Polyarolamino named nylon, has strength, toughness, wear resistance, corrosion resistance, vibration absorber, and good self-lubrication, formability, and the friction coefficient of small, non-toxic and tasteless.But the value of creep is larger, low thermal conductivity.(about metals'1/100, high water absorption, shrinkable forming large, can be used are pa6, pa12 and pa11. Pa6 is more rigidity than pa12, and the pa12 is more soft.