Effective cooling and lubrication play a crucial role in the grinding process, often underestimated by many. Proper coolant application can significantly impact surface finish quality and tool longevity. Dr. John A. Webster has long emphasized the importance of coolant in achieving high-quality surface finishing and micro-precision, proving its effectiveness over time.
The nozzle is responsible for continuously spraying coolant during grinding, helping to regulate temperature in the grinding zone and keeping the wheel clean by washing away debris into the filtration system. This ensures consistent performance and reduces wear on the grinding wheel.
Plastic modular nozzles work well at low pressures (around 2 atmospheres), but they may not perform as well under high-pressure conditions. These nozzles are easy to align with the cooling area, but their position must be adjusted closely to the grinding point for optimal results. On the other hand, rigid metal tubes like copper can introduce air into the coolant stream if not precisely aligned, leading to inefficiencies and potential breakage from frequent bending.
Cluster jet nozzles are highly effective
Over the past two decades, cluster jet nozzles—resembling laser-like streams—have proven far more efficient than traditional plastic modular nozzles, especially when grinding materials that retain most of the heat in the part rather than the chip. At speeds exceeding 6000 SFPM (about 30 m/s), the air boundary layer on the grinding wheel’s surface can prevent low-pressure coolant from reaching the wheel. Cluster jets, with higher impact energy, help break through this layer, clean the wheel, and improve coolant delivery to the grinding zone.
This dual high pressure slotted nozzle system has proven to be suitable for ANCA TX7 grinding machines. The round mouth is aligned with the angle of the grinding wheel, and the flat mouth is aligned with the outer diameter of the grinding wheel. The two outer grinding wheels are lubricated by a rotary nozzle on the ring manifold.
Cluster jet nozzles for medical and aerospace applications
A medical device manufacturer using the ANCA TX7 has benefited greatly from cluster jet nozzles. They report that the grinding wheel angle remains intact for up to five times longer, reducing burrs and burns on tough stainless steel parts. The nozzles are positioned farther from the wheel, minimizing damage and making alignment easier. As a result, productivity increased by 40%.
In the grinding industry, an efficient cooling flow typically ranges between 1.5 to 2 GPM per spindle (5.5–7.5 L/min). For example, a 5HP shaft might require 7 to 10 GPM (26.5–38 L/min). In aerospace, where turbine blades are produced, nozzle aperture sizes have been increasing to prevent grinding burns. One manufacturer found that only five nozzles could be used effectively across 10 machines.
Each machine was equipped with eight 10mm open tubes to cool two grinding wheels on the same spindle. After replacing the original nozzles with five 4.5mm circular cluster jet nozzles, the dressing interval doubled, surface quality improved, grinding power dropped by 40%, flow rate decreased by 66%, and the burn issue was resolved. With these improvements, 10 machines could now operate efficiently within a central system.
The TX7 coolant splitter closes the slotted nozzle system with matching grinding wheel angle
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