Assertion: compressor's piston | /r/MadeOf | aluminum
Facets:
value: typically
type: DEGREE
value: usually
type: TEMPORAL
Source sentences:
text: The piston is usually made of a lightweight material such as aluminum or from cast iron or steel with a hollow center for weight reduction.
text: The piston will typically be made of aluminum alloy, while several bearings will be of white metal construction.