What is the purpose of a 'torque limiter' on a CNC machine spindle, and how does it protect the machine?

The purpose of a 'torque limiter' on a CNC machine spindle is to protect the spindle and other machine components from damage caused by excessive torque. A torque limiter is a mechanical or electronic device that limits the amount of torque that can be transmitted through the spindle. Excessive torque can occur due to a variety of reasons, such as tool breakage, a collision between the tool and the workpiece, or incorrect cutting parameters. When the torque exceeds the set limit, the torque limiter will disengage the spindle drive, preventing further torque from being transmitted. This protects the spindle bearings, gears, and motor from damage. Mechanical torque limiters typically use a slipping clutch mechanism that allows the spindle to slip when the torque exceeds the set limit. The clutch can be reset manually after the overload condition has been resolved. Electronic torque limiters use sensors to monitor the spindle torque and shut down the spindle drive when the torque exceeds the set limit. Electronic torque limiters can often be programmed with different torque limits for different operations. Without a torque limiter, a sudden increase in torque could cause catastrophic damage to the spindle, requiring costly repairs and potentially causing significant downtime. The torque limiter acts as a safety device, preventing such damage by limiting the amount of force that can be transmitted through the spindle.