A method may include thermally joining at least one of a non-round functional component to a shaft and a cam to a camshaft, elastically compressing the functional component during introduction of a round through-opening, and creating a through-opening which is not round when the functional component is unstressed and at least minimizes an asymmetrical deformation of the shaft after the thermal joining of the functional component to the shaft.

An exemplary camshaft for a high pressure common rail oil pump and a manufacturing method thereof is provided. The method achieves interference assembly between the mandrel and cam piece, and satisfies anti-rotating torque of the cam piece relative to the mandrel while ensuring the surface hardness of the cam piece. The camshaft includes a mandrel and a cam piece arranged on the mandrel. The anti-rotating torque of the cam piece relative to the mandrel is at least 500 NM after the cam piece and the mandrel are connected by interference fit by hot charge practice. Surface hardness of the cam piece 1 is at least HRC58. The method includes performing interference assembly of the cam piece and the mandrel while performing quenching heat treatment on the cam piece, then quickly cooling the cam piece equipped with the mandrel at the cooling stage during the quenching heat treatment.