a godet for guiding and heating an advancing yarn , which includes a shaft mounted for rotation about its axis , and a casing coaxially and releasably mounted to the shaft . an induction coil heating system is fixedly mounted between the shaft and the outer wall of the casing , and the heating system includes a tubular core having a plurality of induction coils mounted thereon . a plurality of annular ribs are positioned on the core and on the inside of the outer wall of the casing for providing an advantageous magnetic flux path between a core and casing .