Dosing High-Viscosity Fluids: Precise, Clean, and Process-Stable
Precise dosing of high-viscosity fluids is more challenging than a data sheet might suggest. The more viscous a fluid is, the more energy is required to form a clean droplet and ensure it detaches reliably from the nozzle.
This is precisely where a key challenge in microdosing lies: The droplet must not only form; it must also detach from the nozzle at the right moment. If this does not happen, residues can build up at the nozzle tip. The result is material buildup, inconsistent dosing results, and reduced reproducibility.
To ensure stable metering of high-viscosity fluids, several factors must work together: viscosity, energy input, droplet detachment, nozzle geometry, temperature control, and process parameters. A single mPas value is therefore rarely sufficient to reliably assess metering performance.
Dosing High-Viscosity Fluids
Why High-Viscosity Materials Are Difficult to Dispense
High-viscosity media 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 miniaturization 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.
Why Valve Technology Is Crucial
With high-viscosity fluids, what matters is how much usable energy actually reaches the fluid. This depends not only on drive force or pressure, but also on the interplay of valve mechanics, system stiffness, sealing design, temperature control, nozzle geometry, and parameter settings. The technical in-depth article on improved metering of high-viscosity media demonstrates how marco has further developed valve technology for high-viscosity media with the SJet Power valve. It explains the role that valve mechanics, nozzle geometry, media velocity, and droplet detachment play in ensuring a stable metering process.
Focus on Process Stability
Ultimately, what matters to users is not a single parameter, but rather how the process behaves in real time: clean dosing points, less material buildup at the nozzle, consistent repeatability, and a controllable process window.
Especially when it comes to adhesives, hot-melt adhesives, two-component materials, or curing media, consistent dosing can be the deciding factor in terms of quality, cleaning effort, and process reliability.
Whether a medium can be metered appropriately should therefore always be evaluated by considering the interaction of the material, valve technology, temperature, nozzle, and process parameters.
Can your high-viscosity fluid be dispensed consistently?
Whether a high-viscosity medium can be dispensed reliably does not depend solely on the viscosity value listed in the data sheet. What matters most is how it actually behaves during the dispensing process.
marco supports you in evaluating your application and selecting the right dispensing system configuration.
Please send us a message.