Software provides a representation of a machining process based on CNC codes. Berenice Baker reports
Novel simulation software may help manufacturers design efficient new production processes using a machine’s own computer numerical control (CNC) system, its manufacturers have claimed.
NUM’s True 3D system combines workpiece simulation and collision avoidance with the aim of optimising the machine production process while reducing tool wear. Similar software emulates machine systems based on post-processor data and CAD files, but True 3D claims to be unique in the way it simulates machining based on the actual CNC codes.
True 3D requires a dedicated PC with a graphics card to run as a front end to the CNC system through the company’s NUMpass HMI (human-machine interface). The software can be run in one of two modes. Operators can optimise the machining and eliminate potential collisions before a new process is introduced on the target machine itself while the machine is undertaking its current job. Alternatively, it can be used in trace mode during an existing machining operation.
NUM vice-president and chief scientific officer, Jan Vestbjerg Koch, said: ‘Because we are a niche player in the high-end CNC market, we designed True 3D to be flexible so it handles different machine configurations and machine types, such as milling, turning, tool grinding, and combinations of these. It is fully integrated through the same HMI as the CNC system.’
True 3D takes as its input the kinematics for each machine and the properties of the materials it operates with. This enables machine simulation and collision prevention, and allows the amount of material being taken away at each stage and the associated load on the machine to be calculated. This information is then used to improve efficiency and does not waste any material.
‘Our customers, especially in the tool-grinding area, are using it to run through the simulation, then see if the load is too much in any one area. They can then make adjustments to the programme accordingly to get the optimum load all the way through. This reduces the cycle time for the machining and at the same time secures against an overload, which can deteriorate the finish of the tool,’ added Koch.
True 3D is based on NUM’s existing multi-axis grinding software that typically controls five interpolating axis machines and upwards. Koch claimed this gave the company a head start when developing True 3D as it was already able to handle many types of kinematics and interpolations before milling, turning and combination functions were added.
True 3D has the kinematics of the machine, the tooling and parts programmed into it. When it runs, it is not carrying out an emulation, it is directly simulating what the CNC will do on the machine, based on that machine’s parameters.
Another way of getting the input is to run it in trace mode, while the machining is under way to obtain direct feedback during machine operation to check for overloads, material wastage and whether the machine is being used optimally.
‘When you operate in trace mode as the CNC goes through the part program, based on the data it has, it simulates what is going on in the machine,’ said Koch. ‘We have a CNC system that by default is trying to minimise the error between the commanded position and the actual position at any time. We are simulating down to the shaft of the motor, and if the mechanics are good, you have a true representation of it.’
Operators can also make adaptations and corrections to the CNC functionality that will also be simulated in this operation. However, there are no direct sensors or cameras providing physical feedback.
‘In a perfect world with perfect mechanics, what you would see would be the piece you’re going to get out of the machine and that’s not the case if you’re looking just on post-processor data or CAD files,’ added Koch.
The software is currently being beta tested with some of NUM’s OEM customers who helped tailor the functionality during its development.
NUM’s initial target market is its customers operating five-axis NUM HSC (high-speed cutting) and NUMROTO tool production and cutting machines. But because it can handle a variety of operations, it could be adopted by OEMs looking to simulate one-off machinery.