After the metal ring is heated, the inner hole increases or decreases

After the metal ring (cylinder) is heated, does the inner hole increase or decrease? What does it have to do with the size of the ring (tube)? When I was in middle school, there was a problem of thermal expansion and contraction on the physical test paper. The idea is that after the metal ring is heated, the ring hole shrinks due to thermal expansion of the ring body. The teacher said that the question was taken from a magazine that tutored students. After the internship in the workshop after attending the work, the worker's master told me that after the metal ring (cylinder) is heated, the hole must be enlarged. This is because they often use a static fit method - red sets.

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