The difference between NC and CNC(1)

Another situation similar to the current CNC is that those cars that are not the fastest often require fully-skilled drivers. In the past, only high-end CNCs could guarantee high machining accuracy while cutting at high speeds. Nowadays, the functions possessed by the medium and low-end CNCs are also possible to complete the work satisfactorily. Although the high-end CNC has the best performance currently available, there is also the possibility that the low-end CNC you are using has the same processing characteristics as the high-end CNC of similar products. In the past, the factor that limited the maximum feed rate of mold processing was CNC. Today it is the mechanical structure of the machine tool. When the machine tool is already at its performance limit, a better CNC will not increase the performance.

The inherent characteristics of CNC system

The following are some basic CNC characteristics in the current mold processing process:

1. Non-uniform rational B-spline (NURBS) interpolation of curves and surfaces

This technique uses interpolation along the curve instead of using a series of short straight lines to fit the curve. The application of this technology has become quite common. Many CAM software currently used in the mold industry provides an option to generate part programs in NURBS interpolation format. At the same time, the powerful CNC also provides five-axis interpolation functions and related features. These properties improve the quality of surface finishing, improve the smoothness of motor operation, increase the cutting speed, and make the part processing program smaller.

2. Smaller instruction unit

Most CNC systems transmit motion and positioning commands to the spindle of a machine tool with a unit not less than 1 micron. After making full use of the CPU processing power to improve this advantage, the smallest instruction unit of some CNC systems can even reach 1 nanometer (0.000001mm). After the command unit is reduced by 1000 times, higher machining accuracy can be obtained and the motor can run more smoothly. The smooth running of the motor allows some machine tools to run at higher accelerations without increasing the bed vibration.

3. Bell curve acceleration/deceleration

Also called S-curve acceleration/deceleration, or creep control. Compared with the linear acceleration method, this method allows the machine tool to obtain a better acceleration effect. Compared with other acceleration methods, it also includes straight-line method and exponential method. The bell-shaped curve method can obtain smaller positioning error.