In this issue of the XTreme XChange, we are continuing to provide you with information that will help you get higher productivity from your powder coating operation. In the last issue, the topic of Cyclone Efficiency was reviewed. But how does this correlate to Transfer Efficiency and to System Utilization?

Transfer Efficiency (TE)
Transfer Efficiency is a number associated with how much powder can be applied to a part, in a fixed amount of time, at a fixed rate and desired thickness. Transfer Efficiency is normally measured in a laboratory condition, but can be measured in real world powder system applications. In an actual system, the variables are not controlled, but are set by system operating conditions. It is very important to remember that this performance is based on the actual system operating parameters at the time the test is conducted. Some of the variables that can affect the outcome of an actual system test include: type of powder, gun outputs, product being coated, line density, resistance to ground, booth airflow and part presentation to the guns.

When conducting a system test, actual outputs, product square footage and time are recorded. Testing takes into account actual system parameters and is a more accurate way to gauge application performance. It can also give insights into what parameters should be improved, such as hanging configuration and line density. A great way to improve TE is to add gun triggering. A normal system experiences a TE range of 30 to 60%, but with highly controlled triggering, under ideal racking and airflow conditions, TE can achieve 75% or higher.

System Utilization (System Efficiency-SE)
This is where system Transfer Efficiency and Cyclone Efficiency are combined for a total measurement of the system's performance. Simply, how much powder was loaded, how many parts were coated and how much powder is lost and is unusable. This total is not as easy to measure as the others because it involves the re-spraying and mixing of virgin powder into the process. The over sprayed powder that is captured and re-sprayed is now going through the system a second, third or even fourth time. Each time a portion of the over sprayed powder is recycled, another part of the powder, based on Cyclone Efficiency, is lost. Because it’s a dynamic process, System Utilization tests should be run for a minimum of one hour, so that equilibrium can be obtained.