圈上泽大大等 Thread Form2,3 ·Coarse series >Most common >Recommended for ordinary applications >Especially where repeated insertions and removals of the screw are required,or >Where screw is threaded into softer material 31 圈上大峰 -P. Thread Form2,3 ·Fine threads >More resistant to loosening from vibrations than coarse threads >Because of their smaller lead angle >Used in applications that are subject to vibration. Used in automobiles aircraft Extra fine series threads >Used where wall thickness is limited >Their short threads are an advantage. 3231 Thread Form2,3 • Coarse series Most common Recommended for ordinary applications Especially where repeated insertions and removals of the screw are required, or Where screw is threaded into softer material 32 Thread Form2,3 • Fine threads More resistant to loosening from vibrations than coarse threads Because of their smaller lead angle Used in applications that are subject to vibration. = Used in automobiles = aircraft • Extra fine series threads Used where wall thickness is limited Their short threads are an advantage