Ceratizit and Open Mind unleash the benefits of trochoidal turning

Doosan Precision Engineering 210802020
Doosan Precision Engineering 210802020

While trochoidal milling has been used successfully for many years, the same unfortunately cannot be said about trochoidal turning which has been held back predominantly through the lack of suitable CAM software. Until now that is. PES reports. 

While trochoidal milling has been used successfully for many years, the same unfortunately cannot be said about trochoidal turning which has been held back predominantly through the lack of suitable CAM software. Until now that is. PES reports.

Trochoidal milling and turning provide several distinct benefits such as greatly reduced cycle times and increased tool life. Trochoidal milling makes use of the latest CAM software to generate shorter toolpaths that that give consistent chip thickness, and the low angle of engagement reduces cutter vibrations to enhance tool life.

Similarly, trochoidal turning has reinvented cutter paths and making use of circular and radius inserts allows the tool to move in multiple directions as opposed to more conventional turning insert shapes.

This generates a more fluid cutting motion. This combination of CAM system and tooling technology can deliver cycle time savings of 50 - 70% dependant on application. As with milling, the program creates a softer entry and exit point for the tool and this combined with shorter toolpaths enhances chip control, making the process ideal for difficult to machine materials.

The tables are turned


Business owners are, quite rightly, demanding optimum performance from their machines and, of course, their cutting tools.

The key elements of this are longer tool lives, shorter machining times, and greater process security, all of which help to deliver greater efficiency and, undoubtedly, a competitive advantage.

These factors are of greater importance when machining difficult to machine metals and ductile materials where often indexable inserts used in conventional turning soon reach their maximum operating potential. It is here that Ceratizit Group has been working alongside CAM developer Open Mind to develop trochoidal turning.

While the trochoidal milling process has been with us for many years thanks to the development of high performance machining centres and CAM systems, turning has been somewhat left behind. The ability to use this dynamic machining process on turning centres has been held back by the lack of suitable CAM software – until now.

With Open Mind expanding its HyperMILL and MAXX CAM software it is now possible to apply well-proven trochoidal concepts to the rough turning of components, with typical application areas including turning along with radial and axial grooving.

For any new machining development to gain traction it has to bring significant advantages over current methods and here trochoidal turning delivers on several fronts. Key areas are shorter cycle times, optimised connection paths, more fluid machine movements, extended tool life and increased process security.

The shorter cycle times result from the greater efficiency of tool movement (connection paths) and the more fluid, thereby more efficient machine axis movements. In effect, thanks to the CAM system trochoidal turning generates completely new toolpaths, enabled by use of Ceratizit’s full radius (RCMT/RCGT) indexable inserts or the GX style grooving inserts with Ceratizit’s M3 chip breaker.

Due to these insert shapes tool movement is no longer restricted, and fluid toolpaths can be created and elevated cutting data can be applied, while overcoming challenges found using conventional turning processes. The result are cycle times that can be reduced by 50% in rough turning applications and by as much as 70% for grooving.

A further advantage of the fluid movements that can be applied with trochoidal turning is the softer entry and exit achieved, which leads to improved process security and tool life. In conventional turning, especially when machining ductile or difficult to machine materials, these entry and exit points of the toolpath can create sudden loads that have a negative impact on tool life.

Gently does it


The combination of Ceratizit’s insert technology and the Open Mind CAM system allows for a much gentler tool entry and exit of the component. The innovative plunging action of the insert into the material protects the tool and leads to a significantly longer tool life and less wear, greatly reducing tooling costs while improving the efficiency of the turning process.

These gentler tool paths can be applied to all material groups, but they bring particular benefits when machining materials that often prove difficult to machine efficiently using conventional processes. For example, materials such as stainless and heat-resistant steels, as well as titanium and nickel-based alloys, often represent a particularly difficult challenge for tools.

Ceratizit’s GX-style inserts with the M3 chipbreaker are ideal for trochoidal turning

Due to their abrasive nature and the impact that these materials have on the tool’s cutting edge during the machine process they subject it to especially high loads, resulting in significant wear and early burning out of the cutting edge. Similarly, ductile materials, frequently presented as forged parts, are difficult to machine due to their soft and tough nature.

As a result they can present issues due to the long chipping characteristics of the material causing wrap around issues with the toolholder. The combination of Ceratizit’s chipbreaker technology and trochoidal turning with hyperMILL MAXX Machining means that shorter toolpaths can be generated, eliminating longer chips and enhancing process security.

Trochoidal turning can be applied to virtually any CNC lathe, including those with lower power where the gentler toolpaths have less demand on machine performance. The only investment required, where not already in place, is the Open Mind hyperMILL MAXX CAM software and the optimum tooling system from Ceratizit.

Customer experience: Doosan Precision Engineering embraces trochoidal turning and reaps the benefits


Nottingham-based Doosan Precision Engineering specialises in multi-axis turning and milling with up to 9-axis capability when it comes to its turning centre capability. This forward thinking company prides itself on its one-hit machining capability combined with lights-out operation in order to meet the demands of its expanding customer base.

It was this drive for unmanned machining that brought trochoidal turning to the attention of owner David Booth, as one particular family of components – motorcycle suspension parts machined from 7075 aluminium bar was causing problems due to swarf control issues.

“Under certain machining operations, particularly grooving, this material produces long stringy swarf which meant that we had to stop the cycle regularly to clear tools, eliminating the possibility of running through the night unmanned,” says Mr Booth. “Speaking to Ceratizit and Open Mind, trochoidal turning seemed to provide an answer to the problem, so we made the investment in the HyperMILL MAXX CAM software.”

With the technical support provided by Ceratizit, Doosan Precision Engineering saw immediate improvements, with the chip breaking issue resolved by the insert geometry and shorter toolpaths generated by the CAM software. An added bonus was that the program to machine the parts took less than five minutes to produce. Simple adjustments to the program were all that were required in order to machine the full family of parts.

With the entire family of parts coming from the same 50mm diameter bar stock it is now possible to run lights-out. In addition, machining efficiency has increased significantly with a single 6mm diameter button insert from Ceratizit completing all of the turning operations.

Cycle times are reduced thanks to increased cutting data, with typical feed rates of 0.75mm/revolution at 1.75mm radial depth of cut, with the machine spindle always running in excess of 5,500rpm.

“Cycle times for trochoidal turning are like the difference between night and day compared to conventional turning,” Mr Booth affirms. “We are now completing the turning operations in between 35 to 40 seconds, compared to three to four minutes previously.

“This improved efficiency has helped us to win more work from this customer with batch sizes increasing significantly and work coming back from the Far East. To achieve these gains our only investment was in a single button style insert and toolholder from Ceratizit and the Open Mind HyperMILL MAXX CAM software.

“Of course there was a learning curve as I had previously been using other software packages, but once I got my head around the differences and the ability to download insert and toolholder CAD files directly from Ceratizit, the whole process became straightforward.”

Ceratizit UK & Ireland www.ceratizit.com

Open Mind www.openmind-tech.com

Doosan Precision Engineering www.doosanprecision.co.uk

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