Needle nozzles were pioneered by Aachen University, Germany, in the 1990s. The nozzles use an array of small diameter tubes, fixed to a chamber or endplate, configured to the shape of the grinding wheel Whilst it has been shown that the flow from a straight tube can be mildly disturbed, the favorable length to diameter ratio of the straight tube in the needle nozzle system acts as a flow stabilizer, minimizing dispersion. Typical needle lengths are 2, 3, and 4 inches long.
Hypo-Grind needle nozzles are based on a stainless steel tube size of 0.106” ID and 0.134” OD. The proximity of adjacent needles is 0.167” spacing, or 6 needles per inch. At a pressure of 100 psi (7 bar) each needle will flow 3 GPM (11 LPM) of water-based coolant, represent a maximum specific flowrate of 18 GPM per inch (2.7 LPM per millimeter) The Hypo-Grind nozzle system is available in either fixed needle position or re-configurable needle position formats. The fixed nozzles stocked by Cool-Grind are typically a straight profile but other profiles are available to special order. The re-configurable needle format consists of a plenum chamber and matrix drilled endplate with a hole diameter and profile to accept the individual needle OD including the flared end that locks the needle in place.