Sunday, May 3, 2009

CNC simulator boosts machine productivity with combined collision detection and workpiece simulation

Today, the CNC controls vendor NUM launches a 3D simulation package that combines workpiece simulation with collision monitoring and other powerful features. The computer-aided engineering software allows machine builders to offer new generations of optimisation tools with their machines - to help users to maximise manufacturing throughput and productivity. Designated True 3D, the software tool is a general-purpose version of NUM’s well-known 3D simulator for multi-axis grinding applications.

NUM’s True 3D is one of the first commercial CNC software simulation tools to combine both workpiece simulation and collision monitoring facilities. It allows machinery users to virtually prototype and optimise the entire machine production process, to yield significant gains including improved machine productivity, reduced tool wear, and faster project completion.

The massive increase in PC processor performance in recent years has enabled not only simple machine tools such as milling machines and lathes to be simulated in high-resolution, but also more complex applications such as multi-axis CNC machine tools and tool grinding machines. The simulator visualises the tools, the machine’s kinematic properties and the workpiece blank as 3D volumes. Material volume is removed from the workpiece as the tool moves along the machining track according to the CNC program, while the same volume is continuously subtracted from the workpiece blank. Due to the extremely complex interpolated engagements that can take place between the tool and the workpiece - three linear and two rotating axes are normally in motion in five-axis CNC machines for example - highly precise means of calculation are required.

The 3D simulation calculates the entire process chain of a machine tool, from the ISO standard CNC program and its CNC processing, to the machining process. Consequently, collisions are also detected, avoiding costly damage to the machine. The collision monitor will detect clashes between tool and workpiece, as well as with machine elements such as motor housings and sensors.

The simulator includes an abrasion analysis module that calculates the material removal rate in mm3/s at every point of the machining cycle, as well as the specific material removal rate on the tool surface in mm3/second/mm.

A colour animation of the specific removal rate on the tool surface gives the programmer an at-a-glance visualisation of whether the machine is using the best cutting feed - with rates up to the tool’s maximum being shown as percentage gradations. This helps users to achieve the optimum manufacturing time with minimal tool wear.

One further useful mode of operation is also possible with NUM’s 3D simulator. When the process is trialled on the real-world machine, the virtual 3D animation can be made to run in synchronisation with the real-time axis values of the CNC system. This allows the programmer and users to follow the machining process - in great detail and from any viewing angle. This function can be especially useful if, due to the use of coolant, it is not possible to see exactly what is happening in the working space of the real machine.

The basic 3D model of the machine required to support the simulation of the machining cycle can usually be imported or created for a couple of man-days of effort.

The new software tool supports NUM’s focus on supporting small to medium-sized OEMs, and its target machine tool markets which include tool grinding, gear manufacturing, woodworking, high-speed cutting, and transfer and special-purpose machinery. The software complements a comprehensive range of CNC building blocks for machine builders. These include advanced CNC kernels, industrial PC front ends with soft-PLC functionality, MMI panels, I/O modules, drives, and a broad choice of servo and spindle motors. NUM’s control over the complete motion axis chain secures an unmatched performance with regards to speed and accuracy where it matters most: at the direct mechanical interface to the machine.

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