
Spray Gun Geometry & Calibration
Source : Yenchen Technical Process Consultant, Dr. Fred Rowley
Gun geometry is a collective term for 5 different aspects of arranging the various guns inside the pan.
1. Gun to bed
2. Gun to Gun
3. Gun to side of pan
4. Cocked guns
5. Position of the guns in relation to the tablet bed.
There are two things to consider, the number of guns in the pan and where we aim them once we have them set up correctly. For a single gun, we place it dead center of the boom and place the boom a specific distance to the tablet bed. For multiple guns we have the additional dimensional checks of distance between guns and between the first and last guns on the boom to the sides of the pan. We also need to be sure we do not alter the gun geometry as we install and remove the guns.
Our goal is to have a completely clean coating pan when we finish with multiple coating runs. Any adhension of material on the side of the pan, on the back of the pan or on the door is unacceptable.
Gun Calibration is Important
It is important to calibrate the spray guns so that each one sprays the same quantity of suspension in any unit time. But in most cases due to variation of suspension, damaged nozzle tips, bent needles and variation in pump speed this cannot always be exact.
1. Variance in solution rates between guns in common.
2. Variance of not more than +/- 10% between guns is acceptable for COLOR coating.
If you have any technical questions, please contact with Grace Chiang Email:grace.chiang@yenchen.com.tw
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