Dispensing High-Viscosity Fluids: Precise, Clean, and Process-Stable
Precise dispensing of high-viscosity materials starts with understanding how the material behaves in the real process. Datasheet values provide an important first indication. What matters most is how much usable energy is actually transferred into the material, so that a clean droplet can form and detach reliably from the nozzle.
This is a key requirement in precision dispensing: the droplet must not only be formed, but also detach cleanly from the nozzle at the right moment. When droplet break-off is stable, residue at the nozzle tip can be reduced, material buildup can be avoided and repeatable dispensing results can be achieved.
Stable dispensing of high-viscosity materials depends on the interaction of several factors: viscosity, energy input, droplet break-off, nozzle geometry, temperature control and process parameters. A reliable evaluation is therefore based on more than a single mPa·s value and should consider the behavior of the material under real dispensing conditions.
Dispensing High-Viscosity Fluids
Why Valve Technology Is Crucial
With highly viscous fluids, what matters is how much usable energy actually reaches the fluid. This depends not only on the driving force or pressure, but also on the interplay of valve mechanics, system rigidity, sealing design, temperature control, nozzle geometry, and parameter settings. The technical insight into improved dispensing of high-viscosity material demonstrates how marco has further developed valve technology for such materials with the SJet Power valve. It explains the role that valve mechanics, nozzle geometry, media velocity, and droplet detachment play in ensuring a stable dispensing process.
Process-stable dispensing of high-viscosity materials: measured data and application examples
The more viscous a medium is, the more energy is required to form a clean droplet. This is precisely where the challenge in microdosing lies: The droplet must not only form but also detach reliably from the nozzle. If this does not happen, residues remain on the nozzle. The result is an unstable process that loses dosing quality over time. This becomes particularly critical in applications involving single drops or low frequencies. In such cases, the fluid has more time to spread around the nozzle. Therefore, four factors are particularly crucial: viscosity, energy input, droplet detachment, and process stability.
High-Viscosity Precision Dispensing: What Matters in the Process
High-viscosity fluids respond more slowly than low-viscosity liquids. They offer greater resistance to acceleration and require more energy for a droplet to detach cleanly. This task becomes particularly challenging with small droplets. As miniaturisation increases, the ratio of surface area to volume rises. As a result, surface tension and wetting become increasingly important. Surface tension holds the droplet together and influences how easily it detaches from the nozzle. Wetting describes how strongly the fluid adheres to or spreads across the nozzle tip. The stronger these effects are, the more difficult it can be to achieve a clean droplet break-off.
Focus on Process Stability
For users, what matters in the running process is the stable interaction of several factors: clean dispensing dots, reduced material buildup at the nozzle, repeatable results and a controllable process window.
Especially with adhesives, hot melts, 2K materials or curing materials, stable dispensing makes an important contribution to quality, reduced cleaning effort and process reliability.
For this reason, dispensing performance should always be evaluated in terms of the interaction between the material, valve technology, temperature, nozzle, and process parameters.
Evaluating high-viscosity materials under real process conditions
Whether a high-viscosity material can be dispensed reliably is best evaluated under real dispensing conditions. In addition to the viscosity value in the datasheet, what matters is how the material behaves in the specific process.
marco supports you in the technical evaluation of your application and in selecting the right system setup.
Please send us your inquiry.