Thinking of upgrading your screen- preparation capabilities by adding automatic screen-cleaning and reclaiming equipment? This discussion will help you make some important decisions as you adopt the technology and update your workflow to support it.
Chemical application is handled by high-pressure spray nozzles or brushes. Some manufacturers say spray nozzles do a better job of protecting the mesh and that brushes can excessively abrade screens. Others say brushes are more effective because brushes work the chemicals into the mesh and use less chemicals than spray nozzles. Ericsson says mesh is very tough and that it isn’t normally harmed by the brushes or high-pressure spray. “Only when you apply high pressure manually, then you can harm the mesh—especially when you go in very close to the corners,” he says.
Chemicals applied in automatic screen-cleaning and reclaiming equipment must constantly be kept as useful as possible in order to keep up with the pace at which the systems operate and break down inks and emulsions as expected. Recirculation and filtration facilitates the reuse of solvents. Some systems use pressurized filtration vessels. Others employ a filter that spans the length of the machine. Another option is a centrifuge (Figure 2) that spins waste to separate solids from liquids. Opening the centrifuge reveals a dry cake of waste solids.
A modular inline system allows you to leave yourself an opening for future add-ons. For instance, if you want some automation right away but can’t afford every piece of processing equipment at once, you can start with an automated screen-washing unit, add a reclaiming unit the next year, and hook up a dryer after that. From there, you can integrate an automatic coater, computer-to-screen system, stencil developer, and more. Whichever route you take, be sure to investigate the ways in which each piece of screen-cleaning and reclaiming equipment will protect employees.
“You have standard stop/go buttons. In the case of a jam, a safety clutch would prevent the machine from trying to index a frame,” Weidenhamer explains. “You have sensors that monitor screen movement and prevent operation in the case of blockage. Door-override locks prevent people from arbitrarily opening doors either physically or by the push of a button when the machine is in use. If you’re spraying a solvent at 30 bars (435 psi), it’s going to atomize. If you open a door, you’ll get sprayed. Safety systems keep that from happening.”
Volume and size decisions
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