Smooth boring can be a challenge for many machinists. More accurate than cutting, boring is an internal turning operation used to make holes bigger. After a rough-cut hole is made, the hole is widened with more precise measurements. Through the act of careful chip removal, the sides are made to be smoother than a simpler drilled hole.

Some of the common issues machinists deal with when working with smooth boring are chatter and chip breaking, especially if they’re trying to bore a deeper hole. To create a deeper hole, a larger overhang (the unsupported distance between where the cut occurs and where the boring bar is clamped) is needed. A larger overhang, however, increases the likelihood of excessive deflection and vibration.

Never Boring: About Sanvik Coromant's CoroBore

Sandvik Coromant’s CoroBore rough-boring tools are designed to help machine shops address problems with vibration, chip-breaking and process security. These tools are available in single, twin and triple edge. They are crafted to offer high performance in ISO P (steel), M (stainless steel), N (nonferrous),  K Cast iron), ISO H (hardened steel) and S (heat-resistant super alloy and titanium).

The CoroBore BR20, for example, is a twin-edge rough-boring concept that uses a differential pitch to reduce vibration and enable use at longer overhangs and larger depths of cut. This tool also features built-in step-boring functionality without any need for an extra shim. High-precision coolant nozzles that handle coolant pressure ranging up to 70 bar (1,015 psi) to improve chip removal. The BR20 is also available with vibration-dampening technology for long overhang or where additional stability is needed.

The BR10 and back boring

In the single edge category, the BR10 is designed especially for back boring. It has a back-boring slide and cover that is good for machining a hole with a shoulder that cannot be reached from the opposite direction. It can also be used to optimize concentricity of a hole with a shoulder since the entire hole is machined from only one position. Equipped with three edges, the BR30 has a short, rigid design and differential pitch for high productivity and low vibration.

Formulas for Boring

Sandvik Coromant has provided the following formulas for precise boring speeds, including cutting speed, spindle speed, machining time, metal removal rate, penetration rate, feed per revolution, net power and torque.

Boring tools, including the Sandvik Coromant CoroBore line, can easily be purchased on the BlackHawk Industrial web site. For any questions about boring tools or any other products sold by BlackHawk, give us a call.

We’re happy to help. Our mission is to provide innovative, value-added services and products that reduce our customer’s total cost. Feel free to contact us for more information. Toll Free: 855-610-1001.

BlackHawk Industrial

1501 SW Expressway Drive

Broken Arrow, Oklahoma 74012

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Toll Free: 855-610-1001