Plastic date wheel - for a calendar watch, injection moulded in polyacetal resin and heat treated

摘要

The very thin disc is injection moulded in a metal mould. The synthetic resin, one piece disc is provided with a peripheral circular border of required depth and width and the disc heat treated without being enclosed. The rim is then cut off and the disc again heat treated by placing between two polished metal plates loaded with a specific weight. Pref. the disc is mfd. in polyacetal resin.