Tapered tip needles for dispensing high-viscosity adhesives
1 min read
I&J Fisnar, a US-based company whose products are distributed in this country by Intertronics, is promoting the use of tapered tip needles for the dispensing of high-viscosity fluids such as adhesives.
"When dispensing such fluids with standard blunt-end tips extra pressure is required to overcome the resistance when entering the straight needle tube - the amount of resistance will depend on the internal bore of the tube", says Fisnar's James Dornan. "The effect of this extra pressure to overcome the resistance is to introduce a tertiary element in the control of the dispensing process thus making an accurate deposit difficult or even impossible to achieve.
"A few high-pressure valves offer a snuff-back feature but it is impossible to apply this successfully when using a syringe for high-viscosity fluids."
The solution suggested by Fisnar is to make use of a tapered dispensing needle - a moulded plastic design that prevents or effectively reduces the tertiary pressure phenomenon. "These needles reduce the post-dispensing ooze that can be experienced when blunt-end tips are used, particularly when applying high-viscosity fluids that require higher pressure to dispense", says James Dornan.
