The primary object of total air pressure detection: compressed air
In the field of CNC machine tools, when the system displays a prompt or the operator’s manual refers to “total air pressure monitoring,”In the vast majority of cases, it indeed refers to pressure testing of compressed air.The pneumatic system of a CNC machine is a critical component for its proper operation, with compressed air serving as the system’s primary power source. The main air-pressure monitoring point is typically located at the machine’s air-supply inlet, where it continuously verifies that the compressed-air pressure—whether from the external supply or the internal distribution network—meets the specified standards.
Why CNC Machine Tools Rely Heavily on Compressed Air
Compressed air plays an irreplaceable role in CNC machine tools, with its primary applications including:
- Spindle tool loosening and tightening, and tool-changing mechanism:When a machining center performs an automatic tool change, compressed air is used to actuate cylinders that loosen and clamp the tool. Insufficient air pressure can cause the tool to drop, resulting in a serious safety hazard.
- Workpiece Clamping and Positioning:Many pneumatic fixtures rely on compressed air to provide a stable clamping force, ensuring that workpieces do not shift during high-speed machining.
- Protection and Cleaning:Compressed air is commonly used for purging and cleaning the spindle taper bore, maintaining positive-pressure seals on guideway guards to prevent coolant and chips from entering, and blowing away chips in the machining area.
- Pneumatic component actuation:Such as the actuation of auxiliary functions like pneumatic door operators and pneumatic tool‑removal cylinders.
The important role of total atmospheric pressure monitoring
Because compressed air is involved in numerous critical operations, total air pressure monitoring has become an essential component of the machine tool’s safety interlock system.
1. Preventing Equipment Failures and Safety Accidents
When the compressed-air pressure supplied to the machine tool falls below the safety threshold, the pressure sensor or pressure switch immediately sends a signal to the CNC system. The system then triggers an alarm, pauses the machining program, and may even prevent the spindle from starting. This safeguard effectively prevents serious incidents such as tool drop and fixture loosening caused by insufficient air pressure.
2. Ensuring machining accuracy
The clamping force of a pneumatic fixture is directly proportional to the air pressure. Stable system air pressure ensures consistent clamping force, which is critical for maintaining part dimensional accuracy and surface quality. Pressure fluctuations can induce fretting in the workpiece, thereby degrading machining performance.
In addition to pressure, the quality of compressed air is equally critical.
Although overall air‑pressure monitoring primarily focuses on the “pressure” parameter, in practical applications, CNC machine tools also impose stringent requirements on the quality of compressed air. Raw compressed air contains moisture, oil, and particulate matter; these contaminants can cause pneumatic components to corrode, seals to degrade, and solenoid valves to seize. Consequently, prior to the main pressure‑monitoring point, it is customary to install an air dryer and precision filters to ensure that the compressed air supplied to the machine tool is dry and clean, thereby extending the service life of the pneumatic system.