What's the best dispense tip for syringe dispensing?

There is no one ideal dispense tip for syringe dispensing. The best dispense tip for fluid dispensing depends on several factors, including fluid viscosity, dispensing volume, dispensing speed, and cycle time. Making an informed choice of dispensing tip is a critical part of designing your syringe dispensing system.

How to choose a dispense tip for syringe dispensing

In a syringe-based fluid dispensing system, a pneumatically controlled plunger, or piston, pushes the fluid down through the dispensing tip to deposit a desired volume at a specified rate.

The following factors should be considered when choosing a dispense tip for syringe dispensing:

• Fluid viscosity
• Inner diameter of dispensing tip
• Length of dispensing tip
• Shape/design of dispense tip (hub with steel cannula, tapered plastic, etc.)

Nordson EFD offers a wide range of Optimum® precision dispense tips, also known as dispensing needles.

When fluid passes from the syringe barrel into the dispensing tip, it compresses.

For a thin fluid, this can change the velocity of dispensing, but that can be managed upfront by adjusting pneumatic pressure.

For a thick fluid or paste, however, compression can generate back pressure that counters the force applied by the pneumatic system.

• In the best-case scenario, that back pressure forces the pneumatic system to work extra hard, wasting energy or reducing the accuracy of the dispensing process.
• In the worst-case scenario, back pressure can cause the fluid in the syringe barrel to leak or ooze out of the dispensing tip after the dispensing cycle is complete.

Follow the tips below to choose the best dispensing tip for high viscosity fluids:

• Choose the lowest gauge tip (widest inner diameter) possible
• Choose the shortest tip possible
• Choose a tapered dispensing tip

What if my system or process has specific requirements for tip gauge or length?

If your system or process has specific requirements for tip gauge or length, one parameter can be used to balance the other. If your process requires a longer length, try reducing back pressure with a larger internal diameter (ID) dispense tip. If your process requires a smaller ID dispense tip, use the shortest version possible.

When should I use a plastic dispense tip?

Use a plastic dispense tip in the following circumstances:

• If the part you’re dispensing onto is delicate and could be scratched by a metal cannula
• When you’re dispensing high-viscosity fluids
• When you’re dispensing low- to medium-viscosity fluids onto delicate surfaces, flexible cannulas made of polypropylene are best