"Load" refers to the resistance an angle grinder encounters during operation; variations in load directly affect the motor's rotational speed, current draw, and output torque.
No-Load: When the angle grinder is not in contact with a workpiece, it operates at its maximum speed with minimal current draw. This corresponds to the "no-load speed" specified on the tool's nameplate-a figure typically much higher than the actual operating speed.
Rated Load: This is the load applied when the angle grinder operates continuously at its rated input power. At this stage, the motor reaches thermal equilibrium, with its temperature rise approaching the allowable limit. The corresponding speed is the "rated speed," which is generally lower than the no-load speed. For instance, one angle grinder might have a no-load speed of 9600 RPM and maintain that same speed under rated load, indicating a design capable of sustaining high speeds even when loaded. In contrast, a 230mm angle grinder might have a no-load speed of 6600 RPM, which drops to 4600 RPM under rated load-a trade-off that results in a significant increase in torque (up to 17 N·m).
Overload: When the load exceeds the rated value, the rotational speed drops further, current draw continues to rise, and the motor temperature increases rapidly. Prolonged overloading will shorten the motor's lifespan or even cause it to burn out.
Stall: This occurs when the grinding or cutting disc becomes completely jammed, bringing the rotational speed to zero. At this point, the current reaches its maximum (potentially several times the rated current) and torque is at its peak. However, since no mechanical work is being performed, all electrical energy is converted into heat; this can burn out the motor or create a hazardous situation within just a few seconds.
