Stable processes: reduced machining time

Question: “How long will it take to machine a part using your machine?” Answer: “I can quickly tell you exactly how long it will take by simulating the process in Vericut.” The dialogue is fictitious, but the scenario is realistic, not only because it is theoretically possible, but because Swiss machine tool specialist Starrag Group uses Vericut NC simulation software for this purpose. In addition to the verification and optimisation of NC programs, Vericut provides a precise indication of the run time of the optimised machining cycle.

Starrag Group develops, manufactures and sells precision machining centres with four, five and six axes for small to large workpieces, as well as gantry machining centres and vertical lathes for very large components, turning and grinding machines, associated software packages and special tools. Engineering and process optimisation solutions are also part of the company’s portfolio. Starrag solutions find use in aviation, power generation, transportation, precision engineering and medical technology. Headquartered in Rorschacherberg, Switzerland, the group of companies with more than 1500 employees has production sites in Switzerland, Germany, France, the UK and India, as well as sales and service locations in the most important customer countries.

Thomas Fink is head of application technology for machining centres at Starrag’s headquarters. Located on the edge of Lake Constance, the company has relied on Vericut as a solution for NC simulation for more than 30 years.

“The range of applications is very diverse,” says Fink. “We use Vericut in technology development for customer parts, conduct time and feasibility studies with it, and analyse customer programs in the event of problems or faulty machining.”

Machine-tool buyers naturally want to know what the machine is capable of in a specific application before they buy. So, as already outlined, Starrag builds a bridge to the future by means of NC simulation: the customer’s real NC program is checked for collisions on the virtual machine in Vericut, while the real process is digitised on the basis of the NC program, with the help of the machining centre’s digital twin.

Phillip Block, marketing manager of CGTech Deutschland, which distributes Vericut in the DACH region, classifies this process thematically.

“Vericut offers what Industry 4.0 is all about at its core: possibilities for high-level individualisation, potential for the intelligent production of equally intelligent products, and extensive integration of customers and partners into the company’s value creation processes,” he says.

Fink confirms it is exactly that kind of added value which can make all the difference these days: “As a full-range supplier of machine tools with technology support, it’s often necessary to know the machining times for customer parts as early as the quotation process, in addition to selecting the right machine. When implementing customer projects, the NC programs can be tested, analysed and optimised using Vericut before the real customer machine is even set up.”

The tools and clamping devices are also tested and optimised, which makes it possible to ensure – at a very early stage – that the process will run without collisions, travel violations or damage to the part. In this way, the safety factor as a mere snapshot of the present becomes a tangibly reliable expectation in the future.

Fink is not surprised “that most of our customers use Vericut for machine simulation”, and benefit directly from it. “Since our customers receive a digital twin of their purchased machine from us for pre-acceptance, they can check and optimise their processes even before final acceptance of the machine.”

Starrag as a machine manufacturer thinks in terms of product life cycles, so the use of Vericut even in the case of service is not surprising.

Fink states: “If problems occur during machining after the machine has been delivered to the customer, we are often provided with an NC program or a section of it. Thanks to Vericut, it is then possible to analyse this with very little effort, detect any errors or suggest optimisations.”

Of course, Starrag Group also uses Vericut classically in the simulation, verification and analysis of the NC programs with which Starrag Group manufactures parts for its own machines. Vericut, currently available in version 9.1.2, simulates the original NC code after the post-processor has run and detects programming mistakes such as rapid traverse errors or contour violations before real production. The software is sold in a modular format, so companies purchase only the capabilities they need. At Starrag, this naturally includes feeding Vericut with data from a central single source of truth.

“Due to close co-operation with various customers, Starrag uses several CAM systems,” says Fink. “For central management, a tool database is used that offers interfaces to all systems. The interfaces of the CAM systems to Vericut are also used.”

As one of the software’s early adopters, Starrag Group also uses Verticut Force, a physics-based module that analyses and optimises cutting conditions throughout NC program operation. The module delivers the most effective NC program for the given material, cutting tool and machining conditions.

Dirk Weiß, CGTech’s sales manager for Switzerland, among others, compares the Force application to conventional simulation: “Force is not about the milling strategies of existing programs; it also does not change tool paths. Material removal remains constant by adjusting the feed rate, and sub-dividing tool-path motions as needed to maintain consistent machining conditions for each tool. Everything is controlled by the feed rate: the geometries are not changed in the process.”

The result is significant time savings and improved cutting tool and machine life.

At Starrag, Vericut Force is used to optimise customer projects, design machine components and analyse NC programs in the event of tool breakage.

Fink says: “Tool breakages must be avoided, especially in demanding machining operations. The same applies to thin-walled parts, where avoiding deformation of the part due to excessive cutting forces is key.”

This sums up Vericut Force’s analytical potential to a tee: unsafe cutting conditions, excessive forces, metal removal rates, power, torque and tool deflections are graphically displayed during visual analysis of the NC program.

Lastly, Vericut Force pays off in optimising machining times so that customers have another competitive advantage with their Starrag machining centres.

Fink illustrates this with the example of a demo part for a stator segment: “The tool design, fixture design and CAM programming were completely checked in Vericut and optimised in Vericut Force. As a result, no time was wasted on prove-outs at the machine – the first part has already met the desired requirements in terms of surface and geometric quality. And all this with a 20% reduction in machining time.”

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