A burr is a slight draw of material. It occurs on the bottom side as a result of separating material during perforating and shearing, if applicable. If roller leveled, hole burrs may end up being pushed back into their hole during roller leveling, causing the holes to look less clean. Shear burrs, unless otherwise specified, may occur on the opposite side of hole burrs due to production methods.
Burr height is determined by taking the difference of the measurement of the thickness of the material with and without the burr. These measurements should be taken reasonably close to each other so that they are not influenced by any variation in the thickness of the material. The following are acceptable burr heights under normal perforating & shearing conditions.
|Burr Height (Max.)|
|Diamond Standard||Diamond Superior|
|Material Thickness||Hole and Shear||Hole||Shear|
|30GA to 24GA||.003"||.003"||.003"|
|24GA to 16GA||.005"||.003"||.005"|
|16GA to 1/8"||.006"||.003"||.005"|
|1/8" to 1/4"||.008"||.003"||.005"|