Sometimes reaming is needed because drilling can't be done in one step. Reaming: Reaming is to increase accuracy. Boring: Boring is needed to increase accuracy. Drilling, reaming and reaming can all be done on ordinary machine tools. If a deep hole needs to be drilled, it must be drilled on a deep hole drilling and boring machine.

The main uses of gold:

Used as an international reserve. This is determined by the monetary commodity property of gold. Because of its excellent characteristics, gold has played a role as a currency in history, such as a measure of value, a means of circulation, a means of storage, a means of payment and a world currency. Since the decoupling of gold and the dollar in 1970s.

The gold function of money has also been weakened, but it still maintains a certain functions of money. Gold still occupies a very important position in the international reserves of many countries, including major western countries. Used as jewelry decoration. Gorgeous gold ornaments have always been a symbol of one's social status and wealth.

Application in industry and science and technology. Because of its unique good performance, gold has extremely high corrosion resistance stability; Good electrical and thermal conductivity, the nucleus of gold has a large effective cross section to capture neutrons; The reflectivity of infrared ray is close to 100%.