| 摘要 |
The spools are made with a metal disc, as well as a non-metal (pref. plastic) disc at each end. The metal disc is preferably fitted to the spool's metal core tube, which is burred over to retain it. The outer edge of the metal disc is bent round, and the edge then rolled, so reinforcing rim round the plastic.The spools are used in spinning machines, whose high speeds cause the plastic flanges to disintegrate, under centrifugal force.
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