Dispensing Valve for High-Viscosity Fluids: Precise Micro Dispensing with the New SJet Technology
Precise jet dispensing of high-viscosity fluids with enhanced Dot-Jet technology: marco presents the new piezo jetting valve designed for challenging micro dispensing processes and viscous fluids.
High-viscosity fluids such as silicones, thermosetting adhesives or hot melts pose significant challenges in dot-jet dispensing. It is not just about forming a droplet. The droplet must also receive sufficient energy to detach cleanly from the nozzle.
For particularly demanding media, marco has traditionally relied on the String-Jet dispensing method, which operates at pressures of up to 75 bar. To expand the range of applications for the Dot-Jet method, marco’s SJet technology has been specifically enhanced. At the heart of this is the new SJet Power valve with increased stiffness in the double piezo drive: Both torque blocks have been designed to be wider, making the valve stiffer and more powerful. This advancement is complemented by a new sealing concept, improved temperature control, and new valve seats and nozzles.
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Proven jet dispensing technology viscous fluids
Important components for dispensing highly viscous media are already standard at marco:
🔹Specific seal seats
🔹Short valve closing times
🔹Customized design of the pins in the tight-fitting seat
These factors ensure high fluid velocities and shear rates, as well as a powerful impact on the seal seat. This significantly improves droplet formation and detachment.
For users, this combination establishes the technical foundation for stable dispensing of highly viscous fluids. Small nozzles and tailored seal seats increase the velocity of the medium at the outlet. Short valve closing times support droplet snap-off. The pin geometry influences how precisely the medium is accelerated inside the nozzle. The result is cleaner dispensing dots, reduced material buildup on the nozzle, and a more stable dispensing pattern with demanding fluids.
In addition to these proven components, several new features have been integrated.
The new SJet Power: Piezo dispensing valve for adhesives and pastes
The new generation of the marco SJet Power builds on its successful predecessors but also while incorporating additional key innovations:
🔹A wider double torque block
🔹A case with a solid back panel that increases the mechanical rigidity of the entire system
The higher mechanical rigidity reduces energy losses within the valve system. Thanks to this and the more powerful torque block, more energy is available to accelerate the medium. This is critical, especially for contact-free jet dispensing of high-viscosity fluids, as the droplet requires a greater impulse to detach cleanly from the nozzle. For users, this translates to a more stable droplet snap-off, reduced material buildup at the nozzle tip, and highly reproducible dot formation during continuous production.
Innovative sealing concept for the micro dispensing of pastes
Furthermore, a new sealing concept featuring a rolling diaphragm has been developed, offering superior and longer-lasting sealing performance with high-viscosity fluids.
This extended sealing performance minimizes maintenance overhead during operation. Users can operate with the rolling diaphragm for longer periods before a maintenance cycle is required. This significantly enhances equipment availability, particularly with highly viscous, sticky, or curing fluids, where cleaning and maintenance are typically more demanding than with low-viscosity fluids.
Precision fluid dispensing: Integrated temperature control for hot melts
As an additional measure, marco offers enhanced temperature control. The nozzle temperature can now be adjusted with significantly higher precision by the user, which delivers major benefits, particularly in hot-melt dispensing.
More precise temperature control stabilizes the flow behavior of the medium. Especially with hot melts, a consistent temperature can determine whether the droplet snaps off cleanly or material accumulates on the nozzle. Consequently, temperature regulation does not just affect the medium itself, but directly impacts overall process stability.
New valve seats and nozzles for clean droplet break-off
The new seal seats are combined with nozzles made of ceramic or tungsten carbide. Depending on the application, orifice diameters ranging from 800 µm down to 15 µm are available. The tungsten carbide versions are manufactured on in-house electrical discharge machining (EDM) systems.
The geometry of the valve seat and nozzle determines how much the medium is accelerated and how cleanly the droplet detaches from the nozzle tip. With high-viscosity fluids, this acceleration is vital because the material resists detachment much more than low-viscosity fluids. Tailored nozzle geometries help to specifically increase the fluid velocity and stabilize droplet break-off.
The result: Outstanding dispensing results in practice
Combined with proven measures, these innovations lead to outstanding dispensing results for high-viscosity fluids. The combination of power, high system rigidity, controlled sealing, precise temperature management, and optimized nozzle geometry ensures that more usable energy reaches the medium.
This supports a cleaner droplet snap-off and more stable dot formation in the Dot-Jet process. In practice, this can reduce material buildup on the nozzle, improve repeatability, and expand the process window for demanding fluids.
The new valve - familiar design on the outside - improved technology on the inside.
The new generation of the marco SJet:
Take your micro dispensing to the next level
Prevent material buildup at the nozzle and maximize your equipment uptime. Our experts will configure the SJet Power system specifically for your high-viscosity fluids, adhesives and pastes.
Frequently asked questions on dispensing of high-viscosity fluids
How can high-viscosity fluids be dispensed in a non-contact process?
High-viscosity fluids are jet-dispensed without contact by accelerating the medium inside the valve to very high speeds. The powerful impact of the valve pin against the sealing seat imparts sufficient kinetic energy (momentum) to the droplet to ensure it detaches cleanly from the nozzle tip. With marco's SJet Power technology, a reinforced dual piezo actuator provides the necessary mechanical rigidity to transfer this energy loss-free directly into highly viscous fluids like adhesives or pastes.
Which dispensing valve for highly viscous adhesives and hot melts ?
Piezoelectric dispensing valves with integrated temperature control are ideal for highly viscous adhesives and hot melts. Since the viscosity of hot melts is highly temperature-dependent, precise heating of the nozzle stabilizes the flow behavior. The marco SJet Power valve combines this temperature control with extremely short valve closing times and robust tungsten carbide or ceramic nozzles to guarantee a string-free droplet break-off.
How can maintenance effort be reduced in micro dispensing pastes?
When micro dispensing abrasive or curing pastes, maintenance effort can be reduced through an optimized sealing concept with a rolling diaphragm. Unlike conventional seals, the rolling diaphragm prevents high-viscosity media from entering the mechanical guiding elements of the valve. This can increase system availability and extend maintenance intervals in demanding industrial dispensing processes.