CAD/CAM applications in high speed machining
High-speed machining is a processing technology characterized by high cutting speed, high feed rate and high machining quality. Its machining efficiency is several times higher than that of traditional cutting, or even ten times. After high-speed milling, the mold surface can be used with only a little polishing, which saves a lot of grinding and polishing time. High-speed machining is a system engineering that requires a combination of various aspects to form a complete high-speed cutting process, such as CNC machine tools, cutting tools, cooling lubricants and CAD/CAM systems, and even suitable workpiece shapes. Next page
High-speed machining needs to meet a wide range of application conditions at the same time, and once the parameters are wrong, it will lead to total failure. Some key parameters are easy to define, such as high-quality machines with powerful CNC systems and high-precision spindles, high-rigidity and precisely balanced machine clamping, and high-performance cutting tools. Some parameters are not easy to define, but often due to improper selection of these parameters, high-speed processing fails.
In addition to the above physical factors, the function and correct application of CAD/CAM software is also a major factor affecting high-speed machining. If the CNC program generated by the CAD/CAM system directly determines the processing conditions, this is of course very straightforward, but it is extremely difficult to determine what function from the CAD/CAM system to ensure high-quality high-speed machining.
Below we will analyze some important factors that affect the success or failure of high-speed processing when applying CAD/CAM software.
A, high-speed processing of CAD influence <br> <br> In general, the direct impact of high-speed machining of CAD is not easy to see. Many people think that the CAD model is only used to define the shape of the part. As for how to machine the designed part, it is the responsibility of the CAM user and the processing engineer. This is theoretically not wrong. In many cases, the CAD model does not really define the shape that needs to be machined. There are many reasons why CAD models are not suitable for high speed machining, which is briefly described below.
1. The influence of precision The high precision of machining, the small heat distribution range, and the high quality of the machined surface are all advantages of high speed machining. However, we have seen a strange phenomenon that the tolerance of the CAD model used to build the part is still better than the final machining tolerance of the part. Big, this is obviously unreasonable.
Data exchange is the root cause of the accuracy problem. Parts are usually designed from one CAD system and then converted to another CAD system for additional design and machining preparation. Each time a data transfer is performed, the geometry needs to be converted from one format to another, and some conversions involve approximating by the limit tolerance. Since these tolerances are cumulative, the tolerance of the part model must be set to 1/10 of the finishing tolerance when building the CAD part model.
Exchange formats, such as IGES, allow the system to convert between different geometric descriptions. Since the data transmission system can access the "master" data, it is best to have it perform all conversion work and implement it through the "Flavouring" transmission system IGES. Flavouring will tell the system what type of entity is most likely to be used in the IGES file. Some systems offer a pre-defined IGES Flavours menu that makes it more suitable for popular systems.
One way to reduce the number of problems in the conversion process is to use a direct interface. The direct interface allows the system to directly read files from another system. For example, Delcam's PowerMILL has direct interfaces to mainstream systems such as CATIA, Pro/ENGINEER, and UG.
Because the Stereo lithography (STL) triangle format is very simple, it has become a data exchange format that some companies like to use. Some CAM systems can directly process STL format files, including Delcam's PowerMILL. However, the triangles of this format file are produced tolerated and visible patches may appear on the machined surface. The default tolerances used by the mainstream design system STL format are typically very large (0.1mm) and are hidden behind multiple options and are easily overlooked. Therefore, finishing the machining tolerances of the STL file with a low tolerance can improve the accuracy of the machined surface.