What causes interference in CNC machine tools?

Numerical control machine tools use high-frequency discharge to corrode workpieces, which interferes with intelligent error correction controllers. Interference generally refers to some uncertain and harmful electrical transient phenomena that occur during signal input, transmission, and output processes that are unrelated to the signal. These transient phenomena can cause changes in data transmission in the numerical control system, increase errors, and result in abnormal conditions in local devices or the entire system, leading to malfunctions.

The main reasons for interference in CNC machine tools are as follows:

1. Power interference: Due to the wide coverage of the power grid, multiple devices share the same power grid, especially internal changes such as power switch operations, lightning surges, large-scale power equipment start stop, harmonics caused by AC/DC transmission devices, and transient effects of power grid short circuits. They are all transmitted to the primary side of the power supply through transmission lines, causing temporary voltage changes and resulting in voltage fluctuations in the power grid. In addition, power lines also generate noise and fast transient pulse trains during transmission, polluting the power grid.

2. Radiation interference: Electromagnetic or electric fields are ubiquitous in nature. In addition to electric fields, working CNC machine tools are also affected by magnetic fields. During the operation of machine tools, electromagnetic interference is inevitable due to the harsh working environment.

3. Interference between digital and analog signals: During the operation of machine tools, the entire equipment involves many components, including AC380V and AC220V AC signals, as well as various low-voltage DC signals of DV24V and DC5KV. During the wiring process, cables used to transmit signals may sometimes cause misoperation due to interference from analog signal output devices, servo drives, or frequency converters, affecting the normal operation of the equipment; The frequency used for transmitting I/O input/output signals is affected by clock frequency and harmonic interference.

In addition, due to improper wiring, digital signal lines and analog signal lines are inevitably affected by external interference signals, and various signal lines can also interfere with each other through inter line coupling.

Anti interference measures:

Shielding is currently an effective approach adopted. Shielding technology cuts off the transmission path of radiated electromagnetic noise. Frequently using metal or magnetic materials to surround the area to be shielded, isolating the fields inside and outside the shield, cutting off electromagnetic radiation signals, and protecting the shielded object from interference. Shielding is divided into electric field shielding, magnetic field shielding, and electromagnetic shielding.

In practical applications, when CNC machine tools are disturbed, the metal casing of high-voltage equipment in the system (servo drives, frequency converters, drivers, switching power supplies, motors, etc.) The casing of sensitive equipment such as reliable grounding, active shielding, and intelligent error correction devices should be reliable.