In terms of the type of application in the conveyor system, the solution type coating usually uses a metering pump (Metering Pump), while the hot melt paint uses a melter (Melter) or extruder (Extruder); Among them, the more commonly used metering pumps include
Screw Pump and Gear Pump, and their common features are as follows:
- It can be conveyed continuously with almost no pulsation
- It can be dosed from aqueous liquids to high-viscosity liquids of hundreds of thousands of centipoises (CPS).
- High accuracy of dispensing volume, high reliability, dispensing accuracy within ± 1%.
- The use of variable speed motors can change the flow range to a large extent
- There is no need to use the structure of the valve, so there will be no blockage
- Strong self-priming ability, extremely high suction and discharge pressure
- It can be smoothly operated and conveyed without vibration and noise
- Disassembly, assembly and maintenance are as simple as possible
The coating thickness is completely determined by the feeding system, so the uniformity of the thickness of the coating film in the direction of travel (MD) of the machine depends entirely on the stability of the pump, and the formula for the feed flow rate is:
Pump feed flow = (coating width) x (wet film thickness) x (coating speed)
In addition, it is necessary to avoid the contamination of impurities or the generation of bubbles when the paint is conveyed, so as to prevent the defects in the coating process, so the filter device and defoaming mechanism will be installed in the process of conveying the paint to ensure the coating quality; In addition, the equipment will be equipped with a pressure gauge or digital pressure gauge for online monitoring to prevent the filter pressure from being too high and causing downtime.
