POST PROCESSOR DEVELOPMENT
Post processor is a program that modifies toolpath contour and processing commands (e.g. spindle-on, lubricant coolant on, tool change, swarf extraction, etc.), generated in CAM system, into codes for certain CNC machine taking into account its kinematics. Application of post processor, developed for certain machine and its control system, allows to eliminate necessity in manual adjustment of NC program, accelerate item production and reduce the likelihood of processing issues.
It is also necessary to take into account that «machine – CNC system» combination shall be programmed in accordance with the options, selected by the client. This means that two identical «machine – CNC system» combinations may have totally different methods for programming of commands and functions. Thus, post processor, adjusted for one company, may not fit the requirements of another company by 100%. Even if post processor for specific «machine – CNC system» combinations is supplied with CAM system, it is unlikely that such post processor can generate NC program in strict compliance with machine and client requirements.
Correctly adjusted post processor allows using all capacities of your equipment, since post processor performs considerable amount of functions, for instance: encoding of linear motion consistently with impulse value; linear or circular interpolation of movements along circular arc, as well as encoding movements into impulses; calculation of movement dynamics, with tracing and reduction (if required) of coarse feed during fine movements («machine does not take run in time»); automatic generation of vector or correction function for tool radius into sentence; generating current sentence as per template, automatic enumeration of sentences with N-address; transforming runs, designated by processing engineer, into correct set of symbols with F-address and putting them into certain place of a sentence; determining NC program start and end, as well as sentence structure.
Ensuring perfect interaction of «CAM system – post processor – machine» sequence is one of the most important integration tasks, since maximum efficiency can be achieved only through optimum work of all elements of this sequence.
Post processor development stages are the same as for other software:
• Development, agreement and approval of terms of reference;
• Testing on virtual and real-life equipment;
• Documentation development;
• Post processor commissioning;
• Technical support and consulting.
Code debugging program is required for development of up-to-date post processor. Debugging program allows simultaneous real-time reviewing of the following data, while post processor is running the commands:
• Post processor source code;
• Toolpath data;
• Control software for CNC machine.
In addition, it is possible to monitor variable values and start post processor in different modes to locate errors in text.