Fine-Boring System achieves closed-loop operation.

Press Release Summary:

Allowing users to dial in tolerances while tool is mounted in machine tool, Romicron® systems produce high-accuracy holes at high RPMs. Users can produce finish bores with tolerances of few microns in diameter and bore-to-bore variations of few tenths of one micron. Using cartridges or boring bars, every tool can be adjusted in diameter via dial ring in 2 micron increments to achieve close tolerances. Romicron AVS tooling covers 0.984–3.11 in. dia and can run in spindles up to 20,000 rpm.

Original Press Release:

Achieve Closed-Loop Boring with New and Improved Romicron® Fine-Boring System from Kennametal

Produce high-accuracy holes at high RPMs with no auxiliary setting equipment or previous operator fine boring experienceRomicron® fine-boring systems from Kennametal allow users to dial in extremely close tolerances while the tool is mounted in the machine tool, saving time and easing training.  They can produce finish bores with tolerances of a few microns in diameter (1 micron = 0.001 mm) and bore-to-bore variations of just a few tenths of a micron.

The need for delivering high-quality, tight-tolerance holes is growing significantly in many manufacturing segments, including aerospace, energy, transportation, and medical. Traditionally, this has meant dedicated jig boring or other fine-boring capital equipment requiring expensive setups, sister tooling, extensive operator training, and time-consuming test cuts.

Newly upgraded Romicron® precision fine boring tools from Kennametal can be used at existing machine tools and produce finished bores in automated production with tolerances of a few microns in diameter (1 micron = 0.001 mm or 0.000039 inches). Using cartridges or boring bars, every Romicron® tool can be adjusted in diameter with a dial ring in 2-micron increments to achieve extremely close tolerances. To provide instant adjustment feedback, Romicron has a clicking mechanism so machine operators not only see the adjustment at the scale, but also hear and feel it.

The new Romicron® AVS tooling covers the diameter range of 25 to 79 mm (0.984 to 3.11 inches) and can run in high-speed spindles up to 20,000 RPM. It accommodates standard ISO inserts including the latest Kennametal BeyondTM tooling, and can run with high-pressure coolant systems up to 120 bar for better chip evacuation and reduced temperatures at the cutting edge.

Basically, the Romicron® system consists of proprietary slide-gate mechanics that work similar to a transmission and translates an adjustment in a relationship of about 10:1. This means a small adjustment by the operator at the tool is converted into a still smaller change of diameter at the cut. The slide-gate valve mechanism is self-locking so no clamping screw is required. The spindle is decoupled from the cutting force and the entire mechanism has nearly no backlash. With such straightforward and robust engineering, almost no training or experience is necessary to use Romicron. The nearly backlash-free adjustment mechanism allows adjusting to larger or smaller diameters without rotating more than required compared to numerous back and forward movements with conventional compensating for backlash. Since adjustments with the Romicron system are easy and require no tools or additional measurement devices, adjustments can be made on the machine for higher uptime and process stability. The amount of saved time is amazing, some »clicks» are done in a few seconds, other systems require at least minutes for adjustment.

Furthermore, because the Romicron does not require a lock screw or additional tools, the adjustment process can be automated by a machine tool´s CNC, resulting in a closed-loop boring (CLB) system. With respective in-process measurement equipment, current hole dimension measurement data can be sent to a machine tool´s CNC after machining. The CNC calculates the number of adjustment increments  to bring the hole within tolerance. To achieve this adjustment the machine moves the Romicron tooling inside of the machine to a position. A retractable, spring-loaded locking pin is located and engages at respective CLB holes on the Romicron® tool´s adjustment ring. Based on the calculation, the spindle rotates the required amount of increment to adjust the Romicron tool and continues machining till the next planned measurement and adjustment cycle. Existing machines become capable of extremely close-tolerance hole finishing, increasing a shop´s capabilities and productivity.

Tips for Ultra-Fine Hole Finishing

Romicron boring systems can produce finish bores with tolerances of a few microns in diameter and bore-to-bore variations of just a few tenths of a micron under ideal machining conditions, including the following:

-Stock removal of the finishing cut should be regularly and evenly distributed concentrically, and stock removal should be kept within 0.010 in. (0.25 mm) or smaller.

-Feed should be at 0.006 in. (0.15 mm) or less per revolution depending on the material to machine and surface requirements.

-Tool tip radius should be properly checked prior to boring.

-A tolerance equivalent to ISO precision class IT6 can be achieved under normal conditions. At larger sizes IT5 might be able to be reached as well.

-Solid, secure workholding is key. Thin-walled workpieces, for example, are prone to distortion and must be clamped properly.

-Special shanks may be required if bore lengths exceed 2.5 x D.

-Exotic materials must be carefully examined to determine best machining methods.

Rules and recommendations are by nature general. For specific advice regarding ultra-high-accuracy boring, contact Kennametal or visit


Celebrating its 75th year as an industrial technology leader, Kennametal Inc. delivers productivity to customers seeking peak performance in demanding environments. The company provides innovative wear-resistant products, application engineering and services backed by advanced material science, serving customers in 60 countries across diverse sectors of aerospace, earthworks, energy, industrial production, transportation and infrastructure. With approximately 13,000 employees and nearly $3 billion in sales, the company realizes half of its revenue from outside North America, and 40% globally from innovations introduced in the past five years. Recognized among the »World´s Most Ethical Companies» (Ethisphere); »Outstanding Corporate Innovator» (Product Development Management Association); and "America's Safest Companies" (EHS Today) with a focus on 100% safety, Kennametal and its foundation invest in technical education, industrial technologies and material science to deliver the promise of progress and economic prosperity to people everywhere. For more information, visit the company´s website at

Kennametal Shared Services GmbH

Wehlauer Strasse 73

D-90766 Fuerth

Carsten Gromoll

Phone: +49 911 9735 557

Fax: +49 911 9735 551

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