Turning is a mature machining process that has seemingly been around forever. However, those thinking that their process is rock-solid – tweaking and fine-tuning parameters to maximise output and profitability – need to think again. What if there was a new way of turning that questions established and preconceived ideas about this age-old process? The time has arrived to join the new turning revolution and break through existing production barriers to revel in new-found productivity. By Håkan Ericksson, General Turning Product Manager, Sandvik Coromant.

Throughout its long history, turning in the conventional direction – namely starting at the end of the workpiece and working longitudinally towards the chuck – has prevailed. Although this technique has proved successful, as the process has matured, ongoing advances in productivity and profitability have been increasingly difficult to achieve. Many are bound by the limitations of traditional turning. For instance, while experienced operators are aware that factors such as small entry angles permit increased feeds, they are restricted to around 90 degrees in conventional turning in order to reach the shoulder and avoid the long, curved chips that small entering angles characteristically provide.

In recent years, the advent of globalisation has led to a trading environment for machined parts that is becoming increasingly challenging. Manufacturers need to reduce their costs in order to compete. Production engineers are under pressure to increase cutting parameters and/or reduce tool set-ups, but find that turning is slowing them down. In many cases it has become a bottleneck operation.

Turning in a new direction

Machine shops around the world have only known one way of turning – and that approach has been around for decades, arguably spanning back not just one but two generations. But what if there was something that could deliver genuine competitive gain? To make such a leap, the very principles of conventional turning would have to be challenged.

This is the exact thinking applied by Sandvik Coromant in its development of a revolutionary new process called PrimeTurning. The company’s engineers began by investigating the potential for longitudinal turning to start at the chuck end and cut material ‘backwards’ as the tool traverses towards the end of the component. Although some machine shops have already tried such a method, the problem has always been chip control.

In PrimeTurning, Sandvik Coromant has developed a solution that aims not only to overcome the chip control issue, but to provide multiple additional benefits. For instance, it allows a small entering angle to be applied, which in turn provides considerable productivity gains. In fact, the potential exists to effectively double feed rates and increase speed in comparison with conventional turning. This is because small entering angles or higher lead angles create thinner, wider chips that spread the load and heat away from the nose radius, resulting in increased cutting data and/or tool life. Furthermore, as cutting is performed in the direction moving away from the shoulder, there is no danger of chip jamming, a common effect of conventional longitudinal turning.

Multi-directional benefits

If this sounds appealing, how about if the concept could be taken a step further, allowing for ‘all-directional’ turning? This would mean instead of having new inserts dedicated to ‘backwards’ turning, these tools could also perform conventional direction turning, as well as facing and profiling – one tool for all directions. PrimeTurning offers precisely that, representing a step-change for the future of turning and delivering advantages such as better machine utilisation (due to less set-up time), substantially longer tool life, fewer production stops, less tool changes and reduced tool inventory.

Although the process is relevant for the general turning arena, there are certain applications and machining environments where it will act as a significant gain provider. For instance, it will certainly suit the turning of short and compact components, but still be capable of machining long, slender parts (using a tailstock).

Turning enters a new era

With PrimeTurning, a combination of advanced strategies, tooling and programming codes provides perfect reach at the shoulder and allows for entry angles of 25 to 30 degrees. The result is significantly enhanced metal removal rates, excellent chip control and well-maintained tolerances. Depending on the current set-up, PrimeTurning can boost productivity to levels that are presently unattainable.

Any machine shop not maximising its productivity is not as competitive as it could be. If turning is a bottleneck operation, for example, the company is suffering a restriction on the number of components produced per run. Similarly, if machine utilisation is low, the potential to make more components in less time is being missed. PrimeTurning can help turn these limitations into opportunities and offer companies a quick return on investment.

Suitable for use on CNC turning centres and multi-tasking turn-mill machines, this fresh take on a mature process also offers the flexibility to turn in all directions for extraordinary productivity. A single insert is able to perform longitudinal turning (in both directions), facing and profiling. Temperature control is also improved because heat is generated in a wider and different area to conventional inserts. This means that heat can more easily move away from the cutting zone. The chip is also straight and easier to form.

Parts made from ISO P (steel), S (heat-resistant super alloys and titanium) and M (stainless steel) materials are set to benefit initially, with expansion to more materials in the near future. Additionally, the process will evolve into internal turning operations, providing an indication that this trailblazing development will continue to drive the turning revolution forwards.

First step-change in decades

PrimeTurning represents the first significant step-change in turning strategy for many decades. Of course, it would be remiss to state that this methodology is suitable for all applications – the existing Sandvik Coromant offer for turning will continue to provide optimised tools and tooling systems where PrimeTurning is not the most appropriate solution. For instance, for longitudinal and face turning in steel workpieces, CoroTurn 300 can offer high component quality, increased handling efficiency and long tool life. The tool integrates the latest advances in iLock, Inveio and high-precision coolant technology to take steel turning into the future using an insert with eight, 80-degree cutting edges. More edges also means fewer inserts, which in turn means reduced inventory.

So which type of manufacturer is likely to benefit the most from PrimeTurning? Any company performing conventional external turning in large batches – automotive original equipment manufacturers (OEMs) and tier one, two and three suppliers for example – as well as machine shops working in industries such as aerospace, where several set-ups and tool changes are often required. Essentially any company seeking a boost in productivity; companies that know their cutting data and its current limitations; and companies open to embracing new technologies and industry trends.

Just when machine shop managers, engineers and operators thought they had gleaned every last bit from their production, all-directional turning has arrived to deliver even greater recompenses. The tools, methodology and software provide significantly greater metal removal rates, excellent chip control and achievable tolerances. Ultimately, those wishing to increase cutting data and profits, should simply join the turning revolution.