Assertion: lead pencil's lead | /r/HasProperty | extruded within the plastic casing
Facets:
value: to make a continuous plastic pencil
type: PURPOSE
Source sentences:
text: I worked on the composition of the materials for the pencil casing, which had to be as stiff and sharpenable as its wooden brethren, and Richard Merrill, Bob Eller, and Arthur Drennan worked on developing a co-extrusion process wherein a “plastic lead” could be extruded within the plastic casing to make a continuous plastic pencil.