What Is a Post Processor?
A Post Processor converts the cutting path generated by CAM into an NC program suitable for the configuration of the controller and machine tool.
In Latin, Post means “after” and Processor means “something that processes.” A Post Processor is a post-processor of the main processor.
Typically, company-specific NC machines and CAM systems have corresponding conversion libraries. A typical Post Processor is required for each control or NC machine tool. However, some post processors can register controller- or NC machine tool-specific specifications in parameter form and switch to the NC data corresponding to each machine with a simple operation.
Usage of Post Processor
3D-CAD data is becoming increasingly popular in the manufacturing field to facilitate product data linkage across departments and advance verification in the upstream process. However, in parts machining, multitasking machines are becoming more common in order to respond to diversifying production forms such as process integration and part shapes, and easy conversion to NC programs using 3D-CAM is required. A Post Processor is required to perform this conversion accurately.
Principle of Post Processor
Post Processor performs post-processing using dedicated post-processing applications suitable for various CAM systems, reverse processing the target NC data, and converting it to NC data for other machines by utilizing past NC data assets.
Post Processor supports input of any of the various APT sources, as well as CL data, and can be configured for each machine by setting the specifications of the NC machine tool and control unit.
Machining information such as machining time, machining start coordinates, machining end coordinates, and NC conversion results can be output. In general, the contents of Post Processors are not disclosed.
Types of Post Processors
Major machine tools for which Post Processors are used include 3-axis to 5-axis machining, NC lathes, punch-cut machines, wire-cut machines, laser-cut machines, and multi-tasking lathes.
Examples of controller manufacturers include Yamazaki Mazak, Ohm, Okuma, Fanuc, etc. Specific examples of CAM systems include AUTON, CATIA V4/V5, DELCAM, CIMATRON, Pro-E, I-DEAS, MasterCAM, SURFCAM Unigraphics, VX, WorkNC, etc.
How to Choose a Post Processor
Although a typical Post Processor can be used with the standard system installed at the time of shipment, there are cases where the standard system may not be sufficient for a given machining task. Customization of the Post Processor is necessary to accommodate the desired processing.
However, customizing the Post Processor requires advanced knowledge of the language and control panel, and is highly difficult. Care should be taken when customizing.
Post Processor Structure
General CAM software consists of two types of processors: a Main Processor, which calculates tool path data on a model coordinate system such as CAD, and a Post Processor, which converts CL data into an appropriate NC program.
The main CAM Post Processor converts CL data calculated on the model coordinate system to the machine coordinate system, considering the structure of the machine tool to be used and the specifications of the NC device. It then adds command codes such as feed rate, spindle speed, and macros, and can output appropriate NC data.
Commercially available CAM software clearly distinguishes between Main Processor and Post Processor. Post Processors had to be prepared for each combination of machine tool and CAM software owned by the user. Nowadays, there are general-purpose Post Processors that can be used for any combination of machine tool and CAM software, once the parameters are set.