Broken Cutting Tool Failure Analysis

California failure analysis expert performs examines a failed cutting tool. In this case the cutting tool consisted of a carbide cutting tip brazed to a mild steel "post". The failure of the post initiated as a fatigue crack at a grinding mark where the post was shaped to accept the carbide cutting tip. The final failure ended as a 45° bending overload. The failure was caused by high machining forces caused by the absence of lubricant. The upper left photomicrograph is an overviewof the fracture surface. It shows the two phases of the crack. Upper right shows the grinding mark where the fracture initiated.