Which method is suitable for what?
Precision and repeatability are crucial for dispensing processes. As a result, the choice of the right dispensing method under consideration of all general conditions is essential for the quality of the end product. For processes with the highest quality requirements, piston and gear pump dispensers have established themselves as volumetric dispensing systems in industry. There are different methods for the application of the correct quantity of dispensing material.
Dispensing by mass determination
The filling quantity is monitored and controlled with an electronic scale. The weight of the component to be potted is continuously measured during the potting process. When the target weight is reached, the outlet valve closes.
Dispensing by time measurement
With this principle, the material flow at a constant feeding pressure is controlled by opening and closing an outlet valve at a fixed time. The dispensed quantity depends on the pressure, the cross-section of the dispenser nozzle and time. This system is only suitable for 1C materials.
Dispensing by volume determination
This principle determines the material quantity geometrically on the basis of the diameter and stroke of a hollow cylinder. The cylinder is filled with the potting material by supplying the corresponding material feeding system. The piston in the hollow cylinder is retracted automatically in response to the material pressure. Unlike active retraction, this prevents the piston from pulling away from the liquid material phase and subsequently prevents air from being trapped. This system also simultaneously determines the ratio of two components (resin/hardener). The dispensing pistons push the two components simultaneously into separate channels in the direction of the outlet valve, where they only mix in the static mixing tube to form a homogeneous and reactive medium. This means that there is no reaction between the two components within the dispenser. Piston, gear pump and screw dispensers have proven themselves for volumetric solutions.