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.
Why High-Viscosity Materials Are Difficult to Dispense
High-viscosity fluids behave more sluggishly 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 detachment.
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.
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