Holding Long Overhangs: Turning Performance

When machining component features like deep pockets, long bores or intricate internal cuts, tooling setups with long overhangs are usually unavoidable. While essential for cutting hard-to-reach features, extended- length tools can also complicate achieving the high-quality results modern manufacturing demands.

A long tool overhang is classified by its length-to-diameter ratio. When a tool’s length exceeds its diameter by more than four times (4 × D), the tool will be more prone to vibrations and deflection that can negatively impact tool life, surface quality, tolerances and productivity.

Vibrations, often audible as harmonics and chatter, can oscillate the cutting edges and leave chatter marks in the component, potentially leading to scrap. Vibrations are also detrimental to the life of the tool, which can lead to frequent tool changes and added downtime. Meanwhile, deflection — a physical bending of the tool caused by cutting forces — can lead to deviations from the intended tool path, resulting in compromised part quality or even tool breakage.

These overhang challenges are especially acute in industries like aerospace or power generation, where shops may need to work with extremely long overhangs for large component features while also contending with strict tolerances and difficult materials like HRSAs. But an increasing demand for precision, efficiency and repeatability in nearly every industry makes it essential for shops of all types to find ways to minimize vibrations and secure their long-overhang processes.

Some shops resort to make-shift solutions, like attaching lead weights to soak up vibrations or even wrapping the workpiece or tool with a garden hose. Others, more commonly, will simply reduce their cutting parameters and sacrifice productivity. While these methods may work for occasional one-off jobs, they will fall short when high-volume production is required.

Some shops resort to makeshift solutions, like attaching lead weights to soak up vibrations or even wrapping the workpiece or tool with a garden hose. Others, more commonly, will simply reduce their cutting parameters and sacrifice productivity. While these methods may work for occasional oneoff jobs, they will fall short when high-volume production is required.

Fortunately, there is a better way to tackle long overhang challenges.

By leveraging advanced toolholder technologies and strategies, shops can safely and efficiently meet the demands of machining long overhangs while achieving greater precision, repeatability and productivity at scale.

1. Minimize bad vibrations with dampened toolholders.

When it comes to tackling the excessive vibrations from long-overhang machining, anti-vibration tool adaptors can be a game changer for improving productivity. These specialized toolholders are designed with an integrated dampening device inside the tool body to minimize vibrations and increase cutting parameters.

With a dampened solution, shops can achieve a more secure and stable process to reliably meet close tolerances and attain a better surface finish. The stability also allows for much higher metal removal rates. In some cases, shops can reach cutting speeds two to three times faster than a traditional setup for long-overhang applications, dramatically improving cycle times and throughput.

Additionally, by reducing vibration-induced wear, dampened toolholders can extend tool life, lowering costs of tooling and reducing downtime related to tool changes. Although dampened toolholders may come with a higher upfront cost, their ability to improve cycle times, reduce scrap and ultimately lower costs per component make them a worthwhile investment for shops aiming to stay competitive.

The application range for dampened toolholders is also expanding, as tool providers like Sandvik Coromant continuously introduce more options for turning, milling and boring operations in a broader range of sizes. The technology is also improving. Advances in automated manufacturing have also allowed the latest generation of dampened toolholders to achieve more precise and predictable frequency areas to more effectively counter vibrations. These innovations make it easier than ever for shops to adopt dampening technology to improve the efficiency and profitability of their operations.