Achieve closed-loop boring with Kennametal

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 Beyond? 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, includingAir Jordan 1