This article was originally published by Andreas Groezinger for TRAK Machine Tools has been given permission from Siemens AG to present this content.

When is a machine tool most productive?

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That's an easy one: When it's producing chips!

All activities that stop the machine from producing chips should therefore be moved to CNC production planning if possible. However, this requires that the work environment, i.e. the machine and its CNC application, is simulated as closely as possible there: a case for the digital twin!

Tasks for the digital twin in production planning

Accurate quotation costing thanks to simulation

Before the first chip falls, the company operating the machine needs an order to come in. Most machine tool users do not produce the workpieces for their own products. They are generally CNC contract manufacturers for the automotive or aerospace industries, for example.

A recent quote from the managing director of a typical CNC contract manufacturing company: "Customer loyalty is decreasing all the time. I am constantly having to procure new orders and customers. With my profit margins, I can no longer afford to take up machine time in order to find out how long it will take me to complete a job!"

Programming and verification

In many companies, using the CNC in the machine as a programming station is still common practice. Modern CNCs allow you to program during cutting operations. But in practice production usually comes to a standstill. The programmer is simply too distracted when the machine is producing complex parts at the same time. Process safety is impaired wherever programming and production are taking place simultaneously at the machine. And, of course, the shop floor is not the most pleasant work environment for concentrated programming work.

Many production companies look for an offline programming station for this reason. And not only for creating CNC programs. In fact, software solutions are used to verify the CNC programs of CAM systems before they are transferred to the machine. With longer CNC runtimes, e.g. for freeform surfaces, this must surely be the right approach. If the CNC comes to a standstill after two hours due to a syntax error, production is anything but productive!

Program control and collision avoidance

The danger of the tool colliding with workholders, the blank or the machine itself is particularly an issue with complex machines, such as compact 5-axis machining centers. These bugs in CNC programs should be eliminated during CNC production planning if possible. If the machining spindle needs to be replaced or even realigned after a crash, the machine may not produce any chips for a number of days or even weeks. The trend is therefore to incorporate virtual machines in CNC programming stations.

The challenge of personnel fluctuation

And last but not least, many production companies also have to struggle with increasing personnel fluctuation. New personnel needs to receive instruction on working with the CNC application and the machine itself. Using the machine for this purpose is unproductive and also runs the risk of damaging the machine.

"I use simulation tools to find out whether my 5-axis milling center can even produce a particular part and, if so, how long the CNC program and consequently the production process will take. Only then can I come up with a quotation!"

Statement by a CNC contract manufacturer

Run MyVirtual Machine — for valid, meaningful production simulation

To exploit the machine tool as best possible for actual production and to move everything else into the virtual environment: This is a basic trend and paradigm shift in production facilities of all sizes – from the job shop through to the fully automated production line. Siemens has a software solution for this very task: Run MyVirtual Machine. It is available for the first time for the new high-end CNC SINUMERIK ONE.

Siemens does not only produce CNC equipment, it also operates machine tools – in its motor and gearbox factories, for example. The production managers and CNC production planning departments operating there are constantly required to demonstrate their productivity and competitiveness as internal CNC contract manufacturing companies. They were important input suppliers and pilot users for the new software.

Run MyVirtual Machine — more than a virtual SINUMERIK!

Runtime measurement at the PC for quotations and production planning

What does Run MyVirtual Machine have to offer in concrete terms?

First off, it is a virtual CNC whose behavior is identical to that of the real CNC in the machine. This must not be underestimated! A CNC is adapted to a particular machine based on several thousand items of machine data.

Many simulation suppliers fall down here, as the CNCs in their software solutions only simulate to a sufficiently accurate degree. The testing of CNC programs is only possible to a limited extent and the measurement of CNC runtimes is downright impossible.

The virtual SINUMERIK has a clear advantage here. CNC programs are tested with exactly the same CNC setup as in the machine. The CNC program runtime can be measured with an accuracy of over 90%.

Runtime measurements with Run MyVirtual Machine
Runtime measurements with Run MyVirtual Machine supply valuable information for quotation costing and production planning.
VIDEO: Runtime measurement with Run MyVirtual Machine on the PC

Identical operating and programming interface

Run MyVirtual Machine with SINUMERIK Operate also offers exactly the same CNC interface as on the machine. This means that the same programming tools, such as ShopMill workstep programming, are available – for example, for creating CNC programs during CNC production planning. An advantage not to be underestimated: The operating interface is exactly the same as in the real CNC. Adaptations, such as minor changes in component geometry, can therefore also be carried out quickly on the shop floor.

Identical operating and programming interface in Run MyVirtual Machine
Identical operating and programming interface in Run MyVirtual Machine/Operate, e.g. during workstep programming with ShopMill
VIDEO: ShopMill on the virtual machine. Immediate creation of small NC programs, fast program adaptations, effective and low-risk personnel qualification

Virtual view of the machine space

As well as the virtual CNC, Run MyVirtual Machine can come with the /3D option, which allows it to provide a virtual image of the machine space, tools and clamping devices:

  • The virtual image of the machine and the setup of the virtual CNC are provided by the machine tool manufacturer.
  • Tools and clamping devices can be managed by the machine users themselves.

All in all, this creates ideal conditions for CNC production planning.

Run MyVirtual Machine - 3D
Run MyVirtual Machine /3D provides a virtual image of the machine. Clamping and production of the workpiece can be verified in the simulation – from every conceivable viewing direction and with a zoom for the critical areas of the workpiece and the machine situation.
VIDEO: Preview of clamping situation and production in the machine space with Run MyVirtual Machine /3D

Program monitoring and collision avoidance

One of the main objectives is to prevent a machine crash. Run MyVirtual Machine /3D with its integrated collision detection is perfectly equipped to handle this eventuality. Collisions are displayed visually in the simulation and logged.

Collision with the workholder
Collisions occurring during execution of the NC program are highlighted in color by Run MyVirtual Machine /3D and logged. Here: Collision with the workholder.
VIDEO: Detecting collisions with Run MyVirtual Machine /3D. Damage to machine, tools and workpiece can be effectively prevented as a result.

Uniform interfaces and operation

The full operation of the CNC and the machines is visualized. Run MyVirtual Machine works without smoke or mirrors. Even process actions such as calculating zero offsets are performed to simulate real life on the shop floor. The instruction of new operating personnel or trainees can therefore take place in the virtual environment based on a safe and reliable process – CNC and machine training 4.0, so to speak!

Zero offset in JOG mode
Zero offset in JOG mode with Run MyVirtual Machine /3D
VIDEO: Setting the zero offset during simulation with Run MyVirtual Machine /3D

Run MyVirtual Machine is therefore an important software tool for preparing machine tool users to cope with the demands of the future.

The SINUMERIK ONE CNC is featured on the new production machines by TRAK: the VMCsi Series Vertical Machining Centers and the TC820si Turning Center.