Lag characteristic
The drag is the backward offset of the cutting front at the bottom edge of the workpiece compared to the top entry point. This happens due to speed-dependent friction losses in the deeper material.
Physicochemical Mechanism of Action
Trailing occurs when the cutting jet achieves a higher velocity in a deeper material region than in the upper region during drilling or milling. This leads to velocity-dependent friction losses that pull the cutting jet back and cause a backward displacement of the cutting front.
Metallurgical Relevance & Welding Risks
Trailing can cause uneven material removal, resulting in incomplete drilling or milling and potential material waste. In welding, it can lead to uneven heat distribution and thus different microstructures and mechanical properties in different areas of the weld, posing risks to toughness and behavior under load.
Workshop Practice & Instructions
To minimize trailing, maintain a constant speed during drilling or milling. For deeper holes, it may help to enlarge the drill spindle cylinder or piston to reduce speed in the deeper area. When welding, ensure even heat distribution through proper welding parameters and correct cooling.