Approaches to achieve problem-free powder coating

The final quality of a powder coating finish largely depends on the application plant being consistently operated at optimal conditions and meeting the application conditions required for the powder. Problems with the coating process can be avoided if both requirements are fulfilled. To ensure the highest quality of the final finish, all the application plant components should be covered by a preventative maintenance program. Maintenance directions for the components are provided by the individual manufacturers of each component of the plant or by the plant installation contractors in their manuals. The following recommended maintenance work is the minimum which should be included in the maintenance program:

Daily maintenance

• air-clean spraying elements and check for impact fusion or sinter deposits
• check adjustments of sprayguns and controllers
• check delivery pressure of sprayguns
• check injectors (impact fusion, sinter deposits, abrasive wear)
•  air-clean injectors and hoses
• clean application plant, recovery unit and surroundings
• check extraction efficiency of the recovery unit

Weekly maintanance

in addition to daily maintenance:

• check earthing control
• check compressed air quality (clean, dry, oil-free)
• check spraygun condition and voltage supply
• check powder hoses for impact fusion, sinter deposits and kinks
• check reciprocator stroke movement
• check filters, sieves

Further maintenance activities specific to the individual application plant are shown in the maintenance directions or other information given by the equipment manufacturer. Maintenance operations executed on a regular basis are prerequisite to a problem-free coating process. By applying a comprehensive maintenance program, downtime and servicing by the plant supplier may be minimised. Where there are any problems which cannot be resolved, the plant suppliers service department should be consulted. The application and performance specification of the powder is to be agreed with the manufacturer of the powder and linked to the quality assurance system. The following properties to be agreed are included in the specification and influence the application performance, and film formation behaviour: Particle size distribution, density, melting behaviour, resistance to caking, moisture content, fluidization ability, flowability, and curing conditions. Problems which may relate to the properties of the powder should be reported to the manufacturer of the powder so that appropriate remedial action can be taken.