In the past, various techniques have been employed to manufacture crankshafts for internal combustion engines wherein the crankshaft includes a plurality of open-ended, internal oil passages for supplying lubrication to the main engine bearing journals and the connecting rod bearing journals. One typical approach involves casting the crankshaft in a suitable mold and then drilling the lubrication passages in the cast crankshaft. Lubrication passages formed by drilling are limited to linear passages. Moreover, drilling of the lubrication passages produces metal chips and other debris that must be removed from the lubrication passages.
It has been proposed to cast a crankshaft having a plurality of individual metal tubes cast in-situ therein to form respective individual tubular oil lines in the crankshaft. In this manufacturing approach, the individual metal tubes are manually positioned and aligned in the mold cavity and held in aligned position by a plurality of chaplets or other similar mechanical positioning devices as metal is cast in the mold cavity. As a result, this manufacturing approach is labor intensive, time consuming, and therefore costly as well as prone to error in the positioning and aligning of the individual metal tubes in the mold cavity.