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Drills with helical cooling ducts, bringing the coolant up to the tip of the tool, are quite common, even in small dimensions. However, when machining tough materials with poor heat conductivity, round coolant ducts might not supply sufficient coolant to the drill tip, even with high pressure. The issue is amplified when machining stainless steels and heat resistant alloys.

With CrazyDrill Cool SST-Inox (available in diameters from 0.039" to 0.236"), a single step is sufficient to drill up to 10 × D, without pecking. The company says this performance is possible because of a geometry with a chipbreaking effect and a flute profile that facilitates the flushing out of microchips. But, according to the company, more significant is the coolant concept: two helical coolant ducts to the drill tip guarantee constant cooling during the entire drilling operation. The “drop-shaped” cross section of the ducts provides four times more coolant flow compared with circular channels, the company says. Avoiding overheating of the cutting edges from the start of the operation allows longer tool life, even at higher speeds and feeds.