In most cases, it is important to change paint or paint formulations frequently. Therefore, it is necessary to be able to purge the system or completely clean the mold. This applies to the entire system, including pump filters and piping.
Purging is a simple, common method; however, great care needs to be taken to simplify all flow areas to eliminate dead spaces.
Mold opening and cleaning can be an easy 30 minute experience or a 3 to 4 day nightmare. Slot die designs vary widely; some are simple two-piece designs while others have complex assemblies.
There is usually a dual pump and piping system that allows quick changeover from one coating to the next, followed by cleanup once the line is up and running.
Figure 20.14 Deckling: (A) Rake and (B) Spacer.
