mandrel
noun
man·drel ˈman-drəl 
variants or less commonly mandril
1
a
: a usually tapered or cylindrical axle, spindle, or arbor inserted into a hole in a piece of work to support it during machining
b
: a metal bar that serves as a core around which material (such as metal) may be cast, molded, forged, bent, or otherwise shaped
2
: the shaft and bearings on which a tool (such as a circular saw) is mounted
Example Sentences
Recent Examples on the Web The resin infuses the strands before they are applied to the mandrel. 
Joe Pappalardo, Popular Mechanics, 4 Apr. 2018 This appears to be a mandrel, or mold, around which carbon fiber is wound for the main body of the spaceship, or BFS. Eric Berger, Ars Technica, 9 Apr. 2018
Joe Pappalardo, Popular Mechanics, 4 Apr. 2018 This appears to be a mandrel, or mold, around which carbon fiber is wound for the main body of the spaceship, or BFS. Eric Berger, Ars Technica, 9 Apr. 2018 Word History
Etymology
Medieval Latin maundrellus, probably ultimately from Old Occitan mandre kingpin
First Known Use
1554, in the meaning defined at sense 1a
Medical Definition
mandrel
noun
man·drel
variants also mandril
ˈman-drəl
: the shaft and bearings on which a tool (as a dental grinding disk) is mounted