Meaning
Vertical distance of the sharp protrusion extending from the edge of a cut foil provides a measurable indicator of slitting quality and tool condition. This dimension forms during the shearing process when the material undergoes tensile failure before the knife completes its travel through the thickness. In battery manufacturing, excessive shear burr height can lead to dangerous consequences like separator penetration or localized high points of heat.
Measuring this feature ensures that foil processing remains within tight safety margins. High burrs typically indicate that the cutting clearance is too wide or the tools have become dull through use.
Measurement Process
Accurate values are obtained using a non contact profilometer or an industrial optical microscope focused on the profile. The distance from the base foil surface to the highest peak of the protrusion is recorded in microns. Values are checked at regular intervals along the length of the web to ensure uniformity.
A stable process produces values that stay consistently below ten percent of the total foil thickness. If numbers start to climb, the operator checks the lateral alignment of the rotary knives.
Geometric Impact
Formation of a large lip creates a mechanical hazard during the winding of cylindrical cells. When foils are tightly wound, high points can exert enough localized pressure to wear through insulating layers over several hundred charge cycles. Shear burr height also affects how active materials sit on the edge of the foil during the coating stage.
Coating consistency is harder to maintain when the foil has an irregular profile near the edge. Reducing this height simplifies the downstream assembly tasks.
Tool Maintenance
Knife replacement intervals are often dictated strictly by the measured increase in this dimension over time. As the cutting edge of aisi d2 tools rounds off, the material must stretch further before it shears apart. This extra stretching is what converts directly into added shear burr height on the final electrode.
Precise setting of knife overlap and speed can minimize this deformation even as tools age. Production managers use the trend of this metric to predict when the next grinding session is needed. Steady values indicate a well controlled manufacturing environment with proper tension and tool choices.
