Shenzhen Winna Electronic Industrial Co., Ltd.

Types and Application Scenarios of Core Sensors for CNC Machines

Position and Displacement Sensors - Ensuring Machining Coordinate Accuracy

Application Scenarios: Real - time position monitoring of machine tool axes (X/Y/Z axes), tool holders, and worktables to achieve closed - loop control.

Typical Sensors:

Ruler Gratings:

Principle: Through the change of Moiré fringes of the grating pair (scale grating + indicator grating), the displacement is converted into an electrical signal, and the resolution can reach below 0.1μm.

Example: Installed beside the guide rail of the milling machine worktable, it can timely feedback the position of the tool relative to the workpiece and correct the feed error.

Encoders:

Principle: Rotary encoders (such as optical encoders) generate pulse signals through the scale of the code disk to calculate the motor speed and angular displacement; linear encoders directly measure linear displacement.

Example: An incremental encoder is installed at the end of the servo motor shaft, forming a closed - loop with the servo driver to control the positioning accuracy of the feed shaft (such as ±0.01mm).

Speed Sensors - Optimizing Feed and Spindle Control

Application Scenarios: Spindle speed adjustment, smooth control of feed shaft speed, to avoid impact and vibration during high - speed machining.

Typical Sensors:

Hall Speed Sensors:

Principle: Utilize the Hall effect to detect the magnetic field change of the motor rotor and output an electrical signal whose frequency is proportional to the speed.

Example: A Hall sensor is installed beside the spindle motor of a lathe to monitor the speed in real - time and feedback it to the CNC system, ensuring a stable cutting speed (such as constant linear speed control during thread turning).

Encoders (used concurrently): Calculate the speed through the number of pulses within a unit time. For example, a 1000 - line encoder with a 10 - times frequency - multiplying circuit can achieve a speed resolution of 0.1rpm.

Force and Torque Sensors - Monitoring Cutting Load and Equipment Safety

Application Scenarios: Cutting force monitoring, tool wear warning, overload protection to prevent damage to machine tool components.

Typical Sensors:

Strain - type Force Sensors:

Principle: When the elastic body is stressed, it deforms, and the resistance value of the pasted strain gauge changes. It is converted into a voltage signal through a bridge circuit.

Example: A force sensor is integrated at the tool shank of a machining center. When the cutting force exceeds the threshold (such as tool breakage), the system automatically shuts down and alarms.

Torque Sensors:

Principle: Magneto - elastic or strain - type torque sensors are installed on the spindle drive chain to monitor the change of cutting torque, and judge the hardness fluctuation of the workpiece material or tool wear (such as a sudden increase in torque during aluminum alloy milling, indicating tool dulling).

Temperature Sensors - Preventing Thermal Deformation and Equipment Overheating

Application Scenarios: Temperature monitoring of spindle bearings, servo motors, cutting fluid, and guide rail lubrication systems to reduce thermal errors.

Typical Sensors:

Thermocouples:

Principle: Two different metal conductors are welded to form a thermocouple, and a temperature difference generates a thermoelectric potential (such as the temperature measurement range of a K - type thermocouple is - 200~1300℃).

Example: A thermocouple is embedded in the spindle box. When the bearing temperature exceeds 70℃, the cooling system is activated to avoid a decline in machining accuracy caused by spindle thermal expansion (such as the thermal deformation error of a precision grinder can be controlled within 5μm).

Infrared Temperature Sensors: Non - contact measurement of tool temperature, suitable for high - speed cutting scenarios (such as real - time monitoring of the spot temperature during laser processing).

Liquid - level and Flow Sensors - Ensuring Lubrication and Cooling Systems

Application Scenarios: Cutting fluid liquid - level monitoring, lubricating oil circuit flow detection to prevent dry running of equipment.

Typical Sensors:

Float - type Liquid - level Switches: Installed in the cutting fluid tank, it triggers an alarm when the liquid level is below the threshold to avoid dry cutting of tools (such as drill bit burnout due to insufficient cutting fluid during deep - hole drilling).

Electromagnetic Flowmeters: Monitor the water flow rate of the spindle cooling system to ensure heat dissipation efficiency (such as high - speed spindles require a water flow rate of ≥5L/min).

Vision Sensors - Intelligent Machining and Detection

Application Scenarios: Workpiece positioning, dimension detection, visual recognition of tool wear, suitable for flexible manufacturing.

Typical Solutions:

Industrial Camera + Image Processing System:

Principle: Use a CCD/CMOS camera to collect workpiece images, and algorithms analyze features such as edges and apertures to automatically correct machining coordinates (such as visual centering before stamping automotive body panels).

Example: A vision sensor is installed on a five - axis machining center. Before machining complex - surface workpieces (such as aero - engine blades), a three - dimensional scan is performed to generate a compensation program.