A new spin on turning

Hear from the engineer behind Sandvik Coromant’s new Y-axis turning.

The famous quote “genius is 1% inspiration and 99% perspiration” is often credited to inventor Thomas Edison. Actually, many claim we should be thanking author Kate Sanborn for the wise words. Regardless of their author, the sentiment resonates with many inventors — innovation is rarely a lightbulb moment. Per-Anders Stjernstedt, Senior Engineer at metal cutting expert Sandvik Coromant, understands all-toowell that innovation is a labour of love. In this article, he explains the latest innovation in turning from Sandvik Coromant.

Like any inventor, Sandvik Coromant began with a challenge to solve. How can tooling overcome delays, reduce downtime and support faster production?

Software company Senseye’s True Cost Of Downtime 2022 report reveals unplanned downtime costs manufacturers at least 50% more today than it did in the period 2019 to 2020. The same report states that unplanned downtime will cost Fortune Global 500 industrial companies almost A$2Tn in 2023, equating to 11% of their revenues. To reduce time wasted changing tools, improve process stability and improve tool wear, manufacturers needed the ability to machine several features with a single tool. And here lies the raison d’être for Y-axis turning. Let’s examine how it works.

Turning angles

First, it’s helpful to think about entering angles. Choosing the correct angle between the cutting edge and the feed direction is vital for a successful turning operation, as it influences chip formation, direction of cutting forces and cutting edge length in cut. An angle that’s higher than what’s required results in a weak cutting edge. One that’s too small might cause the tool to rub at high feed rates, ultimately leading to breakages.

In 2017, Sandvik Coromant developed PrimeTurning™, a turning concept that enables ‘all-directional turning’ for greater machining flexibility. Based on the tool entering the component at the chuck and removing material as it travels towards the end of the component, PrimeTurning™ allows for the application of a small entering angle, higher lead angle, and the possibility of machining with higher cutting parameters. Alone, PrimeTurning™ is an innovative feat for turning. But as well as the productivity gains made through chip control, the team also wanted to help manufacturers machine more complex and innovative shapes. PrimeTurning™ acted as one of several building blocks that led to the development of Y-axis turning.

Entering at the Y

So how does Y-axis turning work? As the name implies, the new method makes use of the Y-axis, and all three axes are used simultaneously when machining. The tool rotates around its own centre, the insert is placed for machining in the Y-Z plane and the milling spindle axis interpolates during turning. This way, intricate shapes can be machined with a single tool.

Y-axis turning offers numerous benefits. The possibility to machine several features with only one tool reduces cycle time. The fact that no tool changes are required also minimises the risk of ‘blend points’, or irregularities between adjacent machined surfaces. Main cutting forces are directed into the machine spindle, improving stability and reducing the risk for vibrations. To improve surface finish, wiper inserts are designed with a wiper edge that is situated where the straight edge meets the corner radius.

The method also helps keep chip thickness at a constant, whether turning with a constant cut depth or turning contours in the workpiece. Because the width of chips doesn’t change, risk of chip jamming is significantly decreased. Not only does this allow for more reliable machining operations, but knowing turning can take place without any mishaps could allow manufacturers to step away from their machines and have them run without supervision.

Crafting the future

Developing Y-axis turning was a labour of love. “When the team began, we had an idea that the market had never seen before. It took time to prove that our ambitions could be realised but, after a lot of internal testing, we’ve already seen a 51% reduction in cycle times using Y-axis turning over competing methods,” Stjernstedt revealed. To complement Y-axis turning, Sandvik Coromant has also developed a new CoroTurn® Prime variant suitable for shafts, flanges and components with undercuts and the CoroPlex® YT twin-tool, which is best used at an entering angle of between 60 to 90° for more productive machining. Reflecting on his career, Stjernstedt said: “My advice for anyone with a big idea — just begin. If you’ve spotted a challenge without a solution, you’re already halfway there. I’m lucky Sandvik Coromant gives me the freedom to experiment and learn as I work. Being an engineer doesn’t only require the technical knowledge to develop new products. You have to be a creative thinker, a problem solver and unafraid to challenge the status quo.” sandvik.coromant.com