Abstract: A metallic shell extends in the direction of an axial line and has a threaded portion on its outer circumferential surface for threading engagement with a mounting hole of a combustion apparatus. A process of manufacturing the metallic shell includes a step of forming a metallic shell tubular intermediate having the first tubular portion and the second tubular portion and a rolling step of forming the threaded portion on the metallic shell tubular intermediate. In the rolling step, a bearing member is inserted into the metallic shell tubular intermediate for nipping the metallic shell tubular intermediate in cooperation with working surfaces of the rolling dies, and rolling is performed simultaneously on at least the first tubular portion and the second tubular portion.

Abstract: A metallic shell extends in the direction of an axial line and has a threaded portion on its outer circumferential surface for threading engagement with a mounting hole of a combustion apparatus. A process of manufacturing the metallic shell includes a step of forming a metallic shell tubular intermediate having the first tubular portion and the second tubular portion and a rolling step of forming the threaded portion on the metallic shell tubular intermediate. In the rolling step, a bearing member is inserted into the metallic shell tubular intermediate for nipping the metallic shell tubular intermediate in cooperation with working surfaces of the rolling dies, and rolling is performed simultaneously on at least the first tubular portion and the second tubular portion.

Abstract: Provided are a cutting insert and a cutting tool, capable of maintaining cutting performance for a long time. The cutting insert has a cutting blade made of a ceramic including the base and the cutting blade integrated with each other, wherein the base has a first coefficient of thermal expansion larger than a second coefficient of thermal expansion that the cutting blade has; and a difference between the first coefficient and the second coefficient is from more than 0 ppm/K to not more than 3 ppm/K.