Failure Analysis of a Fractured Saw Blade Carbide Tip

Abstract

A mechanical and metallurgical analysis was performed on a 10-inch circular saw blade involved in a table saw incident in which a fragment of a carbide tip from the saw blade struck an individual in the eye. This individual claimed the saw blade had never previously been used. Examination of the carbide tip fragment revealed yellow paint on the fracture surface indicating a preexisting crack was present during the saw blade assembly process. Chemical analyses indicated that the residue found on the saw blade was consistent with chipboard (OSB). Exemplar testing found similar wear patterns between the subject saw blade and an exemplar used to cut chipboard. Stress analysis of a saw blade tip indicated the stresses generated due to blade rotation alone would not be sufficient to cause fracture or separation of a carbide tip even if the carbide tip contained a preexisting crack. It was concluded that the carbide tip likely fractured and separated from the saw blade due to a preexisting crack in the carbide tip which grew from impact with a hard object during cutting operation.