June, 2012
now browsing by month
Requirements for powder coating over hot dip galvanizing
The following specification is recommended: Use zinc phosphate pretreatment if highest adhesion is required. Surface must be perfectly clean. Zinc phosphate has no detergent action and will not remove oil or soil. Use iron phosphate if standard performance is required. Iron phosphate has a slight detergent action and will remove small amounts of surface contamination. Best used for pre-galvanized products. Pre-heat work prior to powder application. Use ‘degassing’ grade polyester powder coating only . Check for correct curing by solventRead More …
The solutions for the problems of powder coating over hot dip galvanizing
1. Incomplete curing: Polyester powder coating powder is thermosetting resins that cross-link to their final organic form by being maintained at a temperature (typically 180 o C), for about 10 minutes. Curing ovens are designed to provide this time at temperature combination. With hot dip galvanized items, with their heavier section thickness, it is necessary to ensure that sufficient stoving time is allowed to meet the curing specifications. Pre-heating of the heavier work will assist in accelerating the curing processRead More …
The problems with powder coating application over galvanized surface
Polyester powder coating over hot dip galvanized steel provides a high grade architectural finish to steel items with excellent atmospheric weathering characteristics.The powder coated product ensures maximum durability for steel components, which will generally provide 50 year+ rust free life spans in most architectural applications. Even so there are still some problems during this application. Hot dip galvanized surfaces have been acknowledged as difficult to powder coating since the technology was first developed in the 1960’s. Industrial Galvanizers commenced research inRead More …
How to prevent powder dust explosion
An explosion can be prevented if both or either of the conditions Explosive Limit and Source of ignition are avoided. Powder coating system should be designed to prevent both conditions occurring ,but due to the difficulty of totally eliminating sources of ignition,more reliance should be placed on the prevention of explosive concentrations of powder. This can be achieved by ensuring that the powder in air concentration is kept below 50% of the Lower Explosive Limit(LEL). Determined LELs on the range ofRead More …
The causes of dust explosion and fire hazards during manufacturing powder coating
Powder coatings are of the fine organic materials, they can give rise to dust explosions. A dust explosion may break out when the following conditions happen at the same time. A ignition sources is present, including: (a) hot surfaces or flames;(b) electrical discharges or sparks;(c) electrostatic discharges. The concentration of dust in the air is between the Lower Explosive Limit (LEL) and Upper Explosion Limit (UEL). when a layer of deposited powder coating or a cloud comes into contact with anRead More …
More superioritis to liquid coating
For many reasons including environmental speaking,excellent performance ,high productivity and economics application,powder coatings have been used more and more since the 1970’s. It is clean,almost zero VOC. Additionally powder coatings provide easy clean up without harmful solvents and harmful waste. Over-sprayed powder can be recycled and reclaimed for greater economic savings than liquids paint.It reduce the cost of labor to coat products as much of application is automated.Powder coatings can not be modified at the clients site,thus eliminating inconsistency of products.Read More …
Particle Size Distribution
FINE PARTICLES Lower film builds Can blind cartridges and filters Migrate from part into exhaust Reduced fluidization properties Smoother films Absorb moisture more readily COARSER PARTICLES Higher film builds Increased Faraday penetration Increased fluidizaion properties
Powder Coatings Manufacturing
Weigh-up and Mixing ( raw material,such as resins,hardener,pigments,filler,etc) Extrusion Process Milling and Sieving
Phosphating conversion coatings
The recognized pre-treatment for steel substrates just prior to application of powder coatings is phosphating which can vary in coating weight. The greater the conversion coating weight the greater the degree of corrosion resistance achieved; the lower the coating weight the better the mechanical properties. It is therefore necessary to select a compromise between mechanical properties and corrosion resistance. High phosphate coating weights can give trouble with powder coatings in that crystal fracture can occur when the coating is subjected to locallyRead More …
D5 Creation