The blanks, or cores, are then cast at specialized foundries. The big question among cam makers at this stage is: which material is best suited for the valvetrain the cam is going into? In the Honda world, generally speaking there are 2 types of valve trains:
Ones where the rocker arms are the follower or sliding variety (where the cam slides along a pad on the rocker arm), like in B-, H-, and D-series engines.
Ones where the arms have rollers, or roller rockers, as in the heads of F20/22s and K-series mills
Each type of valvetrain requires cams made from different material, based largely on wear resistance and suitability of manufacturing for the projected volumes. Depending on application and whom you talk to, blanks will generally be either some form of chilled cast iron, steel billet, or ductile iron alloy. The performance of each material can further be improved by adding or subtracting certain component elements found in the material alloy and also through optimizing the heat treatment parameters.
First, the journals are ground. Then the camshafts are "rough" ground and ultimately, "finish" ground. Different stones at differing speeds are utilized depending on the stage or material being ground. Traditionally, lobe profile grinding requires using a cam lobe master that is plugged into a cam-grinding machine. A follower mechanism traces the master as the grinding wheel grinds the exact profile of the master onto an un-ground cam, like copying a key. Skunk2 uses CNC master-less cam grinding machines that grind cam profiles directly from the computer generated design data. When compared to traditional cam grinding, CNC grinding is much quicker, more accurate, and eliminates human error from the grinding process. Skunk2 makes a point to use CBN (cubic boron nitride) grinding wheels for superior accuracy and surface finish.
To reduce mass and provide passageways for the oil to penetrate the shaft (for cooling) in certain applications, some manufacturers, like Skunk2, use as-cast or rifle-drilled hollow cams.
Finally, each cam is checked for straightness, and profiles for accuracy. Then, in many cases, they receive a final polish and some form of corrosion resistant finish.