We have to keep in our minds and not forget the expansion of metal when we build a very long metal bridge too.

Coefficient of linear expansion of metal and density of liquid are measured by the experiment device which is composed of AC bridge and Joly spring balance.

My company mainly manages the bolt, the nut, the spring nut, the bolt, the gasket, the tooth stick, the expansion of metal screw, the heterogeneous pressing part, non-tender, hardware tool and so on.