Powder Curing - Ultra Image Powder Coating

Curing

Once the powder is applied, the product is heated in an oven to the correct temperature, for the required time, dependent on the mass and powder type.

'Curing' is the operative word here since the powder goes through four stages while heating. Too high or low of a temperature for too long or short of a time can mean the difference between a poor coating and the 'Ultra Image', quality coating.

"first at the finish line"

Utlra Image - Big Lake
Phone: (763) 262-1500
Fax: (763) 262-1501

In order for the powder to achieve the properties for which it was formulated (decorative, visual, chemical, mechanical), two conditions must exist.

The first is temperature, referred to as metal temperature, and the second is time.

The cure time is actually two times, the 'bring up' time and the 'dwell' time. The bring up time is the time it takes for the metal (substrate) to reach the desired temperature. The dwell time is the time required for the powder to cure properly.

Combining dwell time and bring up time is the oven cycle time

There are three basic ways of heating the parts to the temperature required to cure the powder.

Convection - transmitting the heat by air circulation.
Radiation - transmitting the heat directly to the part without heating the air (infrareds).
Induction - transmitting the heat directly to the part by inducing electrical current.

Ultra Image uses convection heating.

Batch System temperatures are determined by powder type and mass.

The powder must go through four stages during the oven cycle time in order to cure correctly.

1. The powder first melts.
2. Then it will flow. With some powders the flow is almost non-existent and with others the flow can cause drips and runs.
3. The powder then starts its gel stage.
4. In the final stage the powder cures. This is the point where the powder achieves the characteristics for which it was formulated.

Obviously, too long or too short of an oven cycle time can provide a less than adequate finish. Great care must be given during the 'cure' of the powder. Oven temperatures, and times must be monitored and administered to take in account the mass of the part and the bring up time. Then a thorough knowledge of the powder and the dwell times required.
Much of the quality of the finish is also determined by other factors such as shop cleanliness (dust, dirt, oil, moisture, etc.), testing, and maintenance.

The final phase of the process is allowing the part to cool, a part that is still 'hot' can be easily marred.

After a final inspection the part or product is then ready for packaging and shipment.

This was a very general overview of the powder coating process and applies to power conveyor line and batch systems. It is our hope that it provides you with a better understanding of the process. If you have any questions or would like more information on the variety of powders available, or the process, please feel fee to contact us.

Thank you

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