow through spray booth.

Possible Causes Possible Solutions
1. Bag or cartridge filters blinding. 1a. Clean or replace bags or cartridge filters.
1b. Check spray booth air humidity.
1c. Check reverse air cleaning.
2. Final filters clogged. 2. Check filter bags or cartridges for powder leakage, repair or replace as needed.
3. Too large of open area in spray booth housing. 3. Reduce open area. Increased opening reduces booth air velocity.
4. Powder delivery (feed) too high. 4. Reduce the number of spraying or the amount of powder to each gun.