We have successfully addressed one of the factors affecting the accuracy of dispensing high viscosity fluids with standard parallel-sided dispensing needles. Standard stainless steel needles have a steep pressure restriction at the part of their cross-section where the needle joins the hub, which can lead to a higher pressure being needed to generate flow, or a high residual pressure in the needle when the feed pressure is cut – leading to continued “oozing” from the needle tip.
Our solution is a range of tapered dispensing needles, carefully designed to reduce the post-dispensing ooze otherwise experienced when applying high-viscosity fluids with enhanced pressure requirements. These tapered tip needles relieve the ramp up in pressure normally required to overcome the considerable “drag” or resistance to flow, of viscous liquids in parallel needles. They are also good for highly filled materials, like solder paste.